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)

UNITED STATES DEPARTMENT OF THE INTERIOR

BUREAU OF RECLAMATION

HYDRAULIC MODEL STUDIES OF THE

AZOTEA TUNNEL INLET JUNCTION

SAN JUAN-CHAMA PROJECT, COLORADO

Report No. Hyd-551

Hydraulics Branch DIVISION OF RESEARCH

OFFICE OF CHIEF ENGINEER DENVER, COLORADO

December 17, 1965

The information contained in this report may not be used in any publication. advertising. or other promotion in such a manner as to constitute an endorsement by the United States Government or the Bureau of Reclamation. either explicit or implicit. of any material, product. device. or process that may be referred to in the report.

CONTENTS

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Purpose ............................................ . 1

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Acknowledgment. . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Introduction .................................. ·. . . . . . . . 2

The Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

The Investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Test Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Test Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Loss Coefficients. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Design A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Effects of Modifications to Design A. . . . . . . . . . . . . . . 5

Design B .................... 0 • • • • • • • • • • • • • • • • • • 6

Recommended Design..................... . . . . . . . 6

Flow Conditions with the Recommended Design. . . . . 7

Water Depths in Canal and Junction . . . . . . . . . . . . . . . 7

Prediction of Energy Losses through Similar Junctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Example of Head Loss Computations ................ .

Separation of Losses through the Structure .......... .

Prototype Design •••O••••••••••••••••••••••••••••••

i

8

9

10

CONTENTS- -Continued

Location Map, San Juan-Chama Project

Figure

1

Location Map, Azotea Tunnel . . . . . . . . . . . . . . . . . . . . . . . . . 2

Schematic of Diversion Dam and Relationship to Junction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ·3

Preliminary Design Configurations . . . . . . . . . . . . . . . . . . . . 4

Model Layout - Design A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1:12 Scale Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Probes for Total Head and Velocity Measurements . . . . . . 7

Flow Depths at Tunnel Measuring Station. . . . . . . . . . . . . . . 8

Loss Coefficients - Design A

Loss Coefficients - Design B

9

10

Flow With and Without Bearing Wall - Design A . . . . . . . . 11

Flow Conditions and Inlet Depth to Tunnel Transition . . . . 12

Flow Depths in Feeder Canal . . . . . . . . . . . . . . . . . . . . . . . . . 13

Final Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Appendix

Control Section Definition Sketch - Design A,

35

Appendix Figure

No Modifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Comparison of Computed Loss Curve with Experimental Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

ii

ABSTRACT

Hydraulic model studies were performed on a 1: 12 scale model of the .Azotea Tunnel Inlet Junction to find a configuration which would minimize head losses through the junction, to determine critical dimensions of the structure, and to establish canal water depths. The purpose of the junction is to combine the flow from a feeder can~.1 with that from the Oso Tunnel inverted siphon and direct this combined flow into the Azotea Tunnel. The recommended design minimized head losses between the siphon and the tunnel by means of a bearing wall placed in the flow stream which accelerated the flow leaving the canal, thereby making the uniting flow velocities from the canal and the siphon almost equal. This significantly re­duced eddy formation and tended to eliminate retardation of the siphon flow. The bearing wall also reduces the span length of a roof over the inlet junction. The flow conditions ·with this config­uration were good over a large range of siphon, canal, and tunnel discharges. Fairly accurate estimates of losses through a system which is not geometrically similar to the Azotea inlet junction can be obtained by application of momentum and energy equations over two control sections. An example of this procedure is given in the appendix to the report.

Hyd-551 Falvey, H. T. HYDRAULIC MODEL STUDIES OF THE AZOTEA TUNNEL INLET JUNCTION, SAN JUAN-CHAMA PROJECT, COLORADO Bureau of Reclamation, Hydraulics Branch, Denver, 45 p, includ­ing 16 fig, 1 ref, append, November 1965

DESCRIPTORS- - hydraulics/ *model tests/ *hydraulic models/ *head losses/ *hydraulic structures/ canals/ siphons/ tunnels/ *water surface profiles/ open channel flow/ inlets/ velocity/ coefficients/ momentum/ discharges IDENTIFIERS-- Azotea Tunnel, Colo/ San Juan-Chama Proj, Colo/ flow junctions

iii

UNITED STATES DEPARTMENT OF THE INTERIOR

BUREAU OF RECLAMATION

Office of Chief Engineer Division of Research Hydraulics Branch Denver, Colorado December 17, 1965

Report No. Hyd-551 Author: H. T. Falvey Checked by: W. P. Simmons Reviewed by: W. E. Wagner Submitted by: H. M. Martin

HYDRAULIC MODEL STUDIES OF THE AZOTEA TUNNEL INLET JUNCTION

SAN JUAN-CHAMA PROJECT, COLORADO

PURPOSE

A model study of the Azotea Tunnel Inlet Junction was conducted to develop a configuration which would minimize the loss between the siphon and the canal, to accurately determine critical dimensions of the junction, and to obtain information to establish the invert elevation for a measuring flume in the feeder canal.

CONCLUSIONS

1. Design A, which provided a straight flow path from the siphon barrel to the tunnel, produced lower losses between the siphon and tunnel than Design B, which required the siphon flow to turn through an angle of 15° (Figure 4).

2. Minimum losses between the siphon and the tunnel were obtained with Design A having a bearing wall 12 feet long placed between the siphon and the canal at an angle of 7-1 / 2° relative to the tunnel center­line (the recommended design) (Figure 9E).

3. The maximum water depth in the junction was 11. 4 feet with the recommended design.

4. Design B produced lower losses between the canal and the siphon than Design A which required the flow to be turned through 30° in­stead of only through 15° as in Design B (Figure 1 O).

5. A method for estimating the losses through similar junction con­figurations is described.

ACKNOWLEDGMENT

The studies described in this report were accomplished through cooperation between the Hydraulics Branch, Division of Research, and the Canals and Tunnels Section, Canals Branch, Division of Design. Model photography was by W. M. Batts and F. B. Slote, Office Services Branch.

INTRODUCTION

The San Juan-Chama Project is a participating project of the Colo­rado River Storage Project and will make possible the diversion of about 110, 000 acre-feet annually from the upper tributaries of the San Juan River in the Upper Colorado River Basin, through the Con­tinental Divide, into the Rio Grande Basin in New Mexico {Figure 1). The diverted water will provide an irrigation water supply to the land in the Rio Grande Basin and serve as a supplemental water supply for the Middle Rio Grande Conservancy District.

The project's diversion facilities will consist of three concrete diversion dams, one on the Rio Blanco, one on the Little Navajo River, and one on the Navajo River; feeder canals from the head­works of the diversion dams to the tunnel inlet structures; and the Blanco and the Oso Tunnels which collect the diverted water and pass it under the Continental Divide through the Azotea Tunnel {Figure 2).

The inlet junction structure to the Azotea Tunnel serves to combine the flow brought by the feeder canal from the diversion dam on the Navajo River with the flow coming from the Oso Tunnel {Figure 3). The inlet junction structure consists of a transition from the Oso Tunnel inverted siphon, the end of the feeder canal, a junction com­bining these two flow passages, and a transition into th~ Azotea Tunnel {Figure 4).

A model study of the tunnel inlet structure was necessary to develop a junction configuration which would minimize the losses between the siphon and the tunnel, as well as to investigate the combined flow conditions. In addition, the model study was used to obtain canal water depths. Knowledge of the canal depths was necessary so that the invert of a measuring flume in the feeder canal could be placed sufficiently high to prevent backflow into the Navajo River during low river stages.

Model tests were performed on two basic designs. In Design A, water from the siphon passed in a straight line through the junction and into the tunnel (Figure 4A). In Design B, the water was turned

2

through a horizontal angle of 15° before entering the tunnel (Figure 4B). In both cases, the included angle between the canal and the siphon was maintained at 30°.

Depending upon the quantity of upstream rainfall and the downstream water commitments, discharge can vary from zero to a maximum of 550 cfs (cubic feet per second) through the siphon and from zero to a maximum of 65 cfs through the feeder canal. The maximum com­bined flow in the Azotea Tunnel is limited to 950 cfs.

THE MODEL

The studies were conducted on a 1: 12 scale model. Included in the model were about 20 diameters of siphon piping, the siphon transi­tion, a length of diversion canal equivalent to 72 feet of prototype canal, the junction, a transition from the junction to the tunnel, and about 13 diameters 9f circular tunnel downstream from the junction (Figure 5). Although the contractor has the option of constructing either a circular or a horseshoe tunnel, only the circular tunnel was tested in the model (Figure 14).

Discharges through the siphon were measured with calibrated Ven­turi meters located permanently in the laboratory. The discharge through the canal was measured with a portable Orifice-Venturi meter which was placed about 22 pipe diameters downstream from a portable pump and about 30 pipe diameters upstream from the head box which led into the canal. Swirl from the portable pump was minimized through the use of a flow straightener which con­sisted of parallel plates about 3 feet long that were welded to the inside of the 8-inch-diameter pipe immediately downstream from the pump. The water depth or piezometric head was determined in the canal, siphon, and tunnel by connecting stilling wells to pie­zometer stations in these sections and by measuring the depth of water in each of three stilling wells with a point gage (Figures 4, 5, and 6). Velocity traverses at the tunnel and the canal measuring stations were made with a boundary-layer-type, total head tube. At the siphon measuring station a three-hole cylindrical probe was utilized (Figure 7).

THE INVESTIGATION

Test Procedures

The testing was begun with Design A and a tailwater depth of 8. 78 feet (prototype) at the tunnel measuring station. This depth corresponded to that which was computed to occur at the maximum tunnel discharge

3

of 950 cfs in a circular tunnel (Figure 3). The ratio of the flow rate in the canal to the- flow rate in the siphon was varied between 0 and 1. 0 in increments of about O. 2. For each increment, the combined flow was adjusted to total 950 cfs and then the piezometric elevation at each of the three measuring stations was read. This procedure was repeated with various modifications in the junction structure until one was found which resulted in the minimum head loss between the siphon and the tunnel. For this optimum condition, the increments were repeated for a combined flow rate of 475 cfs in the tunnel. The testing with Design B was begun in a simiiar manner; however, it was quickly seen that the addition of walls, etc., would neither decrease the losses between the siphon and the tunnel nor improve the flow conditions. Therefore, the complete range of loss values was obtained for the original configuration only.

Test Results

Loss Coefficients. --The loss coefficients for Designs A and B are presented in Figures 9 and 10, which are plots of s versus a ,

where s1 = head loss coefficient between the canal and the tunnel

s2 = head loss coefficient between the siphon and the tunnel

a = ratio of flow rate in canal to total combined flow rate in tunnel.

The coefficients are defined by Bernoulli's Equation, when written between the various points in question, as:

a. Canal to tunnel

(y2 p ) -+-+Z = 2g 1 canal

(y2 p ) cv2) -+-+z +e -· 2g 7 tunnel 1 2g tunnel

b. Siphon to tunnel

( 2 ) ( 2 P ). (v2\ v +f+z = L+-+z +s -).,_ 2g 1 siphon 2g 7 tunnel 2 2g tunnel

Actually, the velocity head terms in these energy equations should be multiplied by a kinetic energy correction factor which accounts for the nonuniform velocity distribution. The correction factors for the siphon,canal, and tunnel were measured in the model and amounted to 1. 020, 1. 014, 1. 024, respectively. The siphon factor was determined with

4

950 cfs in the siphon and no flow through the canal; the canal and tunnel factors were determined with 950 cfs in the canal and no flow through the siphon. Since these values were so close to 1. 000, and since their inclusion in the equations would add an unwarranted re­finement to the measured head loss values, all were assumed equal to unity.

The value a: is a dimensionless flow parameter, and is defined as

a= Qcanal

Qtunnel

In all loss determinations, the tunnel discharge is 950 cfs unless otherwise noted. Since Qtunnel = Qcanal + Qsiphon, the dimensionless flow parameter can also be expressed as

a= 1 Qsiphon - Qtunnel

For the Azotea Tunnel Inlet Junction the maximum flow rate-s are Qtunnel = 950 cfs, Qsiphon = 550 cfs, and Qcanal = 650 cfs. These values correspond to a range of a: = 0. 421 to a = 0. 684 when the tunnel is flowing at maximum capacity. The range a: = 0 to a = 1. 0 was tested in order to more accurately determine the shap~ of the loss curve, and to generalize the results for broader application. In the following discussions, the remarks are limited to the range of a: values between 0. 421 and 0. 684.

Design A. --The original design contained no appurtenances within the junction box and the only streamlining consisted of a rounded corner at the intersection of the left canal wall with the tunnel inlet (Figure 4A). The loss coefficients obtained with this configuration were used as an arbitrary reference upon which to evaluate the effects of modifications and the performance of other designs (Figure 9A).

Effects of Modifications to Design A. - -The first modification made to Design A was to replace the curve at the intersection of the left wall of the canal and the tunnel with a sharp corner to determine whether this simplification in construction would be detrimental so far as the hydraulic losses are concerned. The sharp corner created a distinct zone of separation at the inlet to the tunnel transition which resulted in increased losses from the siphon to the tunnel and from the canal to the tunnel (Figure 9A).

5

It was anticipated that a roof would be placed· over the inlet junction. · To keep the spans within tolerable limits, some type of supporting member in the flow stream was deemed necessary. The second mod­ification consisted of a 1-foot 4-inch diameter post located within the junction (Figure 9B). The intersection between the canal and siphon wall was rounded with a 9-inch radius. The losses with the post were much greater than with the original design because of flow separation behind the post.

The third modification consisted of a bearing wall 12 feet O inch long (Figure 9C). The length of wall was chosen for structural reasons and consequently no other lengths were tested. This wall tended to slightly increase the loss between the canal and the tunnel because the wall acts as a restriction to the canal flow. However, the loss between the si­phon and the tunnel was substantially decreased. The effect of the wall wa·s to .accelerate the flow leaving the canal, thereby making the flow velocities from the canal and the siphon almost equal where they unite. Making the flow velocities approximately equal s-ignificantly reduces the eddy formation in the junction and tends to eliminate the retarda­tion of the siphon flow. These effects account for the reduction in loss between the siphon and the tunnel with a bearing wall. A wall placed at 7-112° relative to the tunnel centerline resulted in the lowest losses for this type of modification (Figure 9C).

Consideration was given to the possibility that a wall whose top was sloped in the downstream direction might provide a better matching of the two flows entering the junction. The tests showed that the oppo­site occurred, and the sloped wall produced higher losses (Figure 9D).

Design B. --Tests with this design indicated an increase in the loss coefficient between the siphon and the tunnel with respect to the un­modified Design A (Figure 10). Spot checks with a wall such as that used in Design A indicated a further increase in this loss coefficient. Therefore, this design was rejected even though a decrease in the loss coefficient between the canal and t);le tunnel was noted.

Recommended Design. - -The optimum design from the standpoint of reducing the losses between the siphon and the tunnel, is Design A with a 12-foot-long bearing wall which is placed at an angle of 7-112° relative to the tunnel centerline and whose top is horizontal. This design was also tested with one-half of maximum discharge, or 475 cfs, in the tunnel to determine the dependence of the loss co­efficients on the flow rate (Figure 9E). This dependence is due to the changes in Manning's "n" and to changes in the momentum cor­·rection factor ~ as the depth of flow (or flow rate) varies.

6

Flow Conditions with the Recommended Design. --The reason for the decrease in loss between the siphon and the tunnel when a bearing wall was inserted into the junction was explained in a previous sec­tion. In general, the flow conditions were very good with a bearing wall placed at 7-1/2° to the tunnel centerline. A very graphic pic­ture of the improved flow conditions due to the wall can be obtained by comparing the flow conditions in Figure 11. The water surface throughout the junction and tunnel inlet transition was relatively smooth. No large standing waves were observed in the downstream section of tunnel although a tendency for their formation was noted in the velocity traverse at the tunnel measuring station. The zone of separation at the end of the bearing wall might be decreased some­what by rounding the end of the wall. Although tests we;re not made with the end of the wall rounded, it is reasonable to expect that no significant changes in the water surface roughness or loss coeffi­cients will be observed by makin.g this change.

A slight tendency toward separation and drawdown of the water sur­face was noted at the curved portion of the left wall of the junction where the canal joins tunnel inlet (Figure 12). This drawdown could be reduced by using a curve whose radius was larger than the 18-foot 8-inch radius used in the studies. The amount of drawdown and sep­aration is not large enough to cause concern, but it indicates that a smaller radius should not be used.

Water Depths in Canal and Junction. - -Th~ depth of water in the canal at the station from which the losses were determined can be computed from

_ + tunnel 1 _______ AZ Q2 [(1 + s ) a 2 ]

Y'canal - 7tunnel 2g A2 4(by-)2 tunnel canal

where y = flow depth at station (ft)

Q = discharge in tunnel (ft3 / sec)

f1 = loss coefficient between canal and tunnel

A = cross-sectional area of the flowing water in the tunnel (ft2)

a = flow ratio

b = one-half canal width (ft)

AZ = difference in invert elevation between canal station and tunnel station (ft).

7

The canal depth has been computed on this basis for the junction with a bearing wall at 7-1 / 2° to the tunnel centerline for the max­imum discharge in the tunnel (Figure 13). This canal depth can also be used as the depth at the siphon outlet for the determination of free board requirements.

The depth at the inlet to the tunnel transition can be obtained ap­proximately by solving the third degree equation

3 - [~ • b + :i.( g!) ] Y' Y' inlet tunnel 2 i\. A /2unnel inlet

whe·re b2 = one-half width of inlet transition.

A discussion of the assumptions used in deriving the equation is presented in the Appendix. With a discharge of 950 cfs in the Azotea Tunnel, the computation yields a depth of 9. 8 feet. This agrees fa­vorably with depths obtained in the model (note flow depth at inlet to tunnel transition in the photographs in Figure 12).

Prediction of Energy -Losses through Similar Junctions

These results can be directly applied only to junctions which are geometrically similar to the Azotea Inlet ,Junction and whose dis­charges are related to the Azotea discharges by the length scale to the five-halves' power. Normally, such ideal conditions will not be encountered.

Fairly accurate estimates of losses through a system which is not geometrically similar to the Azotea Inlet Junction can be obtained by the application of momentum and energy equations over two con­trol sections. An example of this procedure is given in the Appendix.

Example of Head Loss Computations

The method for computing head loss through the junction is illu -strated by the following example:

Given: Qsiphon = 550 cfs

Qcanal = 400 cfs

Qtunnel = 950 cfs

Bearing wall at 7-1 /2° to tunnel centerline in junction Design A.

8

Find: {a) Head loss between canal and tunnel stations

(b) Head loss between siphon and tunnel stations.

Solution:

For this case 400 a= 950 = o.421

From Figure 9E the loss coefficients are found to be:

; 1 = 0.05, and ~2 = 0.25

The water depth in the tunnel with a discharge of 950 cfs is 8. 78 feet (Figure 8). Entering King's Handbook* with a d/D = 8. 78/10. 916 = 0. 804, one can obtain an expression for the flow area in a circular pipe. This value is Area/D2 = 0. 674 or A= 80. 32 ft2.

Thus the tunnel velocity is

V = ~ = ab:~2 = 11.83 ft/sec

and the veloctty head is y2 2g = 2.17 ft

The required head losses can now be computed.

(a) Head loss from canal to tunnel

h = ; c:\ = (0.05)(2.17) = 0.11 ft L 1 Aunnel

(b) Head loss from siphon to tunnel

Separation of Losses through the Structure

Separating the losses into individual components through the struc­ture was not attempted because a detailed knowledge of the turbulence intensities and velocity distributions through the structure would be

'!<King, H. W., Handbook of Hydraulics, McGraw-Hill Book Company, Inc., New York, 1954, p 7-41, Table 84

9

required. In addition, the total magnitude of the loss through the model is relatively small. Further division of this loss into indi­vidual losses would have resulted in questionable results since the experimental errors would have been large relative to the values being measured.

Prototype Design

The design of the fielg. structure has a slightly different configura­tion from that which was recommended, (Figure 14). The rectan­gular access box has been moved downstream to occupy a position between the junction and the tunnel inlet transition. This additional 20 feet of run will tend to result in a better velocity distribution and a slightly smoother water surface at the inlet to the transition. The radius on the left wall between the canal and the tunnel has been in­creased from 18 feet 8 inches to 20 feet 0 inch, and all sharp breaks at the exit of the siphon outlet transition have been rounded with cir­cular curves. These changes will result in slightly lower prototype losses than those predicted on the basis of model tests.

10

AZOTEA TUNNEL INLET JUNCTION

Location Map San Juan-Chama Project

11

Figure 1 Report Hyd 551

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702

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It_ Navajo River ... ..... .........

.... ,

FIGURE 3 REPORT HYD-551

AZOTEA TUNNEL INLET JUNCTION

· SCHEMATIC OF DIVERSION DAM AND RELATIONSHIP TO JUNCTION

15

70 2

"- Feeder conduit from Oso D version Dom {Rectangular)---

'-­', -------- 1' '-,

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t '

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PLAN OF JUNCTION BOX

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--+--- -- ___ j ________ _ I

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which losses were measured.

LONGITUDINAL SECTION

A. AZOTEA TUNNEL INLET JUNCTION DESIGN A

'-<1_ Azotea tunnel

\ ' '

<1_ Feeder conol from Oso Diversion Dom {Rectongulor)

~ -: ~_____,_______ 0 ---~ "----__

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---------------------

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----40' o" __________ ,_, __ ~-

FIGURE 4 REPORT HY0-551

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8. AZOTEA T U N N EL IN LET J U N C T IO N DESIGN B

AZOTEA TUNNEL INLET JUNCTION

PRELIMINARY DESIGN CONFIGURATIONS

: 12 SCALE MODEL

17

702

Valve to control canal flow

Rack baffle-----

/,--Head box

Diversion canal

Siphan--,,

,/

'- ::::<,:;tc,::::-,,, 11 Tf; H/~ I 1--..:::..:::::: I I I ' f ,;

,---Return to channel /,-,,:,_- from tunnel

FIGURE 5 REPORt HYO -551

;Y 1001 -------'.'--.+- --;:,-- -~-- ------IE'\--+--+- -~-~--+---+--- , ---- -:>------+---- ----l-1---1--~e----

Valve ta control siphon flow rate--,,

B

! r-'--Fram laboratory chase

Approximately 22 feet

o_

P L A N

Siphon measuring station-/

Tunnel inlet transition,

1

I j ~

.....,_ . = . ---------;: . o : :a· P o : o_ . C?

ELEVATION

/' ,

Flow straightener-/

Tunnel measuring station-

-;,,.-

.....,_

,-Tail gate ta control water surface ( elevation 1n tunnel

- ' '1-.,l,_,,;,,

-O· 0 0

t

t

AZOTEA TUNNEL INLET JUNCTION

MODEL LAYOUT, DESIGN A

: 12 SCALE MODEL

19

1400

1200

0 1000 w (/)

.......

i--= LL.

::; <.:>

w (!) Q: <( :I: <.:> (/)

0

...J w z z ::> I-

702

800

600

400

200

v--

0 2.0

FIGURE 8 REPORT HYD-551

Q= 950 ------

/v Based on a Manning's "n" v~

of 0.013 and a slope of 0.002139 in a circular / tunnel,, / ',

' ' V ....

' .... / ' '

~

y /

V

__ / ,,

_/ /

3.0 4.0 5.0 6.0 7.0

FLOW DEPTH IN TUNNEL - FEET

AZOTEA TUNNEL INLET JUNCTION

FLOW DEPTHS AT TUNNEL MEASURING STATION

23

8.0

~ ~ +-a> I l'-1

. I CX) I II y "C

9.0

Figure 7 Report No. Hyd-551

Boundary-layer Total-head Probe (left) and Three-hole Cylindrical Velocity Probe (right)

AZOTEA TUNNEL INLET JUNCTION

Probes for Total Head and Velocity Measurements

22

Figure 6 Report No. Hyd-551

Design A Design B

Stilling Wells for Piezometric Head Measurement

AZOTEA TUNNEL INLET JUNCTION

1 :12 Scale Models

21

"'

·-............ I

'7-~ /,l '--.__--..... a

-' "'

3(Jo

2'-6"­Siphon -->--

. ~

-'< "' - '

f? ,--With radius

:-----;:­,--,:- :

Corner without ~ radius---------·' -~,~,-----~/\

' ' ·,a ·,a

' ' .-<---- --- 40'-o"------ ,_;

,_o ~---~---~---~------~

0.8 --------+----1----+-----1

,,J: .... ! 2 {Siphon ta tunnel)

o,P, '\, I I

/•-Without rodius-r,

0.4 \

Tunnel -->-

"I • ..c § 0.2 w,th 1s'-s"

(Preliminary ,., >

"' of---t--,,,~--+---t-----1 1'

1/' -0.21---,U.----+---I----+----,

(Canal to tunnel)

- 0.4 r.,"' ---f--

-0.6 0 0.2 0.4 0.6 0.8 1.0

CI= ~ Q tunnel

A, EFFECT OF A SHARP CORNER BETWEEN THE TUNNEL ANO THE CANAL ON

THE LOSS COEFFICIENTS

950 CFS IN TUNNEL

-,

Co -....::.::_01 ,,._

~ --------, '

'.,-6-'1?- ~ 39~ I 1·_4"Dio Post

»'- - Tuneel v . --@---;r -->-~ ''----~ ' r-----15-s - ~ __ Siphon r ---- -~ -->-- I

. N

" "I • LC ~

"" >

vJ

,o~---~---~---~---~--~

0.8

~_:y~-{2 (Siphon to tunnel)

0.6 '"',

With o'-9" radius and 1'-4" dio post .,

0.41----+~-~- j - __ ...;.... -........ , ... , _,-'\

021 I ;,~1 - -- I

1/' 1/'

to tunnel)

-06,~---'----~------'----o 0.2 0.4 0.6 0.8 1.0

CI= Q eonol Q tunnel

B, EFFECT OF A CIRCULAR BEARING POST ON THE LOSS COEFFICIENTS

950 CFS IN TUNNEL

--, ~Of

,,._~

~ 'o :-<---12-0--->-;-.2._ ~- ! : , Tunnel . ,r----~'- i--~~ ----------------==t={ ->-

s;phon ~ -~ 1°-,0 -->---r ,s

"tt ~ ' ~ >

"-'

0,8 I

,, ,~--tz ( Siphon to tunnel I

0.6

0.4

0.2

: I"-,.. // i

' "' -

i-- _/ I'- " '-,,

' ~ -' --' /

' ' ' // ' < /

Woll 7'-30' to /0 ~ tunriel <t_--~: / '

I> ' 0 ' I/ ' I

' \ // \

-0.2 ,' 1--- ---.Wall 15" to \/~ _,,-\

-0.4

-Q_6

-a.a

-LO

-1.2

-1.40

tunnel !t_ ---I ,

I

/ / "-- J,-_ I --- --r- ...__l

1 [Canal to tunnel)

I

- -02 - -0,4 0,6

a=Qconol Q tunnel

- -0,8

I I

I

:o

C. EFFECT OF A BEARING WALL (NOT SLOPEO) ON

THE LOSS COEFFICIENTS

950 CFS IN TUNNEL

--~I

,,._~

-T -'

i

WITHOUT SLOPED TOP

SECTION

:-,~~~7 - I : '

f ~ : - I !. n

WITH SLOPED TOP

A-A

i' ::::::t ; i- '""""-_s;_p_h~;_ --1 -

"r £ ' ,, >

"-'

7°~30'

0.6~---~---~--~---~----,

' ~7l2 (Siphon to tunnel)

I j'.-:;1 041 1--'----t /,,--; 02 I I I ,i- ,XY I

0

fxi---wall 5' high at -0.2 downst,re_om end ,:·\ ' ,

and 12 high at . I upstream end---" \

I I ' I I

to tunnel) ,1 r I I

-06

-o.eo1---o"."2--~0"'_4c----=o".•---,,0_"9----,',o_

CI_ Q conal - Qturme1

D. EFFECT OF SLOPED BEARING WALL ON THE LOSS COEFFICIENTS

950 CFS IN TUNNEL

~ ,,,,,,' "', }

~Qo

FIGURE 9 REPORT HYD-!HII

f-<- --12'o'C ---'j __ 1 - ,

f s;pho: r-=---=y---~ -->-

Tunnel -->-

'" '::,_ "I • r; § "" >

.,_,

I ·1· '

7°-30

o~,-----,----,---,-----,----,

----'

--- 950 cfs in tunnel----

' / ,k-0.4 --~ ;

,- /

' - /

, ' "".'. 0.2 . / ,,,, 475 cfs m /, ,,.

tunnel-3/ /

' 0 , I

I \

I \

-~ \

-.-~."-t 1 {Canal to tunnel) \ \

-o.41-~-+----+--+--+--'"-'J /-~

I

I I

l 2 (Siphon to tunnel)--_J.....::---

-0.6 f-+--+----+-----,---+----1

-o.aol----,oc'-_2,----,0~_.;----co"• ___ o~."8----,',o

0 a _Q_,_o_oo_l Q tunnel

E. EFFECT OF TUNNEL DISCHARGE RATE ON THE LOSS COEFFICIENTS WITH A

BEARING WALL (NOT SLOPED)

AZOTEA TUNNEL INLET JUNCTION

LOSS COEFFICIENT, DESIGN A

I: 12 SCALE MODEL

25

702

1.0

0.8

0.6

0.4

0.2

"' C\I

" .J .; .c :§ 0

~ ...... >

VJI -0.2

-0.4

-0.8

-1.0 0 .2

' ' ='

FIGURE 10 REPORT HYD-551

Tunnel --->-- --

' ' I :<---------------- 401-0 11

-- -------- ···----->-l

,,A-~- l 2 ( Siphon to tunnel) ~,, I I

(Canal to tunnel)

.4 .6 .8 1.0

a= Q canal Q tunnel

AZOTEA TUNNEL INLET JUNCTION

LOSS COEFFICIENTS, DESIGN B

I: 12 SCALE MODEL

27

Figure 11 Report No. Hyd-551

A. Qcanal = 400 cfs; Qsiphon = 550 cfs; a= 0. 421 A. Qcanal = 400 cfs; Qsiphon = 550 cfs; a= 0. 421

B. Qcanal = 650 cfs; Qsiphon = 300 cfs; a= 0. 684 B. Qcanal = 650 cfs; Qsiphon = 300 cfs; a= 0. 684

Design A Design A with bearing wall 7-1 /2° to tunnel 't,

AZOTEA TUNNEL INLET JUNCTION

Flow With and Without Bearing Wall - Design A

950 cf s in Tunnel

1 :12 Scale Model

29

. Qcanal = 6 50 cf s

Qsiphon = 300 cfs

a = o. 684

AZOTEA TUNNEL INLET JUNCTION

Figure 12 Report No. Hyd-551

Flow Conditions and Inlet Depth to Tunnel Transition Design A with Bearing Wall at 15° to Tunnel

950 cfs in Tunnel

1: 12 Scale Model

31

FIGURE 13 REPORT HYD-551

I-w w IL.

...J <{

z <{ (.)

a: w 0 w w IL.

z

:c I-Q. w 0

a: w I-<{

3:

14

12

--10

/

8

6

4

2

0 0

; /

No modification /

I I I I I ·- --- ---I I ~ --'1-7 /

/ /

Woll (notsloped)7 1; 2° to tunnel <t,. "/

0.2 0.4 0.6 0.8

Q canal a=--­a tunnel

.l

1.0

AZOTEA TUNNEL INLET JUNCTION

FLOW DEPTHS IN FEEDER CANAL,950 CFS IN TUNNEL

FROM I: 12 SCALE MODEL

702

32

1.2

702

cL

Oso tunnel siphon 96" d10.-----,\

I I

-------

Round to rectangular transition --

~ ;-_:;.__ .-Feeder conduit from

' Oso Diversion Dom

", .

f''!, / ,1 ......... .....___

/ / ......... / f

a '/ "'­~ "'-

'Jo;,

---r­!

,--is;,o·s '\ "C\J

I -"._,___ ___ t_ __ i_, . --~-:-:r-1

l I

·o

----12 -o --------

Precost concrete cover-----.

/

/

/ /

/

I

29'-o"

"' 'o ,I 0

"'

o"-----

-:r ! !

0

I I

I

-----+~-------------~+-i

P L A N

Access box cover from precost concrete and steel grating--------,,

'! ·o

I -<O

I

i

0 O a O o.l__j

;;;_ I o. ;O

I I I I

+

,--El 7662.97 ,, ·o

·o I -,_,,

SECTION C-C

o· C

I I I I

-:::-1 51-0

11

Rectangular to circular transition------

\

,--El 7662 . 97

9:_I

I

I I I

,'

----- 32 1

'g

El. 7662. 87-----,,,

B r;,-

--1------1

I

I

•' I

-0

I I

__ i_ ____ _

L:­s

Azotea tunnel circular or horseshoe----

I I I

"' I -0

",\

£,' I

/ f

______ .,..,

_Jc

-S=-.002139

Fl GURE 14 REPORT HY0-551

IJ. .r ·,·c·

1

I .o,

.1·1

. q' I I I I

·o

ol -,;

·c I I

0 1. · · 6·.: .o · o/Li K----- -- --15'- 0 'c _______ ;,.;

SECTION A-A

SECTION B-B Circular Section

____ ,

o· /r-10'__ 7u

! 0

Ci-~ ..

SECTION B-B Horseshoe Section

AZOTEA TUNNEL INLET JUNCTION

FINAL DESIGN

33

A. p· ·P· E""TD' ·ix···.···.' - ··- . -~N-, < ·_

APPENDIX

The energy loss through structures, which are in general similar to that of the Azotea Inlet Junction, can be approximately d~termined through the proper application of the Energy and Momentum Equa­tions. The following example illustrates the method and compares the theoretical results with energy losses actually measured.

A sketch of the junction configuration and the control sections is given in Appendix Figure 1. For the purposes of this example only the loss between@ and @ will be investigated. Similar computa­tions could be performed to determine the loss between the siphon and the tunnel or the losses with other junction geometries.

The equations which follow are restricted by the following assumptions:

1. The flow depth across AB is the same as the flow depth across BC.

2. Friction forces through the junction are negligible.

3. The water depth at the inlet to the tunnel transition can be determined from

~-[Tp+g::~] where Y = depth

A= area

Q = discharge

g = acceleration of gravity

b = half width of rectangular section at transition inlet

The subscript refers to the station at which the quantities are measured.

This equation is obtained by writing the momentum balance between Section DE and F. To arrive at this expression one must assume:

37

a. The hydrostatic force in the tunnel plus the force of the transition on the water is equal to

i.,. -~·2b 2 P 2

b. The momentum correction factor is equal to 1. 0 for all combination of flows.

The problem might be stated:

Given: b1 = 7.50 ft; b 8 = 5.46 ft; y2 = 8. 78 ft; d8 = 8.o ft

Q2 = 950 cfs; tunnel dia = 10.92 ft

Find: Ypi yDB; YAB; YBc; Yi ; and the energy loss between (D and@for all combinations of the flow ratio a.

The depth at Y1 can be found by utilizing standard techniques for computing backwater curves. For instance the standard step method utilizing only one step gives

when

Yp = 9.21. ft

n = 0.013

The method is not outlined since typical examples can be found in most texts on fluid mechanics or open channel flow.

The second requirement is to find YDB . This can be done by a trial and error solution of the equation given in Assumption 3. After placing the given quantities into the equation and solving for Y DB , one obtains

The depth at AB or BC is found by equating the momentum in the direction of the tunnel centerline to the forces in the same direction over the volume which is outlined by dashed lines.

38

Across AB

The momentum entering the section is

f3AB • P • (l-a)2 • Q: • cos (17° -lJo•) 2 • b • d s s

where 13AB is the momentum correction factor at the section AB and is equal to

The force (acting downstream) on the section is

! • 2 b • ~ • 1 2 s AB

Across BC

The momentum entering the section is

f3BC • P • a2 • Q: • COS 30°

2 • bl. • Y'Bc

The force (acting downstream) on the section is

! • 2 b • cos 30° • 1 • ~ 2 l. BC

Across CD

Since no flow occurs across CD, the momentum is equal to zero.

The force (acting upstream) on the section is

( .,., + Y' )2 ! . 2 b • sin 60° • BC DE • 1 2 l. 2

39

Across DE

The momentum leaving the section is

f3 •P • Q2 DB 2

2 bs • Y'DB

The force (acting upstream) on the section is

The momentum and force along EA, in a direction parallel to the tunnel centerline, are equal to zero.

Thus, equating the momentum entering the control section plus the forces acting downstream with the momentum leaving the control section plus the forces acting upstream gives

f3 • P • (1 - a)2 • Q2 • cos (17° - 4o•) AB 2 + b . Y'2 • "/

2 • b 8 • d 8 s AB

f3BC • P • a2 • Q: • cos 30° + ------------ + bl . ~ . 1 . cos 30°

2 • b1 • Y'BC BC

b. • (y: + y ) 2 • 1 · sin 60° f3 • P · Q2 = ... BC DB +DB 2

2 • ba • yDB

+b ·r- ·1 a DB Equation (1)

Substitution of the given dimensions into this equation and solving gives the desired depth, yAB = Y'Bc . The only difficulty is encoun -tered in the selection of the f3 values. These are dependent upon the velocity distribution in the control sections and are found to have a significant effect on the solution of Equation (1). This strong dependence upon f3 has several far-reaching implications. First, it shows that the loss through the junction is dependent upon the ve­locity distributions in the canal, the siphon, and entrance to the tun­nel transition. If the distributions are significantly different from that which was produced in the model, significant variations in the loss coefficients can-be expected.

40

Secondly, the strong dependence upon ~ indicates that the loss through a compound structure cannot be determined by summing the individual losses, since each component of the compound struc­ture has an effect on the velocity distribution entering or leaving other components. Therefore, to determine the loss through com­pound structures, either prototype or model measurements are required; or the probable velocity distribution through the compound structure must be estimated.

In the model the following values for the momentum correction factor were obtained for Design A having no modifications

~AB= 1.03; ~BC= 1.06; ~2 = l.09

f3m was found to be equal to 1. 223 (1. 0 + . 103 o:) by solving Equa­

tion (1) for the ratios o: = 0 and a= 1. 0 when using depths deter­mined from the model.

Substitution of the ~ values and the prototype dimensions into Equation (1) will yield the following equation after dividing by -, and simplifying:

= 537.299 + 316.491(1 + 0.3600:) - 314.860(1 - a) 2

Solving this equation for yAB with various values of a gives

a 0 0.25 0.50 0.75 1.00

Ye 9.93 10.68 u.09 u.18 10.97

With Design No. 1 and the sharp corners on the wall between the tunnel and the canal, the momentum correction factors become:

The increase in the value of f3DE with the sharp corner reflects the increased loss which occurred with this modification (see Figure 8).

41

If the results of a model study are not available, the momentum cor­rection factors must be estimated. Reference 1 is a good source for obtaining values for established flow in canals and pipes. The values of f3DE obtained in this study provide guide lines for the estimation of the combined flow momentum factor downstream from a junction which is similar to the Azotea Tunnel Inlet Junction.

The depth Yi is obtained by standard backwater curve computations. However, the reach is so short and the velocities so low, that Yi can be assumed equal to YBc·

The energy loss between the canal and the tunnel can be determined from the computed quantities by writing Bernoulli's Equation between the two points. This is

v2 v2 v2 + ...!.+z +~+t ~+Z Yi 2g i = y 2 2g ~i 2g 2

Solving for sl and letting

Q2 v2 = A

2

one obtains

and

With A2 = 80. 75 ft2 and ;_ = Z2 the values of Si were deter­mined as:

a 0 0.25 0.50 0.75 1.00

s1 -o.465 -0.100 0.132 0.249 0.260

A plot of the curve as determined from these values and the ex­perimental points for the given junction configuration are given in Appendix Figure 2. All of the experimental points fall rather close to the computed curve with one exception. No explanation for this aberration could be found.

42

References

1. Streeter, V. L., Kinetic Energy and Momentum Correction Factors for Pipes and for Open Channels of Great Width, Civil Engineering, Vol. 12, n4, April 1942, pp 212-213 .

43

->- -

702

APPENDIX FIGURE I REPORT HYD-551

D I

I I E

AZOTEA TUNNEL INLET JUNCTION

CONTROL SECTION DEFINITION SKETCH

DESIGN A, NO MODIFICATIONS

45

® ->-

->-

APPENDIX FIGURE 2 REPORT HYD-551

702

0.3

0.2

0.1

Cl C\J

" .J Gi 0 .s= C C

Ni= >

II

-'v..fl -0.1 J ;--0.2

)

A~ ----z

-0.3

J -0.4 I

I I

-0.5 0 0.2

/ /

,..

/ /

/4

I I

? !.

.... _ ~ "'-Experimental --

---Computed

.

0.4 0.6

Q canal a=---0tunne1

4 - - -~

0.8 1.0

AZOTEA TUNNEL INLET JUNCTION

COMPARISON OF COMPUTED LOSS CURVE WITH EXPERIMENTAL DATA

DESIGN A, NO. MODIFICATIONS

46

7-1750 (10-64)

CONVERSION FACTORS-BRITISH TO METRIC UNITS OF MEASURllMENT

The t'olloring conversion t'actcn-s adopted ey the Bureau of' Reclamation are those published ey the .Amertcan Society t'cn­Test.ing and Materia1s (.ASTM Metric Practice Guide, JBn111127 1964) except that additiona1 t'actcn-s (*) OClllllllOncy used in the Bureau have been added. Furtber discussion of' definitions of' quantities and units is given on pages 10-11 of' the ASTM Metric Practice Guide.

The metric units and conversion t'actcn-s adopted ey the .AS'lM are based on the "Internationa1 &Ystem of' Units" (designated SI t'cn- &Ysteme Internationa1 d'Unites), t'ixed ey the Internationa1 Committee t'cn- Weights and Measures; this system is a1so knOWn as the Giorgi en- MIISA (meter-kilogram (mass)-second-ampere) system. This system has been adopted ey the Internationa1 Organization t'cn- standardization in ISO Recamnendation R-.'.31.

The metric tecbnica1 unit of' t'cn-ce is the kilogrsm-t'cn-ce; tbis is the t'cn-ce wbicb, when applied to a bod;Y having a mass of' 1 Jig, gives it an acceleration of' 9.80665 u,/sec/sec, the standard acceleration of' t'ree t'all toward the earth's center t'cn- sea level at 4' deg latitude. The metric unit of' t'cn-ce in SI units is the newton (N), wbicb is defined as that t'cn-ce wbicb, when applied to a bocl,y having a mass of' 1 kg, gives it an acceleration of' 1 u,/sec/sec. These units must be distinguished t'rom the (inconst.ant) local weight of' a bocl,y having a mass of' 1 Jig; that is, the weight of' a bocl,y is that t'cn-ce with wbicb a bocl,y is attracted to the !lBrth and is equal to the mass of' a bocl,y llllll.tiplied ey the acceleration due to gravity. However, because it is general practice to use "pound" rather than the tecbnically ccn-rect term "pound-t'cn-ce," the term "kilogram" (en- derived mass unit) has been used in tbis guide instead of' "kilogram­t'orce" in expressing the conversion t'actcn-s t'cn- t'cn-ces. The newton unit of' t'cn-ce will t'1nd increasing use, and is essentia1 in SI units.

~ QllAN'rITIES AND 11NITS OF SPACE

!mltil!!z: ~ To obtain

LENGTH

Mil •• 25 .4 c enctq > • • Micron Inches • 25.4 (exactq) •• • Millimeters

2. 54 ( exact:13' t • Cent:lmeters Feet •• 30 .48 ( exactq •.• • Centimeters

0 .3048 ( exact:13' )* • • • Mi!ters O .0003048 ( exactq )* • • Kilometers

Yards •••••• 0. 9144 ( exact:13') • • Mi!ters Miles (statute) 1,609.3" (exactly)* • • Mi!ters

· 1.609344 (exact!z:} • Kilometers

AREA

Square inches. 6.4516 (exactq) • • Square centimeters Square t'!let. 929.03 (exactq)* •• • Square centimeters

0.092903 (exact:13') • Square meters Square yards 0.8J6127 •• • Square meters Acres •••• 0.40469'S •• • Hectares

4,046.911 •••• • Square meters 0 .0040469M • • Square kilometers

Square ml.lea 2.58999 •• • Square kilometers

VOLUME

CUbic mcbes 16.J87]. •• • cubic centimeters CUbic t'eet • 0 .028Jl68 • • cubic meters CUbic ~s. 0.'764555 •• • CUbic meters

CAPACITY

n111d OU11Ces (u.s.) 29.5737 •• • cubic centimeters 29.5729 •• • Milliliters

Liquid pints (U.S.) 0.473179. • CUbic decimeters 0.473166. • Liters

Quarts (U.S.). 9,463.58 ••• • cubic centimeters

Gal.laDs (U.S.) 0.946358. • Liters

3,785.43* •• • CUbic centimeters 3.78543 • • CUbic decimeters 3.78'33 ••• • Liters 0.00378543* • • CUbic meters

Oal1aas (U .It•) 4.54609 • • CUbic decimeters 4.54596 • • Liters

Cubic t'eet • 28.3160. • Liters Cubic yards 764.55* • • Liters Acre-t'eet. 1,233.5* • cubic meters

• 1,233,500* • Liters

Mlllti.Pl:l,

Qraina (lh ,000 lb) , , , Troy ounces (480 grains) • Ounoes (avdp) , • , • • Pounds (avdp) • • • • • Short tons ( 2 ,ooo lb) •

Lang tana (21240 lb) :

Pounds per square inch

Pounds per square toot

Omlces per cubic inch , , Poullda per cubic toot , ,

T_t!l!!t ( lang) per cubic ia,f4'

Inoh-poomds.

Foot-pounds ,

Foot-pounds ~ izi.;h • Ol!noe-i!J.ol!e~ ...........

Feet par aeocmd

Peet per :year ••• Miles per hour

feat.l!!!:..,aaoaml

By

64. '19891 ( enc ti¥) • • 31,1035 •••• , •• 28.3495 , , , • , •• 0,453'9237 (exact~)

907.U, •••• • 0. 907l.8!I • • • • 1.016.0, , , , , •

1o!ICE/ARM .Q,fTIO'J(17 ••• 0.689476 ••• 4,88243 , , ,

47,8803 , , , , MASS/VOLUMI! (DENSrrI)

1,72999 • 16,0185 , ·• , •• ·0,0160185 1.32894 •••••

MM!BLQ.\PACm

7.4893 • , • , , 6,2362 •••• ,

119,829 , , , • , 99.779 ••• ,

BENDING MlMl!JIT OR TORQUE

0,Oll521 , .!t.. l,J.298' X .WV 0.13825' , ... , 1,35582 X 10• 5,4431 ••••

72,008 I I • I

VELOCrrI 30,48 (enctJ.¥) , , 0,3048 (exactlY)* 0, 965873 X 10-6it , 1,609344 (exacui}) P #794 C exac

~IQNlt 0. :3()48,t. • •

~ cubic teat per seocm4 ( seocmll•

teat) •••••••••••• 0,028311*. 0.4719 •• 0~

CUbio teat per mlnute • • • • ~ cu.s,) per minute •

!!l!!!.li QllAHTITIJ!S .AND UNITS OF MECHANICS

To obtain

• Milllgrems • 01'81118 • Orama • Kilograms • Kilograms • Yotr:l.o tons • Kilograms

• Kilograms par square oantimeter , Newtans par square oent:lmtsr • Kilograms per square meter • Newtans per 1111uare meter

, Q1'8lll8 par cubic centimeter • Kilograma per cubic meter , Orama per cubic omrt:lmater • Q1'8lll8 per cubic ~ctll!l~ilnete~

• Grams par liter • Grams per liter • G1'8lll8 per liter

jlrama_____11f!1' _],i~

• Mater-kil.ogranll • Cantillllter-d;?Dee • Meter-kilograms , Cent:lmtsr-4JUs • Cantimater-111].ograma per omrt:lmtsr • Oram-oantimetera

• Centimeters par aeocmd • Metera per aeocmd • Centimeters par aeocm4 • Kilamatera par h0ur • llatera per -0114

• Meters per aeoaml

• Culll.o meters per aeocm4 • Li tera per aeocm4 • Liters per -~

Mul.til'lT

Pounds •

Br.I. tiah tllermal uni ts (Btu) •

Btu per pound. Foot-pounds,

lloraepower • • Btu per hour • , • • • Foot-pounds per aeocm4

Btu :1.n,/l,r tt2 deg F (k, tberlllll ccmduotivity)

Btu tt/l,r tt2 deg F .. : : :

B~~:~C:~ •

Deg F hr tt2~ (R; ~~ reaiatmiae) , • • • , • , • •

Btu/lb deg F (o, heat capacity). Btu/J.b deg F. ,. , , • , , , , • Ft2/br (t11erma1 dU'tuainv>

Graina/l,r tt2 ( water n.pcr tranaml.saian). • • • • •

Parma (permeanoe), •• , •• Pam-inches (P8l'lDllability) •

~~i,i!l. CUbio teet par square toot per

clq (seepage) • • • • • • • • Pound-aeocm4s per square toot

By

l'OIICE*

0,453592* , , , 4.4482* ••• · • 4 ,4482 X 10-'* •

'IPBK AND 1DflBOY*

, 0.252* ••• , , • 1,05',06 ••••• , • 2,326 (enctJ.¥),

l.3'582* ·~ 1'!)'iiER

745.700 •• , 0 .29'J(111 , 1.35582 •

~-TRANSFER

1,442 , 0.1240 • 1,4880*

0,'68 • 4,882 •

1.761 • 4.1868 • 1,000* • 0.2581 , , 9 .09290* •

J[ATl!R_ VAPOR TRANSMISSIP!I

16,7 , o.659 1,67.

I!!!!!..m 01'IIER QJANTITIES AND_ !!NIT_B_

~

(viaooaity) •• , •••••••• Square test per aeocm4 ( viaoosi v) Fahrellhei-t degree& (obanga)• •

;304.8* • • •••••

4,8824* • , , , , 0,02903* (exactJ.¥) 5/9 exaatJ.¥. • • , 0,03937. , Volta per ml.l, , , • • , • • ,

Lmm,a per square toot (toot-oandlea)

Ohm-circular ml.ls per toot • lltlliour:l.ea par oubio toot ,

, lltlliampa per square toot Gallana par square ;yard l'!)Ullda per :l.noh, • 1 • • , ,

10,764 •• 0,001662 •

35,3147• • 10,7639* ,

4,527219* 0.178,8* ,

Eilogran,a Newtans Bm!,S

To obtain

• Kilogram calories • Joules • Jmles par11'8111 • Joules

, Watts , Watts , Watts

• Milliwatts/om deg C • Kg cal/hr m deg C .Kgoallll/brm1-degC

, Milliwatta/om2 deg C • Kg cal/hr m1- deg C

, Deg C om1-/ml.lliwatt , J/g deg C . ~,e-4egc ~

• Grama/24 hr .. • Jfetr:l.o perms • lfetrl.c perm-centimeters

'{o __ obtain

• Li tera per square mater per clq

• Kilogram aeocm4 per square mater , Square meters per aeocm4 , Celaiua or Kelvin degrees ( obanga )* • Kilovol ta per ml.llimater

, Lumeml per square mater , Ohm-square ml.J.lJ.Jmtara per mater • Milliour:l.ea per cubic meter • Millimqpa per square mater • Li tera per square metar • Kilograms per omrtimeter

GPO 845-237

ABSTRACT

Hydraulic model studies were performed on a 1: 12 scale model of the Azotea Tunnel Inlet Junction to find a configuration which would minimize head losses through the junction, to determine critical dimensions of the structure, and to establish canal water depths. The purpose of the junction is to combine the flow from a feeder canal with that from the Oso Tunnel inverted siphon and direct .this combined flow into the Azotea Tunnel. The recommended design minimized head losses between the siphon and the tunnel by means of a bearing wall placed in the flow stream which accelerated the flow leaving the canal, thereby making the uniting flow velocities from the canal and the siphon almost equal. This significantly re­duced eddy formation and tended to eliminate retardation of the siphon flow. The bearing wall also reduces the span length of a roof over the inlet junction. The flow conditions with this config­uration were good over a large range of siphon, canal, and tunnel discharges. Fairly accurate estimates of losses through a system which is not geometrically similar to the Azotea inlet junction can be obtained by application of momentum and energy equations over two control sections. An example of this procedure is given in the appendix to the report.

ABSTRACT

Hydraulic model studies were performed on a 1:12 scale model of the Azotea Tunnel Inlet Junction to find a configuration which would minimize head losses through the junction, to determine critical dimensions of the structure, and to establish canal water depths. The purpose of the junction is to combine the flow from a feeder canal with that from the Oso Tunnel inverted siphon and direct .this combined flow into the Azotea Tunnel. The recommended design minimized head losses between the siphon and the tunnel by means of a bearing wall placed in the flow stream which accelerated the flow leaving the canal, thereby making the uniting flow velocities from the canal and the siphon almost equal. This significantly re­duced eddy formation and tended to eliminate retardation of the siphon flow. The bearing wall also reduces the span length of a roof over the inlet junction. The flow conditions with this config­uration were good over a large range of siphon, canal, and tunnel discharges. Fairly accurate estimates of losses through a system which is not geometrically similar to the Azotea inlet junction can be obtained by application of momentum and energy equations over two control sections. An example of this procedure is given in the appendix to the report.

{ '! I I I I I I I I I I I I I

I I I I I

l I I I l

I I

ABSTRACT

Hydraulic model studies were performed on a 1:12 scale model of the Azotea Tunnel Inlet Junction to find a configuration which would minimize head losses through the junction, to determine critical dimensions of the structure, and to establish canal water depths. The purpose of the junction is to combine the flow from a feeder canal with that from the Oso Tunnel inverted siphon and direct .this combined flow into the Azotea Tunnel. The recommended design minimized head losses between the siphon and the tunnel by means of a bearing wall placed in the flow stream which accelerated the flow leaving the canal, thereby making the uniting flow velocities from the canal and the siphon almost equal. This significantly re­duced eddy formation and tended to eliminate retardation of the siphon flc;>w. The bearing wall also reduces the span length of a roof over the inlet junction. The flow conditions with this config­uration were good over a large range of siphon, canal, and tunnel discharges. Fairly accurate estimates of losses through a system which is not geometrically similar lo the Azotea inlet junction can be obtained by application of momentum and energy equations over two control sections. An example of this procedure is given in the appendix to the report.

ABSTRACT

Hydraulic model studies were performed on a 1:12 scale model of the Azotea Tunnel Inlet Junction to find a configuration which would minimize head losses through the junction, to determine critical dimensions of the structure, and to establish canal water depths. The purpose of the junction is to combine the flow from a feeder canal with that from the Oso Tunnel inverted siphon and direct .this combined flow into the Azotea Tunnel. The recommended design minimized head losses between the siphon and the tunnel by means of a bearing wall placed in the flow stream which accelerated the flow leaving the canal, thereby making the uniting flow velocities from the canal and the siphon almost equal. This significantly re­duced eddy formation and tended to eliminate retardation of the siphon flow. The bearing wall also reduces the span length of a roof over the inlet junction. The flow conditions with this config­uration were good over a large range of siphon, canal, and tunnel discharges. Fairly accurate estimates of losses through a system which is not geometrically similar to the Azotea inlet junction can be obtained by application of momentum and energy equations over two control sections. An example of this procedure is given in the appendix to the report.

Hyd-551 Falvey, H. T. HYDRAULIC MODEL STUDIES OF THE AZOTEA TUNNEL INLET JUNCTION, SAN JUAN-CHAMA PROJECT, COLORADO Bureau of Reclamation, Hydraulics Branch, Denver, 45 p, includ­ing 16 fig, l ref, append, November 1965

DESCRIPTORS-- hydraulics/ *model tests/ *hydraulic models/ *head losses/ *hydraulic structures/ canals/ siphons/ tunnels/ *water surface profiles/ open channel flow/ inlets/ velocity/ coefficients/ momentum/ discharges IDENTIFIERS-- Azotea Tunnel, Colo/ San Juan-Chama Proj, Colo/ flow junctions

Hyd-551 Falvey, H. T. HYDRAULIC MODEL STUDIES OF THE AZOTEA TUNNEL INLET JUNCTION, SAN JUAN-CHAMA PROJECT, COLORADO Bureau of Reclamation, Hydraulics Branch, Denver, 45 p, includ­ing 16 fig, 1 ref, append, November 1965

DESCRIPTORS-- hydraulics/ *model tests/ *hydraulic models/ *head losses/ *hydraulic structures/ canals/ siphons/ tunnels/ *water surface profiles/ open channel flow/ inlets/ velocity/ coefficients/ momentum/ discharges IDENTIFIERS-- Azotea Tunnel, Colo/ San Juan-Chama Proj, Colo/ flow junctions

Hyd-551 Falvey, H. T. HYDRAULIC MODEL STUDIES OF THE AZOTEA TUNNEL INLET JUNCTION, SAN JUAN-CHAMA PROJECT, COLORADO Bureau of Reclamation, Hydraulics Branch, Denver, 45 p, includ­ing 16 fig, 1 ref, append, November 1965

DESCRIPTORS-- hydraulics/ *model tests/ *hydraulic models/ *head losses/ *hydraulic structures/ canals/ siphons/ tunnels/ *water surface profiles/ open channel flow/ inlets/ velocity/ coefficients/ momentum/ discharges IDENTIFIERS-- Azotea Tunnel, Colo/ San Juan-Chama Proj, Colo/ flow junctions

Hyd-551 Falvey, H. T. HYDRAULIC MODEL STUDIES OF THE AZOTEA TUNNEL INLET JUNCTION, SAN JUAN-CHAMA PROJECT, COLORADO Bureau of Reclamation, Hydraulics Branch, Denver, 45 p, includ­ing 16 fig, 1 ref, append, November 1965

DESCRIPTORS-- hydraulics/ *model tests/ *hydraulic models/ *head losses/ *hydraulic structures/ canals/ siphons/ tunnels/ *water surface profiles/ open channel flow/ inlets/ velocity/ coefficients/ momentum/ discharges IDENTIFIERS-- Azotea Tunnel, Colo/ San Juan-Chama Proj, Colo/ flow junctions