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DEPARTMENT OF MECHANICAL ENGINEERING AND MECHANICS COLLEGE OF ENGINEERING AND TECHNOLOGY OLD DOMINION UNIVERSITY NORFOLK, VIRGINIA 23529 JET VORTEX GENERATORS FOR TURBULENT FLOW SEPARATION CONTROL L i By Gregory Selby, Principal Investigator Progress Report For the period ended May 31, 1990 Prepared for National Aeronautics and Space Administration Langley Research Center Hampton, Virginia 23665 Under Research Grant NAG-I-f071 John B. Anders, Jr., Technical Monitor FLDMD-Experimental Flow Physics Branch V Submitted by the Old Dominion University Research Foundation P.O. Box 6369 Norfolk, Virginia 23508-0369 September 1990 (NAgA-Cq-13A:;,$J) J_ | V, _ ,Y:_ G___'-!L°ATd_',O Fn_ TU_.RULtNT r:tLJW g _AP,ATi"_ U:_:_Ti<_lL Proqr,_t,s Rnporf, p_rio,4 -'!_-_,:'"_L :-_ ,y ic'_ '_, (Old Jnminion Univ.) IJ _: C_-CL OIA G3Io? N90-27_9 https://ntrs.nasa.gov/search.jsp?R=19900018343 2020-02-08T00:05:03+00:00Z

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DEPARTMENT OF MECHANICAL ENGINEERING AND MECHANICS

COLLEGE OF ENGINEERING AND TECHNOLOGY

OLD DOMINION UNIVERSITY

NORFOLK, VIRGINIA 23529

JET VORTEX GENERATORS FOR

TURBULENT FLOW SEPARATION CONTROL

L

i

By

Gregory Selby, Principal Investigator

Progress Report

For the period ended May 31, 1990

Prepared forNational Aeronautics and Space Administration

Langley Research Center

Hampton, Virginia 23665

Under

Research Grant NAG-I-f071

John B. Anders, Jr., Technical Monitor

FLDMD-Experimental Flow Physics Branch

VSubmitted by the

Old Dominion University Research Foundation

P.O. Box 6369

Norfolk, Virginia 23508-0369

September 1990

(NAgA-Cq-13A:;,$J) J_ | V, _ ,Y:_ G___'-!L°ATd_',O Fn_

TU_.RULtNT r:tLJW g _AP,ATi"_ U:_:_Ti<_lL Proqr,_t,s

Rnporf, p_rio,4 -'!_-_,:'"_L :-_,y ic'_ '_, (Old

Jnminion Univ.) IJ _: C_-CL OIAG3Io?

N90-27_9

https://ntrs.nasa.gov/search.jsp?R=19900018343 2020-02-08T00:05:03+00:00Z

ACKNO_LF.J)GNENTS

This attached paper which will be presented at the 12th Symposium on

Turbulence, University of Missouri-Rolla, September 24-26, 1990 is being

submitted in lieu of a progress report for the research project "Experimental

Parametric Study of Jet Vortex Generators for Flow Separation Control." The

work was supported by National Aeronautics and Space Administration, research

grant NAG-I-I071. It was monitored by Mr. John B. Anders Jr., FLDMD-

Experimental Flow Physics Branch.

ii

JET VORTEX GENERATORS FOR

TURBULENT FLOW SEPARATION CONTROL

G. Selby

Old Dominion University, Norfolk, VA 23529-0247

J. Lin and F. Howard

NASA Langley Research Center, Hampton, VA 23665-5225

12th Symposium on Turbulence

University of Missouri-Rolla

September 24-26, 1990

JET VORTEX GENERATORS FOR

TURBUI.ENT FLOW SEPARATION

CONTROL

(;. Selby*

Old Dominion University, Norfolk, VA 23529-4)247

J. Lint and F. llowardf

NASA Langley Research Center, Hampton, VA 23665-5225

Abstract

A parametric study has been performed with jet vor-

tex generators to determine their effectiveness in control-

ling flow separation associated with low-speed turbulent

flow over a two-dimensional rearward-facing'ramp. Results

indicate that flow-separation control can be accomplished,

with the level of control achieved being a function of jet

speed, jet orientation (with respect to the free-stream di-

rection), and orifice pattern (double row of jets vs. single

row). Compared to slot blowing, jet vortex generators can

provide an equivalent level of flow control over a larger

spanwise region (for constant jet flow area and speed).

Nomenclature

Cp pressure coefficient, 2 (P- Poo)/p V_

CO total flow coefficient, Q/rA Vo,_

Do jet orifice diameter

Q total volumetric flow rate

R 0 Reynolds number based on momentum thickness

u' Fluctuating velocity component in the free-stream

direction

V_o free-stream flow speed

VR ratio of jet speed to free-stream flow speed

x coordinate in the free-stream direction

jet inclination angle (angle between the jet axis and

the horizontal plane)

/3 jet azimuthal angle (angle between the jet axis and

the free-stream direction in a horizontal plane)

boundary-layer thickness

momentum thickness

A lateral distance between jet orifices

* Assc_iate Professor

f Aerospace Engineer

I. Introduction

Trailing-edge flaps, such as the Fowler flap, double-

and triple-slotted flaps, are an integral part of conventional

(Boeing 707, 737 and 747) and unconventional (SST and

likely, NASP) aircraft designs for lift augmentation. The

increase in the effective wing area, and consequent lift in-

crement offered by typical muhielement airfoils, is highly

desirable; however, there are penalties that must be ac-

cepted. IBertin and Smith (1989)1 Leading-edge flaps

(e.g., Krueger) create gaps that reduce the effectiveness of

laminar-flow-control (I.FC) techniques. In addition, a large

percentage of the volume of a wing with flaps includes

support structure for the flaps. This negatively impacts the

structural efficiency of the wing design.

A basic objective of the flap-system design is to at-

tain the highest possible LJD ratio at the highest possible

lift coefficient. If a clean flaps-up wing did not stall, a

flap system would essentially not be needed. [Olason and

Norton (1966)] For high-lift wings without flaps, the is-

sue is clearly one of three-dimensional separation control.

If effective three-dimensional low-speed separation-control

techniques can be developed for implementation during air-

craft take-off and landing, flaps can be omitted from air-

craft designs. However, a wing without flaps (with appro-

priate flow-control devices) would need to be flown at a

higher angle-of-attack than one with flaps, in order to cre-

ate equivalent lift. Instead of placing the entire aircraft at

a higher angle-of-attack, a rotating-wing design or airport

"ski jumps" can be used.

Vortex generators are commonly used to alleviate

boundary-layer flow separation problems in internal and

external aerodynamic configurations. One commonly uti-

lized method for flow separation control involves placing

small vortex generators (rectangular, deha-shaped winglets,

Wheeler-type devices, etc.) IWheeler (1984); Rao and

Kariya (1988); Selby (1989); and Lin et al. (1989, 1990)1 in

a spanwise array upstream of a flow separation line. In this

manner, the streamwise vortices generated by the vortex

generators increase longitudinal momentum near the wall

and suppress or eliminate separation.

Another method for generating longitudinal vortices is

through the use of jets blown through holes in a solidsurface. [Wallis (1952); Pearcey and Stuart (1959); Pa-

pell (1984); Zhang and Li (1987); and Johnston and Nishi

(1989)i. These streamwise vortices can then interact with

the separated flow. The holes in the surface are skewed

at an angle to the free-stream direction and can be ar-rayed along the surface like classical vortex generators.

This separated-flow control technique was first studied by

WaUis (1952); however, the idea has not yet been oper-

ationally employed. Wallis (1952) demonstrated that jetvortex generators can significantly delay turbulent sepa-

ration on a NACA 2214 airfoil model in low-speed flow

(V,,o = 18.3 m/s). Pearcey and Stuart (1959) and Zhangand Li (1987) examined the flow physics associated with

jet vortex generators, including the relative strengths of themembers of the vortex pair comprising a skewed jet. Papell

(1984) tested jet vortex-generator orifices of circular and

non-circular cross-section in a study of the fluid mechanics

of the discrete hole film-cooling process as applicable to thecooling of turbine blades. Johnston and Nishi (1989) have

conducted low-speed airflow experiments in a wind tun-

nel at a free-stream airspeed of 14.9 m/s and demonstrated

that the "vortex-generator-jet" method creates longitudinalvortices that are effective in reducing the separated flow

associated with a flat-plate model in an adverse pressure

gradient.

Therefore, one approach to three-dimensional separa-

tion control for aircraft might involve the use of jet vor-

tex generators. The air used in a LFC suction system

near the leading-edge of a wing (operated for leading-edge-

region separation control during takeoff/landing) can be

bled through the jet holes (appropriately located with re-spect to the region of flow separation) to produce stream-

wise vortices that interact with and control the separatedflow.

The objective of the present research is to perform acareful parametric study of jet vortex generators for low-

speed two-dimensional turbulent fiow-separation control.

Parameters that were varied included orifice diameter, jet

orientation, jet speed, longitudinal hole location, and hole

pattern.

2. Experimental Apparatus and Tests

The present separation-control experiments were con-

ducted in the NASA Langley 51x71 cm (20x28 inch)Shear-Flow Control Tunnel. This is a low-turbulence

(u'/Voo < .005), subsonic, open-circuit wind tunnel. In

the current study, all experiments were conducted at a free-

stream speed of 40 m/s. The free-stream reference speed

was measured by a pitot-static probe mounted from the ceil-

ing at the front of the test section.

The test-section floor was modified for the separation-

control experiment. A flow-separation ramp (model) was

located approximately 1.9 m from the lest-section entrance.See Figure i for the test configuration. The tunnel floor

upstream of the ramp was raised 7.6 cm to accommodate

the ramp model. A suction slot at the test-section entrancewas used to remove the converging-section boundary layer

to eliminate any influence of upstream history on the test

boundary layer. The new laminar boundary layer that

developed downstream of the suction device was artificially

tripped with a 5.1-cm wide strip of sandpaper (36 grit). Theceiling height of the test section was adjusted to obtain zero

pressure gradient upstream of the ramp. The boundary layer

just ahead of the separation ramp was fully turbulent and

the thickness, _i, was approximately 3.3 cm. At this samelocation, the spanwise momentum thickness (8) variation

across the test plate was within +2.5 percent (8 = 3.3 ram)

and the momentum thickness Reynolds number, R#, wasapproximately 9(XX).

The baseline (or reference) separation model was a

two-dimensional 25° ramp with a 20-cm shoulder radius

as shown in Figure 2. The model spanned the entire 71-cm

wide test section and produced reasonably two-dimensional

flow separation at approximately the midpoint of the rampor about 7.6 cm downstream of the horizontal tangent point

(see Figure 3). Ten jet vortex generator orifices (lateral

spacing of 3.0 cm) were nominally located 4.4 cm up-

stream of the point of horizontal tangency or 3.5,S upstreamof baseline separation. The orifice diameters (Do) tested

were 0.8, 1.2, 1.6, 3.2, and 4.8 mm (Do/8 --- 0.24, 0.36,

0.48, 0.97, and 1.45, respectively). Orientation of the jets

was varied through changes to the jet inclination angle,

o_ (angle between the jet axis and the horizontal plane;15°< c_ < 90°), and the jet azimuthal angle, /_ (angle be-

tween the jet axis and the free-stream direction in a hori-

zontal plane; 0 ° < _' _<90°). These angles are defined in

Figure 4.

Twenty-five static pressure orifices were located on the

centerline of the separation ramp and twenty orifices werelocated on the centerline of the floor downstream of the

ramp. The pressure tubes for the orifices were connected

to a motor-driven valve which sequentially connected each

orifice to a single differential pressure gauge. All surfacestatic pressure measurement were referenced to the free-

stream static pressure measured at a location near the en-

trance of the test section. Spanwise pressure distributions

were measured by moving the jet vortex generator assemblyin the spanwise direction with respect to the (fixed) row of

pressure orifices.

The "oil-dot" flow-visualization technique was used to

determine surface flow patterns. A mixture of titanium

dioxide and I0 centistoke silicone oil proved to be suitable

for identifying separation and reattacbment lines, as shown

in Figure 3. The oil dots were placed on the model surface

in a square grid approximately 2.5 cm apart in both the

free-stream and spanwise directions

3. Results and Discussion

Longitudinal pressure distributions (jet orifices located

symmetrically with respect to pressure orifices) are pre-

sented in Figure 5 as a function of jet orifice diameter (Do

= 0.8, 1.2, and 1.6 mm or Do�8 = 0.24, 0.36, and 0.48,

respectively) for c_ = 45 °, 3 = 90 °, and flow coefficient,

CQ = Q/A6Voo = 0.034 with 6 measured just upstream of

the separation ramp. Also shown in Figure 5 are baseline

(jets off) and potential flow (computed) pressure distribu-

tions. For a constant value of CQ and variations in Do,

the velocity ratio (VR), the ratio of jet speed to free-stream

speed, is variable. The best performance in terms of pres-

sure recovery and reattacbment line location was obtained

with Do�8 = 0.24 (VR = 6.8). Data presented in Figure

5 generally indicate an increase in pressure recovery and

a reduction in the extent of the separation region with in-

creasing VR (decreasing Do). When examining the base-

line pressure distribution, it should be noted that the flow

around a comer (or a shoulder) accelerates and decelerates

symmetrically from the potential flow perspective; this is

the reason for the pressure drop along the upstream portion

of the shoulder. Baseline separation occurred just before

the sharply increasing Cp distribution began to level off

and reattachment occurred near the region of maximum Cp.

The reattachment distance, therefore, can be defined as the

distance between these two locations.

Figure 6 shows pressure distribution as a ft, nction of

streamwise position for Do = 1.6 mm (Do/0 = 0.48, or =

45 ° , and _ = 90 ° ) as a function of C O (or VR). These

results indicate that the maximum pressure recovery was

achieved at the maximum value of C O (or VR) when Dowas held constant.

The effect of variations in inclination angle on the

pressure recovery (Do/0 = 0.24, CQ = 0.034, and/3 = 90 °)

is illustrated in Figure 7. It appears that maximum pressure

recovery was obtained with 15°< or < 25 °. A positive

effect was also obtained with or = 45°; however, negligible

effect is shown with or -- 90 ° compared with the baseline

case. Surface oil-flow visualization photographs for or = 15 °

and 45 °, (Figures 8 and 9, respectively) and other conditions

as in Figure 7, show that the flow reattaches upstream of

the baseline reattachment line for both inclination angles.

However, in both cases, surface streamlines downstream of

reattachment are skewed toward the (initial) direction of

_'he jets. The skewness is greater at the lower inclination

angle. For both inclination angles, the separation line is

three-dimensional, with pockets of separated flow adjacent

to pockets of attached flow. In addition, the separated flow

appears to have a spanwise component which is stronger

for or = 15 °.

Figures 10 an 1 i show the effect of varying azimuthal

angle on the pressure recovery with er = 15 ° and 45 ° ,

respectively (D,,/0 = 0.2,1 nt_d CQ = 0.034). Maximum

pressure recovery was achieved with fl = 61)° at c_ = 15"

and with /3 = 90 ° at or = 45 °. These figures show positive

effect also for /:1 = 0°, 30 °, and 90 ° at ,, --- 15 ° and for/t

= 30" and 60" at ¢, = 45 °. Though there was a positive

effect at _ = 0 ° with _ = 15 °, the pressure recovery

with o_ = 45 ° was identical to the baseline case. Pearcey

and Stuart (1959) have indicated that as the jet azimuthal

angle, /3, is increased, one member of the pair of counter-

rotating vortices comprising the jet becomes dominant and

is situated close to the surface. The other weaker member

of the vortex pair lies above the dominant member. Based

on the present results, it appears that this "dominant" vortex

was strongest at 60°<g<90 °.

Measurements made to determine the spanwise vari-

ation in the pressure distribution with Do/8 = 0.24, CQ

= 0.034, or = 15 °, and /t = 90 ° are presented in Figure

12. Plane "A" passes through the centerline orifice with

Planes "B", "C", and "D" being ),/4, ),/2, and 3)./4 from

the centerline in the spanwise direction. These results indi-

cate minimal spanwise variation in the streamwise pressure

distributions.

The effect of the streamwise location of the jet ori-

rices on the pressure recovery is shown in Figure 13

(Do/0 = 0.24, Cq = 0.034, or = 15 °, ,and/_ = 90°). For

the three cases shown, maximum pressure recovery was

obtained with the jet orifices located 3,_ to IOt_ upstream

of the reference separation line. Even with the jet orifices

located 406 upstream of the baseline separation line, signif-

icant pressure recovery was achieved, though reattachment

was delayed in comparison with the reattachment location

obtained with jet orifices located at 3 and IO&

Several configurations were examined for which ad-

jacent jets were oriented in a manner that has been

shown by Johnston and Nishi (1989) to produce counter-

rotating vortices (/_ =-1-90 °) rather than co-rotating vor-

tices, as in the case when fl = constant for all

jets. One such configuration is depicted in Figure 14

(Do/8 = 0.24, CQ = 0.034, and or = 45 °) , which shows

that the pressure recovery was lower in the three planes ex-

amined compared with the results with _. = constant. There

was also greater spanwise variability in the streamwise pres-

sure distributions for the configuration with counter-rotating

vortices than with co-rotating vortices. The results for the

latter case are similar to those shown in Figure 12. Figure

15, the flow-visualization photograph for this case, shows

pockets of three-dimensional separated flow on the ramp

whichcausethespanwise variation in the pressure distribu-

tion. Also shown in Figure 15 are regions of surface flow

in which there was early reattachment, as well as delayed

separation, compared to the baseline case (Figure 3).

Several tests were conducted with the orifices arranged

in two rows (5 orifices per row) as depicted in Figure 16.

Jets with Do/0 = 0.24 were oriented at c, -- 15 ° and 3

= 90 °. Results are presented in Figures 16 and 17 corre-

sponding to values of CQ of I).017 nnd 0.034, respectively.

Jets arranged in this manner are expected to be reinforc-

ing in the streamwise direction in terms of vortex strength.

Streamwise pressure distributions obtained with two rows

of jets ate compared to the distributions for one row of jets

(C.Q = 0.034) in Figures 16 and 17. 'The double row of jets

with CQ = 0.017 (Figure 16) have an effective value of CQ

of 0.034. However, the pressure recovery for this double

row of jets (Figure 16) was less than that for the single row

shown. It is concluded that the jets arranged in a double

row are non-linearly reinforced. When the jets are arranged

in a double row (Figure 17) with an effective value of C_.Qof

0.068, the pressure recovery for this arrangement is much

less than twice the recovery for a single row. Figures 16

and 17 also show that the streamwise pressure distributions

for the double row of jets exhibit spanwise uniformity. The

surface oil fl'ow visualization of the double-row configura-

tion of Figure 17 is presented in Figure 18, which shows

skewed, attached flow downstream of the ramp in the region

affected by the jets. The surface flow in the near-region of

the photograph is less effected by the jets due to the orien-

tation angle of the jets.

A double row of jets arranged in the manner shown

in Figures 19 and 20 (produced interacting counter-rotating

vortices) was tested with CQ = 0.017 and 0.034, respec-

tively (Do/0 = 0.24 and o_ = 15°). As with the previous

double-row configuration, the reinforcement of the jets was

non-linear at both values of C O. With C O = 0.017 (Figure

19), the double row of jets oriented to pntxluce counter-

rotating vortices produced a level of pressure recovery com-

parable to that produced by the double row of jets oriented

to produce co-rotating vortices (Figure 16). However, at

the higher value of CO(0.034), the counter-rotating vortex

configuration produced a maximum pressure recovery (Fig-

ure 20) less than that produced by the co-rotating vortex

configuration (Figure 17), but comparable to the configu-

ration with the single row of jets having 15 = constant =

90 °. The spanwise variability in the streamwise pressure

distribution shown in Figure 20 suggests that the counter-

rotating vortex configuration generates a level of reinforce-

ment that varies in the spanwise direction. The oil-flow

visualization photograph (Figure 21) corresponding to the

counter-rotating vortex configuration of Figure 20 shows at-

tached flow downstream of the ramp, but pockets of three-

dimensional separated flow on the ramp which resulted in

the spanwise pressure variations observed.

Air injection through a 0.13 by 23.4 mm rectangular

slot, oriented as shown in Figure 22 ( 3 = 00, VR=6.8,

and C_.Q = 0.034), produced the level of pressure recovery

indicated. The slot was designed with a total flow area

corresponding to 10 jet orifices with D,/O = 0.24. The

pressure recovery produced by slot injection was less than

that prtxluced by jet vortex generators with ,_ = 15 and 45 °

(,8 = 90°). In addition, Figure 23 shows that the flow is

attached only in a small region near the centerline of the

model, where the slot is located. To achieve flow control

with slot injection comparable to that obtained with the jet

vortex generators (with the same exlent of spanwise treat-

ment; i.e., longer slot) would probably require an order-of-

magnitude increa_ in the air volumetric flow rate through

the slot.

4. Conclusions

A parametric study performed with jet vortex gener-

ators has shown them to be effective in controlling flow

separation associated with low-speed turbulent flow over

a two-dimensional rearward-facing ramp. Specifically, the

following conclusions have been drawn from the present

results:

1. For given values of C O, ,_, and l_, jet vortex genera-

tor performance increased with decreasing Do due to

increasing VR.

2. For given values of Do r,, and /_, jet vortex genera-

tor performance increased with increasing CQ due to

increasing VR.

3. For given values of Do, /_, and CO, jet vortex gener-

ator performance generally increased with decreasing

c_, since momentum transfer occt,rred nearer the model

wall.

4. For given values of Do, or, and CQ, jet vortex generator

performance generally increased with increasing 3 up

to values of 600 to c)o° due to the increasing strength

of the dominant member of the vortex pair comprising

a skewed jet.

5. For given values of Do, or, 3, and C__.Q,jet vortex gen-

erator performance generally decreased with increasing

distance upstream of the separation line; however, the

level of flow-sepalation control with jets located as far

as 40_f upstream of the baseline separation line was

still significant.

6. For given values of Do, or, 3, and CQ, streamwise

pressure distributions displayed spanwise uniformity for

asinglerowof co-rotating jets, as well as for a double

row.

7. A single row (or a double row) of jets oriented to

produce counter-rotating vortices (in terms of adjacent

dominant vortex-pair members) were not as effective

as a single row (or a double row) of jets oriented

to produce co-rotating vortices, and exhibited a lower

level of spanwise uniformity in the streamwise pressure

distribution.

8. Jets in a double-row pattern generally reinforced non-

linearly in terms of the effect on pressure recovery.

9. Slot injection produced a level of pressure recovery

somewhat less than that achieved with a single row of

co-rotating vortex generator jets; however, the resulting

region of attached flow was very limited in spanwise

extent.

10. Oil flow visualization photographs generally indicated

attached flow downstream of the ramp; however, sur-

face streamlines were usually skewed in that region,

especially with the higher values of lt.

11. Oil flow visualization photographs also documented the

presence of pockets of three-dimensional separated flow

on the ramp in the vicinity of the flow-separation re-

gion, especially for the counter-rotating vortex config-

urations.

12. The most effective jet vortex generator configurations

tested were the single- and double-row co-rotating vor-

tex configurations with c, = 15 ° and /_ = 90 °.

Acknowledgement

The work of the first author was supported under NASA

grant NAG- 1-1071.

References

Bertin, J.: Smith, M. 1989: Aerodynamics for engineers.

Englewood Cliffs, New Jersey: Prentice Hall.

Johnston, J.: Nishi, M. 1989" Vortex generator jets -- a

means for passive and active control of boundary-layer

separation. AIAA Paper No. 89--0564.

Lin, J.: Howard, F.: Selby, G. 1989: Turbulent flow

separation control through passive techniques. AIAA

Paper No. 89-0976.

Lin, J.: Howard, F.: Selby, G. 1990: Investigation of

several passive and active methods for turbulent flow

separation control. AIAA Paper No. 90-1598.

Olason, M.: Norton, D. 1966: Aerodynamic design phi-

losophy of the Boeing 737. Journal of Aircraft. 3(6),524-528.

Papell, S. 1984: Vortex generating flow passage design for

increased film-cooling effectiveness and surface cover-

age. NASA TM 83617.

Pearcey, H.: Stuart, C. 1959: Methods of boundary-layer

control for postponing and alleviating buffeting and other

effects of shock-induced separation. New York: Institute

of the Aeronautical Sciences. SMF Paper No. FF-22.

Rao, D.: Kariya, T. 1988: Boundary-layer submerged

vortex generators for separation control--an exploratory

study. AIAA Paper No. 88-3546-CP.

Selby, G. 1989: Passive control of three-dimensional sepa-

rated vortical flow associated with swept rearward-facing

steps. Journal of Fluids Engineering. 11(I), 99-101.

Wallis, R. 1952: The use of air jets for boundary-layer

control. Australia: Aerodynamics Research Laboratories.

Aero Note 110.

Wheeler, G. 1984: Means of maintaining attached flow of

a flow medium. U.S. Patent No. 4455045.

Zhang, S.: Li, F. 1987: Experiments about the air jet vortex

generator. Proceedings of the 8th Institute of Aeronautics

and Astronautics. Cincinnati, Ohio. 513-516.

Pltot-statlc probe, Adjustable upper wall__ (set for zero pressure gradient)

_'- 61 :_ Flow=b _ Flow separalionSandpaper trip 7 4=3

• region RearSuction _1_/ __s__ _:__ 193 _. "1 , , floor

] / /.o 3.8/,/ ' Forward floor ....' Model ramp

to suction

Note: all dimensionsare in cm

Figure 1. Test configuration m tunnel.

Flow

8.9 8.6---t__,--. . I/-Tangent

3 -'8 [TangentJI I R

(side view)L "

Note: all dimensionsare in cm

Figure 2. Geometry of the model ramp.

Figure 3. Oil flow visualization of baseline separation.

Do (top view)

Jet orifices -_j/,, Jets

\¥/_ % =0.9FIow,_ -,-O -

(side view)

Figure 4. Geometry of jet vortex generators.

(top view)Jet orifices _.

So_-Jets Z_09Flowdl, _b"_ 8 - '

.5 -ideal Lj_ O_,SL_------I_ Centerllne

.4 - -_ _. "_-Pressure

.3 _ ;_ orifices

2

Cp 0

-.1 -- Baseline

-.2 o DO / 9 = 0.24, VR = 6.8

-.3 t_ Do / 9 = 0.36, VR = 3.0

::j--Location ^ n i,_ . n,_a-.4 _of jets _ -o ........ VR = 1.7

-.5 _2_______L_______-5 0 5 10 15 20

X/6

Figure 5. Pressure dismbutions for jet vortex generators

with variable jet Do for a = 45 °, /3 = 90 °, and

% = 0.034.

Ideal \

.3'

.1

Cp 02 VR = 2.7

ng 1

-.2 _ o CQ=0.024, VR 1,3

".3 _ CQ= 0.013, VR = 0.6

°.4-.5 _ ] _ i , i

-5 0 5 10 15 20

X,6

Figure 6. Pressure distributions for jet vortex generators

with variable CQ fl)r Do/O = 0.48, n = 45 °, and

/._= 90 °

.5

.4

.3

Ideal -_:

.1

Cp 0

-.1

-.3 ^ _t=90 _

°,4

-5 0 5 10 15 2O

X'_5

Figure 7. Pressure distributions for jet vortex generators

with variable _ for Do/0 = 0.24, /3 = 90% VR

= 6.8, and C o = 0.034.

Figure 8. Oil flow visualization for jet vortex generators

with or = 15 °, t3 = 90% Do/0 = 0.24, VR = 6.8,

and CO = 0.034,

G_- 1_00=2 QUALITY"

Figure 9. Oil flow visualization for jet vortex generatorswith _ = 45 °, /:/ = 9(Y', Do/0 = 0.24, VR = 6.8,

and CQ = 0.034.

.5Ideal

.4 -\

.3

Cp 0 Baseline

-._ _/,_, o f)_-0o

-.4 zx 13= 90 °

-5 0 5 10 15 20

X/8

Pressure distributions for jet vortex generators

with variable /3 for _ = 15 °, Do/0 = 0.24, VR

= 6.8, and CQ = 0.034.

Figure 10.

.5

.4

.3

2

.1

Cp 0

-.1

-.2

-,3

-.4

-,5-5

Ideal

Baseline

o 13=0._: a _=30.dlF o _=60

,a _=90"

I I 1 J

0 5 10 15 20

X/8

Figure II. Pre_stnre dislribulion_ for jet vortex generators

with variable /3 for cr = 45 °, Do/a = 0.24, VR

= 6.8, and CQ = 0.034.

;._:,'_G_T'_,L PAGE )S

OF PO0_ QuAL,TY

Cp

., Jets

Jet oriflces-\,_//_. (top view) ,O/ - _,

\t _ _ 4 <_ .. = 0.9

.5 -ideal Flow_'.Tr_ Centerllne o

.3- 4 _ _0"_'A_,'_/,'c.,and,O_are2 q_ spanwlse locations for

.1 _ 'eb_hp.._e_.e._ _ pressure orifices

O j_ -- Baseline

-.1 _ o Measurements along A

-.2 _ _ Measurements along B

-.3 _ o Measurements along C

°.4 - _ o Measurements along D

-.5 _ • i _ __........ )-5 0 5 10 15 20

Figure 12. Pressure distributions for jet vortex generatorsat several spanwise locations with o, = 15°, /_ =

90 °, Do/0 = 0.24, VR = 6.8, and CQ = 0.034.

.5Ideal

.4 \

.32 _

Cp 0 ;a ;e_ln;

-.t

-.2

-,3

-.4

-.5 _----S-_-_ _ _ _ ) !....-5 O 5 10 15 20

X/8

Figure 13. Pressure distributions for jet vortex generatorsat several streamwise locations with c_ = 15°, fl

= 90 °, Do/# = 0.24, VR = 6.g, and CQ = 0.034.

.5

.4

.3

2

.1

Cp 0

%1

*.2

-.3

%4

-5

Jet orifices _ (lop view) _.'\\9 r _ _ = 0.9

F;.... FIowd_ 6_ Centerline _

- ,,... Jets /_,_1 . Spanwvse Iocalvon for

pressure orifices

t -- B.aseline

0 Measurements along A

rJ Measurements along C_/ O Measurements along C'

zx _ = 90 ° = const., measurementsalong C

P I I0 10 15 20

X/8

Figure 14. Pressure distrilJutions at several spanwise loca-

tions for counter-rotating jet vortex generators

with t_ = 45 ° , /3 = + 90 ° , Do/0 = 0.24, VR =

6.8, and CQ = 0.034.

Figure 15. Oil flow visualization for counter-rotating jet

vortex generators with _ = 45°, /7 = +_ 90",

Do/0 = 0.24, VR = 6.8, and C.q = 0.034.

Jet orifices _ __'/ Jets (top view)

o" o _" 0.9FIOW,T_) <_,- Centerllne 8

.4 ,) Spanwise location for

.3 pressure orifices

.t

Cp 0

-.t _ E o Measurements along A

-.2 _ o Measurements along C-.3 A One row of jets, measuremenfs

-.4 along C, VR = 6.8 (CQ= 0.034)

-.5 _ .-S- _':---.. _t _ 1 ;-5 0 5 10 15 20

X/6

Figure 16. Pressure distributions at two spanwise locations

for a double row of co-rotating jet vortex gen-

erators with or = 15 °,/3' = 90 °, Do�8 = 0.24, VR

= 3.4, and CQ = 0.017.

_Jels (top vlew)Jet orifices _ _/ _" = 0.9

Flow _ _ _---_, Centerllne 5.5 Ideal.4 - _, 2 " Spanwlse location for

.3 _ pressure orifices

2

.t

0Q

-.1 g o _Measurements along A

-.2 _ _ M;;;u;;ments along C-.3 ,', One row of jets, measurements

-.4 -- : along C

-.5 _ I i i ___J-5 0 5 10 15 20

X/8

Figure 17. Pressure distributions at two spanwisc locations

for a double row of co-rotating jet vortex gen-

erators with c_ = 15 °, fl = 90 °, Do/0 = 0.24, VR

= 6.8, and CQ = 0.034.

Cp

.4

.3

2

.1

Cp 0

",1

-.2

%3

-.4

-5

Figure 18. Oil flow visualization for a double row of co-

rotating jet vortex generators with o, = 15 °, t7 =

90", DO/0 = 0.24, VR = 6.8, and CQ = O.034.

Jet orifices , (top view)

Flow, 2k] _=0.9

.5 l_ Ideal _ _ _)_ Centerllne

[_ Jets J_ _ _, Lc_

Spanwlse location for' pressure orifices

_- _ -- Baseline

t" _ o Measurements alor_ C'

k o Measurementsa ,.gc_1_ _ One row of Jets, measurements

_- along C, VR = 6.8, 13= 90 ° = const.

t_ (CQ = 0.034)I--_. r . I i ' i

0 5 10 15 20

X/6

Figure 19. Pressure distributions at two spanwise locationsfor a double row of counter-rotating jet vortex

generators with o, = 15 °, Do/0 = 0.24, VR =

3.4, and CQ = 0.017.

.5-

.4

.3

2

.1

Cp 0

%1

-.2

%3

".4

-5

Jet orifices _ (top view)

Flow dl, _ _ = 0.g

_);- Centerline

.Ideal _ dels x _ _T_-c'_5 2 ,c>

' _ Spanwise location for

pressure orifices

aseline

# o Measurements along C'

_1_ _ Measurements along C

One row of Jets, measurementsalong C, _ = 90 ° = consl.

0 5 10 15 2O

X/6

Figure 20. Pressure distributions at two spanwise locations

for a double row of counter-rotating jet vortexgenerators with or = 15°, Do/0 = 0.24, VR =

6.8, and C_.Q= 0.034.

Figure21.Oil flowvisualizationfor a doublerowofcounter-rotatingjetvortexgeneratorswithcr =

15°, Do�8 = 0.24, VR = 6.8, and CQ = 0.1134.

Rectangular slot _, (top view)

[7 7 Pressure orifices

Flow _ .Its-_ _ Centerline

Ill 0.4.5 Ideal -l'-- 0.0070 R = 0.18.4

R//_W.3

2 __p_._ (Side view oRfthe slot)

.1 _ -- Baseline

Cp 0 _ o Jet vortex generators wilh a =15 °,

-.1 _ 13= 90 °, and Do/0 = 0.24

-.2 _ o Jet vortex generators with a = 45 °,

•.3 _i_ 13= 90°, and Do/0 =0.24

..4 o Slot ,_n]ectlon ( [}= 0°1

..5 __ .... _ _- J-5 0 5 10 15 20

X/5

Figure 22. Pressure distributions for rectangular-slot injec-

tion (0.13x23.4 ram) and jet vortex generators

with equal flow areas, VR = 6.8, and CQ =

0.034.

Figure 23. Oil flow visualization for rectangular-slot injec-

tion (0.13x23.4 ram) with VR = 6.8 and Co =0.034.

OF FCO_, QUALITY