kaplan report gaurav

7/31/2019 KAPLAN Report Gaurav

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ABSTRACT

This type of turbine evolved from the need to generate power from much lower pressure

heads than are normally employed with the Francis turbine. To satisfy large power demands

very large volume flow rates need to be accommodated in the Propeller turbine, i.e. the

product QH is large. The accurate analysis of performance characteristics of a Propeller

turbine is not possible but it can almost characterized with help of prototype to know most

efficient way to use it. Performance characteristics are the data with the help of which the

exact behaviour and performance of the turbine under different working condition can be

known. These data are plotted in curves from the results of the test performed on the

turbine under different working condition called characteristics curves.

There are six parameters present during working of propeller turbine namely

1. Inlet pressure

2. Head

3. Volume rate flow

4. Turbine speed

5. Shaft power

6. Spear valve position

To achieve the objectives first experiment is performed keeping constant inlet pressure and

under varied load and different position of guide blades and second experiment is

performed keeping fixed guide vane, under varied load and three different inlet pressures

for propeller type Kaplan turbine. Graphs are plotted to analyse the performance

characteristics of Kaplan turbine.


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INTRODUCTION

The Kaplan turbine is a propeller-type water turbine which has adjustable blades. It was

developed in 1913 by the Austrian professor Viktor Kaplan, who combined automatically

adjusted propeller blades with automatically adjusted wicket gates to achieve efficiency

over a wide range of flow and water level. The Kaplan turbine was an evolution of the

Francis turbine. Its invention allowed efficient power production in low-head applications

that was not possible with Francis turbines. The head ranges from 10-70 meters and the

output from 5 to 120 MW. Runner diameters are between 2 and 8 meters. The range of the

turbine is from 79 to 429 rpm. Kaplan turbines are now widely used throughout the world in

high-flow, low-head power production.Kaplan turbines are widely used throughout the

world for electrical power production. They cover the lowest head hydro sites and are

especially suited for high flow conditions. Inexpensive micro turbines on the Kaplan turbine

model are manufactured for individual power production with as little as two feet of head.Large Kaplan turbines are individually designed for each site to operate at the highest

possible efficiency, typically over 90%. They are very expensive to design, manufacture and

install, but operate for decades.

The objectives of this experiment is

To study the performance characteristics of Propeller Turbine at constantinletpressure and under varied load and different position of guide blades.

To study the performance characteristics of Propeller Turbine at fixed guide

vane,under varied load and three different inlet pressures.


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THEORETICAL PRINCIPLES

The reaction turbine operates with its wheel submerged in water. The water before entering

the turbine has pressure as well as kinetic energy. The moment on the wheel is produced by

both kinetic and pressure energies. The water leaving the turbine has still some of the

pressure as well as kinetic energy.

The primary features of the reaction turbine are:

(1) only part of the overall pressure drop has occurred up to turbine entry, the remaining

pressure drop takes place in the turbine itself;

(2) the flow completely fills all of the passages in the runner, unlike the Pelton turbine

where, for each jet, only one or two of the buckets at a time are incontact with the water;

(3) pivotable guide vanes are used to control and direct the flow;

(4) a draft tube is normally added on to the turbine exit; it is considered as anintegral part of

the turbine.

The pressure of the water gradually decreases as it flows through the runner andit is the

reaction from this pressure change which earns this type of turbine its appellation.

This type of turbine evolved from the need to generate power from much lower pressure

heads than are normally employed with the Francis turbine. To satisfylarge power demands

very large volume flow rates need to be accommodated in theKaplan turbine, i.e. the

product QHis large. The overall flow configuration from radial to axial. Figure 9.16 is a part

sectional view of a Kaplan turbine in which theflow enters from a volute into the inlet guide

vanes which impart a degree of swirlto the flow determined by the needs of the runner. The

flow leaving the guide vanesis forced by the shape of the passage into an axial direction and

the swirl becomesessentially a free vortex, i.e

=


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FIG. 9.16. Part section of a Kaplan turbine in situ (courtesy Sulzer Hydro Ltd, Zurich

The vanes of the runner are similar to those of an axial-flow turbine rotor but designed with

a twist suitable for the free-vortex flow at entry and an axial flow at outlet. Because of the

very high torque that must be transmitted and the large length of the blades, strength

considerations impose the need for large blade chords. As a result, pitch/chord ratios of 1.0

to 1.5 are commonly used by manufacturers and, consequently, the number of blades is

small, usually 4, 5 or 6. The Kaplan turbine incorporates one essential feature not found in

other turbine rotors and that is the setting of the stagger angle can be controlled. At part

load operation the setting angle of the runner vanes is adjusted automatically by a servo

mechanism to maintain optimum efficiency conditions. This adjustment requires acomplementary adjustment of the inlet guide vane stagger angle in order to maintain an

absolute axialflow at exit from the runner.

Just upstream of the runner the flow is assumed to be a free-vortex and the velocity

components are accordingly:

c = K/r c = a constant

The relations for the flow angles are

tan = U/c tan = r/c K/(rc )

tan = U/c = r/c .


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Fig. 2 Section of a Kaplan turbine and velocity diagrams at inlet to and exit from the runner.


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EXPERIMENTAL SETUP

Fig. 3 Experimental system in lab Kaplan turbine


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OBSERVATION

1st

CASE

Constant Inlet Pressure(P4)=0.45 bar

Sr.

no.

Turbine

speedp Flow rate

Hydraulic

power

Turbine

powerEfficiency

Area at

inlet

Area at

throat

RPM BAR m3/s W W % m2 m2

1 1420 0.51 0.0030763 138.433 13 9.390817 0.000907 0.000314

2 1120 0.51 0.0030763 138.433 13 9.390817 0.000907 0.000314

3 1015 0.51 0.0030763 138.433 15 10.83556 0.000907 0.000314

4 920 0.5 0.003046 137.069 16 11.67294 0.000907 0.000314

5 815 0.5 0.003046 137.069 17 12.40249 0.000907 0.000314

6 660 0.49 0.0030154 135.692 14 10.31751 0.000907 0.000314

7 500 0.46 0.0029216 131.472 10 7.606173 0.000907 0.000314

8 375 0.46 0.0029216 131.472 9 6.845556 0.000907 0.000314

9 250 0.45 0.0028897 130.035 7 5.383155 0.000907 0.000314


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2nd

CASE

Constant Inlet Pressure (P4)=0.5 bar

Sr.

no.

Turbinespeed

p Flow rate Hydraulicpower

Turbinepower

Efficiency Area atinlet

Area atthroat

RPM BAR m3/s W W % m2 m2

1 1810 0.6 0.0033367 166.835 2 1.198787 0.000907 0.000314

2 1700 0.59 0.0033088 165.439 8 4.835614 0.000907 0.000314

3 1600 0.58 0.0032806 164.031 12 7.315683 0.000907 0.000314

4 1500 0.58 0.0032806 164.031 18 10.97352 0.000907 0.000314

5 1400 0.58 0.0032806 164.031 23 14.02173 0.000907 0.000314

6 1250 0.59 0.0033088 165.439 15 9.066776 0.000907 0.000314

7 1120 0.59 0.0033088 165.439 19 11.48458 0.000907 0.000314

8 1040 0.58 0.0032806 164.031 19 11.58316 0.000907 0.000314

9 900 0.56 0.0032236 161.178 20 12.40862 0.000907 0.000314

10 820 0.56 0.0032236 161.178 20 12.40862 0.000907 0.000314

11 660 0.55 0.0031947 159.733 16 10.01674 0.000907 0.000314

12 530 0.52 0.0031063 155.315 13 8.370074 0.000907 0.000314

13 400 0.52 0.0031063 155.315 11 7.08237 0.000907 0.000314

14 270 0.5 0.003046 152.299 8 5.252821 0.000907 0.000314


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GRAPHS

0

2

4

6

8

10

12

14

16

0 500 1000 1500 2000

Efficiency%

Turbine Speed (RPM)

Efficiency vs Turbine Speed

efficieny for 0.5 bar

efficiency for 0.45 bar

0

5

10

15

20

25

0 500 1000 1500 2000

TurbinePower(w)

Turbine Speed(RPM)

Turbine power vs turbine speed

0.45 BAR

Series2


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DISCUSSIONS

The discussions on the experimental results are :

Nature of graphs

At constant inlet pressure, under varied load, with turbine speed ranging from 1400to 200 r.p.m the turbine shaft power increases initially until the power reaches to a

maximum value and then decreases. This pattern can be observed in the graph

above.

The turbine efficiency measured at constant inlet pressure, under varied load anddifferent spear valve settings ,with turbine speed ranging from 1400 to 200 rpm

increases as the power increases and the curves for efficiency vs speed follows the

same pattern as that of the curves for power vs speed. Hence the graph plotted

follows a near parabolic pattern.

The efficiency is directly proportional to the turbine shaft power, which is provedexperimentally as both parameters when measured against speed behave in same

manner(from graphs).

The power output of turbine shaft is less than theoretical output due to wind age,mechanical friction, and non-uniform flow.

It is seen that the efficiency, generally increases with increase in turbine power. Insome cases, where hydraulic power is increased abnormally, the efficiency

decreases.


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CONCLUSIONS

The following can be concluded from the propeller turbine experiment:

Shaft power

The maximum power output of turbine measured at 0.45 bar pressure, came whenthe valve was fully open and it was 17w at 815 rpm.

The maximum power output of turbine measured at 0.50 bar pressure, came whenthe valve was fully open and it was 23w at 1400 rpm.

Efficiency

The maximum efficiency of the turbine calculated when operated at 0.45 barpressure when the turbine power was maximum and it was 12.40%.

The maximum efficiency of the turbine calculated when operated at 0.50 barpressure when the turbine power was maximum and it was 14.02%.

From the graphs we can conclude that the efficiency is directly proportional to the turbine

shaft power, which is proved experimentally as both parameters when measured against

speed behave in same manner.


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SAMPLE CALCULATION

Turbine speed N = 1810rpm

Inlet pressure = 0.5bar

Now,flow rate

2

2

1A

2A

1

1

2CvAQv

hgm

Cv= 0.97 ; = 1000 kg/m3

A2 = 0.000314 m2

A1 = 0.000907 m2

m= 13600 kg/m3

Putting the values,

So, Q = 0.0033367 m3/s

Water power = Pi Q =0.5105 0.0033367m3/s

=166.835 W

Turbine shaft power =18W

Also, Efficiency =.

100

= 1.198787%


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REFERENCES

1. http://www.me.metu.edu.tr/courses/me402/EXPERIMENT/ME-402EXP2final.pdf

2. en.wikipedia.org/wiki/Kaplan_turbine

3. Fluid Mechanics and Thermodynamics of Turbo Machinery

4.

kaplan report gaurav

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