TABLE OF CONTENTS

# Description Page

1 Objective 2

2 Theory 3

3 Apparatus 4

4 Procedure 5

5 Observations 6

6 Results 7

7 Discussion and Conclusion 8

8 References 9

APPENDIX 10

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1. OBJECTIVE

The objective of this experiment was to study the design and running of a Rover 1S/60 gas turbine engine using an ideal air-standard analysis Brayton cycle approximation. This was done by conducting a full load test on the engine at steady state and calculating the overall efficiency, power and fuel consumption rate using the data recorded during the observations.

2. THEORY

The quality of any gas turbine engine can be evaluated by calculating its fuel consumption, generated power and the overall thermal efficiency.

A gas turbine engine is mainly used to produce thrust or shaft work and its working can be closely modeled after a Brayton thermodynamic cycle (Figure 1 below) keeping second law of thermodynamics in mind, provided that an air standard analysis is applied.

Figure 1: A comparison between a Brayton cycle and an actual gas turbine cycle [1]

In a Brayton cycle, air as an ideal gas is used as a working fluid while in an actual turbine, a mixture of various fluids such as air, fuel and combustion products are used. The energy released from these combustion products is then used to provide work. Some of this work goes on to produce shaft work for power while some is used to drive the compressor. The total power generated by the turbine is the addition of those two power values as well as the power

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lost due to friction. Rover 1S/60 (Figures 2,3 and4 – Apparatus) is the gas turbine used for this experiment. The power generated by this turbine can be calculated using the dynamometer loading times the dynamometer RPM. The value of the dynamometer RPM is the one at which a balancing torque is applied to the stator by rotating the water past the stator vanes. The power generated by the turbine is actually called the brake horsepower and is measured at the output shaft of the turbine. This is given by the equation below:

W b=WN4500

(Equation 1)

where W is the dynamometer loading (lbf) and N is the RPM.

The total power generated by the turbine can be found by means of the following equation:

(Equation 2)

where W t is the total power, W cis the compression power and W f is the power lost due to friction. A mass and energy balance equation is generally used to find the compressor power.

The fuel consumption can be found using the concept of brake fuel consumption (BSFC) which can be calculated using the equation:

(Equation 3)

Where mf is the mass flow rate of the fuel and W b is the net rate of work for a given rate of heat transfer.

And finally the overall thermal efficiency of the engine can be calculated using the relationship below:

(Equation 4)

(Note: The theory is derived from references [1] & [2])

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3. APPARATUS

Figure 2: A sketch of Rover 1S/60 Rover Gas Turbine [4]

Figure 3: A general schematic of Rover 1S/60 Gas turbine [5]

Figure 4: Rover 1S/60 gas turbine engine used in the experiment

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4. PROCEDURE

1) Atmospheric temperature and pressure was recorded.2) The type of fuel as well as its heating value and specific gravity was recorded.3) Start sequence of the engine was initiated4) Load is added by means of adding water to the dynamometer5) The torque was balanced using the handwheel6) The load is increases until the maximum turbine exit temperature reached approx. 1100oF.7) Dynamometer load was recorded including 50 lbf of extra loading.8) Dynamometer speed was recorded.9) Air flow meter pressure drop, compressor to turbine pressure drop, turbine exit static pressure and compressor inlet and exit pressures were recorded using the instrumental panel near the engine.10) Compressor inlet and exit temperature values were recorded.11) Turbine exit temperature was recorded12) Fuel pressure was recorded.13) Flow rate was recorded.14) Temperature and pressure values of the engine oil as well as dynamometer water was recorded.15) Engine was shut down and rundown time was recorded.

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5. OBSERVATIONS

Fuel Shell diesel CP-48HHV fuel 19876 BTU/lbmSpecific gravity of fuel 0.811Atmospheric pressure (pa) 30.27 inHgAtmospheric Temperature 23oCDynamometer load 57 lbfDynamometer speed 3000 RPMFuel flow rate 10.6 gal/hAirmeter pressure drop (p) 4.3-(-4.5) inOilCompressor to turbine pressure drop 2.2 –(-2.1) inHgCompressor inlet (impeller tip) pressure (p1) 7 ibf/in2

Compressor exit (comp. delivery) pressure( p2

)26.5 lbf/in2

Compressor inlet temperature (T1) 76 oFCompressor exit (comp. delivery) temperature (T2)

380oF

Turbine exit pressure -1.4-1.4 inOilTurbine exit temperature (T4) 1085 oFDynamometer pressure 44.5 lbf/in2

Dynamometer temperature 111 oFOil pressure 18 lbf/in2

Oil temperature 191oFFuel pressure 200 lbf/in2

Run down time 50.13 s

Table 1 : Observations as recorded during the experiment

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6. RESULTS

Brake horsepower (Ẇb) (Calculation a - Appendix)

38 hp

Mass flow rate of fuel (ṁf)(Calculation b - Appendix)

1.44 lbm/min

Total energy added by fuel ˙(Q¿¿¿)¿¿ (Calculation c - Appendix)

28621.44 BTU/min

Equivalent Brayton cycle efficiency (ŋ) (Calculation d - Appendix)

0.0563

BSFC (Calculation e - Appendix) 0.0379 lbm/(hp.h)

Mass flow rate of air (ṁa) (Calculation f - Appendix)

1.52 lbm/s

Turbine work( Ẇt) (Calculations g & h - Appendix)

171 hp

Turbine inlet temperature (T3) (Calculation i - Appendix)

1380oF

BWR (Back Work Ratio)(Calculation j - Appendix)

0.745

Turbine efficiency using cold-air standard analysis (ŋt) (Calculation k – Appendix)

0.157

Table 2: Results obtained through calculations

Comparison of efficiencies (cold air standard to brake horsepower) = 64%

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7. DISCUSSION & CONCLUSION

Table 2 (Results) represents the values obtained from calculations. The percentage difference between the efficiency calculated from cold-air standard analysis and the one calculated using brake horsepower is 64% (Calculation l – Appendix) which is significant.

This percentage indicates a considerable difference in efficiency using cold air analysis to that of a Brayton cycle analysis but the use of this modeling can still be carried out anyways because cold air analysis assumes turbine to be isentropic as well as ignoring any stray heat transfers between components when compared to the other.

Therefore, the experiment was carried out to a successful completion with all the objectives achieved. This also resulted in achieving a familiarity with the Rover engine which would no doubt be trivial in the study and practical use of other gas turbine engines.

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8. REFERENCES

[1] AER 423: Applied Thermodynamics and Heat Transfer Laboratory Manual – J.V. Lassaline – Ryerson 2011

[2] Fundamentals of Engineering Thermodynamics – Moran/Shapiro – 6th Edition – WILEY

[3] Fundamentals of Engineering Thermodynamics – Appendices – Moran/Shapiro – 6th Edition - WILEY

[4]http://www.ite.tuwien.ac.at/department_of_fluid_flow_machinery/laboratory/thermal_laboratory/EN/

[5] http://www.gasturbine.pwp.blueyonder.co.uk/topten.htm

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APPENDIX

CALCULATIONS

(Note: For calculations h and i, A22E in Ref. [3] was used.)

a) Power required by the load:

W b=WN4500

¿ 57× 30004500

¿38 hp

b) Mass flow rate of fuel:

mf =ρQ

¿ 10.6 galh

× 0.811×10.02lbmgal

×1 hr

60 min

¿1.44lbmmin

c) Total energy added by fuel:

Q¿=mf × HHV

¿ 1.44 lbmmin

×19876BTUlbm

¿28621.44BTUmin

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d) Thermal efficiency for the equivalent Brayton cycle:

ŋ=W b

Q¿

¿38 hp ×

42.41BTUmin

1hp

28621.44BTUmin

¿0.0563

e) Brake specific fuel consumption:

BSFC=mf

W b

BSFC=1.44

lbmmin

×60 min

h38 hp

¿0.0379lbm

(hp·h)

f) Mass flow rate of air:

∆ p=ρgh

∆ ppa

=

0.827 ×10.02lbm

gal×

32.2 ft

s2×8.8∈×

1 gal

231¿3×

1 lbf32.2 ft

s2

30.27 inHg ×0.491

lbf¿2

1inHg

¿0.0210

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Using figure 3.2 in the Ref. [1], it corresponds to 0.1175

0.1175=ma √T 1

x0 × pa

0.1175 lbm K❑o

slbf

=ma √273+ 76−32

1.8K❑

o

15¿2×30.27 inHg ×0.491

lbf¿2

1inHg

¿1.52lbm

s

g) Air to fuel ratio:

AF ratio=mf

ma

¿60 s /1min ×1.52

lbms

1.44lbmmin

¿63.3

h) Power developed by turbine:

Assuming compressor is isentropic, where inlet conditions and the exit pressure are fixed:

p1

p2

=pr (T 1)pr (T 2)

Using table A22E,h1 = 128.34 BTU/lbm

726.5

=1.3593pr (T 2)

pr ( T2 )=5.146

From table A22E,

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T 2 = 784 oRh2 = 187.914 BTU/lbm

W c=ma ( h2−h1 )

¿1.52lb m

s×

60 s1min

× (187.914−128.34 ) BTUlbm

×1 hp

42.41BTUmin

= 128 hp

W t = W c + W b + W f

= 128 + 5+ 38 = 171 hp

i) Inlet temperature of turbine:

T4 = 1085 oF = 1545 oRUsing table A22E,

h4 = 381.1 btu/lbm

W t=ma (h3−h4 )

171 hp ×42.41

BTUmin

1hp=1.52

lbms

×60 s

1 min× ( h3−381.1 )

h3=460.62BTUlbm

Interpolating from table A22E we find that T3 = 1840 oR = 1380oF

j) Back work ratio:

bwr=W c

W t

¿ 128171

¿0.745

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k) Thermal efficiency of the Turbine engine using cold air standard analysis:

ŋt=1−(p2

p1

)1−k

k

ŋt=1−( 26.5+30.27 ×0.4917+30 ×0.491

)1−1.4

1.4

= 0.157

l) Comparison of efficiencies:

percentage difference=ŋt−ŋ

ŋt

×100

¿ 0.157−0.05630.157

×100

¿64 %

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