AEROSPACE PROPULSION PROJECT due 10/30/2002 (Wed.)

COMPUTER ANALYSIS OF A TURBO-FAN ENGINE

Develop a computer program for the analysis of a turbo-fan (also turbo-jet). Assume component efficiencies remain constant and the inlet Mach number is subsonic. Use the following data

Fan Efficiency / hf=0.90 / gcold, , ghot / 1.4 1.3
Compressor Efficiency / hc=0.88 / Pressure drop in combustor / 0.98
Turbine Efficiency / ht=0.94 / Turbine inlet temperature / 2400 K
Diffuser Efficiency / hd=0.97 / Fan pressure ratio / 1.95
Nozzle efficiency / hN=0.99 / Inlet diameter (inches) / 86.4
QR Heating Value KJ/Kg / 45000

Calculate the mass flow assuming that the properties and Mach number at the inlet are nearly the same as those far upstream of the engine. Allow the variation of by-pass ratio b, compressor pressure ratio, Mach number and investigate the following.

a.  Assume a turbo-jet configuration first (b=0) and that the fan is removed. Vary compressor pressure ratio and plot a graph of [TSFC, T/ma] versus compressor pressure ratio at various Mach numbers, at an altitude of 35000 feet. Comment on the optimum pressure ratio and interpret the results.

b.  Repeat the same procedure for [TSFC, T/ma] with turbine inlet temperature To4= 1950 K at sea level.

c.  In part (a) keep the compressor pressure ratio at the optimal value with respect to TSFC and plot the performance of the engine [TSFC, T/ma] at various altitudes (10000, 20000, 30000 feet) and at various Mach numbers (M=0.2, 0.6 and 0.95) at each altitude.

d.  Using the optimum compressor pressure (with respect to TSFC) obtained for the turbo-jet (part a), investigate the effect of by-pass ratio b of the turbo fan on [TSFC, T/ma] at M=0.90 and at an altitude of 30000 feet. Plot the results.

e.  Fixing all the variables in the program except the altitude, plot the thrust developed by a turbo-fan engine at various altitudes. Choose parameters that are typical in modern engines and use optimum values (from items a to d).

NOTES:

Make any reasonable approximation/assumption in the analysis of these engines, but clearly state these in the report.

This project needs to be performed by each student. Although we encourage team work, we expect that every student will write his own computer program in this specific effort.

Include the following in the final report:

1.  Equations/models used

2.  Assumptions made

3.  Computer program list ( or spreadsheet output)

4.  Graphs with proper labels, titles and units

5.  Proper interpretation of each graph

6.  Results/final conclusions.