Abstract :
Bleed air is a components affected of the performances engine. Bleed air is
pressurized air taken from the compressor. On cruising condition, the bleed air is
used for pressurization and AC (Air Conditioner). Because the decrease percentage
of the pressure on the compressor, it will influence the value of other parameters.
The method used in this research was Parametric Cycle Analysis of Real
Engine, through manual and numerical calculation methods. This research
analyzed the performance of engine JT8D-15 within bleed air on and bleed air off
condition which had been affected by variations of cruising altitude.
The results of calculations from JT8D-15 engine performance the effect of
bleed air for thrust was higher when the aircraft's altitude rises, both in the bleed
off and on condition. The values are at the altitude of 27000 ft, 31000 ft and 35000
ft when bleed on are 10638,668 lb, 10954,356 lb, 11266,251 lb, otherwise when
bleed off are 10964,851 lb, 11278,715 lb, 11588,257 lb. SFC (specific fuel
consumption) on bleed off has a lower value than the SFC value of bleed on. Values
of SFC at an altitude of 27000 ft, 31000 ft and 35000 ft when bleed on are 1,078
(Ibm / h) / lbf). 1,073 (lbm / h) / lbf), 1,068 and for bleed off are 1,055 (lbm / h) /
lbf), 1,051 (lbm / h) 1bf), 1,047 (lbm / h) / lbf). TSFC (Thrust Specific Fuel
Consumption) in maximum power setting is higher than in lower power setting.
Values at altitudes for 27000 ft, 31000 ft and 35000 ft on the lower power setting
are 1,154 (lbm / h) lbf), 1,142 (lbm /h)/lbf), 1,143 (lbm /h)Ibf) and for the maximum
power setting are 1,840 (lbm/h)/lbf), 1,182 (lbm/h)/lbf), 1,182 (lbm/h)lbf)