The Following data apply to the auxiliary power unit (APU) on the Boeing 777 (si
ID: 1862957 • Letter: T
Question
The Following data apply to the auxiliary power unit (APU) on the Boeing 777 (single shaft unit, driving seperate load compressor and generator):
Load Compressor
Mass flow: 3.5 kg/s
Pressure Ratio: 3.65
Isentropic efficiency: 0.88
Gas Turbine
Pressure Ratio: 12.0
Compressor isentropic efficiency 0.84
turbine inlet temperature: 1390k
turbine isentropic efficiency: 0.87
Combustion delP/compressor delivery pressure: 0.05
Turbine exhaust pressure: 1.04 bar
When operating at 35 degrees celsius and 1.01 bar at take off conditions, the unit must apply 200kW electrical load. Calculate the airflow required for the gas turbine and the specific fuel consumption
(3.1 kg/s, 0.304 kg/kwh)
Explanation / Answer
The Following data apply to the auxiliary power unit (APU) on the Boeing 777 (si