A helicopter gas turbine requires an overall compressor pressure ratio of 10: 1. This is to be obtained using a two-spool layout consisting of a four-stage axial compressor followed by a single-stage centrifugal compressor. The polytropic efficiency of the axial compressor is 92 percent and that of the centrifugal is 83 percent. The axial compressor has a stage temperature rise of 30 K, using a 50 percent reaction design with a stator outlet angle of 20. If the mean diameter of each stage is 25.0 cm and each stage is identical (assume inlet guide vanes are present to give the required pre-whirl), calculate the required rotational speed. Assume a work-done factor of 0.86 and a constant axial velocity of 150 m/s. Assuming an axial velocity at the eye of the impeller, an impeller tip diameter of 33.0 cm, a slip factor of 0.90 and a power input factor of 1.04, calculate the rotational speed for the centrifugal compressor Ambient conditions are 1,01 bar and 288 K

Answer

over 4 years ago

Ayush