Study on alternative cycles for high-pressure low-temperature helium compressor performance experiments based on flow similarity

A low-temperature high-pressure helium compressor is one of the key components in a hypersonic air-breath engine cycle. Its aerodynamic performance is the basis of engine cycle design and control. The low-temperature and high-pressure conditions make it difficult in a laboratory environment to conduct a compressor performance experiment, thus constraining the engine cycle design. An alternative method is to test the compressor with other gas at a reference operation condition and then calculate the helium compressor performance according to the test results using transformation laws. This paper investigates the transformation method based on the dynamic similarity principle and derives transformation equations. CFD simulations performed on the compressors validate the equations. Eventually, the study analyzes the alternative experimental cycles.