Design and Analysis of Outlet Air Collector Duct for Axial Compressor Test Rig

Abstract

AbstractCompressor test rigs are commonly used for evaluating the performance of axial and centrifugal compressors at different operating conditions. Axial flow compressors are tested in rigs by driving the test compressor and throttling the exhaust flow, thus creating a higher back pressure or loading to the compressor. Collector box is an important unit which collects the exhaust air from compressor outlet and directs the flow to throttling valves present at downstream location. It plays a major role in compressor testing by providing intended aerodynamic loading at the exit of compressor. This paper discusses in detail about the design of collector box for a given compressor configuration and the influence of various geometrical parameters on compressor loading. A baseline collector box configuration was studied and compared with other similar configurations. Static pressure distortion and total pressure loss coefficient were considered as major design parameters. 3D RANS analysis was carried out to estimate the performance of collector box. Further, the effect of collector box length, outlet configuration, and outlet duct area on collector box performance is studied. Greitzer ‘B’ parameter is evaluated for all cases to estimate the dynamic instability effects of flow inside the ducting system. Finally, a new configuration with variable outlet duct volume was designed which gave better static pressure uniformity at the compressor exit.KeywordsCollector boxAxial flow compressorCompressor testingStatic pressure distortionGreitzer ‘B’ parameter