Flow measurement and simulation of a radial inlet for centrifugal compressor

摘要

This paper presents an experimental and numerical research on the internal flow of a typical radial inlet for centrifugal compressor. Detailed flow measurements were carried out with five-hole probes, consisting of 106 sampling holes and 2178 measuring points. Automatic calibrating and measuring systems, which made the probe calibrations, measurements and data acquisitions controlled by computer, were developed and used to accelerate the flow measurements. Since separations and vortices in the radial inlet were not able to be accurately measured by five-hole probes, numerical simulation was adopted to assist in the flow analysis of the radial inlet in the present study. The investigation indicated that there were five main flow separations and vortices in the present radial inlet. Four of them were generated in the plenum, making the plenum the primary cause of the flow loss and the major factor of the flow distortions in the radial inlet. The last flow separation was generated on the inlet side of the flange at the 90 degrees turning and extended to the exit of the axial duct. Besides, the symmetrical tangential flows in the radial inlet made positive and negative yaw angles with absolute value up to over 15 degrees distributed in the tangential direction of the radial inlet's exit, which will probably increase the incidence loss in the blade passages and negatively affect the work capability of the impeller. Based on the flow analysis and discussions, preliminary suggestions are proposed to provide references for the improvements of radial inlet.