Optimizing a Suction Channel to Improve Performance of a Centrifugal Compressor Stage

Design parameters for a suction channel of process centrifugal compressors were investigated, and an optimizing method to improve efficiency by using the new design parameters was proposed. Both pressure loss and circumferential flow distortion in the suction channel were evaluated by using computational fluid dynamics (CFD). The main dimensions, which had a large influence on pressure loss and circumferential flow distortion, were identified by using design of experiments (DOE). Next, the passage sectional area ratios A_c/A_e, A_e/A_s, and A_c/A_s were found to be the dominant design parameters for the pressure loss and circumferential flow distortion, where A_c, A_e and A_s are passage sectional areas for the casing upstream side, casing entrance and impeller eye, respectively. Then the shape of the suction channel was optimized using A_c/A_e, A_e/A_s, and A_c/A_s. Finally, to evaluate the improvement effect of optimizing the values of A_c/A_e, A_e/A_s, and A_c/A_s on compressor stage performance, a base suction channel and an optimized type of suction channel were manufactured and tested. The design suction flow coefficient was 0.1 and the peripheral Mach number was 0.78. Test results showed that the optimized suction channel achieved 3.8% higher stage efficiency than the base one while maintaining the overall operating range from surge to choke. The method for optimizing suction channels by using the three described design parameters was concluded to be very effective for improving the stage efficiency.