The influence of the equivalent sand roughness of compressor impeller on the characteristics of centrifugal compressor low-emission stage. a numerical analysis

The results of numerical analysis for the influence of the equivalent sand roughness of compressor impeller on the characteristics of centrifugal compressor low-emission intermediate type stage are presented . Low-emission stags are widely used in high-pressure compressors as the final stages . Compressors of the type are used for natural gas injection as well as in the production of methanol , ammonia , high pressure polyethylene and other processes . Operating ef ficiency of low-emission stages is lower than the one of medium - tificatio n of the mathematical model for the flow path is made and the results of low-emission stage tests are presented . In the second part of the article a modelling of a viscous gas flow under various values of equivalent sand roughness k s for all internal surfaces of the impeller is carried out . N 2 perfect gas is used as a medium for modelling . The operating pressure at the stage inlet is four atmospheres . The characteristics of the stage for four various values of k s are obtained and the losses in the impeller are evaluated . When the values of k s increase a uniform decrease of polytropic pressure head and efficiency coefficient are not observed for all characteristic of the low-emission stage . The characteristics are much lower in the high flow zones and do not differ greatly at minimum flow. The dependence of internal head coefficie nt on k s is low . of design head coefficient on conditional discharge coefficient. k s for the internal surfaces of the 2·10 -6 m impeller