The Effect Of Through Flow Geometry Form For Highly Loaded Centrifugal Compressor

Centrifugal compressor in the industry has widely application, especially used inturbochargers and shaft turbine engine and turboprop engine. Along with the rapiddevelopment of science and technology, the centrifugal compressor performance isrequired more and more in the national economy and defence technology. Moderncentrifugal compressor is developing toward higher loading so that the flow inimpeller channels tends to be complicated, it is important and crucial to improve andenhance the performance of the compressor and realize the complex flow of internalchannels. In recent years effective numerical calculation and experimental researchdeveloped in centrifugal compressor design theory and methods at home and abroad.In this paper the low speed centrifugal impeller NASA LSCC and Krain H’shigh pressure ratio centrifugal compressor were caculated for numerical verifycation.Through the analysis of internal flow condition further understanding of the loss islearnd and the blade tip leakage is inevitable, in high speed conditions, the loss andthe separation flow mainly caused by shock waves and mutual interference with theboundary layer, the secondary flow and wake loss and the interaction betweenimpeller and diffuser leads to the major loss source.To improve the performance of the highly loaded centrifugal impeller, designmethods were discussed. Based on the commercial software, the different shape ofleading edge and trailing edge were considered such as blunt form, round, oval andso on.Oval shape increases the pressure ratio by5%than blunt form, and efficiency2%. The effect of the sweep of leading edge in centrifugal compressor was explored,through the different sweep degrees and distinctive blade height can control the lossand change the blade tip shock wave structure, forward sweep makes the mass flowrate increased by2%, the maximum efficiency increased by1%. Based on the highpressure ratio centrifugal impeller, it can make the impeller weight reduced by11%at most and the maximum efficiency increased by2%. In addition, sweep of leadingedge was explored in splitter blades in the optimal complex form impeller, the resultshows that suitable form of splitter blade can adjust the divided flow passage, andfurther improve the performance centrifugal impeller.The interaction between the impeller and vaned diffuser was studied, which willplay an important role on the stage performance. Diffuser design has a significantmeaning to improve centrifugal compressor loading, wing type and splitter diffuserhave obvious advantage to reduce loss and can enhance the performance.