Numerical Investigation of Bleed Rate on Performance of Multistage Axial Compressor
The research focuses on the first 3.5 stages of NASA 74A compressor,utilizing the source term method to explore the impact of the interstage bleed rate on compressor overall performance and internal flow characteristics.The results demonstrate that as bleed rate increases,there are more significant changes in compressor overall performance.Specifically,compared to the peak efficiency point without bleeding,the mass flow range expands by 25.72%,efficiency rises by 5.6%and total pressure ratio increases by 2.76%at 10%bleed rate.Efficiency in-creasing can mostly be attributed to mass flux increasing which is caused by attack angle reduction and control of flow separation.Additionally,interstage bleeding enhances stall margin,with an optimal bleed rate of 8%resulting in a stall margin increase of 21.80%.It should be noted that the increase in inlet mass flow and bleed rate is not in agreement completely,but both are essentially equalized at the peak efficiency point.For lower mass flow points,the bleed rate is lower than the increment in inlet mass flow,while the phenomenon behaves the opposite way for higher mass flow points,which determines the variations of outlet mass flow and impacts on total pressure ratio in the meanwhile.Furthermore,bleeding has a greater influence on circumferential angle deviation compared to radial angle deviations which caused by bleeding are primarily concentrated near bleed positions.
multistage axial compressorbleed ratesource term methodstall marginoverall performanceaxial velocity
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