高负荷带转速差的离心串列叶轮流动机理研究

Mechanism of Highly-Loaded Centrifugal Compressor Stagewith Differential-Rotating on Tandem Impellers

关键词:  高负荷  带转速差  串列叶轮  射流-尾迹  数值模拟

Key words:  Highly-loaded  Differential-rotating  Tandem impellers  Jet-wake  Numerical simulation

摘要:

为了充分利用材料应力极限，探索高负荷离心压气机的设计方法，在常规离心叶轮的基础上，利用新的设计思路实现了带转速差的离心串列叶轮设计，采用经过校核的数值计算方法，对带转速差的离心串列叶轮压气机内部流动进行了详细数值模拟，从性能与流场细节分析了传统离心叶轮与带转速差的离心串列叶轮的差异。结果表明：相比于常规叶轮，合理布局的带转速差的离心串列叶轮在设计点整级等熵效率提高了1.96%，压比提高了0.14；激波与附面层相互作用引起的损失减小，二次流引起的“射流-尾迹”流动结构得到抑制；叶片载荷分布得到重新分配，改善了叶轮出口流场品质，降低了叶轮出口处绝对马赫数，扩压能力与无叶扩压段的总压恢复系数得到进一步提升，从而有效提高了整级压气机全工况性能。

Abstract:

In order to make breakthroughs in the limitation of the rim speed of the centrifugal impeller due to the material stress level and advance the understanding of the fundamental mechanism of the highly-loaded centrifugal compressor stage,a highly-loaded centrifugal compressor stage with differential-rotating on tandem impellers with impeller of conventional design were investigated at design speed numerically. The differential-rotating on tandem impellers were designed using the new idea design method. Comparison and analysis for the performance and flow field between different impeller configurations showed that the whole-stage isentropic efficiency at the design point with the rational distribution of the differential-rotating on tandem impellers increased by 1.96%, the pressure ratio increased by 0.14. The losses caused by layer interactions between shock wave and boundary layer are reduced. In addition the “jet-wake” flow structure caused by secondary flow is suppressed, and the blade load distribution is redistributed, the non-uniform flow at the impeller exit is improved, and the absolute Mach number at the impeller exit is also reduced. The capacity of impeller diffusion is further improved, which contributed to the gain of the efficiency and performance of compressor stage.