低速离心压气机叶尖小翼设计与扩稳机理研究

Design of Blade Tip Winglet for Low Speed Centrifugal Compressor and Mechanism of Stability Enhancement

关键词:  离心压气机  叶尖小翼  叶尖泄漏涡  流动阻塞  数值模拟

Key words:  Centrifugal compressor  Blade tip winglet  Tip leakage vortex  Flow blockage  Numerical simulation

摘要:

为了揭示叶尖小翼对离心压气机气动性能的影响机理，采用数值模拟方法研究了NASA低速离心压气机（LSCC）附加不同叶尖小翼的气动特性，并在分析离心叶轮失稳机制的基础上探究了叶尖小翼的扩稳机理。研究结果表明：平顶型小翼对离心压气机性能影响较小，凹槽型小翼均使得压气机效率有所降低。凹槽型压力面小翼方案使得压气机综合稳定裕度增加5.4%，凹槽型吸力面小翼方案使得压气机综合稳定裕度降低9.4%。叶顶间隙泄漏所导致的流动阻塞是影响LSCC叶轮失稳的关键因素。凹槽型压力面小翼方案中叶片前缘处部分叶顶泄漏流体进入叶顶凹槽处形成凹槽涡和叶顶分离涡，减弱了离心叶轮叶顶泄漏涡形成时的强度。

Abstract:

In order to reveal the influence mechanism of the blade tip winglet on the aerodynamic characteristics of the centrifugal compressor， a numerical simulation of aerodynamic performance of NASA LSCC（Low-Speed Centrifugal Compressor） with different tip winglets was carried out. Based on the instability mechanism of the low-speed centrifugal compressor impeller， the mechanism of stability enhancement by the blade tip winglet was explored. The research results show that the flat-top winglet has little effect on the performance of the centrifugal compressor， and the grooved winglet reduces the compressor efficiency. The grooved pressure-side winglet increases the compressor’s comprehensive stability margin by 5.4%， and the grooved suction-side winglet reduces the compressor’s comprehensive stability margin by 9.4%. The flow blockage caused by the tip clearance leakage is a key factor affecting the instability of the LSCC impeller. For the grooved pressure-side winglet case， part of the tip leakage fluid at the leading edge of the blade enters the tip groove to form a groove vortex and a tip separation vortex， which reduce the strength of the centrifugal impeller tip leakage vortex formation.