雷诺数对带蜗壳的离心压气机内部流场影响研究

Effects of Reynolds Number on Internal Flow Field of Centrifugal Compressor with the Volute

为了探讨离心压气机性能随雷诺数的变化规律,对带蜗壳的全周流道流场进行数值模拟,分析雷诺数对内部流场结构的影响。结果表明:压气机工作于Re=5.7×104和Re=1.3×104下的最高效率比Re=1.4×105分别下降了4.5%和8.5%,所有工况在10%叶高附近效率最高。受到蜗壳的影响,全周流道计算所得压气机的效率值和工作范围均小于单流道计算结果。低雷诺数时,气流抗逆压梯度能力迅速减弱,叶顶泄漏流向下游发展过程中,会绕过相邻叶片前缘或顶部间隙进入其他流道;叶片表面约化静压沿径向的梯度增加,从而造成更严重的二次流动;前缘激波强度、附面层厚度和尾迹宽度均增加,流道内出现激波,压气机性能严重恶化。

The flow field of a whole flow passage centrifugal compressor with its volute was simulated numerically to investigate the changing trends of the performance at different Re.Effects of Re on the internal flow were analyzed in detail.The results show that,compared with Re = 1.4 × 105,the peak efficiencies of the compressor are down 4.5% with Re = 5.7 × 104 and 8.5% with Re = 1.3 × 104,respectively.The highest efficiency point is near 10% blade span in all working conditions.Due to the influence of the volute,efficiency and working range of the compressor are lower than the calculation results of single passage.In the case of low Re,the air flow ability to resist the adverse pressure gradient decreases rapidly.The leakage flow at one blade tip clearance would bypass the leading edge or blade tip of its adjacent blade with the flow developing downstream.More serious secondary flow is caused by increasing the reduced static pressure gradient on the blade surface along radial direction.The performance of the compressor significantly deteriorates owing to increasing shock intensity,boundary layer thickness and wake width.