叶尖间隙分布对内燃机增压压气机性能影响

采用三维CFD(计算流体动力学)方法,对两种相反叶尖间隙分布方式的无叶扩压器压气机级进行了详细流场分析,研究了叶尖间隙分布对跨声速离心压气机叶轮及扩压器性能的影响机理.结果表明,非均匀分布弦向间隙分布叶轮有较宽的稳定工作范围;出口轴向间隙小于进口径向间隙的压气机级压比和效率明显高于出口轴向间隙大于进口径向间隙的压气机级.较小的出口轴向间隙削弱了叶轮通道后半段间隙流动,显著提高了叶轮后部做功能力,获得更高的级压比;并使叶轮后部间隙涡强度及涡在叶轮通道和扩压器通道内耗散损失小,压气机级效率更高.

Research on the effect of centrifugal compressor blade tip clearance distribution on conbustion engine turbocharger performance

Based on three-dimensional CFD method, the flow fields of two opposite impeller blades tip clearance distribution compressor stages with vaneless diffuser were analyzed. The law and action mechanism of tip clearance distribution effect on the high charging ratio transonic centrifugal compressor impeller and vaneless diffuser performance were researched. It is verified that non-uniform chord direction blades tip clearance distri-bution impellers have wider operating range. The pressure ratio and efficiency of compressor stage whose outlet axial clearance height is smaller than inlet radial clearance height is higher than that of compressor stage whose outlet axial clearance height is larger than inlet radial clearance height. The smaller outlet axial clearance height weakens the flow in aft half of impeller passage, improves impeller aft passage power input and obtains higher impeller pressure ratio and compressor stage pressure ratio. The smaller outlet axial clearance height gets higher efficiency for which reduces impeller aft blades tip clearance leakage vortices intensity and imposes the vortices breakdown and dissipation loss less in impeller passage and vaneless diffuser passage. The research of the im-peller blades tip clearance distribution effect on vehicle transonic centrifugal compressor performance and flow structure lays a foundation for internal combustion engine high performance turbocharger design.