扩压器对基本级性能的影响

Influence of diffuser on basic stage performance

使用数值方法和试验手段研究了带无叶扩压器和不同进口安装角的叶片扩压器对基本级的性能影响.针对带无叶扩压器的基本级,重点研究了近喘振点、设计点、近阻塞点3种工况的内部流动特性,结果表明近喘振点的叶轮叶片进口、叶轮叶片出口、回流叶片背面均存在低速涡流区,而设计点和近阻塞点的流动状态良好,对于近阻塞点,流动速度较大引起的摩擦阻力损失增大,导致了基本级多变效率下降很快;对带单圆弧叶片扩压器的基本级,细致地研究了匹配不同进口安装角的单圆弧叶片扩压器对喘振裕度、阻塞裕度和效率的影响,结果表明:在出口安装角不变的情况下,扩压器进口安装角比设计值降低3°,基本级的多变效率和多变能头系数达到最佳值.

The effects of vaneless diffusers and vaned diffusers with different entrance installation angles on a centrifugal compressor basic stage were studied with numerical calculations and tests.For compressor basic stage with vaneless diffuser,inner flow-field characteristics at nearsurge point,design point,and near-choke point were analyzed,showing that vortex existed in the inlet and outlet of impeller blade and back of reflux blade at near-surge point while flow state was good at design-point and near-choke point;as for near-choke point,friction resistance loss increased with large flow speed,causing stage efficiency drop quickly.For compressor basic stage with single arc vaned diffuser,the effects on surge margin,choke margin and efficiency were analyzed with five different vaned diffuser entrance installation angles.The results show that when entrance installation angle of vaned diffuser decreases 3degrees than the design value while outlet installation angle is fixed,the polytropic efficiency and polytropic energetic coefficient of stage achieve the best value.