脉动背压下涡轮增压离心压气机入口流场试验

为了研究离心压气机在强脉动背压下的入口流场分布,研制了用于非定常流场测量的全自动二维步进装置。使用该装置结合一维热线风速仪测量了不同脉动频率、时均流量下离心压气机入口非定常流场分布。结果表明：背压脉动时,离心压气机入口速度与气流角在周向及径向分布形态均随背压变化呈大幅周期性振荡,且气流角在叶尖处的变化幅度显著高于叶根处。蜗壳上游周向角区内轴向速度显著低于下游,且该周向畸变强度随频率及时均流量增加而增强。径向气流角最大差异出现在约85%叶高处:小流量时最大气流角差异为8°,大流量时为12°。研究探明了脉动背压工况下离心压气机入口流场的非定常演化规律,为针对实际工况的压气机优化设计理论提供了试验基础。

Experiment on inlet flow field of turbocharger centrifugal compressor under pulsating backpressure,

To study the inlet flow field distribution of centrifugal compressor under strong pulsating backpressure, an automatic two-dimensional traversing system for unsteady flow field measurement was developed. The unsteady inlet flow field of the centrifugal compressor under different pulsating frequencies and time-averaged mass flow rate was measured by the traversing system with one-dimensional hot-wire anemometer. The results showed that: both circumferential and radial distributions of inlet velocity and flow angle experienced large periodic oscillations due to the pulsating backpressure. The fluctuation of flow angle was significantly higher at tip than that at the hub. The axial velocity in the circumferential angular region upstream the volute tongue was significantly lower than that in the downstream, and the distortion intensity further increased with the increase of frequency and time average mass flow rate. The maximum radial flow angle difference occurred at about 85% blade height: the maximum flow angle difference was 8 degrees at low mass flow rate and 12 degrees at high mass flow rate. The study proved the unsteady evolution of the inlet flow field of the centrifugal compressor at the conditions of pulsating backpressure, giving the experimental foundation for the theory of the optimal design of the compressor.