Numerical Investigation of Unsteady Interaction between Rim Seal Flow and Upstream Vane

轮缘封严气流与上游导向器非定常干涉数值研究

School of Power and Energy, Northwestern Polytechnical University, Xi’an 710072, China

Received: 4 March 2018

Abstract

To investigate unsteady interaction mechanism between the rim seal flow in turbine stator-rotor cavity and main flow, detailed unsteady numerical simulations of the flow field and unsteady characteristic of the vane were conducted under different rim seal mass flow rate. The results show the blockage effect resulting from the egress flow leads to the pressure to increase and static entropy to reduce on the latter half of suction side near the hub. From the case without a cavity to R_I=1.7%, at 5% span, the maximum pressure coefficient increase on the suction side reaches 6%. Moreover, the blockage effect causes the velocity to decrease at vane exit. Furthermore, the rim seal flow results in the decrease in lateral pressure gradient, causing the strength of hub passage vortex and hub trailing shedding vortex to reduce. Without rim seal flow, the ingress flow contributes to decreasing unsteady fluctuation from the hub to 10% span. When there is rim seal flow, unsteady fluctuation continues to reduce due to coupling effects of the egress flow from the ingress and the egress flow form the cavity inlet.

摘要

为了研究涡轮转静盘腔中的轮缘封严气流与主流的非定常干涉效应，在不同封严流量下对上游导向器的流场分布和非定常特性进行了数值模拟。结果表明，封严出流的堵塞作用引起吸力面后半段轮毂附近静压的升高和熵增的减小，以及导向器出口速度的降低。从无封严腔体到R_I=1.7%，5%叶高吸力面静压系数最大增加了6%。封严出流造成横向压力梯度减小使得轮毂通道涡和轮毂尾缘脱落涡的强度减弱。不存在封严气流时，燃气入侵使得10%叶高以下范围非定常波动降低；存在封严气流时，来自燃气入侵和腔体进口的封严出流的耦合作用使得非定常波动不断减弱。