Investigation on the Reduction of Trailing Edge Shock Losses for a Highly Loaded Transonic Turbine

Abstract

A shock loss reduction method for highly loaded transonic turbine blades with convergent passages is presented. The method is illustrated with an improved blade profile that employs a negative curvature curve on its uncovered suction side. The improved profile and a conventional baseline profile are applied to two cascades with the same solidity, chord and aspect ratio respectively. The numerical simulation results for the two cascades show that a reduction of 4.58% in the total pressure loss coefficient is obtained for the improved profile at the design condition. The effects of back pressures on the performance of both cascades are also presented, and the improved blade profile shows a much better part-load performance. The paper compares the flow fields of the baseline and the improved blade profiles to understand loss reduction mechanism especially by analyzing the shock interactions downstream of the trailing edge. It is found that, for the improved profile, the reflected shock of pressure side leg of the trailing-edge shock rotates forward and the suction side leg of the trailing-edge shock rotates backward. Therefore, the two shocks delay their intersection points where they merge into a relatively strong shock, and consequently produce less shock losses than those of the baseline profile.