槽缝射流和泄漏间隙对轴对称涡轮端壁换热特性的影响

Effects of Slot Injection and Leakage Gap on Heat Transfer Characteristics of an Axisymmetric Turbine Endwall

为了研究槽缝射流和泄漏间隙对一级涡轮导叶轴对称端壁换热特性的影响,利用R35C15W型宽带液晶和稳态测温技术在高速叶栅风洞试验台进行了端壁换热特性的实验研究。在无槽缝射流时,研究了叶栅进口雷诺数(Re=2.2×10^(5),2.8×10^(5)和3.4×10^(5))对端壁换热特性的影响;在有槽缝射流条件下研究了射流质量流量比(0.6%,0.85%和1.07%)和泄漏间隙宽度(3.93和7.86mm)对端壁换热特性的影响。实验结果表明,受到泄漏涡的影响,吸力面附近端壁区域的换热系数明显高于靠近压力面的端壁区域,并且随雷诺数的增大,压力面和吸力面附近区域的换热增幅分别为18%和15%。槽缝射流削弱了马蹄涡和泄漏涡强度的同时,增强了端壁附近流场的扰动,从而提高了端壁表面的换热系数。相比于无冷气射流,随着射流质量流量比的增大,前缘上游区域的换热增幅为12%,34%和40%,压力面附近区域的换热增幅为15%,33%和42%,吸力面附近区域的换热增幅为11%,24%和31%。此外,降低泄漏间隙宽度使叶片前缘上游区域的换热系数降低了17%。

In order to investigate the effects of slot injection and leakage gap on the heat transfer characteristics of an axisymmetric vane endwall of first-stage turbine,an experiment was conducted in a high-speed wind tunnel using steady-state temperature measurement technology with the R35C15W type wide-band liquid crystal to study the heat transfer performance of the endwall.For the cases without slot injection,the effects of the Reynolds numbers(Re=2.2×10^(5),2.8×10^(5) and 3.4×10^(5))on endwall heat transfer characteristics were investigated.For the cases with slot injection,the influences of mass flow ratio(0.6%,0.85%and 1.08%)and leakage gap width(3.93mm and 7.86mm)were studied respectively.The results show that endwall heat transfer coefficient of the region near suction surface is higher than that of the region near pressure surface under the effect of leakage vortex,and with the increase of the Reynolds number,the heat transfer amplification rate of the area near the pressure surface and suction surface are 18%and 15%,respectively.The slot injection enhances the disturbance of flow field on the endwall surface while diminishing the strength of the horseshoe vortex and the leakage vortex,which leads to the augmentation of endwall heat transfer coefficient.With the increase of the jet mass flow ratio,the heat transfer increase rate in the area upstream of the leading edge are 12%,34%and 40%,in the area near the pressure surface are 15%,33%and 42%,in the area around the suction surface are 11%,24%and 31%compared with the non-cooled jet.Moreover,decreasing the width of leakage gap reduces the heat transfer coefficient upstream of the vane leading edge by 17%.