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为了评估可调向心涡轮导流叶片叶顶及叶根间隙尺寸不确定性对涡轮级性能的影响,首先将喷嘴环叶片大开度模型的单通道定常数值结果与实验数据对比;然后以导流叶片小开度涡轮为研究对象,数值模拟导叶两端叶顶间隙尺寸多种分配模型三维流场,总结出导叶间隙不确定性与涡轮级性能之间相应变化规律;最后选取导叶两端间隙平均分配模型和最优涡轮性能下间隙分配模型开展多通道定常/非定常计算,用于分析间隙分配变化对转静干涉影响。研究结果表明:当导流叶片轮缘侧间隙尺寸占全部间隙尺寸5%~15%范围时,涡轮级效率较高;当导叶间隙全部集中在轮缘侧时,涡轮效率较低;最高、最低效率差别约为6%。间隙泄漏流变化将引起下游转子叶片进口气流角发生变化,进而改变转子叶片吸力面前缘分离涡损失大小。此外,导叶两端间隙分配变化可以改变嘴环叶片吸力面激波强度,并通过诱发交变载荷变化方式影响转子叶片可靠性。
In order to evaluate the influence of the uncertainty of the blade tip and root clearance on the performance of the turbine, the single-channel steady-state numerical results of the large opening model of the nozzle ring are compared with the experimental data. The flow field of turbine blade is taken as the research object to simulate the three-dimensional flow field of the multi-distribution model of tip clearance size at both ends of the guide vane numerically, and the corresponding variation rules between the uncertainty of the guide vane clearance and turbine performance are concluded. Finally, Two-end gap average distribution model and optimal turbine performance gap allocation model to carry out multi-channel steady / unsteady calculation, for the analysis of gap allocation changes on the interference of static and rotational interference. The results show that the efficiency of the turbine stage is high when the clearance of the guide vane rim is 5% ~ 15% of the total clearance, and the turbine efficiency is low when the guide vane clearance is all concentrated on the rim. The difference in minimum efficiency is about 6%. The change of gap leakage flow will cause the inlet airflow angle of downstream rotor blade to change, and then change the size of the separation vortex loss on the leading edge of suction side of rotor blade. In addition, the variation of the clearance distribution at both ends of guide vanes can change the shock wave intensity on the suction surface of the mouth ring blade, and affect the rotor blade reliability by inducing the change of alternating load.