1.5级涡轮前后轮缘密封封严流动特性研究

Flow Characteristics of Front and Aft Rim Seal for 1.5-Stage Turbine

关键词:  涡轮  轮缘密封  燃气入侵  封严效率  数值模拟

Key words:  Turbine  Rim seal  Gas ingestion  Sealing efficiency  Numerical simulation

摘要:

为了研究前后腔轮缘密封封严特性和封严出流与主流的交互作用，对转静叶片之间带有前后封严腔的1.5级涡轮进行了三维定常数值模拟，研究了不同封严流量下前后封严腔出口处流场分布并采用附加变量法对比分析了前后腔轮缘密封效率。结果表明：前封严腔主流燃气入侵位置主要受到来自上游导叶尾迹的影响，后封严腔主流燃气入侵位置主要受到下游导叶前缘位势场影响；封严出流影响了20%叶高以下的主流区域，增大了轮毂二次流强度；采用相同封严流量下时前封严腔的封严效率较后腔更低且有着更大的封严效率波动。

Abstract:

Three-dimensional steady simulation of 1.5-stage turbine stage with front and aft cavity has been carried out for the purpose of the seal characteristics of the rim seal and the interaction between the purge flow and the main flow. The flow field distribution at the outlets of the front and aft seal cavities under different sealed flow rates was studied， and the sealing efficiency of the front and aft cavities are compared and analyzed using the additional variable method. The results show that the position of mainstream gas injection in the front seal cavity is mainly affected by the wake of the upstream vane， and the position of mainstream gas injection in the aft seal cavity is mainly affected by the potential field of the downstream vane. The purge flow affects the mainstream area below the 20% span of blades and increases the secondary flow intensity of the hub. At the same purge flow rate， the sealing efficiency of the front seal cavity is lower than that of the aft cavity and has a greater fluctuation in sealing efficiency.