1.5级涡轮轮缘密封燃气入侵特性的数值研究

Numerical Investigation for Ingestion Characteristics of 1.5-Stage Turbine Rim Seal

通过雷诺应力湍流模型(SST)求解三维URANS(unsteady Reynods-averaged NavierStokes)方程组,研究了1.5级涡轮双重径向轮缘密封的非定常封严特性,采用附加变量法研究了主流入侵程度,数值模拟获得的动叶前、后腔时均预旋比和静压系数与实验数据吻合,验证了1.5级涡轮动静交界面设置和数值方法的有效性,并在此基础上研究了变工况对动叶下游压力分布与后腔封严效率的影响规律。结果表明:后腔轮缘密封的封严效率高于前腔;后腔上游主流周向压差的开方与主流流量系数成正比;冷气量不变时,随着主流流量的增大,后腔的封严效率逐渐降低至0.4后变化趋缓。

Characteristics of hot gas ingestion through turbine rim seals in a 1.5-stage turbine are numerically investigated with the unsteady Reynolds-averaged Navier-Stokes（URANS）equations and the SST turbulence model.The additional passive tracer is used to simulate the distribution of mainstream ingestion and the case mixed with sealing flow.The numerical results of the distributions of pre-swirl ratio and pressure in the front and aft wheel-spaces agree well with experimental results,so the relative position of domain interface and the effectiveness of the unsteady numerical calculation of the 1.5-stage turbine rim seal are verified.The unsteady pressure distribution and seal efficiency in the aft wheel-space under off-design conditions are analyzed,and the results show that：1）The seal efficiency in the aft wheel-space is higher than that in the front wheel-space;2）Extraction of square root of the mainstream circumferential differential pressure at upstream of the aft wheel-space is proportional to mainstream flow coefficient;and 3）With the increase in the main flow rate,the seal efficiency of the rear cavity is gradually reduced to 0.4,and then the change is slowed down at the same cooling flow rate.