连续收缩扩张气膜孔排冷却特性的数值模拟
Numerical Simulation for Cooling Characteristics with Continuous Arranged Converging Slot-Hole Rows

为研究连续收缩扩张孔的冷却特性,在C3X静叶片上分别建立了连续收缩扩张气膜孔冷却模型、圆柱气膜孔冷却模型和展向扩张气膜孔冷却模型,连续收缩扩张气膜孔每排23个、孔间距为20 mm,展向扩张孔每排19个、孔间距为24 mm,圆柱孔每排19个、孔间距为24 mm。同时,在叶片前部开设了一个U形冷却通道,尾部开设了一个直冷却通道,冷气通过这2个内部冷却通道进入气膜孔。利用ANSYS-ICEM商用软件对上述3种模型进行了结构化网格划分,采用ANSYS-CFX商用软件和SST湍流模型进行了数值计算和分析比较,结果表明:连续收缩扩张孔的气膜冷却效率高于圆柱孔和展向扩张孔,在孔口附近和高吹风比下的优势最明显;连续收缩扩张孔使冷气射流在相邻两孔的交汇处形成了类似反肾形涡结构,该涡的强度不大,但具有良好的延续性和较大的冷气覆盖面积;复合冷却时冷气射流脱离壁面的现象更明显,孔口附近总冷却效率低于绝热冷却效率。在连续收缩扩张孔的实际应用中选择偏大的吹风比和更小的入射角可以提高气膜冷却效率。
Continuously arranged converging slot？？holes are set on a C3X stator, which contains a U？？bend channel at the front of the airfoil and a radial channel near the trailing edge inside the airfoil by solidworks. Cylindrical hole model and fan？？shaped hole model are also constructed in the same way. Each model has four rows of film cooling holes. In the slot？？hole case, there are 23 holes with a pitch of 20 millimeters in one film cooling hole row. In the cylindrical and fan？？shaped hole case, there are 19 holes with a pitch of 24 millimeters in one film cooling hole row. Cooling air is supplied to film cooling holes through the U？？bend channel and the radial channel. These three models are meshed by structured grids with ANSYS-ICEM. ANSYS-CFX and SST turbulence model is used to calculate the turbulent flow. The adiabatic cooling performance of converging slot？？holes is compared with that of cylindrical holes and fan？？shaped holes in different blowing ratio, the heat transfer enhancement mechanism of converging slot？？holes is analyzed, and the adiabatic cooling effectiveness and the overall cooling effectiveness are compared. The Result shows that converging slot？？hole has the highest adiabatic cooling effectiveness and the advantages become more obvious at the larger blow ratio. A kind of vortex which looks like anti？？kidney vortex is found downstream of continuous arranged converging slot？？holes. The intensity of the vortex is not very high but maintains in a long distance and increases the coverage of the coolant film on the surface of the stator. The internal cooling has a non？？ignorable influence on the numerical result. As a consequence, conjugate cooling has less resistance to jet lift？？off. The overall effectiveness is lower than the adiabatic effectiveness at the exit of slot？？holes. In the practical application of the continuous arranged converging slot？？hole rows, large blowing ratio and small injection angle are beneficial to promote the film cooling efficiency