管网方法在双层壁冷却结构设计中的应用

为快捷有效地计算涡轮叶片双层壁复合冷却结构的冷却特性,将一套适用于气冷叶片换热模拟的管网耦合算法应用于所设计的双层壁内冷叶片上.结合冷却流路的一维管道网络算法以及壁面单元与对应外流场网格间的插值过程,形成HIT3D-Coolnet管网耦合程序,并参考有测量数据的涡轮叶片算例验证其模拟有效性.针对新型的双层壁冷却结构,在已有叶型的基础上初步构建3种配气方式的复合冷却方案.用HIT3D-Coolnet快速得到叶片外壁温度信息以甄选初始方案,借助全三维数值模拟分析初选方案双层壁结构内的流动特性,并据此采取措施改善初始设计.流场分析表明,导入腔内的冷却空气冲击腔壁,并在腔室空间内形成特定的旋涡结构,有效地强化了内部对流换热.在合理的冷气分配下,双层壁冷却技术可获得较好的冷却效果.

Application of network method in the design of double wall cooling structure

To quickly and efficiently calculate the cooling characteristics of double wall composite cooling structure used in turbine blades, a set of pipeline network coupling algorithm which is enforceable for air-cooled blade simulation has been applied to the designed double wall cooling blade. Combining with one-dimensional pipeline network method and interpolation process between blade wall unit and corresponding outflow field grid, HIT3D-Coolnet pipeline network coupling procedure is composed, and the simulation validity of this algorithm has been verified by turbine blade test data. For the new-style cooling technology of double wall cooling structure, three compound cooling schemes have been preliminarily constructed. The HIT3D-Coolnet quickly gets blade outer wall temperature information to select the initial scheme. With the flow characteristics analysis of double wall structure of the primary scheme by full three-dimensional numerical simulation, measures have been taken to improve the initial design. Flow field analysis shows that the cooling air introduced into the narrow cavity impacts the chamber wall, forms specific vortex structures which can effectively enhance the internal convective heat transfer. Under the reasonable cooling distribution, the double wall cooling technology can obtain relatively good cooling effect.