浮升力对双旋转轴间流动换热影响的数值模拟

Numerical investigation for the influence of buoyancy on heat transfer in an annulus between rotating cylinders with turbulent axial flow

关键词:  航空发动机  浮力  传热  双旋转轴+  数值仿真

Key words:  Aircraft engines  Buoyancy  Heat transfer  Twin axis of rotation  Numerical simulation

摘要:

利用Boussinesq假设,采用混合长度模型,对具有轴向通流的双旋转轴间的流动换热进行了数值研究,得到了轴间气体充分发展段的速度分布、温度分布和加热边的对流换热系数,其结果在实验模型参数范围内与PfitzerH的实验研究符合较好。在此基础上,进一步数值模拟研究了同向等速旋转双轴间不可压流的离心浮升力对流动换热的影响,结果表明:离心浮升力对流动换热的影响取决于浮升力与惯性力之比GrB/Re2z。当GrB/Re2z≥24时,浮升力的影响十分显著,不可忽略。

Abstract:

Heat transfer in the air gap of two co-rotating cylinders was numerically studied, based upon the Boussinesq approximation and mixing length theory. The code developed was verified with Pfitzer’s H experimental results and the agreement was satisfactory. Investigation was focused on the influences of the buoyancy force on the heat transfer process. The two cylinders were kept the same rotating speed. The importance of the buoyancy force was found to be dependent upon the non-dimensional number Gr_B/Re~2_z. Numerical studies revealed that the buoyancy force has to be taken into consideration when Gr_B/Re~2_z≥24.