轴承腔内壁与油膜换热的数值模拟与试验

航空发动机后轴承腔内壁与滑油的换热分析是轴承腔热防护结构设计的基础。对航空发动机轴承腔内壁换热模拟试验件开展试验与数值模拟研究,得到了滑油油膜对轴承腔内壁的换热影响。通过测量试验件外壁面、内壁面以及滑油油膜的温度得到了试验件内壁面换热热流密度与换热系数的分布;结合CLSVOF(Coupled Level Set and Volume Of Fluid)油/气两相流以及热-流-固耦合计算方法对试验件进行了换热分析,并将内壁对滑油的局部热流量的计算结果与试验结果进行了对比,结果显示两者在各个工况下均吻合较好。通过将局部换热系数计算值与当地的滑油流动雷诺数Rel进行对比分析,结果显示内壁局部努赛尔数Nuw与Rel的0.7次方成正比关系。另外,对转速对换热的影响进行分析得到Nuw与旋转雷诺数Re_(rot)的0.345次方呈正比关系。

Numerical simulation and experiment for heat transfer between oil film and inner wall of bearing chamber

It is necessary to analyze heat transfer between the lubricating oil and the inner wall of the rear bearing chamber in the design of the heat protection structure for an aero-engine.The characteristics of the influence of the inner wall heat transfer from the oil film is obtained through both experiments and numerical simulation.The temperature distribution of the outer wall,inner wall and the oil film is tested to calculate the heat flux and the transfer coefficient.The simulation of the test rig is carried out using fluid-structure coupling with heat transfer,and the CLSVOF (Coupled Level Set and Volume Of Fluid) model is adopted to simulate the gas/oil flow.Comparisons of the local heat flux are then made between the experiments and the numerical simulation under different conditions,and the results show that the simulation results agree well with the experiment data.The relation between the heat coefficient and the local oil film Reynolds number Re1 is also discussed.The local Nusselt number Nuw near the wall is directly proportional to 0.7 power of local Reynolds number Re1.In addition,analysis of the influence of the rotating speed shows that Nuw is proportional to 0.345 power of the rotary shaft rotational Reynolds number Rerot.