Investigations On Flow And Heat Transfer Characteristics Of Turbine Casing

Turbine casing,as the main load-bearing component of aeroengine,its the deformation under different working conditions has a significant impact on the safe and efficient operation of the engine,and the deformation is closely related to the temperature distribution.In this paper,the flow and heat transfer characteristics of an Aero-Engine Turbine casing were studied by numerical simulation and experimental methods respectively.Based on the numerical simulation results,the transient heat transfer of the casing was calculated,and the variation law of the casing temperature with time was obtained.Firstly,the steady-state numerical calculation of the turbine casing was carried out,and the flow and heat transfer characteristics in the casing under different working conditions were analyzed.It is found that the airflow in the chamber has complex vortex structure.And with the flow of airflow,there are different degrees of leakage in each chamber of the casing,which make the flow rate of cold air gradually decrease during the flow process.In terms of heat transfer,the stagnation zone of the impact target has the best heat transfer because of the impingement structure of the jet in the casing.Then with the flow of air near the wall,the heat transfer decreases gradually.The highest temperature region of the casing model appears on the wall of the ceramic coating in direct contact with the high temperature gas.With the increase of the distance between the ceramic coating,the temperature of the casing decreases gradually.On the basis of steady-state calculation,the heat transfer characteristics of some casing chambers were studied by hot film method.The experimental results show that when the test conditions change,the distribution of heat transfer characteristics of each chamber impact target is almost unchanged,and with the increase of impact Reynolds number,the heat transfer effect of target surface is more remarkable.In the end,two-dimensional and three-dimensional transient calculations of the casing were carried out respectively,and the variation law of the casing temperature with time was analyzed.It is found that the temperature variation law of the casing is basically the same as that of the load.When the load remains unchanged for a short time,the temperature of the casing gradually changes to a stable state with time,and the rate of temperature change gradually decreases.Compared with the load increase stage,the response time of the model in the load reduction stage is longer.The casing is more difficult to cool.The temperature variation law obtained by the two methods is almost the same.When the casing temperature reaches the thermal equilibrium state,the three-dimensional calculation results are slightly higher than the two-dimensional calculation results,and the error is within acceptable range.