Research On Heat Transfer Performance Of Aero-Engine Inlet Strut Based On Aluminum Special-Shaped Vapor Chamber With Acetone Working Fluid

At present,the anti-icing structure of aero-engine inlet strut generally adopts the compressor to introduce high-temperature gas into the strut for heating and anti-icing.Because the inlet strut needs to play the role of guide vane,its leading edge radius is small and the wall thickness is thick.That results in insufficient heat transfer capacity of internal hot gas impact heat transfer to the outer surface of the leading edge,so the leading edge of the strut is easy to freeze.In order to improve the anti-icing ability of the front edge of the strut,the scheme of applying the phase change heat transfer method to the anti-icing structure of the strut is proposed in this paper,and the structural design,heat transfer performance analysis and anti-icing effect engineering verification of the strut based on phase change are systematically carried out.The main contents include:numerical simulation research on heat transfer characteristics of traditional hot gas anti-icing structure with strut,visual experimental research on surface boiling heat transfer characteristics of acetone working fluid in the wick,experimental research on heat transfer performance of aluminum based acetone working fluid vapor chamber,experimental research on structural design and heat transfer performance of strut based on phase change,and engineering verification of anti-icing effect of strut based on phase change.Numerical simulation research on heat transfer characteristics of hot gas anti-icing structure of strut:The single-phase fluid-solid coupling numerical simulation technology is used to carry out the simulation analysis of the temperature field performance of typical aeroengine strut hot gas anti-icing structure.Through the comparative analysis of the temperature field characteristics of the strut under different air-entraining working conditions,the reasons for the insufficient anti-icing ability of the leading edge of the strut are revealed,and the shape structure,hot gas flow rate and temperature parameter range are determined for the subsequent phase change strut anti-icing structure design.Visual experimental research on surface boiling heat transfer characteristics of acetone working fluid in the wick:The visualization experimental system for surface boiling heat transfer characteristics of acetone working fluid in the wick with a cavity of 120 mm×100 mm×30 mm is established.And the visualization experimental research under different heating methods（heat source area/heat source quantity/heat source distribution/heat source power,etc.）and liquid filling ratio are carried out.The influence law of heat source characteristics and liquid filling ratio on the phase transformation process of acetone,two-phase flow pattern evolution,boiling curve and the overall thermal resistance of the vapor chamber are revealed.The experimental results show that the fog two-phase flow state will appear in the cavity,and the phase change on the surface of wick will appear evaporation,nucleation boiling and local drying out.Phase change heat transfer will occur in the vapor chamber under low heating power,and high heat transfer characteristics of vapor chamber is presented.Under the fixed heat source condition,the heating power has little effect on the thermal resistance of vapor chamber,while the distribution characteristics of heating source have certain effect on the thermal resistance of vapor chamber.And the liquid filling ratio has the greatest effect on the phase change flow pattern in vapor chamber and thermal resistance of vapor chamber.When acetone only evaporates,the boiling curve shows the linear relationship.When acetone evaporates and the cavity presents the fog two-phase flow state,the boiling curve shows the quadratic function relationship.After nucleation boiling,the boiling curve shows the linear relationship and the boiling heat transfer coefficient increases.Experimental study on heat transfer performance of aluminum vapor chamber with acetone working fluid:The heat transfer performance test system of aluminum vapor chamber with acetone working fluid is established.A series of 120mm×100 mm×2 mm aluminum vapor chambers with acetone working fluid are prepared,and the experimental research on the influence of different heat source conditions and liquid filling ratio on the overall heat transfer performance of aluminum vapor chamber is carried out.Based on the neural network algorithm,a method for predicting the overall heat transfer resistance of the aluminum vapor chamber with acetone working fluid is proposed,and the analysis method for retrieving the phase change heat transfer intensity of the vapor chamber internal wall based on the external surface temperature field is established.The results show that no matter how the heat source is distributed,the position where the condensation rate on the cold end surface of the vapor chamber is relatively large is concentrated at the corresponding position of the heat source;Different heat source distribution and liquid filling ratio will affect the overall thermal resistance of the vapor chamber.The error of the prediction model of the overall heat transfer thermal resistance of the aluminum vapor chamber with acetone working fluid established by LM（Levenberg Marquardt）neural network algorithm is less than 10^-2.The inversion analysis method of phase change rate and the prediction model of overall thermal resistance provide theoretical support for the design of strut based on phase change.Structural design and experimental research on heat transfer performance of strut based on phase change:Using the shape parameters of aeroengine hot gas anti-icing strut structure,based on the heat transfer mechanism of aluminum vapor chamber,the internal support column,wick and heating structure of strut based on vapor chamber are designed.Two groups of strut based on phase change with different heating modes are prepared.The experimental system for the heat transfer performance of strut based on phase change is built,and the experimental research on the heat transfer performance of the strut based on phase change under the conditions of liquid filling ratio and heat source is carried out.The results show that phase change heat transfer takes place inside the strut based on phase change of the two heating methods.Compared with the traditional imported hot gas anti-icing structure,the front edge temperature of the strut based on phase change with hot gas heat mode is higher.The distribution law of phase change rate on the surface and the overall thermal resistance characteristics of the strut based on phase change under different heating modes are obtained.The optimum liquid filling rate of the strut based on vapor chamber by electric heating and hot gas heating is 84%.The best heating method is that four ceramic heating plates are evenly distributed at the hot end.When the liquid filling rate is fixed,the thermal resistance of the strut is less affected by the heating power.With the increase of hot gas flow,the thermal resistance of strut decreases gradually,but the influence of liquid filling rate on thermal resistance is higher than that of hot gas temperature and flow parameters.Engineering verification of anti-icing effect of strut based on phase change:The engineering verification test of anti-icing effect of strut based on phase change in electric heating mode and hot gas heating mode is carried out in A617 ice wind tunnel of AECC Shenyang Engine Research Institute.The test results show that under the typical icing conditions of cold air speed of 45 m/s,temperature of-11.3℃,water content of 2 g/m³ and average diameter of water droplets of 20μm,the conditions for no icing on the surface of strut based on vapor chamber are electric heating power of more than 480 W or hot gas flow of more than 7.1 g/s.There is still a trend that the anti-icing effect of the strut based on phase change in hot gas heating mode decreases gradually along the flow direction of hot gas,that is the leading edge of the bottom of the strut based on phase change begins to freeze.Based on the research on the heat transfer characteristics and mechanism of aluminum vapor chamber with acetone fluid,this paper has completed the research on the structural scheme design,sample preparation,heat transfer performance test and anti-icing effect engineering verification of aeroengine strut based on phase change.The paper provides the solid theoretical and technical basis for the further popularization and application of phase change in aeroengine.