Numerical Simulation Of Aircraft Skin Temperature Field And Local Icing Process

With the development of demand for high-speed aircraft and infrared properties, aircraft skin temperature field calculation become more and more attention, the usual surface skin temperature field calculation often consider only the external air environment, while the actual skin is not consistent with the overall thermal environment so that the reasonable model and calculation method of thermal analysis needs to be established to analysis the skin temperature field and its influenced factors. In addition, when the aircraft surface temperature is lower or there is air cooled, Icing may occur in some wind at the surface, and thus endanger the flight safety. Therefore, conducting the aircraft overall thermal environment analysis to comprehend the impact mechanism of aircraft skin temperature field also become one of prerequisite in the process of aircraft icing forecast.Aiming at the needs of large aircraft anti-icing and thermal analysis techniques, achieving the internal and external thermal environment coupled by regarding the external thermal environment as the third category of floating thermal boundary conditions. And the computational model to solve the fluid flow and heat transfer on the component surface under anti-icing conditions was established. Then the prediction method of ice shapes on the surfaces was studied. By thermal analysis, mechanism and characteristics of skin temperature field were analyzed, quantitative data of solar radiation, external convective heat transfer, Power level and arrangement of the internal heat impacts were obtained; by anti-icing research, local icing forecast on aircraft of wings and engine lip was analyzed. Based on this, the background surrounding the main work is as follows:Through the mechanism analysis for large complex aircraft surface temperature field coupled heat transfer. The mathematical model for coupled heat transfer of the flow field with structures was established. The convective heat transfer to the external aerodynamic was regarded as a third category floating thermal boundary in order to achieve the indirect decoupling calculation of fluid-structure. Completing calculation of the external thermal environment based on CFX software platform, combined with Sinda / Fluint software platform, using thermal network method combined with Monte Carlo method to carry out the heat transfer between the inner and outer structure coupled system under different complex thermal boundary conditions. Finally, an aircraft using numerical simulation method was taken as an example for verifying the reliability and accuracy, and on the basis of it, various comprehensive factors affecting the internal and external coupled heat transfer was investigated and analyzed. The effects of skin temperature field include solar irradiance, internal heat power and equipment structural arrangements and so on.The CFX’s Continuous / Particle fluid model was based on to solve the equations of motion of water droplets, with the droplet trajectory tracking, programmed to extract information of related track, achieved the calculation of water droplet impingement with Lagrange Method. According to the method above, the example calculation of local water droplet collection efficiency airfoil was verified, and then complete the numerical study of the local Icing on component surface. Based on the quasi-steady-state heat and mass conservation relations, the local icing forecast thermodynamic model was established, through the preparation of procedures to deal with the CFX flow field results extracted to obtain the ice prediction model, and according to the typical airfoil examples, completing the verification of reliability. Finally, according to the method described above, completing the Icing forecasts of the aircraft wings and engines lip, and analyzing the icing conditions, including the effects of different temperatures to flow, Mach number, liquid water content on local icing.These studies provide a valuable reference on the thermal analysis and performance evaluation of large aircraft anti-icing technology.