Numerical Simulation On The Transpiration Cooling Of Metal Porous Materials

Since the aero-engine performance is required increasing higher, the new materials and transpiration cooling and other high efficient cooling technology have attracted a lot of interest. The research on flow resistance and heat transfer characteristics of porous materials such as woven screens are important, since they are the vectors of transpiration cooling. The flow and heat transfer of stacked plain woven screens are investigated. Then the numerical simulation of transpiration cooling are applied based on the macroscopic porous media, with of local non-equilibrium model is considered. The boundary conditions are focused and the inner and external heat transfer of in transpiration cooling process are investigated, the influence of partial block and other pore invalid situation are studied.Firstly, the characteristics of flow and heat transfer, relevant parameters and research method are described. The physical models and mathematical models are studied. The discretization equations are based on the collocated grid and momentum interpolation. The ADI-TDMA algorithm is introduced. A program is developed based on those method using language C, and validation of the program is done.Secondly, three-dimensional model of three kinds of plain woven screens are built based on the real structures and parameters. And the representative unit is chosen to research. The stacked woven screens is simulated by the means of Fluent, and the static pressure and velocity are decreased linearly. The result show fit well with the form of Darcy-Forchheimer model and the correlation of Armour. The temperature and local Nu number are decreased exponentially. The Nu number rises with Re increased, the specific surface area is the main factor of heat transfer in the condition of same Re number.Furthermore, the boundary condition of numerical in transpiration cooling is analyzed, the first one of boundary condition is unreasonable in the specific case, the coupling scheme of the inner and external heat transfer is used. The cooling efficiency is 38% when the injection rate is 2%.Finally, the situation of block in the porous media and partial ablation are researched, the change of porosity will lead to uniform flow field, the block in the heated wall cause the high temperature zone, and the block inner side also lead to the uniform flow velocity and the change of wall temperature. 10 mm wall temperature changed due to the block size of 1mm×1mm.The results of research provide the reference for the new high efficiency transpiration cooling technology with the woven screens being the vector.