Simulation On The Temperature And Pressure Field Of CVD Diamond Blunt Aircraft Under Flight

With the approximative thermoconductivity and hardness as the natural diamond, the optical-quality CVD (Chemical Vapor Deposition) diamond can bear the impact of air current, raindrop and dust and the cataclysm of temperature in supersonic speed. And it is one perfect material for the domes and windows of the blunt aircrafts. So investigation on the temperature and pressure field for simulating the optical-quality CVD diamond film in high speed can help to evaluate the practical application of the diamond film that is used on the blunt domes and windows, and it has an important practical value and national defence significance.Under the application background of the optical-quality CVD diamond thick film on the blunt aircrafts'domes and windows, and on the base of CFD (Computational Fluid Dynamics) theory and its commercial software, two blunt FEM (Finite Element Method) simulation models are built, and the temperature and pressure field in high speed are analyzed, obtaining an important result in initial stage. The main works are as follows:1. High quality computing grids are obtained by using GAMBIT and FLUENT, and the FEM model of the out flow field for simulating the blunt aircraft with the CVD diamond film radome is established under flight condition. By observing the pressure values of the existing wind tunnel experiment in the reference and the theoretical result of the stagnation temperature formula in CFD, the correctness of the FEM model is proved. Also the distribution rule of the pressure and temperature is proposed under different Mach numbers. So the feasibility of using the CVD diamond film as the blunt radome in different Mach numbers is analyzed.2. The temperature distribution FEM model for the thin-wall feature of the CVD diamond film radome is built. In the outside of the blunt radome, gas-solid coupled heat transfer condition is adopted. By simulating the temperature distribution, the effects of heat transfer condition of the radome inside and Mach number are investigated. On this base, the comparison of existing different infrared optical materials'temperature distributions is analyzed and shown, and the advantage of using the CVD diamond as blunt radome is presented farther.3. It is shown that the field's maximum temperature will rise while the Mach number increases. After the Mach number exceeds one, a clear bowshock is obtained in the simulation result, and the Mach angle decreases along with the Mach number. Those are consistent with theoretical results. While the Mach number is 3.5, even the radome inside is adiabatic, the maximum temperature is below 1000K, under the diamond's graphitization temperature, so the CVD diamond film radome can meet practical requirement.