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高速飞行器在大气层中飞行时,其光学头罩承受着严重的气动加热。超声速气膜冷却方法可以有效地隔离外部加热,但是冷却气体和主来流形成的混合层会引起光束退化,影响成像质量。为减少光束退化,优化超声速气膜冷却时的光学性能,基于混合层折射率和压力同时匹配设计思路,提出了两种设计方法,即配置特定温度的冷却气体实现混合层折射率和压力同时匹配设计方法和配置特定组分的冷却气体实现混合层折射率和压力同时匹配设计方法,并对设计方法的可行性和有效性进行了验证。模拟证明,后一种方法在外部流动参数不变的情况下,冷却气体的组分构成仅与其喷流静温有关,为气膜的冷却性能和光学性能同步设计奠定了基础。
High-speed aircraft flying in the atmosphere, the optical hood to withstand severe aerodynamic heating. Ultrasonic film cooling method can effectively isolate the external heating, but the cooling gas and the main flow of the mixed layer will cause the beam degradation, affecting the imaging quality. In order to reduce the beam degradation and optimize the optical performance of supersonic film cooling, two design methods are proposed based on the simultaneous matching of refractive index and pressure in the mixed layer, namely, the configuration of a specific temperature of the cooling gas to achieve simultaneous matching of the refractive index and pressure of the mixed layer Design methods and configuration of specific components of the cooling gas to achieve mixed layer refractive index and pressure at the same time match the design method, and the feasibility of the design method and validation. The simulation results show that the composition of the cooling gas is only related to the temperature of the jet stream when the external flow parameters are the same, which lays the foundation for the synchronous design of the cooling performance and the optical performance of the gas film.