高超声速喷管气膜冷却流动与传热特性研究

Flow and Heat Transfer Characteristics of Film Cooling on Hypersonic Nozzles

关键词:  高超声速喷管  气膜冷却  壁面热流  流场品质  数值仿真

Key words:  Hypersonic nozzle  Film cooling  Wall heat flux  Outflow quality  Numerical simulation

摘要:

基于雷诺时均方法并结合SST k-ω湍流模型，对空气气膜作用下的马赫数6高超声速喷管流动与传热特性进行了数值研究，分析了气膜流量、气膜狭缝几何参数（狭缝高度、台阶厚度）、狭缝流向位置对喷管壁面尤其是喉道热流密度以及对喷管出口气流品质的影响特性。计算结果表明，引入气膜可以显著降低喷管尤其是喉道的壁面热流，而气膜对喷管出口气流速度分布的影响很小，对出口温度分布有一定的影响。当气膜流量仅为主流的3.53%时，喷管喉道热流的降幅达30.1%；增加这一值至14.25%时，喷管喉道热流的降幅升至87.3%。同时，改变狭缝流向位置以及狭缝高度对气膜冷却效率有一定的影响，而改变台阶厚度对冷却效率的影响很小。

Abstract:

Based on the Reynolds Average methods with SST k-ω turbulence model， the flow and heat transfer properties of the Mach 6 hypersonic nozzle with gaseous film cooling are numerically investigated. The effects of mass flow rate， geometric parameters of slot （including slot height and step height） and location of the slot on the heat flux （especially at the throat） and the outflow quality are analyzed carefully. Numerical research results indicate that the introduction of gaseous film cooling can reduce the heat load on the wall effectively， especially at the throat. The velocity distribution at the nozzle exit is not influenced by the gaseous film cooling but the temperature distribution is quite different with and without the film cooling. The numerical research shows that when the mass flow rate of gaseous film cooling M is only 3.53% of the mainstream， the heat flux at the nozzle throat decreases by 30.1%， and when M reach 14.27%， the heat flux at the nozzle throat decreases by 87.3%. The change of slot height and location of the slot can change the cooling efficiency， but the change of step height has nearly no influence.