吸气式高超声速飞行器粘性力工程计算方法

Engineering calculation method of viscous force for air-breathing hypersonic vehicle

粘性干扰对吸气式高超声速飞行器气动、推进及其飞行稳定性有重要影响,基于无粘理论计算的精度不能满足实际需求。针对吸气式高超声速飞行器机体/推进一体化的特点,研究了吸气式高超声速飞行器粘性力工程估算方法。该方法首先利用激波膨胀波理论及一维定常流理论确定气流参数变化,然后计算粘性力系数,最后对粘性力系数进行积分得到粘性力。通过计算飞行器表面粘性力及超燃冲压发动机内流道粘性力,分析了粘性对气动的影响及粘性随飞行高度变化规律。结果表明,粘性力对气动性能影响显著,尤其是阻力特性,粘性阻力占到总阻力的比重最高达到78%左右,粘性影响不容忽视。为了验证该方法,以某飞行器二维混合进气道为例进行了计算,计算结果与CFD基本一致。该方法可用于飞行器概念设计和初步研究阶段,对粘性力进行快速计算和影响分析。

Viscous interference has an important influence on aerodynamic, propulsion and flight stability of the air-breathing hypersonic vehicle. The calculation precision based on inviscid theory cannot meet the actual engineering needs. In the work, the viscous force engineering estimating method was researched for the airbreathing hypersonic vehicle, which has an airframe/propul- sion integration characteristics and is different from the conventional vehicle. First the properties of the flow was determined by using two-dimensional shock expansion theory and one dimensional flow model. Then viscousforce coefficients were calculated. Finally, viscous forces were obtained by integrating viscous force coefficients for vehicle. By calculating the viscous force on the vehicle sur- face and inside scramjet engine, the viscous effects on aerodynamic were analyzed and the law of viscous force varying with flying height was obtained. Result shows that the viscous effects are prominent, especially for drag force characteristic, viscous drag force accounts for 78% of total drag force. To validate the engineering method, a certain air-breathing hypersonic vehicle inlet was com- puted and the results were compared with CFD results. This method can be applied to analysis of viscous effect and rapid calculation of viscous force in aircraft conceptual design and preliminary research stage.