真实气体效应对高超声速轨道器气动特性的影响

基于一个7组元6反应动力学模型，采用NND差分格式求解化学反应Navier-Stokes方程，数值研究高超声速轨道器的绕流特性。重点讨论了轨道器气动特性在真实气体效应作用下对不同来流状态和不同舵偏角的敏感性。研究表明：真实气体效应主要发生在物面附近很薄的激波层内，缩短了激波的脱体距离，使激波层变薄，流动变量的梯度变大；空气的离解和电离导致轨道器的阻力系数比完全气体计算值低，压心位置前移。小攻角下，升力系数和俯仰力矩系数的真实气体计算值高于完全气体计算值，大攻角情形则相反。此外，小攻角时真实气体效应产生小低头力矩，而大攻角时产生小抬头力矩。单就舵面而言，真实气体效应使其阻力系数增大，使其升力系数和俯仰力矩系数在小攻角且非负舵偏角时变小，在大攻角且负舵偏角时变大。特别地，真实气体效应仅在零攻角且零舵偏角时对舵面的压心位置产生较大影响。

Effects of Real Gas on Aerodynamic Characteristics of a Hypersonic Orbiter

Based on a seven-species and six-reaction chemical kinetic model,flow characteristics for a hypersonic orbiter are investigated numerically through using an NND(Non-oscillatory and No-free-parameters Dissipation) finite difference scheme to solve Navier-Stokes equations with chemical source terms.Considering real gas effects,sensitivities of orbiter aerodynamic characteristics to different incoming flow conditions and rudder yaw-angles are discussed emphatically.Results show that effects of real gas are mainly prominent in some regions of quite thin shock wave layers,where are very close to wall surface,and make the outstanding distance of shock wave short,the thickness of shock layer thin,and the gradients of flow variables large.Dissociation and ionization of air bring on lower drag coefficients of the orbiter than that obtained from perfect gas model,while the location of pressure center moves forward.At small angle-of-attack,both lift and drag coefficients for real gas are higher than that for perfect gas,but the large angle-of-attack case is contrary.Moreover,the effect of real gas for small angle-of-attack case results in small downward force moment,whereas that for large angle-of-attack case results in small upward force moment.As concerning the rudder,the effect of real gas makes drag coefficient large,and both lift and pitching moment coefficients small for the case of small angle-of-attack and nonnegative rudder yaw-angle and large for the case of large angle-of-attack and negative rudder yaw-angle.Especially,the effect of real gas on the location of rudder pressure center is dominant only at zero angle-of-attack and zero rudder yaw-angle.