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为分析变来流速度状态下的旋翼翼型气动特性,提出了利用翼型平移来模拟来流速度变化的数值方法.在此方法基础上,采用基于隐式LU-SGS(lower upper symmetric Gauss-Seidal)方法的非定常雷诺平均N-S(Navier-Stokes)(RANS)方程,模拟了SC1095旋翼翼型在定迎角-变来流速度及变迎角-变来流速度状态下的非定常气动特性.通过对比分析发现:翼型在变速度-定迎角状态下会表现出明显的非定常现象,产生了前缘分离涡,气动特性会出现明显的迟滞效应及波动现象,脉动速度越大,非定常效果越明显.并且基准速度越大,翼型气动特性的峰值越大;翼型迎角越大,非定常涡出现的也越早.考虑直升机旋翼翼型实际工作环境,在变速度-动态失速状态下,翼型最大迎角处的气动力会得到一定程度的削弱,在小迎角下的气动力得到一定程度的增强,且脉动速度越大,翼型的非定常特性也越强.
In order to analyze the aerodynamic characteristics of rotor airfoils under varying flow velocities, a numerical method is proposed to simulate the velocity variation of airfoils using airfoil translation. Based on this method, a new method based on implicit LU-SGS (lower upper symmetric Gauss- (Seansa) method with unsteady Reynolds averaged Navier-Stokes (RANS) equations was used to simulate the unsteady aerodynamic characteristics of the SC1095 rotor airfoil at a steady angle of attack-variable flow rate and variable attack angle-variable flow velocity Through comparative analysis, it is found that airfoil exhibits obvious unsteady behavior at variable speed and constant angle of attack, leading to the separation of front vortex and obvious hysteresis effect and fluctuation of aerodynamic characteristics. The greater the pulsation velocity, The more obvious the unsteady effect is, and the bigger the reference speed is, the larger the aerodynamic peak value of the airfoil is. The larger the airfoil angle of attack is, the sooner the unsteady vortex appears. Considering the actual working environment of helicopter rotor airfoil, Under the dynamic stall condition, the aerodynamic force at the maximum angle of attack of the airfoil will be weakened to a certain extent, and the aerodynamic force at a small angle of attack will be enhanced to some extent. The greater the pulsation velocity, the stronger the unsteady aerofoil. .