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翼型绕流的外部无粘流,采用跨音速小扰动速势方程和改进小扰动速势方程对三种差分格式进行对比计算:(1)Murman-Cole非守恒式;(2)守恒式;(3)Engquist-Osher式。在相同的初值条件下,它们的计算稳定性、收敛性和收敛解基本相同,但激波位置(1)在前,(2)在后,(3)在中间。对人工时间阻尼项εφ_(xt)的作用进行了线化分析,所得结论与数值实验结果相符。二级精度格式计算表明:采用这种方案能在几乎不增加计算机时的前提下,大大提高差分计算精度。本文最后采用边界层积分方程法,计算翼型边界层,并与势流进行迭代计算。在弱激波条件下,迭代收敛解与实验值接近。
The non-viscous flow around the airfoil is compared with three differential schemes by using the transonic small perturbation potential equation and the improved small perturbation potential equation: (1) Murman-Cole non-conservative; (2) conservative; (3) Engquist-Osher style. Under the same initial conditions, their computational stability, convergence and convergence are basically the same, but the shock location (1) is before (2) after and (3) is in the middle. The effect of artificial time damping term εφ_ (xt) is linearized and the results are in good agreement with the numerical results. The calculation of the second-level precision format shows that using this scheme can greatly improve the precision of differential calculation under the premise of almost no increase of the computer. Finally, the boundary layer integral equation method is used to calculate the airfoil boundary layer, and iteratively calculate the potential flow. In weak shock condition, the iterative convergence solution is close to the experimental value.