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通过求解雷诺平均Navier-Stokes方程,采用SST两方程湍流模型,研究了蒙皮以不同波长、频率以及波幅作波动时对飞艇流场特性产生的影响。研究结果表明:沿流向蒙皮的波动会引起绕飞艇流场的显著改变。当蒙皮上下表面的波动同相位时,在固定波动幅度和频率条件下,波动的波长减小,流动分离会加剧,时间平均的阻力系数增加;在固定波动波长和频率条件下,波动的波幅增加,流动分离加剧,时间平均的阻力系数增加,而当波幅减小到一定程度时,蒙皮波动对阻力系数基本没有影响;在固定波动波长和幅度条件下,波动频率增加,非定常效应增强,阻力系数减小,甚至出现负值,即可以为飞艇提供推力;此外,适当的波幅和波长组合也可以减小阻力系数。当蒙皮上下表面的波动相位相反时,波长与波幅变化带来的影响与同相位的情况相似;固定波动波长、幅度,波动频率增加,非定常效应增加,由于上下表面的非定常效应是相互抵消的,虽然阻力系数会出现瞬时负值,但是时间平均的阻力系数不会出现负值。
By solving the Reynolds-averaged Navier-Stokes equations and the SST two-equation turbulence model, the influence of the skin on the characteristics of the airship when the skin is fluctuated with different wavelengths, frequencies and amplitudes is studied. The results show that the fluctuations along the flow skin can cause significant changes in the flow field around the airship. When the fluctuations of the upper and lower skin surfaces are in phase with each other, the wavelength of the wave is reduced and the flow separation is aggravated and the drag coefficient of the time average is increased under a fixed fluctuation range and frequency. Under fixed wavelength and frequency conditions, the fluctuation amplitude Increase, the flow separation aggravates, and the time-averaged drag coefficient increases. When the amplitude decreases to a certain extent, the skin friction has no effect on the drag coefficient. Under the conditions of fixed fluctuation wavelength and amplitude, the fluctuation frequency increases and the unsteady effect increases , Drag coefficient decreases, even negative, that can provide thrust for the airship; In addition, the appropriate amplitude and wavelength combination can also reduce the drag coefficient. When the fluctuation phases of the upper and lower skin surfaces are opposite, the effects of wavelength and amplitude changes are similar to those of the same phase. The wavelength, amplitude and frequency of the fixed wave increase, and the unsteady effect increases. Since the unsteady effects of the upper and lower surfaces are mutual Offset, although the drag coefficient will be instantaneous negative, but the time-average drag coefficient will not be negative.