脉冲射流强化圆柱喷流混合的三维数值模拟

对利用脉冲射流强化圆柱喷流混合的流场进行了数值模拟,这项工作将高频高强度信号射流射入亚音剪切层以强化喷流混合.利用有限体积法和重整化群(RNG)k-ε湍流模型求解N-S方程.分别进行了低亚音马赫数及高亚音马赫数喷流直接排入空气的数值模拟.主要计算3个状态:未受激励的状态,斯德鲁哈尔数St分别为0.2和0.4时的状态.数值模拟结果显示,脉冲激励引起喷流在与激励源平行的平面迅速扩展,在与之垂直的平面收缩,当脉冲射流激励的St在0.2附近时,相关的混合较好,而且少量的射流流量可以极大地增加速度的衰减率. 

Mixing enhancement in round jet exhaust using pulsed blowing: 3-D numerical simulations

The 3-D flow fields of the round jets with pulsed jet blowing for mixing enhancement were simulated numerically. This work uses a technique for injecting high frequency and high intensity signals into subsonic shear layers for the purpose of jet mixing enhancement. The finite volume method, RNG k-ε turbulence model were employed to solve N-S equation. Numerical simulations of low Mach 0.23 and high Mach number 0.9 jets exhausting into fluid were conducted. Three cases are considered in detail: a unforced case and two cases that are forced with flapping modes at Strouhal numbers 0.2 and 0.4.These simulations show that pulsed jet blowing at either frequency causes the jet to expand rapidly in the plane parallel with the actuators and to contract in the plane perpendicular to the actuators, the intensity of motion and associated mixing are higher when the excitation Strouhal number is around 0.2, and small injection flow rates can provide tremendous increases in velocity decay rates.