射流齿形喷嘴射流流场与气动声学分析

Analysis of Fluidic and Aero-acoustic Fields of Fluidic Chevron Nozzles

在低马赫数0.12条件下分析对比射流齿形喷嘴与锯齿形尾缘喷嘴湍流流场及声场,通过流场的数值计算与声场的实验测量,根据计算流体力学与气动声学,分析两者流场的湍流特性及远场噪声频谱特点。结果表明,射流齿形速度不高于主流、且对主流倾角较大时的降噪效果较好。与机械锯齿相比,射流齿形对低频噪声的降低幅度不及机械锯齿,但是它起降噪作用的频谱范围较广,对高频噪声的增强也较少。射流齿形相对机械锯齿来说是一种主动控制方式,有着许多优点,可以根据需要调节自身参数,在不需要降噪时关闭。

The turbulent flow field and the acoustic field of fluidic chevron nozzles and chevron nozzles were studied at the Mach number Ma = 0.12, including numerical analysis of the flow fields and measurements of sound pressure. Based on computational fluid mechanics and air dynamics, the characteristics of the two turbulent flow fields and their far-field features were analyzed. Results show that fluidic chevron can bring a better noise reduction effect if the flow velocity is lower than that of the main jet which has larger inclination angle. Decrease magnitude of low-frequency noise of the fluidic chevron is smaller than that of chevron, but the noise reduction effect of the fluidic chevron can cover a broader range of frequencies and has less high frequency penalty than that of the chevron. Compared with chevron, fluidic chevron has some merits. It is an active control manner with adjustable parameters, and can be turned off when denoising is unnecessary.