射流齿形喷嘴射流流场与气动声学分析

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。

AnalysisofFluidicandAero-acousticFieldsof FluidicChevronNozzles

Researches of the flow field and acoustic field of chevron nozzle and fluidic chevron nozzle are conducted at the Mach number Ma=0.12 in order to investigate the characteristics of each nozzle. The study includes numerical analysis of flow field and measurements of sound pressure. Results show that fluidic chevron brings a better noise reduction with lower velocity than the main jet and deeper penetration. Compared with chevron, fluidic chevron has a milder low frequency noise reduction but over a broader range of frequencies and less high frequency penalty than chevron. Fluidic chevron is a way of active control with adjustable parameters, which can be turned off when denoising is unnecessary.