喷管入口气温影响下的射流流场及声场特性

Subsonic Jet Flow Field and Sound Field Characteristics Influenced by Nozzle Inlet Air Temperature

为了研究亚声速喷管入口气温对射流流场及声场的影响,建立了亚声速喷管计算模型,在与实验及模拟数据对比验证的基础上,分别计算了不同喷管入口气温作用下的喷管外流场和远场噪声,探究了喷管入口气温改变时喷管出口射流速度沿轴向及径向的分布规律以及喷管出口轴线上射流温度的变化特性,同时也分析了喷管入口气温对射流流场发展和远场噪声的影响。研究结果表明:射流温度增加会较为显著地缩短势流核心区域长度,势流核心区域宽度会有少许降低;射流轴线上的静温和总温在喷管后一定距离存在一个温度上升过程,各工况静温最高处比总温最高处有延后,且射流温度越高,温度开始上升位置越接近喷管出口;温度的升高对不同频率噪声影响有很大差别,降低工质入口温度有利于降噪。该研究内容为进一步探究射流噪声形成机制打下基础,同时也可为喷流噪声的控制提供新的思路。

To explore the influence of subsonic nozzle inlet air temperature on jet flow field and sound field,a subsonic nozzle calculation model was established.Compared with experimental and simulative data,the flow field and far-field noise radiation were evaluated at different nozzle inlet air temperatures.The distribution laws of jet velocity at the outlet of the nozzle along the axial and radial directions,as well as the variation of jet temperature along the nozzle exit axis,were investigated.The influences of nozzle inlet air temperature on jet flow field development and far-field noise were analyzed.The results show that the increasing temperature of jet significantly shortens the length of the core region of the potential flow,and slightly reduces the width of the core region of the potential flow.The static temperature and the overall temperature at the jet axis with a certain distance from the nozzle rise.The highest static temperature under each working condition is delayed compared with the highest overall temperature.Higher jet temperature brings closer distance from the place where temperature starts to rise to the nozzle outlet.The increasing temperature exerts a great influence on the noise of different frequencies.Lowering the inlet temperature of the working fluid is beneficial to noise reduction.This research may provide a new idea for the control of jet noise.