超声速燃气射流流场特性的三维数值模拟

Three-dimensional Numerical Simulation on Flow Characteristics of Supersonic Gas Jet

针对固体火箭发动机燃气射流特性,建立了高温高压燃气射流的三维计算模型,采用大涡模拟(LES)对不同尺寸喷管形成的欠膨胀超声速射流流场进行了数值模拟。计算结果表明,超声速燃气射流与周围大气剧烈掺混过程中形成了重复出现拟周期的膨胀压缩波结构。在射流中心轴线上,静压、速度等参数在出喷口后出现了较大的波动,随着离喷口距离的增加,波动幅度逐渐减小至平稳变化。射流速度沿径向开始在核心区基本不变,到剪切层后衰减梯度较大。随着喷管尺寸的增加,射流在轴向和径向的扰动区域都增大。

For gas jet characteristics of solid rocket motor,three-dimensional unsteady model of high-temperature and high-pressure gas jet was developed.Large Eddy Simulation（LES）was applied to simulate the under-expanded supersonic jet flow generated by nozzles with different size.Numerical results demonstrates that during the process of strong mixing between supersonic gas jet and around air,the repetitively-generated quasi-steady expansion and compression waves appear.The flow-field parameters such as pressure and velocity along the central axis have large fluctuations at the nozzle exit.The fluctuation range decreases to smooth change with the increase of the distance from the nozzle exit.The jet velocity along the radial direction almost has no changes in the core area,but the attenuation gradient is great in the shear layer boundary.The disturbed regions along the axial and radial direction expand with the increase of nozzle size.