Analysis and prediction of supersonic heated jet noise in axisymmetric air jets

热喷流引入了一些有趣和独特的喷流噪声频谱特征，这些特征还没有被完全理解，或者实际上，自我解释。这些特征之一是在高喷流温度比下，超音速喷流明显变得安静。喷气噪声的这一方面仍然是一个重要的研究领域，尤其是因为了解任何一种喷气噪声降低的机制最终都将有助于减少噪声的战略。然而，此外，静音的存在归功于一种纯粹的流体机械手段，这一事实更有理由理解并开发合理的数学模型来解释它。另一方面，对于低亚声速马赫数射流，温度的升高会产生声音的增加。这个博士项目的主要目的是利用密西西比州立大学的内部代码来绘制声学马赫数和喷流温度比范围内的湍流结构图。之后，我们将在远场噪声频谱的声学类比模型中使用这些信息。这名博士生将成为密西西比州立大学和NASA格伦研究中心的研究人员和学者合作团队的一员。在第二年的学习中，该学生将以密西西比州为基地。这项工作将包括使用大涡模拟对喷流进行计算流体动力学(CFD)，以及使用各种应用数学技术进行气动声学建模。

Heated jet flows introduce a number of interesting and peculiar features of jet noise spectrum that have not been fully understood or indeed, self-consistently explained. One of these features is the apparent quietening of supersonic jets at high jet temperature ratio. This aspect of jet noise remains an important area of research not least because understanding any kind of mechanism of jet noise reduction will ultimately aid noise abatement strategies. In addition however the fact that the quietening owes its existence to a purely fluid mechanical means is more reason to understand and develop rational mathematical models to explain it. On the other hand, for low subsonic acoustic Mach number jets, an increase in temperature produces an increase in sound. The main purpose of this Ph.D. project is to utilize the in-house codes at Mississippi State University to map out the turbulence structure across the range of acoustic Mach number and jet temperature ratio. After which we shall use this information within an acoustic analogy model for the far field noise spectrum.The Ph.D. student will be part of collaborative team of researchers and academics from Mississippi State University and the NASA Glenn Research Center. During the second year of study, the student will be based at Mississippi. The work will involve Computational Fluid Dynamics (CFD) of jet flows using Large Eddy Simulations as well as aero-acoustic modelling using various Applied Mathematical techniques.