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

加热射流引入了许多有趣和独特的射流噪声谱特征，这些特征尚未被完全理解，实际上，也没有自我一致的解释。这些特征之一是超音速射流在高射流温度比下的明显静音。射流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射流降噪机制将最终有助于降噪策略。此外，然而，事实上，它的存在归功于一个纯粹的流体力学手段，更有理由理解和发展合理的数学模型来解释它。另一方面，对于低亚音速声学马赫数射流，温度的增加会产生声音的增加。本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绘制声马赫数和射流温度比范围内的湍流结构。之后，我们将在远场噪声谱的声学类比模型中使用这些信息。这位博士生将成为密西西比州立大学和美国宇航局格伦研究中心的研究人员和学者合作团队的一员。在学习的第二年，学生将以密西西比为基地。这项工作将涉及使用大涡模拟的射流计算流体动力学（CFD）以及使用各种应用数学技术的空气声学建模。

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.