AERODYNAMICS & AEROACOUSTICS OF COMPLEX GEOMETRY HOT JETS

预计到2020年，世界航空运输需求将增加一倍，因此迫切需要采取措施减少飞机起飞噪音对环境的影响。在最坏的情况下，噪音可能不仅仅是令人讨厌的，可能是导致高血压等疾病的一个因素。因此，欧洲航空研究咨询理事会（ACARE）制定了到2020年将感知噪音水平降低50%的目标。允许的起飞噪音水平的不断降低正使更成熟的飞机模型的商业可行性处于危险之中，这对目前的工作产生了强烈的经济影响。这项工作合并和扩展了两个最近竞争和非常成功的EPSRC喷气噪声项目- GR/S43191/01和GR/T06629/01。在GR/T06629/01中，对复杂几何射流的大涡模拟（LES）型预测技术进行了探索。在以前的GR/S43191/01（优秀）项目中，基于声学类比开发了一个基于RANS（雷诺平均纳维尔-斯托克斯）的湍流等温射流噪声模型，该模型由LES提供信息。该模型被证明是更准确的声音预测，无论是边线和船尾角的喷气机，比以前的声学模型。它提供了对噪音产生机制的见解。在这里，我们希望将模型扩展到热射流和复杂喷嘴，如V形和同轴射流，这将是直接感兴趣的发动机制造商。我们还希望将该模型的性能与NASA Glenn，南安普顿大学和其他模型进行对比。对于速度和温度的各种时空相关性的影响，或者这些相关性本身对于热喷流的大小，人们还知之甚少。因此，将探索这种流动物理元素，从而与美国宇航局格伦和普瓦捷大学目前的研究推力。

With the projected demand for air transport set to double the world aircraft fleet by 2020 it is becoming urgent to take steps to reduce the environmental impact of take off noise from aircraft. In the worst case noise can be more than just annoying, potentially being a contributory factor towards illnesses such as hypertension. Hence, the Advisory Council for Aeronautics Research in Europe (ACARE) has set the target of reducing perceived noise levels by 50% by the 2020. Continual reductions in permitted take-off noise levels are placing the commercial viability of more established plane models in jeopardy giving strong economic implications for the current work. The work proposed merges and extends two recently competed and highly successful EPSRC jet noise projects - GR/S43191/01 and GR/T06629/01. In GR/T06629/01 - rated tending to Outstanding - Large Eddy Simulation (LES) type predictive techniques for complex geometry jets were explored. During the previous GR/S43191/01 (rated Outstanding) project a RANS (Reynolds Averaged Navier-Stokes) based model for turbulent isothermal jet noise, based on an acoustic analogy was developed that is informed by LES. The model was proven to be more accurate for sound predictions, both for the sideline and aft angles to the jet, than previous acoustic models. It provided insights into the mechanisms of noise generation. Here we wish to extend the model to hot jets and complex nozzles, such as chevrons and co-axial jets, which will be of immediate interest to engine manufacturers. We also wish to contrast the model's performance with NASA Glenn, Southampton University and other models. There is very little understanding of the impact of the various space-time correlations of velocity and temperature or indeed the magnitude of these correlations themselves for hot jets. Hence, this flow physics element will be explored thus linking with the current research thrusts at NASA Glenn and the University of Poitiers.