Computational modelling and assessment of supersonic flow in centrifugal compressors for aviation air-conditioning systems

该研究项目旨在启动温莎大学的Jeff Defoe博士和荷兰代尔夫特理工大学的Matteo Pini博士之间的合作。工作的重点是在一个新的应用中对离心式压缩机的流动进行计算机模拟。高速电动机的最新进展使得在飞机环境控制（空调）系统中使用这种压缩机成为可能。这就要求压缩机中的工作流体为制冷剂气体。这类制冷剂的行为要比空气等气体复杂得多，因此在流动计算预测的框架内需要详细的流体热力学模型。同时，由于流量不稳定，所有涡轮压气机在低于设计值的流量下运行的能力都受到限制。其中最相关的是旋转失速，在这种情况下，流动在压缩机的两个叶片之间的空间中中断，这种扰动在机器周围传播，导致压升和流量的大幅下降。为了在计算上预测这种现象的发生，需要高保真度的计算，这种计算与大量计算核心并行运行是最有效的。开源流动模拟代码OpenFOAM将用于本项目中的此类计算，但首先必须在代码中实现制冷剂行为的模型。然后确定失速产生机制。压缩机设计和流体热力学模型将由Pini博士的团队提供，Defoe博士的团队将在OpenFOAM中进行实现和模拟。反过来，这些结果将使Pini博士的团队能够快速进行模拟，并将导致两个团队在这种新型应用中压缩机性能领域的进一步合作。进一步的进展可能导致在飞机上采用这种机器，有可能减少总体能源消耗，从而降低对环境的影响。

This research project aims to initiate a collaboration between Dr. Jeff Defoe at the University of Windsor and Dr. Matteo Pini at the Delft University of Technology in the Netherlands. The focus of the work is computer simulations of flow through centrifugal compressors in a novel application. Recent advances in high-speed electric motors have enabled the possibility of using such compressors for aircraft environmental control (air-conditioning) systems. This requires that the working fluid in the compressor is a refrigerant gas. Such refrigerants have much more complex behaviour than gases like air and so detailed thermodynamic models of the fluid are needed within the framework of computational predictions of flow. At the same time, all turbo-compressors are subject to limits on their ability to operate at flow rates lower than the design value due to flow instabilities. The most relevant of these is rotating stall, in which flow breaks down in the space between two blades of the compressor, and this disturbance spreads around the machine, leading to a large drop in pressure rise and flow rate. To computationally predict the onset of this phenomenon requires high-fidelity computations which are most efficiently run in parallel with a large number of computing cores. The open-source flow simulation code OpenFOAM is to be used for such computations in this project, but first a model for the behaviour of the refrigerant must be implemented into the code. Stall inception mechanism(s) will then be identified. The compressor design and fluid thermodynamic model will be provided by Dr. Pini's group, and Dr. Defoe's group will carry out the implementation and simulations in OpenFOAM. In turn, the results will enable Dr. Pini's group to carry out simulations quickly, and should lead to further collaboration between the two teams in the area of compressor behaviour in this novel application. Further advances may lead to adoption of such machines on aircraft, with a potential to reduce overall energy consumption and thus lower environmental impact.