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Control of Cyclone Flow Instabilities for Increased Efficiency, Reduced Pressure Loss and Lower Noise

控制旋风分离器流动不稳定性以提高效率、减少压力损失并降低噪音

基本信息

批准号：
1611004
负责人：
金额：
--
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2015
资助国家：
英国
起止时间：
2015 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1611004
关键词：
Control Cyclone Flow Instabilities Increased

项目摘要

The precessing vortex core (PVC) in a cyclone separator is detrimental to separation performance, accounts for 80% of velocity fluctuations, increases aerodynamic tonal noise, and dissipates mechanical energy thereby increasing the pressure loss. The PVC arises because the swirling flow in the cyclone is hydrodynamically unstable. Recent studies at Cambridge (Grimble PhD, Mehl MPhil, Tsailouski & Foster MEng, Inigo PostDoc) have shown that the two regions of the flow that cause this instability (the wavemaker regions) lie (i) in the neck between the cyclone and the dust collector and (ii) at entry to the vortex finder. In region (i), the instability is driven by the strong shear in this region and is not convected out of this region because the same mass of air flows in both directions. These studies have also shown that it may be possible to control this instability by altering the flow, although they have not investigated the consequent influence on separation efficiency. The overall aim of this project is to reduce the amplitude of PVC oscillations or to eliminate them entirely, without adversely affecting separation performance. Intermediate milestones are: 1 to find the wavemaker region of the instability using local and global stability analysis; 2 to perform an adjoint base state sensitivity analysis to identify how the flow should be changed to reduce the growth rate of the instability; 3 to alter the flow in an existing CFD simulation to test the results of the stability analyses; 4 to perform an adjoint double-decker sensitivity analysis to identify changes to the shape of the boundary that will reduce the growth rate of the instability; 5 to develop a numerical model for separation efficiency of the cyclone, building on work by Dyson and its collaborators, and to validate it against experimental data by Dyson and in the open literature; 6 to work with engineers at Dyson to incorporate this knowledge

旋风分离器中的旋进涡核（PVC）对分离性能是有害的，占速度波动的80%，增加气动音调噪声，并且耗散机械能从而增加压力损失。PVC的出现是因为旋风分离器中的旋流是流体动力学不稳定的。最近在剑桥进行的研究（Grimble PhD，Mehl MPhil，Tsailouski & Foster MEng，Inigo PostDoc）表明，引起这种不稳定性的两个流动区域（造波器区域）位于（i）旋风器和集尘器之间的颈部和（ii）涡流探测器的入口处。在区域（i）中，不稳定性由该区域中的强剪切驱动，并且不对流离开该区域，因为相同质量的空气在两个方向上流动。这些研究还表明，通过改变流动来控制这种不稳定性是可能的，尽管他们还没有研究对分离效率的影响。该项目的总体目标是降低PVC振荡的幅度或完全消除它们，而不会对分离性能产生不利影响。中间里程碑是：1.利用局部和全局稳定性分析找到不稳定性的造波区域; 2.进行伴随基态灵敏度分析，以确定应如何改变流动以降低不稳定性的增长率; 3.改变现有CFD模拟中的流动，以测试稳定性分析的结果; 4.进行伴随双层敏感性分析，以确定边界形状的变化，这将降低不稳定性的增长率; 5.在Dyson及其合作者的工作基础上开发旋风分离器分离效率的数值模型，并根据Dyson的实验数据和公开文献对其进行验证; 6与戴森的工程师合作，将这些知识融入其中