Fundamental investigation on the impact of a swirling through-flow in a rotating cavity on the formation of acoustic modes

旋转腔内旋流对声模形成影响的基础研究

• 批准号: 429153912
• 负责人: Professor Dr.-Ing. Dieter Brillert
• 金额: --
• 依托单位: Lehrstuhl für Strömungsmaschinen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/429153912?language=en
• 关键词: Fundamental; investigation; impact; swirling; through

Impeller side clearances in turbomachines usually are confined by the outer walls of the hub and the shroud disk of the radial impeller and the inner walls of the casing. The rotor stator cavities are filled with fluid and because of a leakage at the seals there is a through-flow radial inward or radial outward depending on the operating conditions of the machine. Beside the complex flow structure in the side cavities pressure fluctuations occur which excite the fluid volume to vibrations. The existing coupling of the fluid and the disk structure leads to vibrations of the disk which are able to provoke considerable damage at the disks. Particularly in case of high pressure and a corresponding high density of the fluid the excited vibrations can be harmful. In addition, the existing flow structure and the fluid parameters have a strong impact on the development of acoustic modes in the cavities and influence the vibration characteristic of the impeller disks significantly.The acoustic excitation of the fluid and the disk will be reproduced in this project in a specially raised test facility and the impact of disk rotation, amount of through-flow, through-flow direction and cir-cumferential velocity component of through-flow on the formation of acoustic modes will be investi-gated experimentally. The available generic test facility is essential for specification of the boundary conditions for the tests which shape the vibration behavior. In order to reach the target of investigat-ing basic phenomena it is important to use a disk geometry which is not subject to the technical re-quirements of a hub or a shroud disk of a turbomachine. Supporting the aspired basic research the disk should be approximated by a flat surface and the casing should be realized flat and without any rims as well. In this way an “academic” rotor stator cavity is generated. In this way the gained basic findings can be adopted not only for turbomachines but can contribute to a general understanding of the vibration behavior of a disk in a fluid filled cavity excited by acoustic pressure fluctuations.

涡轮机中的叶轮侧间隙通常由轮毂的外壁和径向叶轮的护罩盘以及壳体的内壁限制。转子定子腔充满流体，并且由于密封处的泄漏，根据机器的操作条件，存在径向向内或径向向外的通流。除了侧腔中复杂的流动结构之外，还会发生压力波动，从而激发流体体积振动。现有的流体和盘结构的耦合导致盘的振动，这能够对盘造成相当大的损坏。特别是在高压和相应高流体密度的情况下，激发的振动可能是有害的。此外，现有的流动结构和流体参数对腔内声模态的发展有很大影响，并对叶轮盘的振动特性产生显着影响。本项目将在特制的试验装置中再现流体和盘的声激励，以及盘旋转、通流量、通流方向和圆周速度分量的影响。 将通过实验研究通流对声学模式形成的影响。可用的通用测试设施对于规范影响振动行为的测试边界条件至关重要。为了达到研究基本现象的目标，重要的是使用不受涡轮机轮毂或罩盘技术要求限制的盘几何形状。为了支持所期望的基础研究，磁盘应该近似为平坦的表面，并且外壳应该实现平坦并且没有任何边缘。这样就生成了“学术”转子定子空腔。通过这种方式，所获得的基本发现不仅可以用于涡轮机，而且可以有助于对由声压波动激发的流体填充腔中的盘的振动行为的总体理解。