Flow-Induced Noise and Vibration Control in Engineering Structures via Geometric Modifications

通过几何修改控制工程结构中的流动引起的噪声和振动

• 批准号: RGPIN-2014-05512
• 负责人: Ekmekci, Alis
• 金额: $ 1.75万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=611682
• 关键词: Flow; Induced; Noise; Vibration; Control

The proposed research program will experimentally investigate the passive control of adverse flow effects in the context of two major engineering problems: The first problem is the control of flow-induced vibration in cylindrical structures, such as offshore risers. Adoption of certain protrusion devices (helical strakes, staggered separation wires, rings, etc) on the structures' surface or slight modifications in their external shape can, in some cases, succeed in suppressing the flow-induced structural vibrations. However, at this point, the knowledge base for the design of such control technologies is still incomplete. The first research campaign in the proposed program aims to address this deficiency by comprehending the flow control induced by various protrusion devices. The central emphasis will be on the exploration of the modified flow characteristics in relation to the structural loads and vibration. Tests will be conducted in the UTIAS water tunnel on stationary, forced- and free-vibrating rigid circular cylinders fitted with a variety of different protrusion devices. Velocimetry (PIV, V3V, and CTA) as well as hydrogen bubble visualization techniques will be used to decipher the flow manipulations. The identified flow patterns will also be linked to the structural loads through synchronized velocimetry and force measurements. This program will progressively build a knowledge base through which efficient control means can be designed to suppress flow-induced vibrations on cylindrical bodies. Many applications of engineering that are in need of guidelines for the development of control measures against flow-induced vibrations will benefit from the outcomes of this program. The other problem is the flow-induced noise issue associated with aircraft landing gears. Owing to the ever-increasing requirements in noise policies, this problem has become a recent subject of interest to aircraft manufacturers. At this point, noise-generation mechanisms for landing gears are still not well understood, and it is therefore difficult to develop efficient strategies to mitigate them. Landing gear noise is a consequence of the unsteady flow formations and their interactions with the aircraft components. For this reason, the proposed program will identify the possible causes of noise generation in 2- and 4-wheel landing gear systems by developing a comprehensive understanding of the coherent, unsteady flow structures forming around them. Using this understanding, where possible, the program will develop new strategies aiming noise reduction. Aerodynamic tests will be carried out in the UTIAS water tunnel. Although typical Mach numbers fall into the incompressible range during approach and takeoff for several airplane, a water facility has never been used before for the investigation of landing gear flows. The advantage of the water facility over traditional wind tunnels is that the water medium slows down the flow dynamics enabling time-resolved capture of the flow behavior using global velocimetry tools (PIV and V3V). In the program, simplified models of landing gears will be studied first. Step by step, test models will incorporate additional geometrical details from real-life landing gears to quantify their effects onto the flow. The accumulated knowledge of the unsteady flow topology will then be used to develop modifications on traditional landing gears to realize noise reduction. The effectiveness of those modifications will be assessed by acoustic tests in the UTIAS anechoic wind tunnel. This research can eventually lead to the development of novel landing gear designs, sensitive to environmental and health issues related to noise. Canada's aviation industry would greatly benefit from such an outcome.

拟议的研究计划将在两个主要工程问题的背景下对不利流动效应的被动控制进行实验研究： 第一个问题是控制圆柱形结构（例如海上立管）中的流致振动。在结构表面采用某些突出装置（螺旋列板、交错分隔线、环等）或对其外部形状进行轻微修改，在某些情况下可以成功抑制流引起的结构振动。然而，目前此类控制技术设计的知识库仍然不完整。拟议计划中的第一个研究活动旨在通过理解各种突出装置引起的流量控制来解决这一缺陷。重点将放在探索与结构载荷和振动相关的改进的流动特性。测试将在 UTIAS 水隧道中对装有各种不同突出装置的固定、强制和自由振动刚性圆柱体进行。测速（PIV、V3V 和 CTA）以及氢气泡可视化技术将用于破译流量操作。确定的流动模式还将通过同步测速和力测量与结构载荷相关联。该计划将逐步建立一个知识库，通过该知识库可以设计有效的控制手段来抑制圆柱体上的流动引起的振动。许多需要制定针对流引起振动的控制措施的指南的工程应用将从该计划的成果中受益。 另一个问题是与飞机起落架相关的流动引起的噪音问题。由于噪声政策的要求不断提高，这个问题已成为飞机制造商最近关注的话题。目前，起落架的噪声产生机制仍不清楚，因此很难制定有效的策略来减轻噪声。起落架噪音是不稳定流动形态及其与飞机部件相互作用的结果。因此，拟议的计划将通过全面了解在两轮和四轮起落架系统周围形成的连贯、非定常流动结构来确定其产生噪声的可能原因。利用这种理解，在可能的情况下，该计划将制定旨在减少噪音的新策略。空气动力学测试将在 UTIAS 水隧道中进行。尽管有几架飞机在进近和起飞过程中典型的马赫数落入不可压缩范围，但以前从未使用水上设施来调查起落架流动。与传统风洞相比，水设施的优势在于水介质减慢了流动动力学，从而能够使用全局测速工具（PIV 和 V3V）对流动行为进行时间分辨捕获。该项目将首先研究起落架的简化模型。测试模型将逐步融入现实生活中起落架的额外几何细节，以量化它们对流动的影响。所积累的非定常流拓扑知识将用于对传统起落架进行改进，以实现降噪。这些修改的有效性将通过 UTIAS 消声风洞中的声学测试进行评估。这项研究最终可能导致新型起落架设计的开发，该设计对与噪音相关的环境和健康问题敏感。加拿大航空业将从这一结果中受益匪浅。