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Experimental and theoretical modelling of hot-gas ingestion through gas-turbine rim seals

通过燃气轮机边缘密封吸入热气的实验和理论模型

基本信息

批准号：
EP/J014826/1
负责人：
GD Lock
金额：
$ 67.87万
依托单位：
University of Bath
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2013
资助国家：
英国
起止时间：
2013 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FJ014826%2F1
关键词：
Experimental theoretical modelling hot gas

项目摘要

This proposal is in the EPSRC portfolio research area of fluid dynamics and aerodynamics (maintained) and will contribute to the experimental capability and measurement instrumentation knowledge base of the science community. The primary industrial impact of the research will be improvement in energy efficiency, which is one element of the EPSRC energy theme.The gas turbine engine is an adaptable source of power and has been used for a wide variety of applications, ranging from the generation of electric power and jet propulsion to the supply of compressed air and heat. Competition within the industry and, more recently, environmental legislation from government have exerted pressure on engine manufacturers to produce ever more cleaner and efficient products.The most important parameter in governing engine performance and life cycle operating costs is the overall efficiency. High cycle efficiency depends on a high turbine entry temperature and an appropriately high pressure ratio across the compressor. The life of turbine components (vanes, blades and discs) at these hot temperatures is limited primarily by creep, oxidation or by thermal fatigue. It is only possible for the turbine to operate using these elevated mainstream gas temperatures (as hot as 1800 K) because its components are protected by relatively cool air (typically 800 K) taken from the compressor. However, this cooling comes at a cost: as much as 15-25% of the compressor air bypasses combustion to provide the required coolant to the combustor and turbine stages. Ingress is one of the most important of the cooling-air problems facing engine designers, and considerable international research effort has been devoted to finding acceptable design criteria. Ingress occurs when hot gas from the mainstream gas path is ingested into the wheel-space between the turbine disc and its adjacent casing. Rim seals are fitted at the periphery of the system, and a sealing flow of coolant is used to reduce or prevent ingress. However, too much sealing air reduces the engine efficiency, and too little can cause serious overheating, resulting in damage to the turbine rim and blade roots. It is proposed to build a new fully-instrumented rotating-disc rig to measure the flow structure and heat transfer characteristics of hot gas ingress in an engine-representative model of gas-turbine wheel-spaces. An annular single-stage turbine will create an unsteady circumferential distribution of pressure, which in turn will create the ingestion of hot air in the wheel-spaces. The rig will be designed specifically for optical access, with transparent rotating and stationary discs coated with thermochromic liquid crystal and illuminated by a strobe light synchronised to the disc frequency. This will be a new, bold application of the advanced thermal-imaging technology developed at Bath and will provide both qualitative 'thermal visualisation' and quantitative measurements of heat transfer coefficient in the regions on the rotating and stationary surfaces affected by ingress. Miniature unsteady pressure transducers, pressure taps, pitot tubes, fast-response thermocouples and concentration probes will also be used inside the seal annulus and in the upstream and downstream wheel-spaces. In parallel with the experimental programme, new theoretical models developed at Bath will be used extensively in the analysis and interpretation of the experimental data obtained from the new rig. These generic models will be of use to any gas turbine manufacturer, and here this will be demonstrated by specifically translating them into the engine-design methodology used at Siemens. The research will generate unique and practically-useful data which can be rapidly exploited. The successful completion and implementation of this research through improved secondary air system design should result in a competitive advantage for the UK-based company.

这项建议属于EPSRC流体动力学和空气动力学(维护)组合研究领域，将有助于科学界的实验能力和测量仪器知识库。这项研究的主要工业影响将是能源效率的提高，这是EPSRC能源主题的一个元素。燃气轮机发动机是一种适应性较强的动力来源，已被广泛应用于从发电和喷气推进到提供压缩空气和热量的各种应用。行业内的竞争，以及最近政府的环境立法，都对发动机制造商施加了压力，要求它们生产更清洁、更高效的产品。控制发动机性能和生命周期运营成本的最重要参数是整体效率。较高的循环效率取决于较高的涡轮入口温度和压缩机上适当的较高压力比。涡轮部件(叶片、叶片和轮盘)在这些高温下的寿命主要受蠕变、氧化或热疲劳的限制。涡轮机只能使用这些较高的主流气体温度(高达1800K)运行，因为其部件受到来自压缩机的相对较冷的空气(通常为800K)的保护。然而，这种冷却是有代价的：多达15%-25%的压缩机空气绕过燃烧，为燃烧室和涡轮级提供所需的冷却剂。进气是发动机设计者面临的最重要的冷却空气问题之一，国际上已有大量的研究工作致力于寻找可接受的设计标准。当来自主流气体路径的热气体被吸入涡轮盘与其相邻机壳之间的轮隙时，就会发生入口。在系统的外围安装了轮缘密封件，并使用冷却液的密封流来减少或防止进入。然而，太多的密封空气会降低发动机的效率，太少的密封空气会导致严重的过热，导致涡轮轮缘和叶片根部损坏。提出了建立一种新型的全仪表式转盘试验台，用于测量燃气轮机轮距发动机代表模型中热气体入口的流动结构和换热特性。环形单级涡轮将产生不稳定的周向压力分布，这反过来又会在轮隙中产生热空气的吸入。该试验台将专门为光学访问而设计，带有透明的旋转和静止圆盘，表面涂有热致变色液晶，并由与圆盘频率同步的闪光灯照明。这将是Bath开发的先进热成像技术的一个新的、大胆的应用，并将提供受入口影响的旋转和静止表面上区域的热传递系数的定性和定量测量。微型非稳定压力传感器、压力接头、皮托管、快速响应热电偶和浓度探头也将用于密封环空内和上下游车轮空间。在实验方案的同时，巴斯开发的新理论模型将被广泛用于分析和解释从新试验台获得的实验数据。这些通用模型将对任何燃气轮机制造商有用，这里将通过专门将它们转化为西门子使用的发动机设计方法来演示这一点。这项研究将产生独特的、实际有用的数据，这些数据可以迅速利用。通过改进的二次空气系统设计成功完成和实施这项研究，应该会为这家总部位于英国的公司带来竞争优势。