燃机透平冷却耦合传热特性及多因素影响机理研究

发布时间：2018-06-03 14:18

本文选题：燃气轮机 + 透平冷却　；参考：《清华大学》2015年博士论文

【摘要】：燃气轮机作为一种高效清洁的动力装备,随着其热效率的不断提升,透平进口温度持续升高;冷却技术成为先进透平设计的关键之一。现代先进的透平冷却结构趋于复杂化、多样化,综合冷却效果是各冷却部件和多种传热方式共同作用的结果。随着透平冷却技术探索的深入,反映综合因素影响的耦合传热特征,逐渐成为冷却传热研究的重点。本文首先以端壁冷却机理实验台为基础完成了多参数的流动传热测量,建立了端壁冷却从流动到传热,从绝热到耦合的全面且详实的实验数据库。对实验结果的分析表明,综合冷却效率和绝热气膜效率都会随着冷气流量的提升而明显增高。比较综合冷却效率和绝热气膜效率可以发现,由于内部冷却对流及固体导热的作用,综合冷却效率分布更为均匀,气膜冷却主要影响近气膜孔区域的综合冷效分布。为分析耦合传热下综合冷却效率的多因素影响机理,本文构建了能分离各局部冷却参数影响的一维耦合传热模型;其适用性在与实验结果的比对中得到了验证。借助模型分析表明,各冷却参数中,绝热气膜效率、内部换热系数、热障涂层毕渥数与综合冷却效率正相关,冷气温升系数、金属毕渥数与综合冷却效率负相关;热障涂层的存在会同时削弱内部和外部冷却参数的敏感性;通过对综合冷却效率等值线图的分析,可以进一步得到各参数更细节的影响特征结论。比较无量纲参数相同的高-低温工况实验结果,主流高温使得综合冷却效率偏低;根据所发展的温度修正预测方法,能够对温度的影响进行修正。在高温高湿环境中,辐射作用增强,将对透平冷却传热产生影响。对辐射因素影响的实验及数值研究表明,由于水蒸气介质辐射的作用,随着主流高温燃气中水蒸气体积分数每增加7%,平板综合冷却效率降低约0.02;热障涂层在各组分工况下都有明显的温降效果,且燃气的水蒸汽含量越高,温降效果越明显。由于辐射在高温高湿工况下的综合作用,在透平冷却设计中必须综合考虑不同燃气组分在导热/对流/辐射耦合传热下的影响。本文以多工况变参数流动传热测量为基础,发展了相关数值模拟方法及理论模型,分析了包括各冷却部件、不同温度工况及辐射等多因素在耦合传热下的影响作用,揭示了透平冷却耦合传热机理。
[Abstract]:As a kind of high efficiency and clean power equipment, the inlet temperature of gas turbine is rising with the increasing of its thermal efficiency, and the cooling technology has become one of the key points in the design of advanced turbine. The modern advanced turbine cooling structure tends to be complicated and diversified. The comprehensive cooling effect is the result of the joint action of various cooling parts and various heat transfer modes. With the further exploration of turbine cooling technology, the coupled heat transfer characteristics, which reflect the influence of comprehensive factors, have gradually become the focus of research on cooling heat transfer. In this paper, the multi-parameter flow heat transfer measurement is completed on the basis of the endwall cooling mechanism experimental bench, and a comprehensive and detailed experimental database of endwall cooling from flow to heat transfer and from adiabatic to coupling is established. The experimental results show that both the comprehensive cooling efficiency and the adiabatic film efficiency increase with the increase of the air flow rate. Compared with the comprehensive cooling efficiency and the adiabatic film efficiency, it is found that the distribution of the integrated cooling efficiency is more uniform due to the effect of internal cooling convection and solid heat conduction, and the film cooling mainly affects the comprehensive cooling efficiency distribution in the near film hole region. In order to analyze the multi-factor influence mechanism of integrated cooling efficiency under coupled heat transfer, a one-dimensional coupled heat transfer model which can separate the influence of local cooling parameters is constructed, and its applicability is verified by comparing with experimental results. The results of model analysis show that the adiabatic film efficiency, internal heat transfer coefficient, thermal barrier coating number and comprehensive cooling efficiency are positively correlated with the cooling parameters, and the temperature rise coefficient of cold air and the number of metal outings are negatively correlated with the comprehensive cooling efficiency. The existence of thermal barrier coatings will weaken the sensitivity of both internal and external cooling parameters. Compared with the experimental results of high and low temperature with the same dimensionless parameters, the mainstream high temperature makes the comprehensive cooling efficiency low, and the influence of temperature can be corrected according to the developed temperature correction prediction method. In high temperature and high humidity environment, the enhancement of radiation will affect the cooling and heat transfer of turbine. Experiments and numerical studies on the effects of radiation factors show that, due to the radiation of water vapor media, With the increase of steam volume fraction in mainstream high temperature gas, the comprehensive cooling efficiency of flat plate is decreased by about 0.02, and the thermal barrier coating has obvious effect of temperature drop under each working condition, and the higher the steam content of gas is, the more obvious the effect of temperature drop is. Due to the comprehensive effect of radiation under high temperature and high humidity conditions, the influence of different gas components on heat conduction / convection / radiation coupling heat transfer must be considered in turbine cooling design. In this paper, based on the measurement of flow heat transfer under various working conditions and variable parameters, the relevant numerical simulation methods and theoretical models are developed, and the effects of various factors, such as various cooling components, different temperature conditions and radiation, on coupled heat transfer are analyzed. The coupled heat transfer mechanism of turbine cooling is revealed.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TK471

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