气膜冷却与复合冷却气热耦合研究

发布时间：2018-02-15 14:51

本文关键词： 气膜冷却复合冷却气热耦合多场耦合热应力　出处：《中国科学院研究生院(工程热物理研究所)》2015年硕士论文　论文类型：学位论文

【摘要】：现代燃气轮机的透平叶片已经发展出了气膜冷却、对流冷却和冲击冷却等多种冷却方式相结合的冷却形式,采用气热耦合的方法预测透平叶片的表面温度分布及换热特性,利用多场耦合分析来评价冷却结构,具有十分重要的意义。本文对气热耦合状态下的平板气膜冷却与平板复合冷却的综合冷却效果和壁面换热情况进行了较为详细的研究,并运用多场耦合分析对复合冷却平板的冷却结构进行了评价。搭建了平板耦合实验台和红外热像仪图像采集与数据处理系统,采用红外测温技术测量了耦合状态下气膜冷却平板与复合冷却平板耦合壁面的表面温度分布,进而得出综合冷却效果的分布。采用气热耦合方法研究了吹风比、气膜孔孔型和Bi数等参数对平板气膜冷却与复合冷却的综合冷却效果、壁面换热特性的影响。结果表明,耦合状态下平板气膜冷却在整个耦合壁面上的综合冷却效果都大于零；在气膜孔出口上游,随着吹风比的增加,综合冷却效果逐渐升高；在气膜孔出口下游,采用圆柱孔时在低吹风比时的综合冷却效果更好,而采用扇形孔时则在高吹风比时的综合冷却效果更好;Bi数的减小使整个耦合壁面的综合冷却效果分布变得更加均匀,同时耦合壁面热流为正的区域逐渐减小。与气膜冷却相比,采用复合冷却的方式,明显改善了耦合壁面的冷却效果；随着吹风比的增加,整个耦合壁面上的综合冷却效果都随之升高；复合冷却中的气膜冷却平板采用扇形孔时耦合壁面的综合冷却效果在高吹风比时要明显好于圆柱孔,冲击冷却中冲击孔的布置方式及冲击靶面距离都对复合冷却的综合冷却效果分布有一定的影响；Bi数减小能使复合冷却中气膜孔出口上游耦合壁面的综合冷却效果分布更加均匀,而对下游耦合壁面的综合冷却效果和整个主流侧耦合壁面的换热系数分布影响较小。运用多场耦合分析方法,以热应力为参数对复合冷却平板的冷却结构进行评价,研究了吹风比、气膜孔孔型和冲击冷却结构对气膜冷却平板热应力分布的影响。结果表明,热应力集中主要发生在气膜孔周边位置,具体位置因孔型而有所不同,吹风比增加会使热应力集中现象更加明显,冲击冷却结构也会对热应力分布产生一定影响。
[Abstract]:The turbine blades of modern gas turbines have developed a variety of cooling methods, such as film cooling, convection cooling and impact cooling. The surface temperature distribution and heat transfer characteristics of turbine blades are predicted by gas-heat coupling method. It is very important to evaluate cooling structure by using multi-field coupling analysis. In this paper, the comprehensive cooling effect and wall heat transfer of flat film cooling and plate composite cooling under gas-heat coupling state are studied in detail. The multi-field coupling analysis is used to evaluate the cooling structure of the composite cooling plate, and the image acquisition and data processing system of the plate coupling test bench and infrared thermal imager is built. The surface temperature distribution of the coupled wall of the gas film cooling plate and the composite cooling plate was measured by using infrared temperature measurement technique, and the distribution of the integrated cooling effect was obtained. The blowing air ratio was studied by using the gas-heat coupling method. The effects of hole shape and Bi number on the comprehensive cooling effect and the heat transfer characteristics of the flat film cooling and composite cooling are studied. The results show that the integrated cooling effect of the flat film cooling on the whole coupled wall is greater than zero in the coupled state. In the upper reaches of the outlet of the film hole, the comprehensive cooling effect increases gradually with the increase of the blowing ratio, and the comprehensive cooling effect is better when the cylinder hole is adopted at the low blowing ratio downstream of the outlet of the film hole. When the fan hole is used, the comprehensive cooling effect is better when the air blowing ratio is high. With the decrease of Bi number, the integrated cooling effect distribution of the whole coupled wall becomes more uniform, and the area where the heat flux of the coupled wall becomes positive gradually decreases. Compared with the film cooling, the heat flux of the coupled wall decreases gradually. The cooling effect of the coupling wall is improved obviously by using the compound cooling method, and the comprehensive cooling effect on the whole coupling wall increases with the increase of the blowing air ratio. The integrated cooling effect of the coupled wall surface of the gas film cooling plate with a fan hole is obviously better than that of a cylindrical hole when the air blowing ratio is high. The arrangement of the impact hole and the distance of the impact target surface have certain influence on the comprehensive cooling effect distribution of the composite cooling. The decrease of Bi number can make the integrated cooling effect distribution of the upstream coupling wall of the gas film hole in the composite cooling more uniform. But it has little influence on the cooling effect of the downstream coupled wall and the distribution of the heat transfer coefficient of the whole mainstream side coupling wall. The cooling structure of the composite cooling plate is evaluated by using the multi-field coupling analysis method and the thermal stress as the parameter. The effects of blowing ratio, film hole pass and impact cooling structure on the thermal stress distribution of the film cooling plate are studied. The results show that the thermal stress concentration mainly occurs in the peripheral position of the film hole, and the specific position varies with the pass type. The increase of blowing ratio will make the thermal stress concentration more obvious, and the impact cooling structure will also have a certain effect on the thermal stress distribution.
【学位授予单位】：中国科学院研究生院(工程热物理研究所)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK471

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