| Turbine inlet temperature restricts the development of turbine performance.When the growth rate of the temperature limit of metal materials can not fully meet the needs of increasing the inlet temperature of the turbine,the importance of turbine cooling technology is increasing day by day.Film cooling is one of the commonly used cooling methods,and various influencing factors of film cooling have been widely studied,but the complex three-dimensional flow in the turbine will affect the cooling effect.How to make a reasonable cooling layout has always been a hot issue.In this paper,a series of studies on the end wall of the static blade of a heavy gas turbine are carried out by using the method of pressure sensitive paint and numerical simulation.the main contents are as follows:(1)A series of film cooling characteristic test was carried out on a test piece designed for a scheme of arranging film holes along the isobaric line using a high-speed wind tunnel,and the film cooling efficiency distribution of the endwall was obtained.On this basis,the effects of blowing ratio and pressure drop ratio on film cooling efficiency were studied.From the experimental results,for the fan-shaped hole,the film adhesion is better than the circular hole when increasing the blowing ratio,and the cooling efficiency is improved,but due to the design of the end-wall film cooling layout,the circumferential average efficiency does not change much in the direction of flow direction.however,the change of pressure ratio only mainly affects the film cooling efficiency at the front of the channel,which proves that the blowing ratio is a more important factor.(2)Based on the flow characteristics and heat load of each region of the end wall,endwall is divided into different regions.The traditional horizontal arrangement of film holes is changed into arranging in separated zones along the flow direction,and then experimental and numerical studies are carried out.The cooling performance in different areas of the end wall is discussed emphatically.For the low film cooling efficiency area in the leading edge zone,compound angle film holes are used to reduce the hole spacing properly.After further design,the endwall is fully covered by coolant gas when the blowing ratio is 0.9,and the performance is improved under other working conditions.At the same time,the arrangement of film holes along the flow direction near the pressure surface helps to limit the development of the pressure surface branch of the horseshoe vortex.(3)At the same blowing ratio,increasing the temperature ratio can reduce the momentum ratio between the air conditioner and the mainstream,so that the adhesion effect of the air conditioner is better.The cooling efficiency of the same film hole layout scheme at the high temperature ratio is higher than that at the small temperature ratio.When the temperature ratio is high,the area near the leading edge is the most difficult area for the end wall to cool.Increasing the temperature ratio basically does not change the circumferential average efficiency distribution along the axis. |
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