Experimental Research On The Effects Of Film Cooling Hole Shapes

As a new efficient power plant, gas turbine is used in every area of domestic economy andnational defense. The thermal efficiency would improve with the gas turbine inlet temperatureincreases. However, with the increase of inlet temperature, the thermal load and mechanical loadeffect on the gas turbine blade increase, will reduce the safety of the blade and its service life. Soit is very necessary to cool and protect the turbine blade. One of the most important coolingtechnology of gas turbine blade is film cooling. To improve the film cooling adiabatic efficiencyhas important significance on designing and improving the modern gas turbine.To optimize the film cooling parameters and improve the film cooling adiabatic efficiencyas the main purposes in this paper, make the flat as the research object, do the experimentalresearches which are based on the infrared thermal imaging technology to study the film coolingeffectiveness on the flat plate with different hole shape. The experiments are in six differentblowing ratios of0.3,0.5,0.7,1.0,1.5and2.0, using pass flat plate with cylindrical gasfilm holes of different injection angle α=30°,60°,90°, different compound angle β=15°,30°,90°for single hole and single row experiment, film holes in-line arrangement and staggeredarrangement with injection angle α=30°for two-row film cooling experiment, obtaining a largenumber of relative experimental data. Select the model of injection angle α=30°with nocompound angle for single row numerical simulation at the same experimental situation, thencompare the numerical results with the experimental results. Analyzing the related data ofeach experimental conditions, the results are as follows:(1)In different injection angles of single hole jet flow conditions, the film cooling adiabaticefficiency of α=30°is better than the other two angles, the field region near the film hole, smallblowing ratio has higher film cooling adiabatic efficiency, the far away field region high blowingratio cooling efficiency is slightly better.(2)In different injection angles of single row jet flowconditions, because of the cooling gas interactions between two adjacent holes, the coolingefficiency are better than single hole’s conditions. But there is film cooling dead area in the fieldbetween two adjacent holes near the film hole.(3)In different compound angle jet flowconditions, because of the existence of transverse component, cooling jet flow is deflected to thelateral offset as the compound angle changes, that increased the cooling gas lateral area andreduced the jet flow component along the main flow direction, the cooling gas is better to attachto the wall, the film cooling adiabatic efficiency is more higher than single holes with nocompound angle jet flow condition.(4)Different compound angle of film hole single row layout,the cooling efficiency are relatively improved than the single hole. The film cooling dead areabetween two adjacent holes decreased with the increase of the compound angle, when β=90° film cooling effects is best.(5)In two kinds of double row film holes jet flow conditions, becauseboth of the before and after film hole row jet flow affect on the downstream area, the adiabaticefficiency are increased. The film cooling dead area between two adjacent holes has been wellimproved. When the film holes staggered arranging, the cooling dead area almost disappeared, itis the best film cooling effect in this condition.(6)The film cooling numerical simulation of filmhole α=30°single row layout and the results are compared with the experimental results andshow that the selected experimental model is correct.