Study Of Film Cooling Characteristics With Auxiliary Vertical Hole Injection

The film cooling was widely used in turbine blades cooling.The principle of film cooling is that the flow at low temperature is send into the mainstream through the cooling holes of turbine blade surface to protect the blade surface from overheating.The characteristics of air and gas were changed by vertical hole assisted jet structure so that the coverage of the air-conditioned exhibition was effectively extended and the film cooling efficiency was improved obviously.Therefore,it is significant in engineering to study conducted for the film cooling of the structure.The CFD numerical simulation method was used in this paper and the cooling holes of turbine blade as the model was calculated by using the separation of implicit solver and the realizable κ-ε model and the enhanced wall treatment was used to analyze the near wall region.The SIMPLE algorithm was applied to the pressure-velocity coupling,and the second order upwind was used for the discretization of the physical quantities.The convergence condition was that the residuals of each parameter were less than 10-6.The film cooling characteristics of different structures were studied under the conditions of blowing ratio of 0.5,1.0,1.5,2.0and temperature radio of 1.2,1.5,2.0.The results showed that: the effect of the positions of auxiliary vertical hole on the film cooling was significant,and the suppression effect on kidney-shaped vortex was the best when the auxiliary hole located on the x/D=-1.The kidney-shaped vortex of the auxiliary vertical hole was effectively suppressed when the blowing ratio was high,the highest average efficiency was 0.44 when the auxiliary hole located on the x/D=0.Compared with the single-hole structure,the average efficiency increased 20.7%.and compared with other auxiliary vertical hole structure increased 16%.With the temperature ratio increased,the average efficiency of the cooling surface was also obviously improved.The highest average efficiency was 0.51 when the temperature ratio was 2.0 and auxiliary hole located on the x/D=-1.The average efficiency increased 22.0% when the temperature ratio was 1.2.Inconclusion,with the increase of blowing ratio and temperature ratio,the film cooling efficiency was greatly improved.