| Modern gas turbine to continuously upgrade the entrance temperature of working medium in order to enhance the cycle thermal efficiency, but also lead to the working parts of the mechanical load and thermal load increasing. In order to ensure the equipment performance, prolong the service life, effectively cooling gas turbine internal high temperature components is very important. At present, cooling measures have been developed mainly film cooling, convection cooling, transpiration cooling and composite cooling, wherein, the use of film cooling technology is the most widely, particularly broad industrial application prospect. Domestic and foreign scholars study the influence factors of film cooling efficiency from the geometric parameters of gas film holes and the cooling flow field aerodynamic parameters.In this paper, for the purpose of observation and research on the flat film cooling flow field temperature field, velocity field and vorticity field characteristics. The early stage of the design in the experimental bench and schlieren optical system and debugging has done a lot of preparatory work, and points out the problems of existing experimental device and proposed the improvement method is possible. In the mainstream 1.8m/s, jet angle is 30 degrees,45 degrees and 60 degrees, the jet velocity for the experimental conditions of 0.35m/s, 0.58 m/s,0.81m/s,1.16m/s and 1.74m/s, the use of wind tunnel device, using the high speed photograph system of circular single hole were no mainstream jet flow field and film cooling flow mainstream gas schlieren experiments, obtain many schlieren pictures. In numerical simulation, mainly on the film cooling flow field temperature field, velocity field, density field and vorticity field are analysed carefully. According to the experimental data and numerical simulation results of the main work, there are some conclusions:1, using the schlieren method can be clearly observed shape of the structure and characteristics of jet flow, and the difference changes is able to distinguish between the free jet flow field in the jet angle and speed condition.2, analysing jet flow transient schlieren image can observe the jet flow motion, development trend, especially the vortex generation, development, migration, diffusion and crushing process.3, It is to verify the existence of jet flow K-H instability phenomenon:if the initial flow is laminar flow state, then the jet flowshear layer will form the axisymmetric vortex ring, and in the delivery of transfer to the downstream process interactions and mixed to form a vortex structure is complex, to the end will be unstable and rupture of the formation of turbulent flow. The article also analyzes the formation mechanism of the vortex, the characteristics of vortex field in detail.4, in the numerical simulation of film cooling, temperature field and density field have similar distribution rule, the velocity field above the speed will be increased because of the presence of throat contraction effect, vorticity field in higher jet velocity of windward side has a row of a series of vortex ring exists. |
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