| Brayton Cycle has been known for a long time, but until the end of WWII, the rapid growth of gas turbine occurs after human step into the age of jet. The gas turbine is the one of the power machine with knowledge-intensive, so it is called "the most shining pearl on the crown of human industry". Independent design, development and manufacture of this machine are the embodiment of the industry and technology strength. The efficient way to increase the cycle efficiency is to increase the pressure and temperature at the inlet of turbine, based on the principle of Brayton Cycle. For example, the turbine inlet temperature of F-119jet engine exceeds1900C, which is far beyond the limit of alloy used in high-temperature components of gas turbine. For this reason, the cooling is needed for high-temperature components inside gas turbine to decrease the heat load and ensure the safety and life time.Film cooling was firstly applied in aero engine since1970s and now it has been widely used in modern gas turbines. The principle of film cooling is such that the air from compressor is introduced into the hollow turbine blade and then issued from the cooling hole and jet into the mainstream to create the film to cover the solid surface. The film cooling involves one of the basic flow in fluid mechanics-Jet In Cross Flow(JICF). In order to get deep insight into the JICF and assess the performance of curved cooling hole, the single hole, one row of holes on a flat plate and single hole on the leading edge were studied experimentally and numerically under various blowing ratios to investigate the vortical structure, coherent structure and the influence of curved hole on cooling effectiveness etc.Firstly, a test rig was built for flat plate film cooling and particle image velocity (PIV) method was used to investigate the influences of hole curvature on turbulent flow structures and characteristics downstream of a cooling hole on a flat plat under the blowing ratios M=0.5,1.0. The data were measured in5planes including one symmetric plane and four cross section planes. The influences of curved hole passage on velocity profiles at hole exit, averaged jet trajectory and flow field downstream were analyzed. The characteristics and evolution of vortical structures in the jet wake were also discussed. The measurements show that the curved hole enable lower trajectory and it could suppress the evolution of CVP which would lift the cooling film beyond wall surface.In order to assess the improvement of film cooling by curved hole. The TLC (thermochromic liquid crystal) sheet is used to investigate the heat transfer performance downstream of the cooling holes on a flat plate with zero and positive streamwise pressure gradient. In the experiments, both local and transverse averaged cooling effectiveness and heat transfer coefficient off the surface are studied for single and one row of holes over a range of blowing ratio from0.5to1.22for single hole and0.32to1.18for one row of holes. The results show that the curved hole could promote the film cooling and the cooling effectiveness was increased differently for all tested case.On the other hand, on the basis of experiments, the numerical investigations were done with DES(Detached-Eddy Simulation) based on Spalart-Allamas one equation turbulence model to investigate the flow structure downstream of the cooling hole on a flat plate under blowing ratio0.5and1. The evolution of vortical structure and the underlining mechanics of cooling improvement by curved hole are detailed analyzed.At last, in order to assess the performance of curved hole on the leading edge film cooling, the flow fields of the AGTB cascade with leading edge cooling hole on pressure side or suction side are investigated by means of DES under the overall blowing ratios M=0.7. The results show that the curved hole could efficiently increase the cooling effectiveness under the flow environment with huge surface curvature and favorable pressure gradient.
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