Experimental And Theoretical Research On Gas Turbine Film Cooling

Hot section should be cooled as the turbine inlet temperature increased, forwhich film cooling is one of the most important cooling methods. A plate filmcooling test rig and a linear cascade film cooling test rig was built up in present work,pressure sensitive paint(PSP)was used to measure the film cooling effectiveness. Theeffects of various flow and geometry factors were studied for the film coolingmechanism. The film cooling effectiveness and discharge coefficient were studied onthe first nozzle of a heavy-duty gas turbine for the numerical validation and design.The film cooling effectiveness distributions of cylindrical, fan shaped, andlaidback fan shaped holes, trenched hole, double jet film cooling holes are measured atdifferent blowing ratios and density ratios in a low speed wind tunnel. Fan-shaped holecan improve the film cooling effectiveness greatly. Double jet film cooling benefitsfrom the interactive between the two holes, but the film cooling effectiveness is notgood as the fan shaped hole. A new45°compound angle geometry was proved to give ahigher film cooling effectiveness both in numerical and experimental studies. Theblowing ratio, density ratio and Re number effects are also studied at the same time.The round and fan-shaped hole film cooling were measured and compared in thelinear vane cascade on pressure side and suction side. Another F class-heavy duty gasturbine first nozzle vane with thirteen rows of film cooling holes is measured andmodeled at different density ratio. The test vane contains5rows of showerhead roundholes,4rows of fan-shaped holes on the suction side and4rows of round hole on thepressure side. Density ratio increases film cooling effectiveness on the pressure surfaceand suction surface except for the small region on the suction side. CFD calculation wasconducted using RANS model, and the results were compared with experimental data.Four different blade tip geometry and film cooling designs were compared usingnumerical method. The leakage mass flow, heat transfer coefficient and film coolingeffectiveness were compared to improve the blade design, for which the squealer tipwith two rows of film cooling holes presents a best performance.