Improvement Research Of Cooling Structure In Low Pressure Turbine Blade

The development of gas turbine cooling technology is a key factor restricting theimprovement of the machine performance. This paper uses commercial software tonumerically investigate the performance of a low pressure turbine blade, in order toseek the alternative structure of the crossed-rib prototype blade to achieve a bettercooling performance. The direction of the research in this paper is rib-roughenedserpentine passage.Based on pro/E model、the ICEM mesh and the usage of CFX to make conjugateheat transfer numerical simulations, this paper performs numerical simulations ofseven simplified different models under eight conditions. The models consist ofcrossed-rib, single or double bend over parallel rib, V-shaped rib structure, and thestudy of the heat transfer and flow resistance characteristics of several kinds ofstructures. The results shows that one form of parallel ribs serpentine passage has abetter comprehensive effect, which the Nusselt number is greater than, flow resistancecoefficient and is less than the crossed-rib channel. And then the characteristics offlow and heat transfer is analyzed in detail.In order to verify the effect, it is necessary to recalculate to the above two modelsunder rotating condition at the rotate speed of2000r/min，5000r/min and8000r/min.The result shows that in rotation serpentine passage structure also has a higher heattransfer, lower flow resistance coefficient, and with the increasing of rotating speedheat transfer is enhanced. The paper also analyses the influence on the development ofthe vortex inside the channel with the increasing rotational speed and the change ofthe Coriolis force to the flow in the runner caused by rotating.Putting the rib-roughened serpentine passage structure in the actual cooling bladeto verify its performance, cooling performance is calculated by low pressure turbineblade which prototype composed of complex crossed-rib. No-rib, six and four cavitiesinternal cooling structure conditions are simulated, and all these results are analyzedand compared with each other. The result indicates that the using of serpentinepassage structure in blade can significantly reduce the temperature of blade surfaceand shroud, and along the radial blade also has a better cooling performance. At the same time this structural style has a low impact on main flow. Through thecomparative study of different cooling schemes, advantages and disadvantages ofcooling structure used in low pressure turbine blade are analyzed, which indicated adirection on optimization and improvement in cooling structure.