Optimization Design of Cooling Structure in Low Pressure Turbine Blade
|School||Harbin Engineering University|
|Course||Power Machinery and Engineering|
|Keywords||blade cooling conjugate heat transfer crossed-rib pin fin|
In the modern high performance gas turbine engine, with the continuous increase of theinlet temperature of the gas, the cooling of the turbine blade is becoming more important, andthe blade cooling technology is playing much more significant role in improving gas turbineoutput and thermal efficiency. The structure of crossed-rib has good cooling effect, but itsstructure is too complex to machining, the rate of finished products is low. Therefore, by thefurther study of the cooling structure for crossed-rib to improve the structure has importantsignificance.From the perspective of relative literatures published at home and abroad, a lot ofresearch were conducted to optimize the structural parameters of crossed-rib, and obtainedmany important conclusions. However, the heat transfer and the composition of pressure lossof the cooling structure are still not deep enough. Consequently, the further research onquantify the heat transfer and the composition of pressure loss is beneficial to optimize andimprove cooling structure.The simplify crossed-rib, trapezoidal crossed-rib and the crossed-rib as internal coolingstructure of low pressure turbine blade are choose to as the object of research in this paper,ANSYS software was used to simulate the three kinds of structure of crossed-rib models, toanalyze the composition of the heat transfer and flow resistance, and adding pin fin in thesub-channel crossing to simplify the structure of crossed-rib and enhance heat transfer ability;the optimization structure of the crossed-rib is applied to low pressure turbine blade toconduct conjugate heat transfer calculation, the cooling effect of the improved crossed-ribstructure on the turbine blade is also analyzed.The results show that for flat crossed-rib structure, heat transfer area、disturbance ondownstream of the impact at the fold and disturbance of the sub-channel are approximately73%、15%and12%respectively, the affection of total pressure loss caused by crossed-ribchannel、 turning structure disturbance on downstream of the impact at the fold anddisturbance of the sub-channel re approximately60%、32%and8%respectively; by addingpin fin to the flat crossed-rib, it can strengthen the disturbance, improve staggered rib andsignificantly rise the heat transfer capacity. For trapezoidal crossed-rib, contraction sectioncan reduce secondary heat exchange surface area and improve the wall heat transfer coefficient; When the trapezoidal plane angle is1.5o, the cooling effect will reduce by5%comparing with taking the same improvement measure of flat crossed-rib. The compositecooling structure of the crossed-rib with increasing width-to-pitch ratio and pin fin to the lowpressure turbine blade can achieve better cooling effect, it can replace the intensive layout ofcrossed-rib.