Effects of Blades Rows Clocking on Aerodynamics of a Gas Turbine Low Pressure Axial Turbine

Detailed numerical simulations have been carried out to investigate effects of blades rows clocking on aerodynamic performance of a low-pressure turbine unit of an axial multistage turbine. Clocking mechanism is imposed on the fixed blades row of the second stage, and results of numerical flow simulations are presented and discussed in this paper. Frozen rotor and transient rotor-stator approaches have been undertaken through the numerical analyses. Three dimensional results of the flow fields, in terms of distributions of vorticity strength, entropy and total pressure are presented and discussed in detail for different clocking positions of the blades rows. Steady results illustrated that under the optimum position of clocking the aerodynamic efficiency and output power of the second stage increases by ۰.۳۹% and by ۰.۳۳%, respectively, in comparison to the worst position of clocking. The optimum clocking case is convoyed with upstream wake impingement on the second stator leading edge region. In addition, regarding with time-averaged results, flow enters the second rotor blades row with a higher total pressure; something about ۰.۳۲% more than that for the worst case. Furthermore, according to both the steady and time-resolved results, it is shown that higher pressure at stator outlet under optimum clocking is strongly accompanied by higher dynamic pressure at the stator exit.

کلیدواژه ها:

Axial turbine ، Blades row clocking ، Wake flow trajectory ، Blade-to-blade analysis ، Performance optimization