Numerical Investigation On Flow Field Of Large Pressure Ratio Turbine Stage

The single stage turbines, whose pressure ratio is more than30, play animportant role in national defense system and economy. Their characteristics, suchas small volume, large pressure ratio, high load, large energy density, et al, cansatisfy the needs of many special occasions. In this paper, an analysis, whichincludes through-flow pneumatic design,3D steady and unsteady pneumaticcalculations, is performed to investigate the flow details.The structure form of this kind turbines, the design theory of main workingcomponents (scarfed nozzle and high-load blade), and the loss in turbine are studied.1D pneumatic design, nozzle modeling and impulsive blade modeling are carriedout by program. The turbine designed uses the dry steam and the pressure ratio is35,while the outlet Mach number of scarfed nozzle is2.5, which is achieved by usingsupersonic nozzle.Based on the1D pneumatic design result of the high-pressure-ratio turbine,3Ddesign is processed. According to3D numerical calculation result, the flow detailsare studied, including the interaction among the nozzles, the nozzle wake, the affectof the shock wave on the boundary layer, the vortex inside the rotating passages andthe flow deviation between intake arc and non-intake arc, etc.3D unsteady numerical calculation is processed to review unsteadycharacteristics of the high-pressure-ratio turbine. The transportation and dissipationof the nozzle in the rotating passages, as well as the affect of the nozzle wake on theaerodynamic load of rotating blades are the focal points.