Numerical investigation of the pre-swirl rotor–stator system of the first stage in gas turbine

Three-dimensional viscous steady Reynolds Averaged Navier–Stokes (RANS) solutions are employed to investigate the flow and heat transfer characteristics of the pre-swirl rotor–stator system. The applicability of computational fluid dynamics (CFD) with Shear Stress Transport (SST) turbulence model is verified by a comparison of CFD results with experimental measurements. First, the influences of geometrical parameters, including the pre-swirl angle, the fillet and the ratio of length to diameter of pre-swirl nozzle, on the pre-swirl efficiency and total pressure loss have been numerically investigated to pick out an optimal structure. Then, eight different pressure ratios and four rotating speeds are selected to study the flow dynamics of the pre-swirl system in terms of the pre-swirl efficiency, total pressure loss, discharge coefficient of the pre-swirl nozzles and receiver holes, non-uniformity of velocity and flow angle at the outlet of nozzles, sealing leakage coefficient and technical work. It shows that the pressure ratio has a strong influence on all the flow parameters while the influence of the rotating speed on them looks different. Eventually, the relation between the heat transfer coefficient (HTC) and the pressure ratios as well as the rotating speeds is presented. Results show that the pressure ratio exerts an influence on the magnitude of HTC and the rotating speed has a significant effect on the movement of the regions with high HTC.