Numerical investigation on the flow and heat transfer characteristics in radial pre-swirl system with different fillet radius at the junction of inlet cavity and nozzle

This paper conducts a numerical study to investigate the effect of the fillet radius at the junction of inlet cavity and nozzle on the flow and heat transfer characteristics of a radial pre-swirl system. The Reynolds averaged Navier-Stokes equations, coupled with SST turbulence model, are adopted and solved. In this paper, four fillet radii at three nozzle length to diameter ratios are selected to study the flow dynamics of the radial pre-swirl rotor-stator system. The results obtained in this paper indicate that considering the effect of the ratio of fillet radius to nozzle diameter, r(f)/D, on the adiabatic effectiveness, the discharge coefficient of the receiver hole and the total pressure loss in the pre-swirl nozzle and the pre-swirl cavity, there is an optimum value of r(f)/D which can provide the best performance of the pre-swirl system. The effect of r(f)/D on the heat transfer coefficient h is also conducted. Numerical results clearly show that h on the rotor wall at low radius increases with r(f)/D. The uniform distribution of h on the rotor wall at receiver hole radius can be observed as synchronous rotation between the receiver hole and the cooling air occurs. (C) 2016 Elsevier Ltd. All rights reserved.