Numerical investigation of the flow and heat transfer characteristics for a pre-swirl rotor–stator system with center inflow

• We study the pre-swirl rotor–stator system with center inflow.
• The influences of the center inflow on flow dynamics have been studied.
• A theoretical expression of adiabatic effectiveness with center flow has been derived.
• The center inflow effects on heat transfer characteristics have been studied.

The effects of the center inflow on the flow and heat transfer characteristics in a pre-swirl rotor–stator system are numerically investigated using the CFD software ANSYS-CFX. The investigation of the pre-swirl system without center inflow is also conducted to be served as a contrast and these results are compared with experimental measurements to verify the computational method. In this paper, five mass flow rate ratio of the center flow to the pre-swirl flow, mf, four dimensionless mass flow rate of pre-swirl flow, Cw, and five rotation speeds, n, are selected to study the flow dynamics of the pre-swirl system in terms of the flow structure, the air swirl ratio, the total pressure loss coefficient, the discharge coefficient of the receiver holes and the adiabatic effectiveness. It shows that the maximum value of the discharge coefficient occurs as swirl ratio in the core at the receiver-hole radius equals 1 and mf reaches as a high value as possible, and the adiabatic effectiveness decreases as mf increases. In addition, the relation between the Nusselt number, Nu, and mf, Cw as well as n is also illustrated and discussed.