Investigation of the massflow regulation and temperature drop characteristics for the modulated pre-swirl system based on partial inlet closure

The pre-swirl system of aero-engines delivers sufficient cooling air to turbine blades. The traditional fixed-geometry pre-swirl system conventionally squanders coolant during cruise, leading to losses in engine performance and economy. Therefore, the modulated pre-swirl system has been introduced to advanced aero-engines for better fossil fuel energy management. For the modulated pre-swirl system based on partial inlet closure, the massflow regulation efficiency and average temperature drop efficiency are specially defined. The effects of massflow adjustment demands, inlet closure modes, and key structure parameters (the number of pre-swirl nozzles, receiver holes, and impellers) on the cooling air supply performance are investigated. The results demonstrate that with the closed inlet area expanding, the massflow regulation efficiency increases while the average temperature drop efficiency shows a first increasing and then reducing trend. The concentrated one-side closure mode is recommended for superior massflow regulation efficiency. Enlarging the nozzle number contributes to improving the massflow regulation efficiency but at the cost of lower temperature drop. A larger number of receiver holes and impellers is beneficial for coolant saving and temperature drop. In comparison with the non-impeller cover-plate cavity, adding 60 impellers increases the massflow regulation efficiency by 0.9 % and the average temperature drop efficiency by 22.5 %.