燃气涡轮发动机预旋系统压比和熵增的作用机制与理论分析

The pre-swirl system has the complex problem of power and heat conversion of rotating and stationary components, and can provide important guarantee for high-temperature thermal protection of turbine rotating blade. Theoretical analysis of the correlation mechanism and evolution law of pressure ratio, entropy increase, and temperature drop of the pre-swirl system is conducted in this paper. A mathematical model of pressure ratio efficiency is proposed. The influence mechanism of the impeller effect of rotating component is comprehensively evaluated. It is found that under the condition of adiabatic constant specific heat, the pressure ratio and entropy increase of the station system decreases monotonously with the increase of air supply flow rate. The pressure ratio-entropy increase characteristic of rotor system depends on the effect of air supply flow rate, rotational speed of turbine disc, and system temperature drop. By decomposing the mechanism of temperature drop into a strong correlation function between the velocity coefficient and the rotating Mach number, it is clearly pointed out that the system pressure ratio decreases with the increase of the air supply flow rate, and basically increases with the increase of the turbine disc rotational speed. When the airflow swirl ratio of preswirl nozzle is greater than the reciprocal of pre-swirl radius ratio, the system pressure ratio decreases with the increase of turbine disc rotational speed. It can be revealed that the decrease of entropy loss is an important way to improve the system pressure ratio when the inlet flow condition and the pre-swirl radius ratio are constant. By systematically evaluating the impeller effect of rotor component, it is found that the impeller can increase the nozzle outlet velocity coefficient, increase the system temperature drop, and reduce the system power consumption without changing the rotating Mach number and keeping the system pressure ratio unchanged. Therefore, the correlation mechanism of pressure ratio and entropy increase characteristics can effectively evaluate the design of pre-swirl system.