Numerical analysis of air supply parameters and non‐uniform characteristics in a cover‐plate pre‐swirl system with the adjustable flow path
Lei Zhao, Gaowen Liu
Abstract
The pre-swirl system can transfer the cooling air from the compressor to the turbine rotor blades with a lower relative total temperature to avoid extreme thermal shock. This work proposes a novel test rig to investigate the flow and aero-thermal characteristics in a cover-plate type pre-swirl system. The performed experimental and numerical studies focus on the effects of the partial pre-swirl nozzle closing modes on the mass flow rate of air supply, temperature, and uniformities in a pre-swirl system by application of the pre-swirl nozzle adjustable flow path. Especially, the transient problem of the pre-swirl system with the time-space variation characteristics is approximately explored by changing the rotor-stator phases, within the framework of a frozen-rotor formulation. Results show that the opening of the pre-swirl nozzle is of great importance for flow uniformity. A pre-swirl nozzle closing of 14.3% will result in a 10.9% decrease in the mass flow rate of the pre-swirl nozzle and a 9.9% decrease in the mass flow rate of air supply at the system pressure ratio of 1.32 and the rotating Mach number of 0.678. The maximum amplitude of the non-uniformity coefficient of mass flow rate increases from 1.1% to 5.4% for a single supply hole. Moreover, the relative total temperature of air supply decreases by about 1 K with the increase of the fluctuation from 0.5 to 1.5 K. Thus, the performance of the aero-engine can be improved due to a reduction in the amount of cooling air into the rotating turbine blades.