Numerical and Experimental Studies of Reynolds Number and Stator Clocking Effect on Performance of a High-Loaded Two-Stage Compressor With 3.7 Total Pressure Ratio

Abstract

One of the vital tasks related to the improvement of the efficiency of turbomachines is an increase in their operating altitude by reducing the influence of Reynolds numbers, Re, on the turbomachine parameters. Therefore, the results presented in this work on the effect of Re on parameters of an axial compressor composed of two high-loaded stages are attractive both from scientific and practical points of view. This work presents the results of experimental investigations of Re effect on gas-dynamic characteristics of a highly-loaded two-stage compressor (HPC-2), simulating the first two stages of the High Pressure Compressor, (HPC), for an advanced engine. The compressor has the following key gasdynamic parameters: – corrected mass flow rate: 31.8 kg/s – total pressure ratio: 3.7 – coefficient of aerodynamic load: 0.421 The experimental study of HPC-2 is carried out at the Central Institute of Aviation Motors, (CIAM), C-3 test facility. Reynolds number is changed by decreasing pressure at the inlet from 1 bar to 0.2 bar and changing the clocking position of stator rows at optimal points of performance for two rotational speeds, 0.7 and 0.88. Tests of HPC-2 compressor show that a stepwise decrease of the inlet pressure from 1.0 0.7, 0.4 down to 0.2 bar (a decrease in Re from 1785000 to 294000) leads to a smooth decrease in maximum compressor efficiency by 1% and a shift of compressor characteristics towards lower air flow rates (by 2%). The experimental studies of compressors for present-day engines show that unsteady processes play a key role in compressor efficiency and stability. One way to control unsteady flow in compressors is clocking effect. Recently clocking of stators and rotors has been investigated in details using the HPC-2 two-stage compressor (total pressure ratio 3.7) in H = 0; M = 0 conditions. The effect of Reynolds number on compressor characteristics is studied in this work for the HPC-2 compressor while also investigating stator clocking effect. The rotor clocking effect is not studied. Tests of HPC-2 compressor show that a decrease in the inlet pressure and changes in Re results in a stronger clocking effect, which is 0.5% in terms of efficiency under atmospheric conditions at the inlet and reaches 1% with a decrease in the inlet pressure from atmospheric pressure down to 0.2 bar.