Fluctuating characteristics of air-mist mixture flow with conjugate wall-film motion in a compressor of gas turbine

Abstract

A feasible method of injecting water mist into the air can improve the operation performance of gas turbine. This study aims to develop a deeper understanding of aerodynamic characteristics of fluctuating quantities and its influence caused by air-mist two phase flow with conjugate the liquid film. The effect of various mist injection conditions on transient characteristics of compressor was investigated by the frequency attribute analysis. The results show that the film attached to the blade surfaces will aggravate the aerodynamic fluctuation. Notably, the fluctuating quantities, such as pressure, temperature, mass flow, flow loss and compression work, center on the lower frequency region, indicating that the dominant component of disturbance source appears a weak fluctuation because of unevenly distributed flow field after mist injection. Within the range of 0.5–5% mist concentrations and 1–9 μm mist diameters, mist injection can weaken the fluctuation of pressure and tip leakage flow, meanwhile the fluctuations of temperature and entropy increase are a good improvement in large mist ratio or small mist size. However, the fluctuation reduction is marginal as mist concentration and particle size increase. Therefore, the fluctuation characteristics in the compressor can be controlled by manipulating mist injection conditions.