650 / 2019-02-22 10:50:54

Study on a High Subsonic Centrifugal Compressor with Water Injection

High subsonic centrifugal compressor; Two-phase flow; Droplet breakup; Water droplet motion; Numerical simulation.

全体主题 > 数值模拟、建模与CFD

As an economical and effective means, inlet fogging technology is currently used widely to improve the power and efficiency of gas turbines. It is of significance to understand fully the mechanism of the two phase flow in order to make full use of the technology to improve the flow condition in compressor. Based on the commercial CFD software, numerical study of inlet fogging was carried out on an isolated high subsonic centrifugal compressor. In present study, the multiphase flow model of Eulerian-Lagrangian was chosen, in which Eulerian method and Lagrangian method were used to solve control equations for the continuous phase and for the discrete phase respectively. During the solving process, two-way coupling method was employed to consider the mutual influences between the two phases through equation sources of mass, momentum and energy. The simulation results show that fogging into the centrifugal compressor can effectively improve its performance including reducing remarkably the temperature of compression process, elevating the pressure ratio, augmenting the intake air mass flowrate, as well as increasing the compression efficiency. However, the droplet diameter of fogging should be selected carefully. The result shows that due to the strong centrifugal force of the compressor impeller, most droplets are ready to accumulate on the pressure side of the impeller and show obvious radial migration, and only small droplets (less than 5μm) can better follow the gas flow downstream. This phenomenon may cause a very uneven distribution of droplets with different sizes which may result in instability of the flow field in the compressor.