Research Of Compressor Wet Compression Performance And Water Droplet Motion

As one of the components of gas turbine,the consumption of compressor account for 1/2 to 2/3 of expansion work of turbine.Thus reduce the consumption of compressor in order to largely improve the gas turbine output power and it was proved to be an efficient way.The wet compression technology can use the effect of tiny water droplets evaporation and cooling on air flow inside compressor so that it can reduce the consumption of compressor,improve the output power and thermal efficiency.It can be used as an effective measure to improve the gas turbine performance and has attacted much attention in recent years.A series of study on the inlet fogging mechanism of wet compression process is included in this paper.The compressor internal gas-liquid two phase heat and mass transfer process is analyzed.Considering the effect of two-way coupling between cotinous and discrete phase,the heat and mass transfer model for water droplets is adopted in the compressor wet compression process in this paper.The droplet-wall interaction model and secondary breakup model of droplets are established in order to consider the effect of droplets impact on the blade and breakup causing by aerodynamic force in compression process.Considering the effect of droplet-wall interaction and secondary breakup causing by aerodynamic force,inlet fogging into a single-stage and multistage compressor are numerically simulated and analyzed by using CFD method.The author make a comparison between the wet compression case and dry case and make a detailed analysis on performance and flow field.In the study of wet compression process for the multistage compressor,the wet compressor performance stage-on-stage and the radial migration characteristic of water droplets are discussed under different water injecting condition.Results indicate that the improving amplitude of single stage and multistage compressor is relatively high with appropriate water injecting rate and small droplet size except with the wet condition of large injecting rate and water droplet size so that controlling of the wet condition becoming very important;for multistage compressor with water injection,the local volume flowrate of the front stages is much closer to the dry case relatively large flowrate,the last stages much closer to the dry case with relatively low flowrate;the total pressure and rotor torque distribution is consistent with the characteristic "former descreased and back increased".Based on the effect of wet compression on the single stage and multistage compressor,the research for the influence of wet compression on the stability boundary of compressor has been on the agenda.The flow capacity,overall performance and the change of performance parameters stage-on-stage internal the multistage at the rotating stall and chocking boundary are discussed and analyzed.The results show that the performance and flow capacity of the compressor could be improved with proper water injecting conditions at the rotating stall of the dry case and the stall phenomenon can be suppressed or even eliminated;but near the chocking boundary,the blockage degree of compressor is closely related to the injecting condition.Water droplets will be accumulated and form liquid film on the blade surface after water injecting.The author introduce Wall-film model of the blade surface to unsteady CFD computation of the wet compression on NASA Rotor 37.The moving process and the film formation process on the blade surface is simulated and analyzed under different water injecting conditions.Water film forming and tearing process on the blade surface is also analyzed and the performance parameters with wall film model and no wall film model are discussed in this article.