Numerical Investigation Ofwet Compression Characteristic In A Three-stage Axial Flow Compressor

Wet compression has been a focus in the field of compressor during these years for the fact that it can effectively improve the characteristic of gas turbine. Although wet compression can reduce the outlet temperature of compressor and compression work under certain conditions, water injection in the compressor would bring extra loss to affect the effects of wet compression. So it is necessary to investigate the characteristic of compressor with wet compression technology, especially to analyze the side effects brought by wet compression.In this dissertation, the basic theory of wet compression is explained firstly, and the heat transfer and mass transfer phenomenon are emphatically analyzed. On the basis of the theoretic analysis, the mathematical model of wet compression is improved and the relevant program is compiled in this dissertation according to the relevant knowledge of thermodynamics. By applying this model, the influences of water mass flow rate, pressure ratio, water droplets'diameter, compression efficiency and different atmospheric temperature on the characteristic of the compressor are analyzed.The assumptions of the mathematical model limit the range of its application. In order to further understanding wet compression technology, on the basis of the numerical simulation theories, the geometrical model and computational grids are built with Turbo grid in the second part of this dissertation. Besides, with the simulation model of a three-stage axial flow compressor, a full three-dimensional calculation of dry and wet compression under different operation conditions is conducted by utilizing ANSYS CFX. By simulation, under different operation conditions(water mass flow rate is 1% of the air flow of the compressor), the influences of wet compression on the compressor characteristic curves, the outlet temperature, compression work etc., the change of flow field and the parameters along the axial are presented in this dissertation. Besides, considering the change of separation points on the rotor suction side as a factor affecting the stability of compressor, whether wet compression would improve the stability of compressor are analyzed. Further more, with this model, the calculations have been performed with regard to a variety of conditions: different liquid drop diameters, values of water mass flow rate, initial water temperature and different atmospheric temperature.The results show the operating conditions of compressor and the condition of humidification have a great impact on the effects of wet compression, especially, it would lead side affects under the operating condition of low speed and high flow, and meanwhile, it is necessary to choose the optical humidification condition according to the specific condition of the compressor.