Numerical simulation for the impact of wet compression on the performance and erosion of an axial compressor

The compressor of the gas turbine set consumes around 50 %-60 % of thepower generated by its turbine. Reducing the power consumed by the compressorincreases the net power produced by a gas turbine set. This power gain is attributedto the redistribution of the power flow within the set. Therefore, this powerincrease does not accompanied with increase in thermal or mechanical stresseswithin the set. One of the most common technologies for the augmentation of thegas turbine power is wet compression. Wet compression can be achieved byintroducing liquid DROPlets into the compressor. DROPlets evaporation duringcompression process has what could be called micro-inter-cooling effect. Thisleads to a reduction in the compressor consumed power.In this study a numerical model is developed to study the effect of wetcompression on the performance of axial compressors. A commercial CFD code,FLUENT, is used to solve the governing equations in a three dimensional, unsteady,and turbulent flow simulation of a three stage axial flow compressor. LiquidDROPlets are introduced as a dispersed phase and are tracked in a Lagrangian frameto simulate the wet compression process. The model accounts for DROPlet-flow,DROPlet-DROPlet, and DROPlet-wall interaction. Turbulence phenomenon is treatedusing the RNG k - & turbulence model. The effect of turbulence on the dispersionof DROPlets is taken into account using a stochastic model.The flow field is solved in the dry case and the compressor performance isanalyzed in terms of; variation of air properties, characteristics of the operatingpoint, and consumed specific power. Performance change due to wet compressionis calculated. Parametric study has been performed to find out the effect ofimportant parameters on the compressor performance. These parameters include;the injected coolant mass flow rate as a ratio of the dry air mass flow rate (injectionratio), the DROPlet size, and the effect of DROPlet-DROPlet interaction.