Numerical Analysis on Spray Cooling of Gas Turbine Exhaust Gas
Numerical study was conducted to investigate the water spray cooling performance on gas turbine exhaust gas. A k-ε turbulence model, species transport equations, and a discrete phase model were solved simultaneously to capture heat and mass transfer effects. Actual gas composition and gas turbine operating condition were introduced to the numerical model. Parametric study was carried out by varying spray water droplet diameter, spray water flow rate, spray system configuration, ambient air condition, and exhaust gas composition effects. A non-dimensional parameter, spray cooling performance index was introduced to evaluate the spray cooling performance. It was found that the spray water cooling method reduces exhaust gas temperature significantly compared to a simple ejector system. Among considered variables, spray water droplet diameter played the most important role and other parameters effects showed minor effects as long as water droplet diameter size was small.
Keywords: Spray cooling, gas turbine, CFD, discrete phase model, evaporative cooling, weapon system cooling.