Numerical Study on Non-uniform Inlet Spray Cooling of Gas Turbine Exhaust Pipe
In order to study the influence of non-uniform inlet conditions on the internal flow field,evap-oration motion trajectory of spray droplet,and cooling effect during the spray cooling process in the ex-haust pipe of a gas turbine,a spray cooling numerical study based on the Realizable k-ε model com-bined with the wall function and DPM model was conducted.The influence of the distribution of spray nozzle positions,different spray droplet diameters and spray flow rates on the pipe wall and outlet cooling effect under non-uniform inlet conditions was explored.The exhaust pipe was a cylindrical pipe with an e-qual diameter of 1.524 m,a front straight section of 5 m,a rear straight section of 8 m and a turning ra-dius of 2.8 m.The cone angle of spray jet was 45°,the velocity was 30 m/s and the temperature was 328.15 K.The study shows that under non-uniform inlet conditions,the best cooling effect are obtained with non-uniformly distributed spary nozzles concentrated in the high temperature region,with a wall tem-perature drop of 111.08 K and an outlet temperature drop of 97.14 K,and the effect of the number of nozzle rows on the cooling effect is small.The standard deviations of the pipe outlet planar velocity distri-bution before and after spray cooling are 12.77 and 11.14 m/s,respectively,indicating that spray can improve the uniformity of the flow field in the straight section.Non-uniform inlet conditions have a greater impact on droplet smaller than 25 μm in diameter,with rapid evaporation and insufficient vaporization heat absorption due to insufficient collision with the wall.As the flow rate increases,the influence of spray on the pipe wall and outlet cooling effect is similar,and the vaporization of spray droplet is affected by the spray flow rate,with larger flow rates resulting in longer vaporization lengths of spray droplet.
gas turbineexhaust pipenon-uniform inletspray coolingcooling effect
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