Effect of Water Spray Evaporative Cooling on Boundary Layer Separation in a Compressor Blade
A numerical study of the spray cooling process has been carried out using the Eulerian-Lagrangian coordinate system to investigate the flow field characteristics of NASA Stage 35 under spray conditions and the effect of droplet cool-ing on boundary layer pair separation,and to investigate the viscous losses resulting from boundary layer pair separation. The results show that spray cooling leads to an increase in mass flow rate and a decrease in temperature at the inlet of the flow field. As the drops evaporate,the fluid composition changes and the kinematic viscosity of the flow field increases,delaying boundary layer separation and reducing boundary layer strength. Boundary layer separation occurs at 25％ chord length under dry air conditions. Spraying moves the boundary layer to 29％ chord length where separation occurs. Although viscous loss from boundary layer separation increases under droplet cooling,thinning of the boundary layer separation plays a dominant role in lobe loss,and lobe loss decreases by 3.68％ under spray cooling.
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