Numerical Investigations of PGT10 Gas Turbine Exhaust Diffuser Using Hexahedral Dominant Grid

Numerical investigations have been carried out on 35% scaled down model of PGT10 gas turbine exhaust diffuser under the condition of with inlet guidevanes and without struts. Numerical simulations were carried out to determine the static pressure development and pressure recovery, by varying the area ratio and divergence angles varying from θ = 7 to 13 by keeping the diffusion length constant. The flow conditions at the inlet are varied to evaluate how they affect the flow development in the passage. The value of Reynolds numbers at inlet is varied from 3.36537 10 to 6.73075 10.In the present study a quarter part of the model is considered for the analysis, due to symmetry. The results with guidevanes indicates that, the static pressure and the pressure recovery coefficient goes on increasing with the increase in divergence angle up to 11, thereafter, further increase in the divergence angle shows decrement in the pressure recovery coefficient near the exhaust of the diffuser, which results in reducing the efficiency of the turbine.