Analyzing the exergy and aerodynamic performance of Wells turbine near stall

This study offers a second law analysis of the isothermal flow through a Wells turbine. Numerical computations are carried out in OpenFOAM by solving steady, incompressible and three-dimensional Reynolds-averaged Navier-Stokes equations with Spalart-Allmaras turbulence model. To verification of the OpenFOAM solver, the amount of dimensionless torque is compared with the experimental and numerical data available in a wide range of flow coefficients. It is observed that the results of the present simulation have good agreement with experimental data. Then local entropy generation rates due to viscous dissipation around the rotor blades are added to numerical code and accumulated with other irreversibilities to calculate the exergy efficiency. The results show that separation and interaction between boundary layers of the hub and the blade have a direct effect on the entropy generation and thus efficiency. Exergy efficiency decreases about 90% with considering the viscous dissipation term