Biradial turbine rotor aerodynamic design and parametric analysis

Abstract

The paper presents a study on the aerodynamic design of self-rectifying biradial turbine rotors for applications in wave energy conversion. The aim is to improve the biradial turbine efficiency and understand the specific speed range for which the turbine operation is most efficient. A rotor geometry generation method is presented, adding more degrees of freedom to the original method by improving the rotor meridional profile definition and relative flow velocity distribution. The new meridional channel definition allows tuning the rotor specific speed in the design phase. The prescribed relative flow velocity distribution improves the rotor inlet-to-outlet pressure gradient distribution. The research comprises geometry parametrisation, and three-dimensional flow simulations with a Reynolds-averaged Navier–Stokes equations solver to understand the effect of the design parameters on the rotor performance. The increase in total-to-total efficiency of the new rotor design is near 1%, demonstrating the good aerodynamic performance of the original design. It is shown that the turbine’s specific speed can increase by 5.4%, and the specific diameter can decrease by 6.0% compared to the original design without reducing turbine efficiency.