Numerical analysis on impeller behavior of vertical axis water turbine for underwater vehicles

In order to supply energy to autonomous underwater vehicles (AUVs), a small-scale vertical axis water turbine (VAWT) was designed. The influence of structural parameters including the foil section profile, the foil cord length and the block ratio on the turbine performance at different tip-speed-ratios (TSRs) was investigated with the two-dimensional transient computational fluid dynamics (CFD) method. In the numerical simulation, the time-averaged Reynolds Navier-Stokes equation and the RNG k-ε turbulence model are adopted. The computation domain is divided into a stationary subdomain and a rotating subdomain, and they are connected by a sliding mesh method. The results show that the higher torque peak and capture power peak can be achieved at the smaller TSRs when the blade thickness is larger. The block ratio has significant influence on the impeller output. The turbine with three unit-length NACA0015 foils can generate a maximum averaged power of 25 W at a water velocity of 0.5 m/s and other given parameters.