Shape optimization of a shrouded Archimedean-spiral type wind turbine for small-scale applications

Small-scale wind turbines are increasingly gaining importance despite they are still in the shadow of the megawatt-sized wind turbine development boom. Areas far removed from the electricity grid pose great potential for small-scale wind turbines. In such instances an Archimedean-spiral type wind turbine (ASWT) which is a new kind of horizontal-axis wind turbine maybe used for small-scale applications including off-grid power. The ASWT performance is improved in this work by designing a shroud with a flange at its inlet during an optimization technique aims to maximize the coefficient of power (Cp). The employed optimizer is an Evolutionary Algorithm over a Kriging interpolative model. A set of straight lines is applied to identify the shape of the shroud. The output power coefficient (Cp) is calculated by solving the Reynolds-averaged Navier-Stokes (RANS) equations with the SST k-Ω turbulence model using the commercial code software ANSYS-FLUENT. The simulation results are verified through GCI and validated with an experimental result. It is proved that the optimal shroud design yielded important enhancements in the Cp when it is applied to an ASWT. The results indicated that the optimal shrouded ASWT introduces a maximum Cp-value of 0.502, which is 2.58 times the Cp-value of the bare ASWT (Cp = 0.195) at λ = 2.5.