Numerical simulation on the dynamic characteristics of VAWT with different cavity layouts

Purpose This study aims to understand the aero-acoustic performance of H-type vertical axis wind turbine (VAWT) with different cavity configurations through numerical simulation, improving its overall performance and making it suitable for urban applications. Design/methodology/approach Numerical simulation of VAWT was carried out in ANSYS FLUENT software with turbine modelled through SOLIDWORKS. Unsteady Naiver–Stokes equation coupled with SST k-ω turbulence model was used to model the flow field around VAWT. Ffowcs Williams–Hawkings analogy was used for acoustic prediction from VAWT. Two cavity positions, i.e. at 0.25c from the leading edge and at 0.75c from the trailing edge were fixed with five different layouts considered. The cavity layouts are trailing edge single cavity (TESC), trailing edge double cavity (TEDC), leading edge single cavity (LESC), leading edge double cavity (LEDC) and BASE models. The power curve for five different VAWT configurations was evaluated and validated with experimental, computational fluid dynamics works. The qualitative aspect of wake length and wake recovery rate was evaluated for each configuration. Acoustic readings were carried out through receivers placed in circumferential directions as well as downstream directions. Findings The power curve of VAWT shows that TESC tends to be the optimum for urban applications, as it provides maximum power performance compared to other models investigated. TESC delivers a maximum power enhancement of 72.5% compared to BASE models. The cavity in the trailing edge reduces the negative torque and provides enhanced self-starting capability. Cavity-configured VAWT shows better wake recovery than BASE models at near and far fields, enabling them ideal for wind farm applications. In the acoustic case, TESC and TEDC models tend to be quieter at low tip speed ratio (TSR), while at higher TSR, LESC and LEDC prove to be silent. LESC and LEDC tend to reduce sound pressure level value at blade passing frequency compared to BASE models. Originality/value Since the rotor performance of VAWT with different cavity configurations has been explored over the past few years, this is the first research work that deals with wake dynamics and acoustic dynamics of VAWT with cavities. This work identifies the acoustic nature of VAWT with cavity depends upon cavity position which in turn depends on operating TSR as well as the direction in which noise is perceived. The application of a cavity in VAWT will be an ideal solution for urban applications with enhanced power performance and lower operating noise.