Design optimization of a purely radial turbine for operation in the inhalation mode of an oscillating water column. (June 2020)

• Record Type: Journal Article
• Authors: Ansarifard, Nazanin; Kianejad, S.S.; Fleming, Alan; Henderson, Alan; Chai, Shuhong
• Is Part Of: Renewable energy. Volume 152(2020)
• Page Start: 540
• Page End: 556
• Publication Date: 2020-06
• Subjects: Radial air turbine -- Optimization -- Vented oscillating water column -- Parametric turbine design -- Inflow turbine configuration; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2020.01.084
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: A vented Oscillating-Water-Column (OWC) simplifies the pneumatic energy conversion problem by rectifying air flow and enabling a unidirectional-air-turbine to be employed. It shifts power-extraction to the inhalation phase of the cycle and provides equivalent pneumatic power to a full-wave-cycle. Conventional Radial-air-turbines feature a low global-efficiency in OWC applications, however they offer simpler designs and lower thrust loads. The aim of this study is to modify the design of a centripetal-radial-turbine for optimum efficiency in steady-state using CFD methods for application with the pressure/flow profile experienced by the vented-OWC. Nine design variables were used to control the shape of the rotor and its adjustment to the inward-flow direction. The optimized rotor was found to achieve significant efficiency and output power by using asymmetric and non-zero-staggered blades. The downstream section was optimized for an efficient matching with the optimized-inflow-rotor and four parameters were used to control the shape of the downstream section. A diffuser with a 7-degree diffusion-angle was found to be the optimal connection between the turbine and the chamber. The inflow radial turbine obtained 81% peak efficiency in the steady-state, and its average efficiency over the expected flow coefficients is comparable to the axial-turbines used with OWCs. Highlights: Optimization studies were used to optimize the rotor of a radial inflow turbine. Angles of the blades and guide vanes were found to have the highest sensitivity. The losses in all sections of the optimized inflow turbine are highly reduced. The optimized inflow turbine was found to obtain 81% peak efficiency in steady-state.