Optimization Design Procedure of a Radial Impulse Turbine in OWC System

Abstract

Wave energy exploitation is of great interests nowadays due to its sustainability, reliability and large potential. This paper aims to firstly represent the turbine designs used in oscillating water column (OWC) system for wave energy conversion, and secondly to improve the rotor blade performances of a bidirectional radial impulse turbine which is in use in this system. Symmetrical blade profile based on use of circular arcs and straight lines has been adopted. A new procedure for optimizing the geometrical blade parameters has been introduced in this work. The design of experiments (DOE) method has been adopted with four blade geometrical parameters and two levels for reducing the number of numerical tests to determine the optimal profile in order to maximize and equilibrate the efficiency between exhalation and inhalation modes. Numerical tests in the whole turbine geometry have been carried out with ANSYS FLUENT 15.0. Significant differences have been noticed by varying the rotor blade profile. A flow analysis for the duct and the turbine elements; IGV, rotor and OGV has been performed. Performances of the turbine equipped with rotor designed with circular profiles in the present study have been compared to those of a previous design based on use of elliptical profiles. An increase of about 18% in terms of the peak efficiency in the inhalation mode has been noted for the improved design, and the performances have been equilibrated in both mode; inhalation and exhalation.