Numerical model on the flow patterns in a radial impulse turbine for an OWC plant

Abstract

One of the most promising alternative energy sources for potential use is wave energy. This thesis focuses on designing and assessment of a new optimized prototype of radial impulse turbine used within Oscillating water Column (OWC) which is specialized in harnessing ocean wave energy. Radial impulse OWC turbines are one of the most current and promising turbine configurations. The radial turbine with fixed guide vanes is a compelling idea to investigate as for the self-rectifying privilege the turbine acquired by guide vanes. Even though the radial turbine has been around for over a decade, there are still several issues to be resolved in terms of improving its geometry and efficiency. The current study's primary goal is to improve the efficiency of self-rectifying air turbines. Despite the obvious advancement in the conversion of oscillating wave hydraulic power to electricity, it is clear that more work needs to be done to improve their efficiency, extend their operating range, and ensure technical reliability. Firstly, establishing a full framework calculation (2D) to determine the minimal incidence to possess in the radial turbine, alterations infiltrated each portian of the turbine. A new optimized geometry prototype was introduced with discrepancies in vanes and blade profiles as well as changes in the setting angle. The calculations paved the way for numerical simulation which is considered as an essential technique in assessing impulse turbine were used in the form of CFD, which is becoming increasingly popular with researchers looking for visual assessments of real-world turbines, and it was used in this study to evaluate a full-scale radial impulse turbine. Secondly, the three key processes in assessing the new optimized geometry were engaged in Fluent-Ansys® software packages: pre-processors, solvers, and postprocessors managing the advancement process throughout this dissertation. After specifying the boundary conditions as the preceding geometries, the validation and verification process using the Fluent-Ansys® software packages demonstrate the model's durability to undergo the analysis. Afterwards, a synergistic step was the solidity optimization protocol which was used to select the correct number of guidance vanes and blades in terms of solidity, specified as a basis for the geometry generation technique used. Subsequently, numerical validation was complementary to compare the new optimized prototype to the previous geometry by Pereiras et al., (2011c) to reassure the model's reliability. With the aid of turbines that underwent the solidity optimization procedure, the new "M" series was launched. The steady and unsteady performance parameters were used to compare the turbines that were tested. The M27 was more efficient in the inflow mode without sacrificing performance in the outflow mode in the steady performance, also, in the non-steady performance, M27 showed the highest efficiency and endurance at high flow coefficients when compared to the previous geometries (M16, M8). Finally, a quantitative review of the flow pattern on the M27 low and high flow coefficients in comparison to previous geometry by Pereiras et al., (2011c). The M27's high performance was vindicated by this study, which provided a visualization of losses across elements and sections usinQ total oressure contours and angle measurements along each line.