SIMULATION AND ANALYSIS OF PERFORMANCE OF A MARINE CURRENT TURBINE IN FREE SURFACE FLOW

Abstract

Renewable energy is that form of energy which is extracted or tapped from resources which do not get depleted during the course of energy extraction. Marine currents, unlike other sources of renewable energy, are highly predictable and, hence, tapping of tidal power from the same could prove to be efficacious for further electricity generation. Marine current turbines (MCTs) are very much like underwater windmills except the rotors are driven by consistent, fast-moving currents. The submerged rotors harness the power of the marine currents to drive generators, which in turn produce electricity. As part of the dissertation work, a thorough literature survey has been carried out. Research works, experimental, theoretical and numerical, on turbines and turbulent flow past objects have been analysed in detail. Marine turbines have the fundamental design of propellers with the difference being in the fact that the rotational motion is produced by the undersea currents. Experimental analysis of open water propellers is available as past literature. The available design of controllable pitch marine propeller, VP1304 has been numerically simulated in STAR CCM+ and the performance characteristics of the same have been compared against experimental data to validate the numerical modelling of propeller blades and the marine environment which could, in turn, be applied to the design of a marine turbine. A model of a conceptual marine turbine with NACA 0012 blade profile made in SOLIDWORKS is already available from literature. The same has been imported in ICEM CFD and suitably meshed. The meshed structure was imported in ANSYS CFX. The analysis was carried out in CFX Pre and CFX solver to bring out the pressure and velocity plots after specifying assumed boundary conditions. Additionally, plots for torque, power and efficiency of the turbine have been generated for the conceptual design operating at different rotational speeds using data generated by CFX post and MS Excel. The meshing and specification of the marine environment was done in accordance with the procedure validated by the STAR CCM+ analysis.