Session: 08-08-02: Design Analysis and Optimization of Energy Conversion Systems - 2

Paper Number: 145873

145873 - Performance of a Ducted Cross Flow Turbine With Different Blade Configurations for Marine Current Energy Extraction 

Marine current energy is a clean source of energy and an alternative energy source for fossil foil. Energy demand for Pacific Island countries can be met by renewable energy sources like marine current energy. Horizontal axis marine current turbines (HAMCT) have been developed and can be installed for commercial use, HAMCT performs well at velocities over 2 m/s and need to be installed at depths of 20 - 40 m [1]. Placing an appropriately designed duct or shroud around the turbine significantly improves turbine performance. Studies are carried out by researchers on ducted turbines and it was found that placing ducts can significantly improve the turbine performance [2]. Ducted cross flow turbines can operate at lower depths since large clearance is not required because turbulent flow has little effect on the performance of the Savonius rotor. A ducted cross flow turbine was designed for a location in Fiji, the passage is called gun-barrel passage; the coordinates of the location are 18°12'1.78"S and 177°38'58.21"E, the average marine current speed at this location is 0.85 m/s and maximum velocity exceeds 2.5 m/s. The inlet of the duct is 3.25 m x 3.25 m, and the converging and diverging section of the duct was optimized to improve the performance. The model of the ducted Savonius turbine, scaled down to 1:10, was fabricated and tested in a water stream with a velocity of 1.04 m/s. Commercial Computational Fluid Dynamics (CFD) code ANSYS-CFX was validated with the experimental results. A full-scale numerical model was constructed to study the flow characteristics. In addition to this, a rotor with three different blade configurations was modeled and simulated using ANSYS-CFD. Finally, the performance of ducted cross flow turbine with 26-blades, 30-blades, and 36-blades was analyzed at free stream velocities of 1 m/s, 2 m/s, 3 m/s, and 4 m/s. The ducted cross flow turbine with 30 blades performed better than the turbine with 36 blades and 26 blades, at free stream velocity of 2 m/s and 3m/s achieving theoretical efficiency of approximately 55%. Whereas, the 26-blade cross flow turbine performed slightly better than the 30 and 36-blade turbines at a free stream velocity of 4 m/s with maximum efficiency of around 56%. The 36-blade cross flow turbine performs better at a free stream velocity of 1m/s and at lower TSR for the case of 2m/s, 3m/s, and 4m/s compared to 26-blade and 30-blade rotors. The 36-blade rotor will be ideal for locations with marine current velocities up to 1.5 m/s and also for locations with highly turbulent flows.

References:

[1] Goundar, JN and Ahmed, MR 2014, ‘Marine Current Energy Resource Assessment and Design of a Marine Current Turbine for Fiji’, Renewable Energy, vol. 65, pp. 14-22.

[2] Goundar JN, Prasad, DD and Ahmed, MR 2018, ‘Design of a ducted cross-flow turbine for marine current energy extraction’, Proceedings of the ASME 2018, International Mechanical Engineering Congress and Exposition, Pittsburgh, PA, USA.

Presenting Author: Jai Nendran Goundar The University of the south pacific

Presenting Author Biography: I'm an assistant lecturer at the University of the South Pacific. My master's and PhD thesis were based on marine current energy extraction. I have published several journal articles and conference proceedings in the field of energy. I have also contributed several papers to ASME conferences and journals

Authors:

Jai Nendran Goundar The University of the south pacific