Modelling and testing the vertical axis, impulse rotor tidal power pontoon

Hardisty, Jack

Abstract

The specification of a new tidal power pontoon is described. The device consists of a 500kW asynchronous generator connected through gearbox and drive shaft to a twelve bladed, vertical axis rotor 4.00m x 4.00m mounted at the impact point of a jet in a symmetrical Bernoulli duct beneath a 16.00 m x 10.00m pontoon. Analytical models are developed for (1) the flow through the duct, (ii) the torque and speed of the rotor and (iii) the efficiency as functions of the device's dimensions and the tidal current speed. Results from computational fluid dynamic simulations confirm the principles of the theory and emphasise the importance of the duct as both accelerator and diffuser. The overall efficiency is shown to depend upon the tip speed ratio of the blade to the Jet velocities. Results from laboratory experiments with a 1/40(th) scale model in a unidirectional flume support the theoretical considerations, provide empirical relationships for the device's efficiency as a function of the jet Reynolds Number and confirm that the optimum TSR lies in the range 0.45-050.

• Journal Article Type: Article
• Publication Date: Apr 30, 2008
• Journal: JOURNAL OF MARINE ENGINEERING AND TECHNOLOGY
• Print ISSN: 1476-1548
• Peer Reviewed: Peer Reviewed
• Issue: A11
• Article Number: K007
• Pages: 15 - 23
• APA6 Citation: Hardisty, J. (2008). Modelling and testing the vertical axis, impulse rotor tidal power pontoon. Proceedings of the Institute of Marine Engineering, Science, and Technology. Part A, Journal of marine engineering and technology, (15 - 23). ISSN 1476-1548