Incorporating turbulent inflow conditions in a blade element momentum model of tidal stream turbines

Abstract

Blade element momentum theory (BEMT) is a well-established method for evaluating the performance of turbines designed to extract energy from a flowing fluid. In this paper, we discuss a modified version of BEMT that allows for greater variation in the permissible inflow conditions, paying particular attention to inflow conditions that model turbulence in coastal waters in order to calculate the power output and other performance parameters of tidal stream turbines (TSTs). In the first part of the paper, we describe the modification we have made to standard BEMT analysis. In the second part, we describe how we create an appropriate representation of a turbulent tidal stream or marine current, and what parameters we can extract from measurements of a real current in order to create this representation. Some preliminary results are presented and their significance discussed. Copyright © 2011 by the International Society of Offshore and Polar Engineers (ISOPE).