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Contra Rotating Marine Turbines Tank Tests to Analyse System Dynamic Response

Date: October 15, 2013 at 15:24 GMT

Abstract: Experiments have been undertaken within a repeatable and controlled environment at the University of Strathclyde flume and tow tanks. This was to identify and better understand the influential parameters which dictate how tethered turbines respond in changeable tidal flow conditions. 

Two design types of a neutrally buoyant turbine were considered:

  1. a contra-rotating turbine consisting of two and three blade rotor configurations, for the upstream and downstream set respectively; and
  2. three and four blade rotor configurations, for upstream and downstream sets respectively.

These devices were subjected to towing velocities ranging from 0.5m/s to 1.5 m/s. A mechanical brake controls the torque load of each rotor. The power generated by each turbine configuration when operating in different flow velocities was measured.

This paper thus presents the experimental work undertaken; identifies the individual parameters impacting upon turbine stability when supported by a flexible mooring; reports and discusses device performance, dynamic response and thrust forces; and comments on the ability to balance the reactive torque for different configurations of contra rotating rotors.

The paper concludes by showing the differences in turbine performance and stability for each configuration by applying a torque control strategy. 

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