Coaxial Water Turbine System Modeling and Optimization

Research Abstract:
In recent years, there has been increasing interest in developing ways to extract energy from the Gulf Stream – a wide and relatively fast current of warm water passing close to the Eastern seaboard.The depth of the seafloor at the location of maximum Gulf Stream velocity 1 is roughly 3000m, making rigidly mounted tower structures for Horizontal Axis Turbines (HATs), similar to regular commercial wind turbines, effectively impossible to install and maintain. Therefore, a much more viable option for hydrokinetic energy extraction from the Gulf Stream is via tethered devices moored to the ocean floor by flexible cables. For tethered operation, the turbine must produce zero net torque to avoid tangling the tether. This can be accomplished via coaxial counter-rotating rotors. The coaxial turbine configuration also has the advantage of increasing the relative angular velocity between the turbine rotors, potentially reducing the need for a high gear ratio to drive the generator. In addition, a coaxial turbine requires less structure and components than a parallel axis turbine of the same power rating, which has one generator per rotor disk and a rigid structure separating the two. This potentially lowers both material and deployment cost for the coaxial configuration.

iSSRL Researchers:
  • Mikayla Nichols
  • Research is in collaboration with Dr. Granlund’s and Dr. Mazzoleni’s labs

Publications:

  1. Khatri, D., Chatterjee, P., Metoyer, R., Bryant, M., Mazzoleni, A., Granlund, K., “Dual Actuator Disc Theory for Turbines in Yaw,” AIAA Journal, Vol. 57, No. 5, 2019.
  2. D. N. Khatri, P. Chatterjee, R. Metoyer, M. Bryant, A. P. Mazzoleni and K. O. Granlund, “Investigation of a Novel Approach for Ocean Current Power Generation: The Inclined-Axis Coaxial Turbine,” OCEANS 2018 MTS/IEEE Charleston, Charleston, SC, 2018.