Effect of shroud on the performance of horizontal axis hydrokinetic turbines

• Published in: Ocean engineering Vol. 96; pp. 215 - 225
• Main Authors: Shahsavarifard, Mohammad, Bibeau, Eric Louis, Chatoorgoon, Vijay
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2015
• Subjects: Gain; Horizontal; Horizontal turbines; Hydrokinetic turbines; Mathematical models; Maximum power; Ocean engineering; Shrouded turbines; Shrouds; Turbine efficiency; Turbines; Wind turbines; Turbine efficiency; Shrouds; Horizontal turbines; Hydrokinetic turbines
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2014.12.006

The idea of wind turbine power enhancement by means of a shroud has been investigated for decades with no commercial success. However, due to some beneficial aspects, shrouds are poised to serve the hydrokinetic turbine industry. We report on the experimental measurements performed in a water tunnel on a 19.8cm diameter horizontal axis hydrokinetic model turbine utilizing two shrouds. Power and thrust coefficients of the model turbine with and without the shrouds investigated are obtained over the range of the power curve. A maximum power enhancement of 91% over the unshrouded turbine is obtained with one of the shrouds. Maximum power coefficients are recalculated based on the maximum area of shroud and are found to be comparable to that of the unshrouded turbine. At flow speed of 1m/s, an extended blade that generates the same power as the shrouded turbine is found to have a diameter equal to the diameter of the shroud exit. This aspect is critical as the use of shrouds contrary to much of the literature is not to increase the hydrokinetic turbine efficiency, but to gain advantages in the powertrain design, and have the turbine power less impacted by changes in the flow direction. •We report on the design of a shrouded kinetic turbine and the water tunnel experiments.•A maximum power enhancement of 91% is obtained with one of the shrouds examined.•Experiments show that a shroud is more effective at lower Reynolds number tested.•A turbine with an extended blade generates the same power as a shrouded turbine.•At 1m/s flow speed, the extended blade diameter is equal to the shroud׳s exit diameter.