Performance enhancement of hydrokinetic turbine using augmentation techniques: a review

Hydrokinetic (in-stream) technologies generate renewable energy by capturing the kinetic energy of water flowing in rivers, streams, and irrigation canals without changing the course of river. Hydrokinetic energy conversion systems are gaining popularity because they are considered an efficient and reliable way to provide energy security to people living near flowing streams. However, energy conversion systems inherently suffer from poor efficiency. Although a number of studies have been conducted to improve the performance of hydrokinetic systems by modifying various geometric parameters, these modifications have not been enough to meet the required efficiency for practical application. In addition to this, different types of augmentation techniques, such as duct, shroud, diffuser, nozzle, blocking plate, deflector plates, curtain, etc. have also been proposed in an attempt to improve the power coefficient. While augmentation techniques are more effective than other geometrical parameters, however, they add complexity to the system. This paper reviews the different flow augmentation techniques that have been used with hydrokinetic turbines. The review summarizes the key findings of studies that have used different augmentation techniques and discusses their pros and cons. This study may be useful to design and develop more efficient and cost-effective hydrokinetic energy conversion systems.