Increasing the energy conversion efficiency for shrouded hydrokinetic turbines using experimental analysis on a scale model

Rareş-Andrei Chihaia,Lucia-Andreea El-Leathey,Gabriela Cîrciumaru,Nicolae Tănase,M.C Balan,M Sandu,C Georgescu,F Bode,A Dogeanu,I Nastase,A Georgescu,C Croitoru

doi:10.1051/e3sconf/20198506004

Abstract

The objective of the paper is to study the influence of certain shroud types suitable for horizontal axis hydrokinetic turbines using experimental testing in order to increase the energy conversion efficiency. The scale model of the shrouded hydrokinetic turbine is tested on a dedicated experimental bench for axial hydraulic turbine models. Two types of shrouds were tested in order to be compared: convergent shroud and divergent shroud. The rotor and shroud were made using 3D printer technology and were tested at a water velocity of 0.9 m/s on the closed-circuit testing bench. The testing facility allows the determination of the power extracted for each shroud at five distinct positions. Thus, the rotor can be moved within the shroud from inlet to outlet in order to establish the proper operating position. The mechanical power is measured using a torque transducer and an electromagnetic particle brake. The testing results will be analysed based on the variation of power curves obtained for different shroud types and operating positions. The optimum design and the best operating position will be recommended by comparing the testing result with the data collected from the bare turbine using the same rotor placed directly in free flow.

Highlights

In order to avoid building a dam, the kinetic energy of a river can be used directly using hydrokinetic turbines
The main recorded parameters are the useful torque at the turbine shaft and rotational speed of the shaft recorded at the same water velocity
The curves P = f(n) can be determined. Another important characteristic curve for describing the operation of a hydrokinetic turbine is that of the power coefficient - Cp in relation to λ (TSR Tip Speed Ratio) - which is the ratio of the peripheral velocity to the considered fluid velocity

Summary

Introduction

In order to avoid building a dam, the kinetic energy of a river can be used directly using hydrokinetic turbines. This type of turbine has a simple design, is easy to install with reduced cost and low-maintenance. The issue of increasing the efficiency of converting the kinetic energy of water remains a topic of high interest, which was always in the focus of the researchers worldwide [1],[2],[3].Conventional solutions are continuously improved and new solutions are emerging that offer higher yields. The only way to increase the power extracted at the same flow rate remains the use of shrouds of different shapes, sections and opening angles

Objectives

Results

Conclusion