Performance analysis of a horizontal axis 3-bladed Savonius type wave turbine in an experimental wave flume (EWF)

Abstract

a b s t r a c tThe present experimental study investigates the generation and propagation of regular water waves and their interactions with an in-house fabricated horizontal-axis 3-bladed Savonius rotor in an experimental wave flume (EWF) equipped with a piston-type wave maker with active absorption capability to assess the rotor performance for different parametric conditions namely, wave height, wave period and submergence level in intermediate-to-shallow water depths. The motion of the wave particles around the Savonius rotor is observed during the experiments as well as measuring the power and torque performance of the rotor to make a reliable assessment of the water movement with the rotor positioning for different inflow wave boundary conditions. The wave-to-mechanical energy conversion efficiency (ECE) of the present device is determined for each case to suggest a possible optimum positioning accompanied with optimum wave heights and frequencies for the manufactured small scale prototype. The present results suggest that experimental solutions within the wave flume can provide a proper guideline for performance analysis of such devices in intermediate-to-shallow water depths for further studies of optimization of design of Savonius rotor type sea and/or ocean wave energy conversion devices for different operating conditions provided that optimum physical flow conditions are satisfied.

Experimental wave flume study of Savonius-type multiple rotor arrays

“…Three different wave heights, specifically, 100 mm, 150 mm, and 200 mm, and wave periods of 1.5 s, 3.0 s, and 4.5 s (the performance curve of the wave maker is limited to a narrow range of wave parameters for the pre-selected water depth of h ¼ 0.5 m for the present EWF) are used in the present experiments for both a single rotor and multiple-rotor array at three different submergence positions of z ¼ À50 mm, 0, and þ50 mm and three different longitudinal centre-to-centre spacings between the rotors, namely, L ¼ 1.15 and d ¼ 290 mm (Array 1), L ¼ 1.78 and d ¼ 450 mm (Array 2), and L ¼ 2.77 and d ¼ 700 mm (Array 3), in the threerotor array arrangement. All of the experimental cases are performed at the same water depth of h ¼ 0.5 m. 18 The wave length is determined in terms of the wave period of the flume system for an intermediate water depth (1=20 < h=k < 1=2), 25 as follows:…”

“…18 The height of the wave is limited to a maximum board stroke of 1.0 m. The flume floors and walls are all made of tempered glass for optimal observation and non-intrusive measurement with laser and optical techniques. The flume floor is flat and horizontal and is also equipped with two pumps for generating reversing currents with a discharge capacity of up to 120 l/s.…”

“…14 Although the Savonius rotors develop high torque at low rotational speeds, they have a low power coefficient, 15 and when they are used for extracting wave energy, their effective rotation depends strongly on the wave height, which also determines the size of the orbits in the water waves. 16,17 There have been a limited number of studies of Savonius rotors with different modified geometries and wave conditions characterized in an Experimental Wave Flume (EWF), 14,18 for different operating conditions, and attempts have been made to achieve performance improvement and clarification of low-efficiency Savonius rotors by optimizing different governing parameters. [18][19][20][21][22][23][24] This study proposes fabrication and performance testing of a new type of Savonius wave energy converter, which captures incident wave energy from surface waves with the use of three rotors, each of which consists of three blades, placed in parallel in an array arrangement with their axis horizontal to the direction of the wave propagation.…”

Upstream Flow Control for the Savonius Rotor under Various Operation Conditions

“…The method of producing wavy upstream flow is crucial for investigating the performance or flow characteristics of the Savonius rotor used to absorb the wave energy. In [61], a wave generator is deployed upstream of the Savonius rotor, while in [62], a wave flume assumes the similar role. Alternatively, numerical simulation can produce the oscillating upstream flow [63].…”

CFD-Based Performance Analysis and Experimental Investigation of Design Factors of Vertical Axis Wind Turbines under Low Wind Speed Conditions in Thailand

“…In wind engineering research, there are many attempts of improving the mechanical performance of Savonius rotors in various approaches. In an experimental investigation [12], the number of blades is increased for multiple blades in different operating conditions under ocean flows. With design modification of blades, a helical Savonius VAWT, twisted 90˚, was proposed to eliminate the excessive shaking of blades [13].…”