Numerical Analysis of the Influence of Design Parameters on the Efficiency of an OWC Axial Impulse Turbine for Wave Energy Conversion

Abstract

Oscillating water column (OWC) axial impulse turbines permit the conversion of wave energy into electrical power. Unlike other hydropower units with a mature and well established technology, such turbines have been recently developed, there are still few prototypes operating and therefore there is a large space for optimizing its design. Many recent studies focus on the improvement of the efficiency and transient characteristics by means of experimentation and also simulation techniques. In the present paper we use a 3D numerical simulation model (computational fluid dynamics model with ANSYS-Fluent 18) to analyze the influence of different geometrical parameters on the efficiency of the turbine, which have been less discussed yet. A reference configuration case has been used to validate our simulation model by comparing it with previous experimental results. Then, parametric variations in the guide vane number and type, gaps between the rotating and stationary part and hub to tip ratio have been introduced in the model to discuss the influence of these effects. It is found that some of these parameters have an important influence on the efficiency of the turbine and therefore, the results presented in this paper can help to optimize future designs of OWC impulse turbines.

Floating Oscillating Water Column Wave Energy Converters: A Review of Developments

“…The literature on OWC PTO systems primarily focuses on improving the converter's efficiency through the optimization of air turbine characteristics ( [191][192][193], among others) and the installation of high-speed safety valves [75,194,195]. On the other hand, only a few papers deal with the joint study of air turbines and generators, developing control algorithms under different sea states.…”

Analysis of OWC impulse turbine flow characteristics considering the blade tip clearance

“…Figure 3 shows the CFD simulation results of the impulse turbine under steady-state conditions, which include the input coefficient CA, torque coefficient CT, and overall efficiency  of the turbine under different flow coefficients . In addition, the numerical results are compared with the experimental results of Setoguchi [16], the experimental results of Liu [17], and the simulation results of Luo [18]. As shown in figure 3(a), the input coefficient CA of the turbine shows an upward trend followed by a slow decline as the flow coefficient increases.…”

Influence of the blade leaning angle on the performance of a radial impulse turbine for OWC converters

“…Only a few references, e.g. [13], analysed some basic parameters in the case of axial impulse turbine. Nevertheless, an important design parameter such as skew, lean and sweep angle, which have been extensively studied for Wells turbines, have not been almost studied for impulse turbines.…”