ABSTRACT:

This paper deals with the design and analysis of a 250kW-class impulse turbine for wave energy conversion. Numerical analysis was performed using FLUENT. The size and the performance of turbine for providing a demanding power could be estimated using a series of performance chart built through the present study. Temporal and spatial variations of flow field were also considered to compare with those of uniform inflow. It was concluded that a rather simple steady flow analysis still provided the practically useful way for the design and performance prediction of turbine using performance charts.

INTRODUCTION

Impulse turbine installed on OWC chamber is considered as one of the best wave energy extracting device suitable for the full-scale application, especially because of its wide operating range and relatively low rotational speed. As an example of full-scale turbine, a 250kW-class impulse turbine was chosen to analyze the aerodynamic performance of internal duct flow around a turbine rotor as well as the whole air flow passage. A basic turbine model of Setoguchi et al. (2001) was employed for CFD calculation in a systematic manner for flow analysis with and without turbine rotor. In order for field engineers and designers to easily estimate the system performance, the steady flow analysis at high Reynolds number was made to obtain the performance charts at various operating conditions of mean velocity field inside duct, turbine power and pressure drop. For general and convenient applications, the inflow was assumed to be steady in this case, and the nonuniform effect created by specific air chamber and duct assembly was considered separately. The unsteady analysis was also made for a reciprocating air flow inside the air chamber and duct in the absence of turbine rotor to evaluate the stability and effectiveness of air flow passage.

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