Experimental flow field comparison for a series of scale model oscillating water column wave energy converters
Fleming, AN and MacFarlane, GJ, Experimental flow field comparison for a series of scale model oscillating water column wave energy converters, Marine Structures, 52 pp. 108-125. ISSN 0951-8339 (2017) [Refereed Article]
This paper presents an analysis of 2D PIV model test
experiments performed on a series of forward-facing bent-duct type of
oscillating water column (OWC) models with varied underwater geometry.
Experiments of this complexity involving particle imaging velocimetry
(PIV) to compare performance difference between differing geometry is the
first of its type. The intent of the experiments was to investigate
conversion losses and device performance by modifying the underwater
geometry based on previous work by the authors. Four models were tested
in total; the base model and three variations that had additional
segments to afford different chamber length and lower/upper lip angles
(10, 20 and 30 degrees). Dynamic similarity was assumed to be maintained
between models by using a constant lower lip depth and a constant ratio
of chamber length to projected underwater cross-sectional area.
Performance comparisons were undertaken using phase-averaged wave probe,
pressure transducer and PIV data. Additional qualitative analysis of
velocity fields was performed using temporal averaging. In most test
cases the new geometry with a 10 degree lip angle had marginally superior
performance in terms of capture width and total power production.
However, due to a number of issues, including the difference in damping
factor between models; the difference in chamber length; and the void
behind the upper lip on some models, it was not possible to definitively
conclude that the 10 degree model was the best performer, but rather, the
range of all new geometries presented have the potential for significant
performance gains over the base geometry with additional modifications.
Recommendations for future design of geometry are provided.
Wave energy; Oscillating water column; Orifice calibration; Oscillating flow