Pneumatic power measurement of an oscillating water column converter

[摘要] ENGLISH ABSTRACT: A measurement device was developed to accurately determine the pneumaticpower performance of an Oscillating Water Column (OWC) model in a waveflume. The analysis of the pneumatic power is significant due to the wave-topneumaticenergy being the primary energy conversion process and where themost energy losses can be expected. The aim of the research study is to addressthe accurate pneumatic power measurement of unsteady and bidirectional airflowin OWC model experiments.The two fundamental measurements required for the pneumatic powermeasurement are the pressure difference over an orifice on the OWC model andthe volumetric flow rate of air through the outlet. The designed, constructed andassembled measurement device comprised of a venturi flow meter, containing ahot-film anemometer, which could measure the pressure drop and the volumetricflow rate in one device. The assembled pneumatic power measurement devicewas calibrated in a vertical wind tunnel at steady state. The results from thecalibration tests showed that the volumetric flow rate measurements from thepneumatic power measurement device was accurate to within 3 % of the windtunnel's readings. The pneumatic power measurement device was incorporatedonto a constructed Perspex physical model of a simple OWC device. Thisassembled system was used as the test unit in the wave flume at StellenboschUniversity (SUN).The results from the experimental tests underwent comparative analysis withthree analytical OWC air-flow models which were simulated as three scenariosusing Matlab Simulink. These results showed that the measurement device has theability to measure the pneumatic power but there is difficulty in modelling thecomplex air-flow system of the OWC device. This results in varying levels ofagreement between the experimental and simulated pneumatic power results.The research study has revealed that there is difficulty in designing an accuratedevice for a wide range of test parameters due to the variance in output values.The unsteady and bidirectional nature of the air flow is also difficult to accuratelysimulate using a one-dimensional analytical model. Recommendations for furtherinvestigation are for CFD systems to be used for the analysis of the air-flow in anOWC system and to be used to validate future pneumatic power measurementdevices.

[发布机构] Stellenbosch University