Verifying of ‘Orifice Plate’ Connecting Duct Lengths to Validate Performance of a ‘Vent Test Rig at Australian Maritime College’ by Computational Fluid Dynamics (CFD) as Part of the Oscillation Water Column Power Take Off

Abstract

Oscillating Water Column (OWC), ocean wave energy converter, transforms the energy of ocean waves into low pressure pneumatic power. This pneumatic power is extracted by a turbine and converted to electric energy through a generator. Australian Maritime College (AMC) has set up a vent test rig to conduct experiments on ‘OWC’ operation, quantify air leakage, and find differential pressures across the orifice plate as per the Australian standard of fan performances. However, the upstream and downstream of duct lengths of vent test rig did not match the given specified standards due space restriction. Therefore, the technical team of AMC chose Computational Fluid Dynamic (CFD) application as an alternative method to continue the investigation with economy of effort. Subsequently, it is understood that, CFD is a very attractive method to carry out investigations and obtain a detailed report with all tested parameters and conditions. In addition, it is revealed that the shape of the flow pattern which cannot be seen during the experimental study. The objective of this investigation was to apply CFD instead of vent test rig experiment and carry out modelling, and then compare the outcomes with experimental results. Further, CFD application was used to test differential pressure across the orifice plate with the same upstream and downstream lengths of pipe, which were utilized during the vent test rig experiment. In addition, CFD was applied again for specified lengths of pipe with the same orifice plate to measure the differential pressure across it. Finally, it was proven that specified duct lengths directly impacted the performance of the vent test rig and decreasing of the generating pressure along with the length of the pipe due to relative roughness.