Current generation systems consisting of pumps or impellers are conventionally used in deepwater model test facilities for producing realistic full-depth steady current flows. A typical current inlet design involves the diversion of current into a mixing chamber which is then channeled into the basin through an array of flow-conditioning filters (screens) installed along the width of the basin. The screens are used to reduce turbulence and create an overburden pressure within the mixing chamber to enhance inflow uniformity. However, one undesirable consequence of this setup is that it increases energy loss to the system which leads to a higher operating cost.
In order to address this problem, the present work is aimed at establishing an effective and energy-efficient inlet design and screen configuration to improve spatial uniformity of inflow with minimal energy loss to the system. A wind tunnel study is carried out to determine an optimal tapered culvert angle and honeycomb screen configuration to achieve the aforementioned objectives. Uniformly-distributed wind flow of up to 20 m/s is channeled into a Perspex chamber and allowed to escape sideways through plastic honeycomb screens. Pressure drops are measured with an array of transducers at locations upstream and downstream from the honeycomb screen, while streamwise velocity distribution across the width of the chamber is captured with a pitot-static tube mounted on a traversing mechanism. Three cases of flow resistance are investigated, i.e. no screen, thin honeycomb screen (thickness = 12mm), and thick honeycomb screen (thickness = 50mm). For each case, the culvert angle is varied between 7°, 13° and 21°. A CFD model is developed with OpenFoam and compared with the present experimental data. The validated model is expected to be used to investigate more complex inlet configurations and assess the performance of realistic ocean basin geometry.
