排桩式波浪能发电装置附近流场特性研究

Study of flow characteristics around row of oscillating water column pile under regular waves

基于雷诺时均Navier-Stokes方程和k−ω湍流模型,研究单排桩式振荡水柱式波浪能发电装置在规则波作用下的桩基附近流场特性.通过物理模型实验验证所建数值波浪水槽的准确性.模拟规则波作用下装置附近的流场特性,分析装置附近的涡特征以及其对装置附近泥沙冲刷情况的潜在影响.结果表明,测试工况下,在桩式振荡水柱装置桩柱体的桩基附近观察到马蹄涡和尾涡现象,马蹄涡强度随着Keulegan–Carpenter(KC)数的增大而减小,尾涡强度随着KC数的增大而增大.马蹄涡因强度过小,在模拟的KC数范围内不是装置桩基泥沙冲刷的主要因素,高强度的尾涡很可能成为装置桩基附近泥沙起动、输运和冲刷的重要影响因素.

A numerical wave tank was developed based on Reynolds-Averaged Navier-Stokes equations with k-ω turbulence closure. The accuracy of numerical model was first verified by laboratory experiments. Then, the model was used to simulate the flow field characteristics near the device under the effect of regular waves. The vortex characteristics and its implication to local erosion mechanism were analyzed. Results show that under tested conditions, a concave horseshoe vortex is formed at the toe of the oscillating water column pile and wake vortices are formed around the structure. The strength of the horseshoe vortices decreases with the increase of the KeuleganCarpenter(KC) number, and the strength of the wake vortices increases with the increase of the KC number. The horseshoe vortices are too weak to be the main factor in sediment scour at the range of KC number in this simulation,while the strong wake vortices are likely to be a main control factor of sediment initiation of motion, transport and scour near the pile foundation.