合成射流抑制方柱绕流载荷的数值模拟

Numerical Simulation on Suppression of Flow Load around a Square Cylinder by Synthetic Jet

海洋平台涡激运动会影响其系泊系统的疲劳寿命并威胁作业人员的安全,因此探索抑制海洋平台涡激运动的方法具有重要意义。以海洋平台中常见的方形立柱为研究对象,采用数值模拟方法探索合成射流对方柱升力和阻力的影响。建立方柱的数值模型,在方柱表面设置狭缝状射流出口,用与其连接的三角形空腔模拟射流的产生。调整射流出口位置、动量系数和射流频率等关键参数,研究合成射流对方柱绕流载荷的抑制效果。结果表明:当射流出口位于方柱前驻点,且动量系数为0.5、无量纲频率为2时,对阻力的抑制效果最佳,时均阻力系数最大减小率达98.3%;当射流出口位于方柱流动分离点,且动量系数为0.1、无量纲频率为2时,对升力脉动的抑制效果最佳,升力系数脉动值最大减小率达95.2%。

The vortex-induced motion(VIM)of offshore platforms will damage mooring systems and threaten the safety of operators.Therefore,it is critical to explore methods to suppress the VIM of offshore platforms.The influence of synthetic jet on the lift fluctuations and drag of square cylinder in offshore platform is studied.To establish the three-dimensional model of square cylinder,the slot of jet outlet is set on the surface of the square cylinder,and the cavity connected with the slot is used to simulate the generation of jet.To study the suppression effect of the synthetic jet on the flow load around the square cylinder,the critical parameters including jet outlet position,momentum coefficient,and jet frequency are tuned.The results demonstrated that the resistance suppression effect of the jet is strongest when the jet exit is at the front stagnation point of the square cylinder,the momentum coefficient is 0.5,and the dimensionless frequency is 2.The average resistance coefficient can decrease at a maximum rate of 98.3%.The best suppression for lift fluctuation occurs when the jet exit locates at the square cylinder flow separation point,the momentum coefficient is 0.5,and the dimensionless frequency is 2,and the maximum decrease rate of lift coefficient fluctuation can reach 95.2%.