带焊缝圆灯柱气动特性及焊缝影响机理研究

Study on aerodynamic characteristics of circular light pole with weld and the effect mechanism of weld

为了研究某实桥带焊缝圆灯柱的气动特性以及焊缝对灯柱涡激振动的影响机理,开展了灯柱刚性节段测压模型风洞试验,测试了无焊缝工况以及0°~180°焊缝位置的灯柱周向压力分布,分析了灯柱气动力以及流体卡门涡脱强度,揭示了焊缝对灯柱涡激振动的影响机理。研究结果表明:焊缝对灯柱的气动特性影响显著,不同的焊缝位置可以激发不同的流动模式,当焊缝在灯柱前驻点或者原分离点后侧时,灯柱气动特性受焊缝影响较小。当焊缝在B区域(21°~33°)和C区域(36°~63°)时,流体在焊缝附近发生分离-再附-再分离现象,卡门涡脱强度降低,灯柱的涡激振动被抑制。当焊缝在D区域(63°~78°)时,流体在焊缝位置直接涡脱,伴随着脉动风压和卡门涡脱强度的增强,使灯柱的涡激振动增大;焊缝尺寸的变化不会改变灯柱的气动力系数随焊缝位置的变化规律,但是可能会影响涡激振动风速锁定区间和振动幅值。

To investigate the aerodynamic characteristics of light pole with weld and the effect mechanism of weld on vortex-induced vibration(VIV)of light pole,experimental tests were carried out using a static sectional pressure model in a wind tunnel.The distribution of the wind pressure of the light pole was measured with and without considering the weld on the surface through electronic pressure scanning valve system,and the aerodynamic force and Karman vortex shedding of light pole were also investigated.Then,the effect mechanism of weld on VIV of light pole was proposed.It was found that the weld had a dramatic effect on the aerodynamic characteristics of the light pole and different flow patterns could be triggered when the weld was located in different positions.When the weld is located near the forward or leeward stagnations,the weld has no significant effect on the aerodynamic characteristics of the light pole.When the weld lies in the region B(21°~33°)and the region C(36°~63°),flow reattachment occurs and the Karman vortex shedding is suppressed.When the weld position is located in the region D(63°~78°),the flow directly separates from the weld without reattachment,and the fluctuating lift and Karman vortex shedding were increased.In addition,the sizes of weld would not change the variation patterns of aerodynamic force coefficients,but could affect the wind speed range and the amplitude of VIV.