航行气垫船激励浮冰响应的模型实验研究

MODEL EXPERIMENT ABOUT RESPONSE OF FLOATING ICE SHEET SUBJECTED TO MOVING AIR CUSHION VEHICLE

基于弹性薄板振动微分方程和相似理论,建立了气垫船在浮冰上运动的原型系统与模型系统参数之间的相似对应关系.导出了浮冰层自由振动波形传播的相速度和群速度计算公式,明确了相速度的极小值和浅水波传播速度即为气垫船的第一、第二临界速度.根据研制的高精度非接触式激光位移测量系统,在变水深拖曳水槽中,开展了不同速度移动气垫载荷激励薄膜变形响应的系列实验,证实了存在使薄膜变形达到最大的移动气垫载荷临界速度.第一临界速度使气垫载荷之后的薄膜产生最大的下陷变形,第二临界速度使气垫载荷之前的薄膜产生最大的上凸变形.通过实验结果进一步分析了气垫速度、高度、压力及水深等参数对薄膜变形和临界速度的影响,揭示了移动气垫载荷激励薄膜变形响应的聚能共振增幅机理,为利用气垫船实施有效破冰提供了依据.

According to the differential equation of thin elastic vibrating plate and the similarity theory, the similar relationships of corresponding parameters were determined between model and prototype about floating ice sheet subjected to moving air cushion vehicle(ACV). The calculation formulas of phase speed and group speed about wave propagation of floating ice sheet with free vibration were derived, and the minimum phase speed and propagation speed of shallow wave were as the first and the second critical speed of ACV, respectively. A high accuracy non-contact laser system was developed to measure the surface displacement, and a series of experiments were carried out about response of film deformation causing by air cushion load(ACL) moving at different speeds in towing channel with variable depth. The existence of critical speeds of ACL which could bring maximum film deformation was confirmed. The first critical speed made maximum depression deformation of film after ACL, and the second critical speed made maximum raised deformation of film before ACL. The influence of moving air cushion speed, height, pressure and water depth on film deformation and critical speeds was further analyzed by experimental results; the resonant effect of energy accumulation and mechanism of amplification about film deformation caused by moving ACL were revealed, and the research provides the theoretical basis and technical support to develop a efficient ice-breaking way by ACV.