大尺度储舱液体晃荡砰击压力测量方法研究

Experimental investigation of violent liquid slamming pressure in large-scaled tank

超大型浮式液化天然气生产储卸装置(Floating Liquefied Natural Gas,FLNG)储舱中液体晃荡引起的砰击荷载会导致舱壁结构强度破坏.室内大尺度晃荡模型实验是最能真实反映砰击物理过程的研究方法.由于液体和气体均具有可压缩性,导致砰击压力瞬时增大,因此,实验研究中如何准确地测量砰击载荷是关键问题.为了研究测量砰击载荷的准确性、灵敏性和可靠性,采用了大吨位的六自由度运动平台与大尺度模型舱,分别采用薄膜型和针孔型压阻式传感器对储舱中液体晃荡引起的砰击载荷进行测量,并对砰击过程进行了实验观测.从时域角度提出了从砰击发生时间来分析流体砰击垂直舱壁的过程,并采用相关性方法分析测量区域内砰击载荷的空间相关性(垂直、水平).结果表明,针孔型压力传感器对气体衰减振荡的物理现象更敏感,而薄膜型压力传感器测量的均值效应较突出;冲击点位置下方的区域在水平和垂向上具有线性相关的特性,建议在冲击点附近采用阵列式压力传感器布局,可以更准确地捕捉冲击点的发生位置和载荷量级.

Structural strength of the cargo containment systems of the very large-scale Floating Liquefied Natural Gas （FLNG） can be damaged by the sloshing-induced slamming load. Large scale sloshing experimental investigation can truly reveal the process of slamming. Due to the compressibility of liquid and gas, slamming load instantaneously increases dramatically. So, accurate measurement of impact pressure is one of key issues in experimental investigation. In order to study the measurement of impact pressure accurately, sensitively and reliably, six-degree of freedom hexapod and large-scale model tank are employed. Not only the impact pressure but also the slamming process are recorded by both membrane and pinhole piezoresisitve sensors. The procedure of liquid slamming on the vertical wall is further provided by the impact occurrence in time domain. Furthermore, the spatial correlation of impact pressure is analyzed by correlation method. The results illustrate that the pinhole sensor is more sensitive to the bubble effect, and the membrane type acts averaging effect. It is reported that the slamming load performs linear correlation both in the vertical and horizontal direction below the impact point. Therefore, it is recommended that pressure sensors should be installed with an array near the impact point in the larges-scaled model test.