动力定位供应船流载荷数值计算及研究

发布时间：2018-03-04 13:54

本文选题：动力定位供应船　切入点：流载荷　出处：《武汉理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：本文以计算流体动力学Fluent为平台，计算一定雷诺数范围内动力定位供应船流载荷系数，并研究船型参数、呆木参数以及雷诺数对流载荷系数的影响规律，最终得到流载荷系数的估算方法。在计算动力定位供应船之前，先对一艘有试验资料的油船进行0~180°内的流场计算，借由与试验资料对比，对数值计算方法的合理性进行验证，并通过分析船体表面压力及剪切力，，总结粘压阻力系数和摩擦阻力系数随流向角的变化规律。然后以一艘动力定位供应船为母型船，通过控制排水量和船长不变，对裸船进行船型变换，采用CFD方法计算一定雷诺数范围内裸船流载荷系数。通过变换母型船的呆木面积及形心位置，计算不同呆木参数下的流载荷系数。最终在考虑呆木参数及雷诺数的影响下，采用偏最小二乘回归（PLS）对单个角度下的流载荷系数进行回归，线性插值得到任意角度下的流载荷系数。数值计算方法及计算结果如下：（1）数值计算方法：计算域选择内域圆柱形，外域方形，当计算不同流向角下的流载荷时，只需转动内域网格。对于网格划分提出了几点不同于直航时的要求：稍微降低紧邻船体表面区域的网格密度；减少平行中体处的网格间距；增加船体外围的网格密度。选择SST湍流模式进行定常计算，即适合低雷诺也适合高雷诺数。（2）针对动力定位供应船的纵向流载荷系数，在小角度时，摩擦阻力系数占主要成分，在40°和130°时粘压阻力系数剧增，40°~130°时，粘压阻力系数占主要成分，且粘压阻力系数与船首尾压差在纵向上的投影相关。（3）针对动力定位供应船的横向流载荷系数，在60°左右达到峰值，该方向上的摩擦阻力系数较粘压阻力系数为小量，可忽略不计，粘压阻力系数由船首尾压差在横向上的投影决定；（4）添加的呆木，改变尾部压力分布，增加尾部的漩涡阻力，导致流载荷系数增加，并回归呆木的影响因子，且验证估算公式的预测性良好；（5）雷诺数主要影响摩擦阻力系数，且随着雷诺数的增加而减少；（6）影响流载荷系数的船型参数主要是方形系数Cb和船长船宽比L/B，通过偏最小二乘方法对单个流向角下的流载荷系数进行回归，线性插值可得到任意角度下的流载荷系数，最终编写流载荷系数计算程序。
[Abstract]:In this paper, based on the computational fluid dynamics (Fluent) platform, the flow load coefficients of the supply ship in a certain range of Reynolds numbers are calculated, and the influence of ship form parameters, stonewood parameters and Reynolds number convection load coefficients are studied. Finally, the method of estimating the flow load coefficient is obtained. Before calculating the dynamic positioning supply ship, the flow field of a tanker with test data is calculated within 180 掳, and the rationality of the numerical calculation method is verified by comparing with the test data. By analyzing the surface pressure and shear force of the hull, the variation law of the viscous pressure coefficient and friction resistance coefficient with the flow angle is summarized. Then a dynamic positioning supply ship is taken as the mother ship, and the displacement and the captain are not changed by controlling the displacement. In this paper, the ship form transformation of bare ship is carried out, and the flow load coefficient of bare ship is calculated by using CFD method in the range of certain Reynolds number. By changing the area and center of shape of the parent ship, Finally, considering the influence of parameters and Reynolds number, the flow load coefficient at a single angle is regressed by partial least square regression (PLS). The flow load coefficients at any angle are obtained by linear interpolation. The numerical method and results are as follows:. 1) numerical calculation method: the inner cylinder and the outer square are chosen in the computational domain. When calculating the flow load at different flow angles, It is necessary to rotate the mesh in the inner domain. The requirements of grid division are different from those of direct navigation: reducing the density of the grid near the hull surface, reducing the mesh spacing between the parallel bodies and the center of the ship, reducing the mesh density of the adjacent hull surface, reducing the space between the meshes. Choosing SST turbulence model for steady calculation, that is, suitable for both low Reynolds and high Reynolds number, for the longitudinal flow load coefficient of dynamic positioning supply ship, friction resistance coefficient is the main component when the angle is small. At 40 掳and 130 掳, the viscous pressure resistance coefficient accounts for the main component at 40 掳and 130 掳, and the longitudinal projection correlation between the viscous pressure coefficient and the pressure difference between the front and the tail of the ship is related to the transverse flow load coefficient of the dynamic positioning supply ship. At about 60 掳, the friction resistance coefficient in this direction is smaller than the viscous pressure coefficient, which can be ignored. The viscosity pressure coefficient is determined by the projection of the ship's head and tail pressure difference on the transverse side to change the tail pressure distribution. Increasing the swirl resistance in the tail leads to the increase of the flow load coefficient and the regression of the influence factors of the stumped wood, and it is verified that the prediction formula has a good predictability and the Reynolds number mainly affects the friction resistance coefficient. With the increase of Reynolds number, the ship form parameters affecting the flow load coefficient are mainly square coefficient CB and the captain's ship width ratio L / B. The flow load coefficient under a single flow direction angle is regressed by partial least square method. The flow load coefficient at any angle can be obtained by linear interpolation. Finally, a program for calculating the flow load coefficient is compiled.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U662.2

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