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Research on the Scale Effect of Water Impact

水冲击尺度效应研究

基本信息

批准号：
08651095
负责人：
TAKAGI Ken
金额：
$ 1.54万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08651095/
关键词：
Water Impact Impact Pressure Slamming Trapped Air Hydro-elasticity 尺度影響 3次元スラミング圧縮性

项目摘要

Since it is hardly to see flat surface in high seas, a three-dimensional theory taking effects of distortion of the water surface into account has been developed as-a main feature of this research. It is possible to discuss about the trapped air by this theory without a difficulty at a corner of the body which is found in the previous theories. Objectives of this research are investigating the influence of trapped air, elasticity and three-dimensional distortion and explaining the scale effects which arises when the experimental results are converted into the ship scale by obeying Floude's law. New theory stated above is the main body of this research to achieve the objectives.The following results has been obtained during this three-years research. When the bottom has the elasticity, if the elasticity is taken into account the linear theory would give good results and it suggests that the effect of air-flow is negligible. When the water surface is distorted, the reduction by the trapped air is not big, however the averaged impact pressure is greatly reduced. In the case of the axisymmetrical body. With attached cavity, the linear theory gives good estimations of pressure of the trapped air. Therefore, it is stated that the linear theory is good enough to predict the impact pressure when the water surface is not flat. Then, the scale effect between the model scale and the ship scale has been investigated by this theory and it is found that the scale effect is big. But, the general method to predict the scale effect has not been obtained because the scale effect is strongly depend on the shape of the body and the entry speed.

由于在公海上很难看到平坦的表面，因此，考虑到水面变形的影响，开发了三维理论作为本研究的主要特点。这是可能的讨论有关被困的空气由这个理论没有困难在一个角落的机构，这是发现在以前的理论。本研究的目的是调查滞留空气，弹性和三维变形的影响，并解释当实验结果被转换成船的规模时，遵守弗劳德定律的规模效应。本研究以上述新理论为主体，通过三年的研究，取得了以下成果。当底部有弹性时，若考虑弹性，则线性理论的结果较好，说明气流的影响可以忽略不计。当水面发生畸变时，滞留空气对冲击压力的影响不大，但平均冲击压力却大大降低。在轴对称体的情况下。在附加空腔的情况下，线性理论给出了很好的滞留空气压力的估计。因此，当水面不平坦时，线性理论足以预测冲击压力。然后，用该理论研究了模型比尺与船舶比尺之间的比尺效应，发现模型比尺与船舶比尺之间的比尺效应较大。但是，由于尺度效应强烈依赖于物体的形状和进入速度，目前还没有一种预测尺度效应的通用方法。