波浪模型试验中水密度对相似性的影响

在海浪作用下的防波堤或护岸工程等水工物理模型试验中,一般采用淡水模拟海水。由于模型中淡水密度小于工程中的海水密度,会导致模型中水工建筑物或块体受到的浮力、压力、波浪力等比用海水时小,并使模型中水工建筑物或块体的稳定性相似受到影响。从工程角度考虑,这种影响是偏于危险的。文中基于重力相似准则,推导了考虑原型和模型水密度差异的相似关系。海水压力及波浪力可采用新的相似关系,对于可以控制密度的水工建筑物或人工块体,通过减小密度的办法减小质量,保证其运动相似。对于原型块石,为满足运动相似,可直接减小其质量,体积也相应减小。利用本文修正方法,将使波浪模型试验数据更接近真实情况,研究成果更科学、合理。

Influence of water density on similarity in wave model experiments

In the wave model experiment of harbor engineering,it is usually to adopt fresh water emulating salt water.The density of the fresh water in the model is smaller than the density of saltwater in the prototype.So it will lead to the smaller buoyancy,water pressure and wave force in the model,and the stability similarity of the building or the block in the model also will be influenced.From the angle of engineering,this kind of influence is too dangerous.According to the gravity similarity criterion of hydraulic model test,the scale relationship between model and prototype is obtained,which is under the consideration of the density difference between fresh water and saltwater.For the hydraulic building and artificial blocks,which density can be controlled in the model test,in order to make the kinematic similarity,the density of the building or blocks can be reduced.For the prototype piece stone,the weight of the stone can be reduced in order to satisfy kinematic similarity,and the volume of the stone can be reduced too.The method presented will make the wave model experimental results more correct and more reasonable.