无量纲参数对水下冲击射流流态的影响

Influence of dimensionless parameters on flow pattern of submerged impinging jet

为明确无量纲参数对水下冲击射流流态的影响过程,采用自由能格子Boltzmann方法,对同一水深条件、不同弗劳德数、雷诺数和韦伯数等无量纲参数下水下冲击射流的流场进行了数值模拟,得到了各个工况下射流的流态,并结合实验数据,分析了弗劳德数、雷诺数以及韦伯数等对水下冲击射流流态的影响。结果表明:在一定水深条件下,(1)若射流出口宽度给定,存在临界雷诺数和临界韦伯数,当射流雷诺数大于临界雷诺数或韦伯数大于临界韦伯数时,射流处于振翅冲击流态;(2)弗劳德数大于某一临界值时,射流将处于振翅冲击流态。临界弗劳德数可以作为评价振翅运动发生的参数。

In order to study the influence of dimensionless parameters on the flow pattern of submerged impinging jet,a submerged plane jet impinging onto a free surface is investigated based on the free energy lattice Boltzmann method for a given water depth and different Froude numbers,Reynolds numbers and Weber numbers.The flow patterns are obtained for different working conditions.Combined with the experimental data,dimensionless parameters influencing the flow pattern are studied including Froude number,Reynolds number and Weber number.Results show that for a given value of jet-exit-width,there appear to be critical Reynolds number and critical Weber number and if the Reynolds number or Weber number of jet is larger than the corresponding critical value,the jet flaps.On the other hand,the jet can be in a flapping mode if Froude number is greater than a critical value.It is suggested that the critical Froude number can be used as a critical parameter for the onset of flapping motion.