连续均匀气流中单液滴破碎特性试验

Experimental Investigations of Breakup Characteristic of Single Droplet in Continuous Uniform Airflow

关键词:  液滴破碎  雾化  热气流  喷雾  高速摄像机

Key words:  Droplet breakup  Atomization  Heated air flow  Sprays  High-speed cameras

摘要:

为了获得均匀气流中单液滴变形、破碎特性，采用高速摄像机对液滴的变形、破碎过程进行了测量。试验设计工况下所得结果表明: (1)冷态气流中，液滴变形速率随[We]数的增加呈线性增加的变化趋势，[We]数在15～40液滴变形速率在0.2m/s～0.8m/s变化，[We]数在45～60液滴变形速率在0.6m/s～1.4m/s变化；(2)模糊数学模型计算结果表明，冷态气流中，液滴初始直径对液滴变形速率的影响能力弱于初始气/液相对速度，[We]数在15～40液滴直径、气/液相对速度的权重系数分别为0.29，0.71，[We]数在45～60液滴直径、气/液相对速度的权重系数分别为0.343，0.657；(3)液滴的初始直径增加使得液滴发生破碎的临界[We]数增大；(4)液滴的破碎时间分别随气流流量、气流温度的增加呈负指数的变化趋势，且变化趋势都随气流流量或气流温度的增加而减弱。

Abstract:

In order to obtain characteristics of single droplet deformation and breakage in a continuous and uniform air flow，the high-speed cameras was applied to measure single droplet deformation and breakage. In the experimental conditions ，experimental results show that:(1)In the unheated air，droplet deformation rate linearly increases with increasing [We] numbers，droplet deformation rate ranges from 0.2m/s to 0.8m/s when [We] number ranges from 15 to 40，droplet deformation rate ranges from 0.6m/s to 1.4m/s when [We] number ranges from 45 to 60.(2)Based on fuzzy mathematics theory，the calculation results show that the impact of initial gas/liquid relative velocity is stronger than the impact of the droplet initial diameter on droplet deformation rate in the unheated air，the weight coefficient of droplet initial diameter and initial gas/liquid relative velocity are 0.29 and 0.71，respectively，when [We] number ranges from 15 to 40，the weight coefficient of droplet initial diameter and initial gas/liquid relative velocity are 0.343 and 0.657，respectively，when [We] number is between 45 and 60.(3)Critical [We]number increases with increasing droplet initial diameter.(4)The tendency of droplets broken time is negative exponent with the increase of air flow or air temperature，and the tendency of droplets broken time is much flatter with increasing air flow or air temperature.