工艺参数对同轴送出粉末流动状态的影响

Effect of process parameter on powder flow statues in coaxial powder feeding

关键词:  高速摄像  灰度值  粉末束流  高斯分布

Key words:  high speed camera  gray value  powder flow  gaussian distribution

摘要:

借助高速摄像拍摄同轴送粉粉末束流宏观形貌，结合图像灰度化处理方法，系统研究不同工艺参数对粉末束流动状态的影响.针对所用研究方法的可行性进行了评估.结果表明，用灰度值表征粉末空间浓度大小具有较高的可行性.粉末束流焦点处及上、下间隔3 mm左右范围内横截面的粉末空间浓度分布基本呈典型的高斯分布；送粉速率对粉末束流焦点位置影响较小；随着载气量增加粉末焦点位置逐渐上移，粉斑直径逐步变小；同轴保护气流量不易过大，8 L/min是其临界值，大于该值可能会因产生"涡流现象"而导致粉末的运动轨迹发生变化.

Abstract:

In this study, the macro morphology of the powder flow was obtained using a high speed camera, and image gray processing was implemented to study the effect of process parameters on powder flow feed behavior. The feasibility of research method was estimated. Results showed that the powder density can be obtained accurately from the gray level information. Distribution of the powder density in cross section at the focus position typically obey Gaussian distribution. The effect of powder feed rates on the position of powder focus can be neglect. With the increase of carrier gas flow rate, the position of powder focus and diameter of the focus plan decrease. The critical value of the coaxial protect gas flow rate was 8 L/min, the trajectory of powders maybe changed for vortex phenomenon when greater than this value.