A novel method of online laser measurement for slumping angles of granular flow in rotating drums

SHENG Xubo; YANG Hui; LI Ran; MA Sheng; ZHENG Gang; ZIVKOVIC Vladimir

doi:10.7510/jgjs.issn.1001-3806.2016.03.009

Image method was often used to measure the slumping angles. However, the method has a problem that measurement standard deviation is large (about 0.5). In order to resolve the problems, online measurement method of dynamic speckle contrast slumping angle was proposed. When laser irradiated on the granules in rotating drum, dynamic speckle formed in far field. Linear CCD camera was used to get the speckle image with the changing of time. Through the analysis of the contrast of speckle images, the speed fluctuation of granular flows was calculated and interval time between two slumping angles was found. Finally slumping angles can be calculated out by using speed multiplied by interval time. Glass beads with diameter distribution of 1mm~1.25mm were used. Dynamic speckle contrast method and image method were used respectively to measure the slumping angles under different rotational speeds. The results show that online measurement of dynamic speckle contrast slumping angle is high spatial and temporal resolution. The standard deviation of measurement data is small, repeatability is better and the determination of data fitting coefficient is high. Dynamic speckle contrast method is applicable for online measurement and scientific research of granular flow in rotating drums.

A novel method of online laser measurement for slumping angles of granular flow in rotating drums

Corresponding author: YANG Hui, yanghui@usst.edu.cn;

1. School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China;

2. School of Chemical Engineering, University of Adelaide, Adelaide 5005, Australia;

3. School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle NE1 7RU, United Kingdom

Received Date: 2015-05-15

Accepted Date: 2015-12-03

Available Online: 2016-05-25

Abstract: Image method was often used to measure the slumping angles. However, the method has a problem that measurement standard deviation is large (about 0.5). In order to resolve the problems, online measurement method of dynamic speckle contrast slumping angle was proposed. When laser irradiated on the granules in rotating drum, dynamic speckle formed in far field. Linear CCD camera was used to get the speckle image with the changing of time. Through the analysis of the contrast of speckle images, the speed fluctuation of granular flows was calculated and interval time between two slumping angles was found. Finally slumping angles can be calculated out by using speed multiplied by interval time. Glass beads with diameter distribution of 1mm~1.25mm were used. Dynamic speckle contrast method and image method were used respectively to measure the slumping angles under different rotational speeds. The results show that online measurement of dynamic speckle contrast slumping angle is high spatial and temporal resolution. The standard deviation of measurement data is small, repeatability is better and the determination of data fitting coefficient is high. Dynamic speckle contrast method is applicable for online measurement and scientific research of granular flow in rotating drums.

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A novel method of online laser measurement for slumping angles of granular flow in rotating drums

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