This work aims to investigate the application of ultrasound Doppler velocimetry in multiphase flow.The experimental results show that in the homogeneous liquid-solid system,the amplitude of the received echo energy de...This work aims to investigate the application of ultrasound Doppler velocimetry in multiphase flow.The experimental results show that in the homogeneous liquid-solid system,the amplitude of the received echo energy decreases exponentially with measurement depth,and attenuation rate increases with increase of solid holdup monotonously.A model based on the ultrasound reflection and refraction law and scatter characteristics of particles is proposed to predict the relationship between received echo energy and solid holdup.In the gas-liquid system,liquid velocity and bubble rise velocity can be directly obtained from the velocity profile by Dop 2000 when the bubble number is small,while in medium gas velocity range,FFT must be executed to calculate velocity distribution, resulting in a two-peak distribution,which in turn can be used to obtain liquid velocity and bubble velocity by further data processing.展开更多
Effects caused by precipitation on the measurements of three-dimensional sonic anemometer are analyzed based on a field observational experiment conducted in Maoming, Guangdong Province, China. Obvious fluctuations in...Effects caused by precipitation on the measurements of three-dimensional sonic anemometer are analyzed based on a field observational experiment conducted in Maoming, Guangdong Province, China. Obvious fluctuations induced by precipitation are observed for the outputs of sonic anemometer-derived temperature and wind velocity components. A technique of turbulence spectra and cospectra normalized in the framework of similarity theory is utilized to validate the measured variables and calculated fluxes. It is found that the sensitivity of sonic anemometer-derived temperature to precipitation is significant, compared with that of the wind velocity components. The spectra of wind velocity and cospectra of momentum flux resemble the standard universal shape with the slopes of the spectra and cospectra at the inertial subrange, following the-2/3 and-4/3 power law, respectively, even under the condition of heavy rain. Contaminated by precipitation, however, the spectra of temperature and cospectra of sensible heat flux do not exhibit a universal shape and have obvious frequency loss at the inertial subrange. From the physical structure and working principle of sonic anemometer, a possible explanation is proposed to describe this difference, which is found to be related to the variations of precipitation particles. Corrections for errors of sonic anemometer-derived temperature under precipitation is needed, which is still under exploration.展开更多
Two kinds of measurement errors have been observed in the recently developed UAT-2 ultrasonic anemometer.One is the flow distortion produced by a"blocking effect",and the other is the angle of attack caused ...Two kinds of measurement errors have been observed in the recently developed UAT-2 ultrasonic anemometer.One is the flow distortion produced by a"blocking effect",and the other is the angle of attack caused by the vertical misalignment of the instrument.Here,we study these errors and discuss the possible correction methods.Via a wind tunnel experiment and numerical simulation,a 3D calibration matrix was developed to correct the"blocking effect".In the field test,the angle of attack was detected by an inclinometer settled on the reference plane of the anemometer,and the instrumental misalignment or tilt was corrected by a coordinate transformation.The combined use of an inclinometer and the proposed correction method may help find a new approach for vertical velocity correction.展开更多
文摘This work aims to investigate the application of ultrasound Doppler velocimetry in multiphase flow.The experimental results show that in the homogeneous liquid-solid system,the amplitude of the received echo energy decreases exponentially with measurement depth,and attenuation rate increases with increase of solid holdup monotonously.A model based on the ultrasound reflection and refraction law and scatter characteristics of particles is proposed to predict the relationship between received echo energy and solid holdup.In the gas-liquid system,liquid velocity and bubble rise velocity can be directly obtained from the velocity profile by Dop 2000 when the bubble number is small,while in medium gas velocity range,FFT must be executed to calculate velocity distribution, resulting in a two-peak distribution,which in turn can be used to obtain liquid velocity and bubble velocity by further data processing.
基金supported by the National Key Basic Research Program of China (Grant Nos. 2014CB953903,2015CB953904)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA 11010403)the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘Effects caused by precipitation on the measurements of three-dimensional sonic anemometer are analyzed based on a field observational experiment conducted in Maoming, Guangdong Province, China. Obvious fluctuations induced by precipitation are observed for the outputs of sonic anemometer-derived temperature and wind velocity components. A technique of turbulence spectra and cospectra normalized in the framework of similarity theory is utilized to validate the measured variables and calculated fluxes. It is found that the sensitivity of sonic anemometer-derived temperature to precipitation is significant, compared with that of the wind velocity components. The spectra of wind velocity and cospectra of momentum flux resemble the standard universal shape with the slopes of the spectra and cospectra at the inertial subrange, following the-2/3 and-4/3 power law, respectively, even under the condition of heavy rain. Contaminated by precipitation, however, the spectra of temperature and cospectra of sensible heat flux do not exhibit a universal shape and have obvious frequency loss at the inertial subrange. From the physical structure and working principle of sonic anemometer, a possible explanation is proposed to describe this difference, which is found to be related to the variations of precipitation particles. Corrections for errors of sonic anemometer-derived temperature under precipitation is needed, which is still under exploration.
基金The National Basic Research Program of China(Grant No.2010CB951804)The Strategy Guide for the Specific Task of the Chinese Academy of Sciences(Grant No.XDA10010403)+2 种基金The National Natural Science Foundation of China(Grant No.41375018)Special finance from the China Meteorological Administration(Grant No.GYHY200706034)The National Science and Technology Pillar Program(Grant No.2008BAC37B02)
文摘Two kinds of measurement errors have been observed in the recently developed UAT-2 ultrasonic anemometer.One is the flow distortion produced by a"blocking effect",and the other is the angle of attack caused by the vertical misalignment of the instrument.Here,we study these errors and discuss the possible correction methods.Via a wind tunnel experiment and numerical simulation,a 3D calibration matrix was developed to correct the"blocking effect".In the field test,the angle of attack was detected by an inclinometer settled on the reference plane of the anemometer,and the instrumental misalignment or tilt was corrected by a coordinate transformation.The combined use of an inclinometer and the proposed correction method may help find a new approach for vertical velocity correction.
