Turbulence modulation measurements in a charged monodispersed droplet stream

Wei Fu Lu, Wei Hsiang Lai, Keh Chin Chang, Tung Hsiao Tsai

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

As reported in the study of Chang et al., the modulation of the carrier-phase turbulence, that is, the effect of the presence of dispersed phase on the turbulence structure, is heavily dependent on the term of (〈u giupi〉-2k), where 〈 〉 denotes the ensemble averaging quantity; k is the turbulent kinetic energy, ugi and upi are the i-th component of fluctuating velocities of carrier and dispersed phases, respectively. Nevertheless, very few experimental data of 〈ugiupi〉 can be found in the literature. Wang and Huang made the 〈ugi upi〉 measurements by using a phase Doppler anemometer in a planar mixing-layer flow leaded with polydispersed spray. However, the accuracy of the measured 〈u giupi〉 data made by Wang and Huang was in doubt according to the comparison results with the model predictions in the study of Chang et al. Prevost et al. preformed the 〈ugiupi〉 measurements using a phase Doppler anemometer in the far field of a polydispersed particle-laden jet. Due to unavailability of the thorough measured data that could be used as the inlet conditions required in the theoretical simulation, the experimental works of Prevost et al. can not serve as a benchmarked case. In this study, a monodispersed droplet stream, instead of polydispersed spray, is generated using a monosized atomizer. However, the occurrence of break-up or coalescence due to droplet collisions in the stream downgrades the uniformity of droplet size in the downstream. To avoid the downgrading of the size uniformity in the downstream stream, the electrohydrodynamic (EHD) technique is used. Monodispersed droplets can be made toward rigid body after charging electrons. When two charged droplets move closer, the Coulomb force will help the droplets keep distantly and avoid the occurrence of droplet break-up or coalescence. Measurements of particles' velocity and size in a turbulent stream are made using a Particle Dynamic Analyzer (PDA). Quantities of 〈ugiu pi〉 and k will be computed using the measured velocities of both carrier and dispersed phases.

Original languageEnglish
Title of host publicationMULTIPHASE FLOW
Subtitle of host publicationTHE ULTIMATE MEASUREMENT CHALLENGE - Proceedings of the 5th International Symposium on Measurement Techniques for Multiphase Flows, 5th ISMTMF and 2nd International Workshop on Proces
Pages133-139
Number of pages7
DOIs
Publication statusPublished - 2007 Sep 24
Event5th International Symposium on Measurement Techniques for Multiphase Flows, 5th ISMTMF and 2nd International Workshop on Process Tomography, IWPT-2 - Macau, China
Duration: 2006 Dec 102006 Dec 13

Publication series

NameAIP Conference Proceedings
Volume914
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other5th International Symposium on Measurement Techniques for Multiphase Flows, 5th ISMTMF and 2nd International Workshop on Process Tomography, IWPT-2
CountryChina
CityMacau
Period06-12-1006-12-13

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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