Microphysical Measurements of Fog Formed in a Turbulent Jet

Strum, Madeleine; Toor, H. L.

doi:10.1080/02786829208959545

Cited by 8 publications

(5 citation statements)

References 9 publications

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“…Particles that pass through the viewing volume scatter light that is detected by three photomultiplier tubes in the receiver. The signals are analyzed to yield the droplet size and the component of the droplet velocity in the plane of the crossed beams (Strum and Toor, 1992). We optimized the PDPA collection optics for droplets in the expected size range by using a 100 mm transmitting lens and collecting the scattered light through a 250 mm lens placed at a 30° forward angle.…”

Section: Methodsmentioning

confidence: 99%

Mist Deposition onto Hairy Root Cultures: Aerosol Modeling and Experiments

Wyslouzil

Whipple

Chatterjee

et al. 1997

Biotechnology Progress

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We analyzed the applicability of the standard models for aerosol deposition in randomly packed fibrous filter beds to mist deposition across a bed of hairy roots in the nutrient mist bioreactor. Although the assumptions inherent in the models are met on a local level, the overall structure of the root bed introduces some uncertainty into the correct choice of root packing fraction and gas velocity required by the model. For reasonable parameter values, the minimum in the deposition efficiency curves is close to the peak in the mist number and mass distributions, and good penetration of the root bed is possible. We then measured the deposition of mist across a packed bed of Artemisia annua transformed roots as a function of droplet size, bed length, and gas flow rate at a root packing fraction alpha = 0.5. We compared the experimental measurements with the predictions of the aerosol deposition model and found good agreement between the measured and predicted values for the diameter where the deposition efficiency across the bed is 50%, D0.5. Agreement between the model and the experiments broke down when the flow rate was increased to the point where the creeping flow assumptions were no longer valid.

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Section: Methodsmentioning

confidence: 99%

Mist Deposition onto Hairy Root Cultures: Aerosol Modeling and Experiments

Wyslouzil

Whipple

Chatterjee

et al. 1997

Biotechnology Progress

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“…Despite the fact that turbulence is characterized by its extraordinary mixing ability, the research of nucleation of vapor in turbulent flows is of great scientific and industrial value. Early investigations in this field are almost exclusively theoretical and experimental approaches (Wegener and Pouring 1964;Okuyama et al 1987;Strum and Toor 1992;Friedlander 1995, 1998;Vatazhin et al 1995), as "calculations of absolute nucleation rates in turbulent gas flows are unreliable because of uncertainties in nucleation kinetics and insufficient information on the turbulent concentration, temperature and velocity fields" (Lesniewski and Friedlander 1998). However, the fast development of computational fluid dynamics (CFD) makes it possible to provide "sufficient information" for such calculations combined with the classic nucleation kinetics theory.…”

Section: Introductionmentioning

confidence: 98%

Simulation of Homogeneous Particle Nucleation in a Free Turbulent Jet

Zhou

Chan

2011

Aerosol Science and Technology

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The homogeneous particle nucleation in a free turbulent jet is simulated at Reynolds numbers of 3400 and 34,000 by using large eddy simulation (LES) coupled with our newly developed equivalent mean nucleation method (EMNM) for the present study. The simulated velocity field, passive scalar concentration, and nucleated particle concentration are compared with various available measurements in the literature. Both the simulated mean velocity and mean scalar concentration show self-similarity properties and agree well with the experimental measurements quantitatively in the literature. Using the EMNM, it is found that the nucleation primarily occurs in a very narrow region around the jet centerline. It is also found that the position of maximum nucleation is a function of the vapor temperature and concentration at the jet exit and its surrounding background (i.e., T 0 , T ∞ , c 0 , and c ∞ ), and the function varies monotonically with respect to these four parameters. Present numerical simulation and analysis also show that the group, Nu 0 /d (where N is the mean particle number concentration, u 0 is the jet velocity, and d is the jet exit diameter), is constant along the axial direction of the jet, which was first observed in the experiment of Lesniewski, T. K., and Friedlander, S. K. (1998). Particle Nucleation and Growth in a Free Turbulent Jet. Proc. R. Soc. Lond. A, 454:2477-2504. However, a different physical explanation of the fact is provided. In this study, it is found that the maximum nucleation occurs around 20d away from the jet exit, other than in the shear layer (less than 5d), which was supposed by Lesniewski, T. K., and Friedlander, S. K. (1998). On the basis of the additional simulated results, more comprehensive and reasonable explanations of their measurement data are provided. In this study, an efficient and rigorous numerical method is presented to simulate the homogeneous particle nucleation in a free turbulent jet, and this has provided a deeper and thorough understanding of the process.

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“…Lognormal particle size distributions were observed with geometric standard deviations of less than 1.3. Strum & Toor (1992) made detailed measurements of particle number density and size distribution profiles in a turbulent jet. They used a phase Doppler particle analyser to detect water droplets with diameters larger than 0.5 µm at different positions in the jet.…”

Section: Introduction and Previous Experimental Workmentioning

confidence: 99%

Particle nucleation and growth in a free turbulent jet

Lesniewski

Friedlander

1998

Proc. R. Soc. Lond. A

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Liquid dibutyl phthalate (DBP) particles were generated by homogeneous nucleation as a heated gas stream laden with DBP vapour exited a nozzle and mixed with room temperature particle-free air. The nozzle diameters were 0.235 and 0.375 cm, the nozzle temperature was 413 K, and DBP vapour concentrations were 100-500 ppm. Conditions were chosen to make the jet turbulent (Reynolds number 4000-7000) and to keep nucleation rates low so that the particle growth could be studied in the absence of coagulation and in the early stages of the transition to coagulation. Aerosol size distributions and number concentrations were measured at different positions and jet velocities. For low values of DBP vapour mole fraction, the size distributions were unimodal and the aerosol concentration followed jet dilution profiles, indicating that the particle formation was confined to the initial region of the jet. The final aerosol concentrations were correlated by simple scaling laws. For higher vapour mole fractions, nucleation continued to occur downstream from the shear layer, resulting in bimodal size distributions. Data for nozzles of different diameters indicate that the overall particle formation rate can be decreased by splitting a large nozzle flow into multiple smaller streams.

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Microphysical Measurements of Fog Formed in a Turbulent Jet

Cited by 8 publications

References 9 publications

Mist Deposition onto Hairy Root Cultures: Aerosol Modeling and Experiments

Mist Deposition onto Hairy Root Cultures: Aerosol Modeling and Experiments

Simulation of Homogeneous Particle Nucleation in a Free Turbulent Jet

Particle nucleation and growth in a free turbulent jet

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