Particle drag in a dilute turbulent two-phase suspension flow

Lee, S.L.

doi:10.1016/0301-9322(87)90032-2

Cited by 35 publications

(7 citation statements)

References 12 publications

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“…The motion of a stream of monosized drops in quiescent air was studied by Arrowsmith and Foster [1973], which basically confirms the works by Rowe [1961]. There are numerous other investigations on the drag and motion of particles in dense two-phase flows [Liu et al 1988, Nouri et al 1987, Tsuji et al 1984, Lee 1987, Lee and Durst 1982, and Stinzing 1971 which support the above general findings.…”

Section: Introductionsupporting

confidence: 79%

Variation of drag coefficients in an interacting drop stream

Poo

1991

Experiments in Fluids

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Abstract. Variation of the drag coefficient of closely spaced drops in a stream injected into a turbulent flow is studied experimentally. Three different regions are identified. In the first region, close to the injector, drops flow in the wake of each other. The drag coefficient in this region is much smaller (by a factor of 4 to 5) than the standard drag coefficient, and its magnitude is dependent on the drop initial spacing. Shortly downstream of the injection point, the transition region starts, where the drag coefficient increases rapidly approaching the drag coefficient of a single isolated drop. And further downstream when drops are dispersed significantly, the drag coefficient will behave the same way as a single isolated drop.

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Section: Introductionsupporting

confidence: 79%

Variation of drag coefficients in an interacting drop stream

Poo

1991

Experiments in Fluids

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“…varies with the droplet concentration or interdroplet spacings (Poo & Ashgriz, 1991) and depends on the turbulence character (S. Lee, 1987). The extent of interactions between droplets has been given up to seven droplet diameters parallel to the airflow and two droplet diameters normal to the airflow (Poo & Ashgriz, 1991).…”

Section: Stokes Number Of Dropletsmentioning

confidence: 99%

Air–liquid interactions in a pressure-swirl spray

Jedelský

Malý

Corral

et al. 2018

International Journal of Heat and Mass Transfer

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The energy transfer between a liquid hollow cone spray and the surrounding air has been studied using both imaging and phase-Doppler techniques. The spray was produced by a pressure-swirl atomizer discharging Jet A-1 fuel at inlet over pressures of p = 0.5, 1.0 and 1.5 MPa into quiescent ambient air. The liquid exits the nozzle as a conical film which thins as it spreads and develops long-and shortwave sinusoidal instabilities with breakup occurring, at the length smaller than that predicted by the inviscid model, to form film fragments and ultimately droplets downstream the spray. The single shot imaging characterised the spray regions of near-nozzle flow, the breakup processes and the developed spray. The phase-Doppler system resolved the three components of velocity and size for the droplet flow as measured on radial profiles for four axial distances from the nozzle exit. A Stokes number, Stk, analysis of the droplets' response times to the airflow timescales showed that droplets < 5 µm followed the airflow faithfully and so were used to estimate the local airflow velocity. This allowed a comparison of both the droplet and airflow fields in terms of their mean and fluctuating velocity components to be made. The formation of the hollow cone spray and the interaction of the fragments and droplets with the air, through viscous drag, induce complex entrained airflows. The airflow was found to be highly anisotropic, fluctuating preferentially in the downstream direction, and spatially varying within three distinct spray regions. The air drag establishes a positive size-velocity correlation of droplets; their Stk reduces with axial distance and increases with droplet size and p; so that Stk ≈ 1 for 20-40 µm droplets and the largest droplets (80-160 µm, Stk > 10) move ballistically. The spatially resolved mean and turbulent kinetic energies of the air and spectra of the droplet velocity fluctuations are detailed in the paper. These findings are relevant to scientists and engineers modelling the complex two-phase flows.

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“…From the foregoing analyses, it is evident that the main shortcoming of these theories lies in the assumption of the artificial boundary which separates the two artificial transverse regions : the turbulent core and the quasi-laminar region. In order to overcome this difficult problem, Lee [7] proposed a new unified theory on particle transport in a turbulent dilute two-phase suspension flow. This new unified thcoretical approach for the entire transverse flow region from the turbulent core to the quasilaminar region next to the boundary wall is much in order.…”

Section: Lee and Srinivasan [5]mentioning

confidence: 99%

On the Droplet Deposition and Mist Supercooling in a turbulent channel flow

Yang¹,

Lee²

1991

Part & Part Syst Charact

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A combined experimental and theoretical study of the droplet deposition and mist supercooling in a turbulent channel flow has been perfotmed. The measurement of dropld deposition on the unheated and heated channel wall was carried out using a particle-sizing two-dimensional reference-mode laser-Doppler anemomentry technique in a 41 mm x 41 mm vertical square channel at Re = 1.0 x lo4 -6.05 x lo4. The dimensionless deposition coefficient k, / u * is analyzed theoretically based on a new unified theoretical approach for the entire transverse flow region from the turbulent core to the quasi-laminar region next to the boupdary wall. The proposed an?Jytical model shows satisfactory agreement with the results of present experimental measurement. In the mist supercooling, the heated surface is cooled by the evaporation on the outside surface of an extra thin continuous liquid film which is maintained by the continuous deposition of extremely small droplets of an optimal size determined by a selection process on the droplets transverse migration due to the dynamic interaction between the phases in a parallel turbulent mist flow. The heat transfer enhancement coefficient depends on droplet deposition rate, droplet size, concentration and the Reynolds number.

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Particle drag in a dilute turbulent two-phase suspension flow

Cited by 35 publications

References 12 publications

Variation of drag coefficients in an interacting drop stream

Variation of drag coefficients in an interacting drop stream

Air–liquid interactions in a pressure-swirl spray

On the Droplet Deposition and Mist Supercooling in a turbulent channel flow

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