A Rectilinear Droplet Stream in Combustion: Droplet and Gas Phase Properties

Virepinte, J. F.; Biscos, Y.; Lavergne, G.; Magre, P.; Collin, G.

doi:10.1080/00102200008952121

Cited by 29 publications

(24 citation statements)

References 15 publications

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“…Important parameters such as the distance between the droplets are modified in order to characterize their influence on the droplet evaporation. Monodisperse droplet streams have been used in previous studies of droplet evaporation (Castanet et al 2005(Castanet et al , 2011Deprédurand et al 2010;Virepinte et al 2000). These studies emphasized the role of the dimensionless spacing parameter C, defined as the ratio between the droplet spacing L and the droplet size d. For low values of C, the heating and evaporation rates are reduced in comparison with the isolated droplet whose evolution can be predicted using classical models (Abramzon and Sirignano 1989).…”

Section: Introductionmentioning

confidence: 99%

Characterization of the evaporation of interacting droplets using combined optical techniques

2015

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Section: Introductionmentioning

confidence: 99%

Characterization of the evaporation of interacting droplets using combined optical techniques

2015

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“…The horizontal PLIF profiles at y=3 mm displayed in Figure 8 show that the PLIF intensities are significantly lower for the reacting condition than for the corresponding non-reacting case. This is expected for two reasons: First, CARS measurements for reacting monodisperse droplet chains showed that gas temperatures on the centerline are typically in the range of 1200-2000 K [1][2][3], which implies a strongly reduced gas density and thereby a reduced volumetric vapor concentration. Secondly, the fluorescence quantum yield of acetone for excitation at λ=266 nm is significantly reduced for temperatures larger than, say, 600 K [14].…”

Section: Results For Reacting Conditionmentioning

confidence: 99%

“…This is apparently caused by the intense heat transfer from the flame front at r=1.5 mm to the droplets at r=0 mm. As a rough estimate, the CARS measurements for a reacting chain of monodisperse ethanol droplets by Virepinte et al [3] showed that the gas temperature reaches a maximum of 2000 K at the flame front at r=1.5 mm and reduces to 1300-1500 K at the centerline, which corresponds to a substantial temperature gradient of 330-470 K per mm driving the fuel vaporization. …”

Section: Results For Reacting Conditionmentioning

confidence: 99%

“…A classical canonical configuration for the investigation of droplet evaporation and combustion is the linear monodisperse droplet chain. Several quantities have been characterized experimentally for this configuration, such as, e.g., gas phase temperature using coherent anti-stokes Raman spectroscopy (CARS) [1][2][3], droplet temperature using laser-induced fluorescence (LIF) [4][5] and rainbow thermometry (RT) [6][7][8], vapor concentration using planar LIF (PLIF) [9,10], and droplet size using RT, interferometric laser imaging for droplet sizing (ILIDS) [10,11] and droplet imaging [12,13] (mentioning only a part of the numerous works). The dynamics of the liquid-vapor mass transfer, however, is governed by strong gradients of concentration and temperature in the close vicinity of the gas-liquid interface.…”

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confidence: 99%

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Experimental study of liquid-vapor mass transfer in non-reacting and reacting droplet chains

Stöhr¹,

Werner²,

Meier³

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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The dynamics of liquid-vapor mass transfer largely determines the performance of internal and gas turbine spray combustors. The key mechanisms however typically take place on small spatial scales of less than 100 μm which have been difficult to measure. The present work thus aims at the development and application of an experimental technique for the characterization of droplet evaporation with high spatial resolution. Single chains of monodisperse acetone droplets with diameters of 125 and 225 μm are injected into a channel with a cross-section of 60x60 mm² and quartz glass side walls for optical access. The droplet chains are surrounded by a laminar air flow with velocity and temperature of about 0.1 m/s and 300 K, respectively. The distribution of acetone vapor around the droplets is measured using planar laser-induced fluorescence (PLIF) excited by the 4th harmonic of a Nd:YAG laser at 266 nm. The measurements are performed in thin transversal sections between the droplets in order to avoid signal corruption by halation effects that occur when the laser directly hits the droplets as reported in previous studies. In addition, the spatial resolution of the PLIF setup was enhanced by using proper sheetforming and imaging optics. The resulting in-plane resolution and out-plane-resolution (i.e. thickness of the laser sheet) are both determined to about 20 μm, which thus allows an accurate characterization of the small-scale vapor distribution near the droplets. Using a separate calibration measurement, quantitative acetone concentrations are obtained for non-reacting conditions. As a complementary technique, the droplet evaporation is measured using shadowgraphy droplet sizing. Both non-reacting and reacting droplet chains are studied. The results for the non-reacting cases show that the droplet chains are surrounded by a column of nearly-saturated acetone vapor with a concentration maximum at the centerline. For increasing radial distances, the vapor concentration decays quickly with a half width of 0.5 mm and reaches almost zero for r>1 mm. It is further seen that the width of the vapor column increases with streamwise distance. For the experiment with a reacting droplet chain, which is continuously ignited by a heating wire at the channel inlet, a cylindrical reaction zone around the chain with a radius of about 1.5 mm is observed. The shadowgraphy measurements show that the rate of droplet evaporation is significantly enhanced for the reacting conditions. This is attributed to the high rate of heat transfer from the flame to the droplets and the resulting enhanced acetone mass transfer to the sink at the reaction zone. KeywordsDroplet evaporation, Laser-induced fluorescence, Monodisperse droplet chain, Liquid-vapor mass transfer Introduction Several important energy conversion devices such as internal combustion engines and gas turbines are driven by the combustion of liquid fuels. The liquid fuels are typically first atomized into a spray of small droplets, which are then dispersed in a turbulent flo...

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“…between the instants t =5.3 ms and t =9.6 ms, where t =0 was taken at the injector exit. The droplet diameter reduction because of evaporation was evaluated between t =5.3 ms and t =9.6 ms, with the help of the experimental results of Virepinte et al (2000) obtained in a similar situation. This diameter reduction was less than 5 lm and was therefore neglected in the data reduction process, since the uncertainties linked to the positioning of the measurement points caused by the random motions of the droplet were of the same order of magnitude.…”

Section: Experimental Results In Combustionmentioning

confidence: 99%

Measurement of the temperature distribution within monodisperse combusting droplets in linear streams using two-color laser-induced fluorescence

Castanet

Lavieille

Lebouché

et al. 2003

Experiments in Fluids

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A Rectilinear Droplet Stream in Combustion: Droplet and Gas Phase Properties

Cited by 29 publications

References 15 publications

Characterization of the evaporation of interacting droplets using combined optical techniques

Characterization of the evaporation of interacting droplets using combined optical techniques

Experimental study of liquid-vapor mass transfer in non-reacting and reacting droplet chains

Measurement of the temperature distribution within monodisperse combusting droplets in linear streams using two-color laser-induced fluorescence

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