Experimental Study of Droplet Evaporation in a High-Temperature Air Stream

Renksizbulut, Metin; Yuen, M. C.

doi:10.1115/1.3245590

Cited by 196 publications

(75 citation statements)

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“…For the comparison of Nusselt numbers, the definition of the Reynolds number from [34] is used [see (21)]. Agreement with the reference data is good except for very low Reynolds numbers (see Table 3).…”

Section: Validation Of the Simulation Setupmentioning

confidence: 99%

Numerical Investigation of the Time Scales of Single Droplet Burning

Beck

Koch

Bauer

2008

Flow Turbulence Combust

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The effect of gas phase velocity fluctuations on single droplet burning is investigated numerically. The main objective of this study is to understand the effect of gas phase turbulence on nitric oxide formation in single droplet flames. Since the interaction of gas phase velocity fluctuations with droplet burning is of sequential character, a separate investigation of droplet momentum coupling and droplet burning is performed. Momentum coupling controls droplet relaxation against changes of the gas phase velocity along the droplet trajectory and, thereby, determines to what extend gas phase velocity fluctuations translate into droplet slip velocity fluctuations. This coupling effect acts as a high pass filter with a cutoff frequency determined by the droplet Reynolds number and diameter. In the simulation of single droplet burning detailed models for chemical reaction, diffusive species transport and evaporation are used. A significant effect of slip velocity fluctuations on the mean values of NO formation rate is observed. The effect of slip velocity fluctuations on the mean NO formation rate is frequency dependent. The frequency response of the droplet flame is similar to that of a low pass filter. The droplet flame time scale characterizing the response to slip velocity fluctuations is found to correlate with chemical time scales. This time scale is not affected by droplet diameter.

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Section: Validation Of the Simulation Setupmentioning

confidence: 99%

Numerical Investigation of the Time Scales of Single Droplet Burning

Beck

Koch

Bauer

2008

Flow Turbulence Combust

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“…Several models, e.g. [19,20], based on the correlation model of Ranz and Marschall [21], have been developed to model these parameters. The evaporation rate model of Abramzon and Sirignano [22] considers additionally the latent heat flux of the evaporated liquid leaving the droplet.…”

Section: Introductionmentioning

confidence: 99%

Comparative study of Euler/Euler and Euler/Lagrange approaches simulating evaporation in a turbulent gas–liquid flow

Groll

Jakirlić

Tropea

2008

Numerical Methods in Fluids

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SUMMARYThis study deals with the Reynolds-averaged Navier-Stokes simulation of evaporation in a turbulent gasliquid flow in a three-dimensional duct, focussing on the results obtained by a four-equation turbulence model within the framework of the Euler/Euler approach for multiphase flow calculations: in addition to the two-equation k −ε model describing the turbulence of the continuous (C) phase, the computational model employs transport equations for the turbulence kinetic energy of the disperse (D) phase and for the velocityIn the present study, the evaporation model according to Abramzon and Sirignano (Int. J. Heat Mass Transfer 1989; 32:1605-1618) has been extended by introducing an additional transport equation for a newly defined quantity a, defined as the phase-interface surface fraction. This allows the change in the drop diameter to be quantified in terms of a probability density function. The source term in the equation describing the dynamics of the volumetric fraction of the dispersed phase D is related to the evaporation time scale . The performance of the new model is evaluated by performing a comparative analysis of the results obtained by simulating a polydispersed spray in a three-dimensional duct configuration with the results of the Euler/Lagrange calculations performed in parallel. Prior to these calculations, some selected (solid) particle-laden flow configurations were computationally examined with respect to the validation of the background, four-equation, eddy-viscosity-based turbulence model. Multiphase flows encountered in energy and process engineering are often characterized by a phase interchange due to dispersed phase evaporation. When simulating the motion of liquid drops in a dry gas, it is important to capture not only the evaporation but also the interaction between the discrete and continuous phases. For instance, strong evaporation rates at the interfacial surface and the relative humidity influence the shear stress dynamics at the interface and the overall droplet drag in the air flow. Typical applications include direct injection of a diesel spray (break-up, evaporation and combustion are occurring sequentially), spray drying in the foodstuff or pharmaceutical industries or spray painting. These are only a few illustrative examples for industrial research areas, which use powerful optimization tools for the prediction of multiphase transport processes. The capability of a computational scheme to account for all important phenomena featuring these processes is a major prerequisite for successful design and optimization of many industrial, multiphase systems.Commonly used computational schemes describing the interaction between the continuous carrier phase and a particulate phase in such multiphase processes are the Euler/Lagrange and the Euler/Euler approaches. The most widely used approach in technical applications is the Euler/Lagrange method, which solves the governing equations only for the carrier phase. In this concept, the associated dispersed (here liquid) phase is ...

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“…[20]. The modification is based on the experimental correlation of Renksizbulut and Yuen [21]. The development of the Abramzon and Sirignano model is essentially the same as the Spalding model, but now the Nusselt number for Re>25 is given by,…”

Section: Model Formulationmentioning

confidence: 99%

A New High Pressure Droplet Vaporization Model for Diesel Engine Modeling

Curtis

Uludogan

Reitz

1995

SAE Technical Paper Series

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A droplet vaporization model has been developed for use in high pressure spray modeling. The model is a modification of the common Spalding vaporization model that accounts for the effects of high pressure on phase equilibrium, transport properties, and surface tension. The new model allows for a nonuniform temperature within the liquid by using a simple 2-zone model for the droplet. The effects of the different modifications are tested both for the case of a single vaporizing droplet in a quiescent environment as well as for a high pressure spray using the KIVA II code. Comparisons with vaporizing spray experiments show somewhat improved spray penetration predictions. Also, the effect of the vaporization model on diesel combustion predictions was studied by applying the models to simulate the combustion process in a heavy duty diesel engine. In this case the standard and High Pressure vaporization models were found to give similar heat release and emissions results. However, the results show that a more realistic representation of the vaporization process is achieved with the new model. In particular, less unburned fuel is predicted to remain in the combustion chamber late in the power stroke.

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Experimental Study of Droplet Evaporation in a High-Temperature Air Stream

Cited by 196 publications

References 0 publications

Numerical Investigation of the Time Scales of Single Droplet Burning

Numerical Investigation of the Time Scales of Single Droplet Burning

Comparative study of Euler/Euler and Euler/Lagrange approaches simulating evaporation in a turbulent gas–liquid flow

A New High Pressure Droplet Vaporization Model for Diesel Engine Modeling

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