Numerical analysis of convecting, vaporizing fuel droplet with variable properties

Chiang, Chen‐Yu; Raju, M. S.; Sirignano, William A.

doi:10.1016/0017-9310(92)90186-v

Cited by 189 publications

(82 citation statements)

References 11 publications

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“…[18][19][20] In these studies, however, the main interest was the change of the drag force due to the Marangoni effect in the presence of a strong convective flow. Furthermore, many simplifying assumptions employed in these studies, such as quasi-steadiness, 18 quiescent liquid, 19 or vorticity-stream function formulation, 19,20 along with the existence of strong forced convective flow limit the understanding of thermo-capillary flow effect and the mechanism of vapor jet ejection. Considering the difficulties in detailed experimental measurements, high-fidelity computational modeling is well suited to investigate the physical mechanism for these phenomena.…”

Section: Introductionmentioning

confidence: 99%

A computational study of droplet evaporation with fuel vapor jet ejection induced by localized heat sources

Sim

Chung

2015

Physics of Fluids

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A computational study of droplet evaporation with fuel vapor jet ejection induced by localized heat sources Droplet evaporation by a localized heat source under microgravity conditions was numerically investigated in an attempt to understand the mechanism of the fuel vapor jet ejection, which was observed experimentally during the flame spread through a droplet array. An Eulerian-Lagrangian method was implemented with a temperaturedependent surface tension model and a local phase change model in order to effectively capture the interfacial dynamics between liquid droplet and surrounding air. It was found that the surface tension gradient caused by the temperature variation within the droplet creates a thermo-capillary effect, known as the Marangoni effect, creating an internal flow circulation and outer shear flow which drives the fuel vapor into a tail jet. A parametric study demonstrated that the Marangoni effect is indeed significant at realistic droplet combustion conditions, resulting in a higher evaporation constant. A modified Marangoni number was derived in order to represent the surface force characteristics. The results at different pressure conditions indicated that the nonmonotonic response of the evaporation rate to pressure may also be attributed to the Marangoni effect. C 2015 AIP Publishing LLC. KAUST Repository[http://dx

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Section: Introductionmentioning

confidence: 99%

A computational study of droplet evaporation with fuel vapor jet ejection induced by localized heat sources

Sim

Chung

2015

Physics of Fluids

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“…For the specific types of droplet flows to be considered in this research, the Lagrangian appears to be better suited for the three following reasons: 1) it avoids the numerical cell diffusion associated with Eulerian treatments, 2) it conveniently allows multiple droplet size and velocity distributions, and 3) it allows for use of a stochastic eddy dispersion treatment (Solomon, et al, 1985). A drag 4-9 coefficient formulation can be implemented to handle the entire slip Reynolds number regime and possibly take into account the slip boundary condition (Faeth, 1987;Chiang, et al 1989). Droplet evaporation, gravitational acceleration, Magnus effects, and Saffman lift can be readily included in such a formulation.…”

Section: Proposed Computer Methodologymentioning

confidence: 99%

USAF Summer Research Program - 1994 Graduate Student Research Program Final Reports, Volume 11, AEDC, FJSRL, and WHMC.

Moore¹

1994

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Public reporting burden for this collection of information is estimated to average 1 hour per response, incdudii gathering and maintaining the data needed, and completing and reviewing the collection of information. Send com )Ilection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directoras Dynamic re-synthesis of an executing system is supported, allowing the system structure to adapt to the external or internal environment. The paper describes an application of these techniques to a large, high performance parallel instrumentation system used for analysis of turbine engine strain gauge signals produced during altitude testing. The unique features of this approach include: explicit domain-specific declarative models; graphical representation of models; multiple aspect models; automatic specification of the necessary hardware architecture; and on-line re-synthesis of dynamic systems. 1-2 MODEL-BASED SOFTWARE SYNTHESIS FOR LARGE SYSTEMSBen A. Abbott IntroductionOne of the most challenging problems in software engineering is to build large, high-performance systems that must perform continuous interaction with their environment. The behavior of these reactive systems is typically complex, concurrent, and non-deterministic. This makes them difficult to build.Automatic program synthesis is one of the prime disciplines that can contribute to the advancement of the software engineering of reactive systems. The technique has been successfully applied to a specific "real-world" application: a large-scale, parallel instrumentation system, called Computer Assisted Dynamic Data Analysis and Monitoring System (CADDMAS). The CADDMAS system was developed in cooperation with the US Air Force at Arnold Engineering Development Center (AEDC). The software synthesized is a complex, reactive, signal processing system running on a heterogeneous network of nearly 100 processors. TerminologyBefore describing the software synthesis technique utilized, the main terms and concepts used in automatic program synthesis, reactive systems, and model-based systems are briefly defined and discussed. In some cases, the definitions are constrained to the specific needs of this paper. Parallel Instrumentation SystemParallel Instrumentation systems use multiple computers to cooperatively convert a set of acquired input signals into a more desirable format. The need for a parallel system as 1-3 opposed to a single processor system can be a result of the raw data rate requirements, or as a result of the number of simultaneous input signals that must be processed. Reactive SystemsMost Instrumentation Systems have their behavior driven by external inputs. In such cases, they may be classified as reactive systems (26]: embedded real-time systems characterized by continuous interaction with their environment. Process monitoring and control systems, and real-time signal processing systems are typical examples of this category. The complexity, concurrency, and non-deterministic behavior of reactive sys...

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“…The unit cell length is 1.25 μm in this domain. The ratios of the unit cell length and the droplet initial diameters are less than the value of the grid independent solution in [15].Therefore, the effect of grid number on numerical results can be ignored. The time step is Δ t=0.5 μs which is less than the droplet characteristic time .…”

Section: Modeling Processmentioning

confidence: 99%

Numerical Simulation on Two Droplets Burning at Different Droplet Radius Ratios

Hong¹,

Zhao²,

Zhang³

et al. 2015

Proceedings of the International Conference on Logistics, Engineering, Management and Computer Science

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Abstract-It has some significance to study the influences of the droplet radius ratios on spray combustion due to the varying droplet radius ratios among droplets in the actual spray combustion. The volume of fluid (VOF) formulation is applied to model the combustion process of two decane droplets with different radiuses in a hot convective flow and the effects of the droplet ratios on burning rates of two droplets at fixed droplet center spacing are analyzed. The results show: when the burning rates of the front and the back droplets compare with that of the corresponding single droplet, the interaction reduces the burning rate of either droplet under different droplet radius ratios. For the same initial droplet radius, the burning rate of droplet located at the front is larger than that at the back under different droplet radius ratios. The results obtained provide some reference for the basic researches of spray combustion.

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Numerical analysis of convecting, vaporizing fuel droplet with variable properties

Cited by 189 publications

References 11 publications

A computational study of droplet evaporation with fuel vapor jet ejection induced by localized heat sources

A computational study of droplet evaporation with fuel vapor jet ejection induced by localized heat sources

USAF Summer Research Program - 1994 Graduate Student Research Program Final Reports, Volume 11, AEDC, FJSRL, and WHMC.

Numerical Simulation on Two Droplets Burning at Different Droplet Radius Ratios

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