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Thin liquid films with time-dependent chemical reactions sheared by an ambient gas flow.

Bender, Achim ; Stephan, Peter ; Gambaryan-Roisman, Tatiana :
Thin liquid films with time-dependent chemical reactions sheared by an ambient gas flow.
[Online-Edition: https://doi.org/10.1103/PhysRevFluids.2.084002]
In: Physical Review Fluids, 2 (8) 084002-1-084002-16. ISSN 2469-990X
[Artikel], (2017)

Offizielle URL: https://doi.org/10.1103/PhysRevFluids.2.084002

Kurzbeschreibung (Abstract)

Chemical reactions in thin liquid films are found in many industrial applications, e.g., in combustion chambers of internal combustion engines where a fuel film can develop on pistons or cylinder walls. The reactions within the film and the turbulent outer gas flow influence film stability and lead to film breakup, which in turn can lead to deposit formation. In this work we examine the evolution and stability of a thin liquid film in the presence of a first-order chemical reaction and under the influence of a turbulent gas flow. Long-wave theory with a double perturbation analysis is used to reduce the complexity of the problem and obtain an evolution equation for the film thickness. The chemical reaction is assumed to be slow compared to film evolution and the amount of reactant in the film is limited, which means that the reaction rate decreases with time as the reactant is consumed. A linear stability analysis is performed to identify the influence of reaction parameters, material properties, and environmental conditions on the film stability limits. Results indicate that exothermic reactions have a stabilizing effect whereas endothermic reactions destabilize the film and can lead to rupture. It is shown that an initially unstable film can become stable with time as the reaction rate decreases. The shearing of the film by the external gas flow leads to the appearance of traveling waves. The shear stress magnitude has a nonmonotonic influence on film stability.

Typ des Eintrags: Artikel
Erschienen: 2017
Autor(en): Bender, Achim ; Stephan, Peter ; Gambaryan-Roisman, Tatiana
Titel: Thin liquid films with time-dependent chemical reactions sheared by an ambient gas flow.
Sprache: Englisch
Kurzbeschreibung (Abstract):

Chemical reactions in thin liquid films are found in many industrial applications, e.g., in combustion chambers of internal combustion engines where a fuel film can develop on pistons or cylinder walls. The reactions within the film and the turbulent outer gas flow influence film stability and lead to film breakup, which in turn can lead to deposit formation. In this work we examine the evolution and stability of a thin liquid film in the presence of a first-order chemical reaction and under the influence of a turbulent gas flow. Long-wave theory with a double perturbation analysis is used to reduce the complexity of the problem and obtain an evolution equation for the film thickness. The chemical reaction is assumed to be slow compared to film evolution and the amount of reactant in the film is limited, which means that the reaction rate decreases with time as the reactant is consumed. A linear stability analysis is performed to identify the influence of reaction parameters, material properties, and environmental conditions on the film stability limits. Results indicate that exothermic reactions have a stabilizing effect whereas endothermic reactions destabilize the film and can lead to rupture. It is shown that an initially unstable film can become stable with time as the reaction rate decreases. The shearing of the film by the external gas flow leads to the appearance of traveling waves. The shear stress magnitude has a nonmonotonic influence on film stability.

Titel der Zeitschrift, Zeitung oder Schriftenreihe: Physical Review Fluids
Band: 2
(Heft-)Nummer: 8
Fachbereich(e)/-gebiet(e): 16 Fachbereich Maschinenbau
16 Fachbereich Maschinenbau > Fachgebiet für Technische Thermodynamik (TTD)
DFG-Sonderforschungsbereiche (inkl. Transregio) > Transregios > TRR 150 Turbulent chemisch reagierende Mehrphasenströmungen in Wandnähe
Exzellenzinitiative
Exzellenzinitiative > Exzellenzcluster > Center of Smart Interfaces (CSI)
DFG-Sonderforschungsbereiche (inkl. Transregio) > Transregios
Exzellenzinitiative > Exzellenzcluster
DFG-Sonderforschungsbereiche (inkl. Transregio)
Hinterlegungsdatum: 28 Aug 2017 16:01
Offizielle URL: https://doi.org/10.1103/PhysRevFluids.2.084002
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