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  • 1
    Electronic Resource
    Electronic Resource
    Simultaneous concentration and velocity measurements using combined laser-induced fluorescence and laser Doppler velocimetry: Application to turbulent transport (1996)
    Springer
    Experiments in fluids 20 (1996), S. 319-327 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper describes the implementation of an optical technique, allowing to perform concentration and velocity measurements simultaneously and at the same point. This method is based on the coupling of laser-induced fluorescence of rhodamine B, applied to the determination of local concentration, and laser Doppler velocimetry. The method developed provides an accurate measurement of the concentration-velocity cross-correlation. The latter is a parameter linked to the eddy diffusivity tensor of a passive contaminant. This method was tested with a turbulent submerged free jet and it allowed the determination of the mean field of concentration and velocity, the concentration-velocity cross-correlation, and the local eddy diffusivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191013
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Simultaneous temperature and 2D velocity measurements in a turbulent heated jet using combined laser-induced fluorescence and LDA (1999)
    Springer
    Experiments in fluids 26 (1999), S. 315-323 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  This paper presents an efficient technique for the characterization of thermal transport properties in turbulent flows. The method is based on the temperature dependence of fluorescence, induced by laser radiation, of an organic dye. The laser-induced fluorescence technique is combined with 2D laser Doppler anemometry, in order to measure in the same sample volume simultaneously and instantaneously the temperature and velocity. The technique is demonstrated on a turbulent heated round jet: the mean and fluctuating dynamic and thermal fields are investigated, and the temperature-velocity cross-correlations are determined in order to characterize the turbulent diffusivity and the turbulent Prandtl number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050294
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Temperature measurements on droplets in monodisperse stream using laser-induced fluorescence (2000)
    Springer
    Experiments in fluids 29 (2000), S. 429-437 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents a novel technique based on laser-induced fluorescence in liquids, allowing the temperature of 200-μm diameter monodisperse droplets to be measured. The droplets are seeded with an organic dye (rhodamine B), and the temperature dependence of the fluorescence quantum yield is used to determine temperature. The use of LDA optics and a single argon laser source allows to obtain an additional simultaneous velocity measurement. The method appears particularly interesting for the validation of numerical models of evaporating and combusting droplets in the field of design of the combustion chambers of aeronautical and automotive engines, where fuel is injected in droplet form. The measurement technique and data processing are extensively described in the paper. The method is demonstrated on a heated monodisperse droplet stream: the temperature and velocity distribution along the jet were determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480000109
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  • 4
    Electronic Resource
    Electronic Resource
    Wall shear measurements inside corrugated channels using the electrochemical technique (1998)
    Springer
    Experiments in fluids 24 (1998), S. 17-26 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  We report on an investigation of adiabatic single-phase flow inside two-dimensional and three-dimensional channels, with a hydraulic diameter of 0.033 m. This work is a preliminary study to another one that will be carried out with a gas–liquid mixture. The flow structure is studied using the electrochemical technique. Circular single probes and rectangular sandwich probes are inserted flush to the wall. This equipment allows us to give an accurate description of the flow at the wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050146
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  • 5
    Electronic Resource
    Electronic Resource
    Heat transfer and flow of a thermodependent and yield stress fluid (1994)
    Springer
    Heat and mass transfer 29 (1994), S. 243-249 
    Details
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung In dieser Arbeit wird das Strömungsverhalten eines Fluids mit temperatur- und scherspannungsabhängigem Fließvermögen in einem mit konstanter Wärmestromdichte beaufschlagten Kreisrohr untersucht. Hierbei fallen experimentell und numerisch gefundene Ergebnisse an. Besonders interessiert der Einfluß verschiedener Parameter auf die Nusselt-Zahl und den Druckverlust. Es wird ein Modell zur Berücksichtigung der Auswirkung temperaturabhängiger Stoffwerte auf beide Intensitätsparameter vorgeschlagen. Die hieraus resultierenden Korrelationen stimmen gut mit den experimentellen Befunden überein.
    Notes: Abstract In this paper, we study the flow of a fluid possessing a yield stress, in a cylindrical pipe being the wall heated with a constant flux; experimental and numerical results being presented here. We are interested in the influence of the different parameters on the Nusselt number, and in the pressure variation. We propose a model which enables us to estimate the Nusselt number and pressure variation, which takes into account the variation of the physical properties due to temperature variations. The proposed correlations agree well with experimental measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01539756
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Thermal convection for a thermodependent herschel-bulkley fluid in an annular duct (1996)
    Springer
    Heat and mass transfer 31 (1996), S. 257-267 
    Details
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Wir stellen eine numerische und experimentelle Analyse der thermischen Konvektion in einem temperaturabhängigen Herschel-Bulkley Fluid vor. Das Fluid strömt durch eine Ringleitung, deren innere Zylinderwand mit einem konstanten Wärmfluß beauschlagt wird: die äußere Zylinderwand ist hingegen thermisch isoliert. Die numerische Analyse erfolgte unter folgenden Voraussetzungen: (1) Das rheologische Fließverhalten des Fluides wird beschrieben durch eine Gleichung des Typs $$\tau = \tau _s + K\dot \gamma ^n $$ ; (2) Die Strömung ist bereits am Einlauf ausgebildet; (3) All physikalischen Eigenschaften des Fluids werden als konstant angesehen, mit Ausnahme der DichteK, deren Temperaturabhängigkeit durch die GleichungK=K 0exp(−bT) gegeben ist. Die erzielten Resultate erlaubten uns, das dynamische und thermische Profil des Fluides vollständig zu beschreiben. Die numerischen Werte sind in guter Übereinstimmung mit den experimentellen Ergebnissen.
    Notes: Abstract This article presents a numerical and experimental investigation of the thermal convection for a thermodependent Herschel-Bulkley fluid in an annular duct under the conditions of a uniform heat flux density on the outer wall and an insulated inner wall. In the numerical analysis, it is assumed that: (i) the rheological behavior of the fluid can be expressed through the Herschel-Bulkley law: $$\tau = \tau _s + K\dot \gamma ^n $$ ; (ii) the flow is fully developed at the inlet; (iii) all fluid properties except consistency indexK are constant. TheK−T relation used isK=K 0exp(−bT). The results obtained enable us to characterize completely the dynamical and thermal fields. The numerical solution is in good agreement with the experimental data, showing the reasonableness of the computed results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02328618
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Thermal convection for a thermodependent Herschel-Bulkley fluid in an annular duct (1996)
    Springer
    Heat and mass transfer 31 (1996), S. 257-267 
    Details
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung  Wir stellen eine numerische und experimentelle Analyse der thermischen Konvektion in einem temperaturabhängigen Herschel-Bulkley Fluid vor. Das Fluid strömt durch eine Ringleitung, deren innere Zylinderwand mit einem konstanten Wärmfluß beauschlagt wird: die äußere Zylinderwand ist hingegen thermisch isoliert. Die numerische Analyse erfolgte unter folgenden Voraussetzungen: (1) Das rheologische Fließverhalten des Fluides wird beschrieben durch eine Gleichung des Typs τ=τ s +Kγ˙ n ; (2) Die Strömung ist bereits am Einlauf ausgebildet; (3) All physikalischen Eigenschaften des Fluids werden als konstant angesehen, mit Ausnahme der Dichte K, deren Temperaturabhängigkeit durch die Gleichung K=K 0exp (−bT ) gegeben ist. Die erzielten Resultate erlaubten uns, das dynamische und thermische Profil des Fluides vollständig zu beschreiben. Die numerischen Werte sind in guter Übereinstimmung mit den experimentellen Ergebnissen.
    Notes: Abstract This article presents a numerical and experimental investigation of the thermal convection for a thermodependent Herschel-Bulkley fluid in an annular duct under the conditions of a uniform heat flux density on the outer wall and an insulated inner wall. In the numerical analysis, it is assumed that: (i) the rheological behavior of the fluid can be expressed through the Herschel-Bulkley law: τ=τ s +Kγ˙ n ; (ii) the flow is fully developed at the inlet; (iii) all fluid properties except consistency index K are constant. The K–T relation used is K=K 0exp (−bT ). The results obtained enable us to characterize completely the dynamical and thermal fields. The numerical solution is in good agreement with the experimental data, showing the reasonableness of the computed results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002310050054
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Caractéristiques rhéologiques, coéfficient de frottement et écoulement en situation réelle de fluides à seuil (1988)
    Springer
    Rheologica acta 27 (1988), S. 628-633 
    Details
    ISSN: 1435-1528
    Keywords: Dilute polymersolution ; yield ; laser velocimetry ; abruptcontraction ; polyacrylic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Abstract This work deals with the study of very dilute solutions of polyacrylic acid in water (weight concentration about 0.1%). These fluids seem to exhibit a yield effect. The determination of the fully developed velocity field by laser velocimetry allows us an accurate determination of the rheological indexn′ which is an essential parameter for the proposed rheological relationship: $$\tau = \tau _s + K\dot \gamma ^{n\prime } + \eta _\infty \dot \gamma $$ . Other constants can be determined from classical rheological experiments (high shear strain). It is possible to correct the experimental pressure gradientΔP/L so as to get the real value, noted asdp/dz. An analysis of the flow in an abrupt expansion shows that the yield effect strongly influences the recirculation zones.
    Notes: Résumé Ce travail porte sur l'étude de solutions diluées d'un polymère de l'acide acrylique dans l'eau (concentration en poids ≃ 0,1%). Ce fluide présente des effets de seuil. La mesure du champ de vitesse par vélocimétrie laser permet une détermination précise de l'indice rhéologique,n′, étant un paramètre essentiel de la loi de comportement proposée: $$\tau = \tau _s + K\dot \gamma ^{n\prime } + \eta _\infty \dot \gamma $$ . Les autres constantes peuvent être déduites d'essais rhéologiques classiques, à fort taux de cisaillement. Il est possible de corriger le gradient de pression mesuréΔP/L, afin d'obtenir la valeur véritable de ce gradient, notéedp/dz. L'analyse de l'écoulement dans un élargissement brusque montre que le seuil a une forte influence sur les zones de recirculation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01337458
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Mass and momentum transfer enhancement due to electrogenerated gas bubbles (1985)
    Springer
    Journal of applied electrochemistry 15 (1985), S. 557-566 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The effect of electrogenerated gas bubbles with simultaneous bulk liquid flow on the mass and momentum transfer at a wall of an electrolytic cell is experimentally determined. The local mass transfer coefficient and electrolyte shear stress are obtained using two types of microelectrodes imbedded in the channel wall. The influence of the most important parameters (electrolyte velocity, position along the wall, gas electrogeneration rate) on the transfer enhancement is studied and an analogy between mass and momentum transfer in the presence of bubbles is clearly demonstrated from the experimental results. The comparison with classical correlations, valid for systems involving natural turbulence, shows the higher energetic efficiency of devices where the turbulence is artificially generated by electrolytic gas bubbles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01059297
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Wall shear measurements by electrochemical probe for gas-liquid two-phase flow in vertical duct (1984)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 30 (1984), S. 338-341 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690300224
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    Paper (German National Licenses)
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