Measurement of interfacial structure for co-current air–water flow

Lilleleht, L. U.; Hanratty, Thomas J.

doi:10.1017/s002211206100086x

Cited by 35 publications

(10 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Note that the fluid properties are constant (air and water at atmospheric conditions) for all experiments. As an assumption, the effect of phase velocities will be given by the relative velocity, U br = U bg − U bl , and the wave height will be taken as the mode of the probability density functions of H. A dimensional analysis gives rise to the following relation (Lilleleht & Hanratty, 1961):…”

Section: Short Note On the Depth Limited Mode Heightmentioning

confidence: 99%

Statistical characterization of interfacial waves in turbulent stratified gas-liquid pipe flows

Ayati

Carneiro

2018

International Journal of Multiphase Flow

View full text Add to dashboard Cite

This study presents a statistical analysis of interfacial waves in a turbulent stratified air-water flow inside a 10 cm diameter pipe. Wave elevation measurements were acquired using conductance probes with high sampling rate, Sr = 500Hz. Local wave parameters (elevation, crest height, trough height, etc.) were extracted using a zero-crossing technique. The evolution of their corresponding statistical distributions and statistical moments was investigated for varying flow conditions.The main goal of this study is to offer an alternative method for distinguishing between various wavy flow patterns. The proposed approach is based on the Gaussian model, which is widely used in the characterization of ocean waves. Instead of the traditional sub-regime categorization which is based on a combination of visual observations and qualitative spectral description, this method categorizes a wave field depending on its degree of non-linearity and statistics of elevation parameters. This approach also allows parametrization of the interfacial structure. As a first step, this approach was carried out only for a selected set of flow rate combinations, in which the liquid superficial velocity was kept constant at U sl = 0.10 m/s whilst the superficial velocity was increased from 1.0 m/s to 4.0 m/s with increments of 0.25 m/s. Subsequently, statistical moments of the interface elevation were computed and compared to literature data, for varying U sl and U sg . Based on the detailed statistical description of wave data, two flow regimes are categorized: wave amplitude growth and saturation. These regimes were also identified as quasi-Gaussian and non-Gaussian, respec-Email addresses: awalaa@math.uio.no (A.A. Ayati),

show abstract

Section: Short Note On the Depth Limited Mode Heightmentioning

confidence: 99%

Statistical characterization of interfacial waves in turbulent stratified gas-liquid pipe flows

Ayati

Carneiro

2018

International Journal of Multiphase Flow

View full text Add to dashboard Cite

show abstract

“…Available methods can be classified based on the physical principles, acoustic, electrical or optical, involved for the measurements. In particular, numerous optical methods have been developed, including interferometry methods (Ohyama et al 1988), fluorescence intensity methods (Makarytchev et al 2001), methods based on imaging a diffusive liquid (Berhanu & Falcon 2013) or light absorption methods (Lilleleht & Hanratty 1961;Kim & Kim 2005). Mouza et al (2000) compared two methods to measure liquid film thickness, a photometric technique based on the absorption of light passing through a layer of dyed liquid and a conductance measurement and found a very good agreement between these two methods.…”

Section: Sheet Thickness Measurementmentioning

confidence: 99%

Free radially expanding liquid sheet in air: time- and space-resolved measurement of the thickness field

2015

View full text Add to dashboard Cite

The collision of a liquid drop against a small target results in the formation of a thin liquid sheet that extends radially until it reaches a maximum diameter. The subsequent retraction is due to the air-liquid surface tension. We have used a timeand space-resolved technique to measure the thickness field of this class of liquid sheet, based on the grey-level measurement of the image of a dyed liquid sheet recorded using a high-speed camera. This method enables a precise measurement of the thickness in the range 10-450 µm, with a temporal resolution equal to that of the camera. We have measured the evolution with time since impact, t, and radial position, r, of the thickness, h(r, t), for various drop volumes and impact velocities. Two asymptotic regimes for the expansion of the sheet are evidenced. The scalings of the thickness with t and r measured in the two regimes are those that were predicted by Rozhkov et al. (Proc. R. Soc. Lond. A, vol. 460, 2004, pp. 2681-2704 for the short-time regime and Villermaux and Bossa (J. Fluid Mech., vol. 668, 2011, pp. 412-435) for the long-time regime, but never experimentally measured before. Interestingly, our experimental data also provide evidence for the existence of a maximum of the film thickness h max (r) at a radial position r h max (t) corresponding to the cross-over of these two asymptotic regimes. The maximum moves with a constant velocity of the order of the drop impact velocity, as expected theoretically. Thanks to our visualization technique, we also provide evidence of an azimuthal thickness modulation of the liquid sheets.

show abstract

“…The uncertainty of the extension coefficient U γ p , on the other hand, does not depend on the operating condition but only on the calibration. From eq.10 it is: (14) and leads to a relative uncertainty of U γ g /γ g = 2%. Introducing eq.14 and eq.12 in eq.11 gives the thickness uncertainty as a function of the thickness and the extinction coefficient.…”

Section: Labs Uncertainties and Sensitivity Analysismentioning

confidence: 99%

“…In the LAbs technique the film thickness is retrieved by measuring the intensity of the light transmitted through the liquid film. Developed as a point-wise technique, using photodiods or photomultipliers as light receivers [14,15], the LAbs has later become a full field technique using digital video cameras and basic image processing operations [17][18][19]. While this method can provide high spatial and temporal resolution, its main limitation is in the assumption that the light transmittance is solely linked to light absorption, disregarding spurious effects such as light refraction, reflection or scattering.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Liquid Film Thickness via Light Absorption and Laser Tomography

Mendez

Németh

Buchlin

2016

EPJ Web of Conferences

View full text Add to dashboard Cite

Abstract. This paper presents film thickness measurement over a vertical falling liquid film, carried out with Light Absorption (LAbs) and a 2D laser tomography techniques known as Level Detection and Recording (LeDaR). The presented test cases are in the low Reynolds regime (Re = 1 − 8) and include undisturbed conditions, i.e. constant flow rate, and inlet-forced conditions, i.e. flow rate pulsing at frequencies in the range f p = 12 − 18Hz. The liquid used is Dipropilene Glycol (DPG), with Kapitza number Ka = 4.6. The results include average film thickness in the steady case, wave celerity and wave profile in the forced conditions. All the measurements are scaled using the Skhadov scaling, to facilitate the comparison with analytical low-dimensional models. Both LAbs and LeDaR techniques are presented in detail, including calibration, uncertainties and data processing aspects.

show abstract

Measurement of interfacial structure for co-current air–water flow

Abstract: A method for measuring the interfacial structure between a co-current air-water flow using the absorption of light is described. Measurements of the root-meansquared displacement and the frequency spectrum are presented. The use of a Gaussian model to describe the interface is explored.

Cited by 35 publications

References 4 publications

Statistical characterization of interfacial waves in turbulent stratified gas-liquid pipe flows

Statistical characterization of interfacial waves in turbulent stratified gas-liquid pipe flows

Free radially expanding liquid sheet in air: time- and space-resolved measurement of the thickness field

Measurement of Liquid Film Thickness via Light Absorption and Laser Tomography

Contact Info

Product

Resources

About