Real-Time Measurement of Two-Phase Flow Turbulence Using a Dual-Sensor Anemometry

Serizawa, Akimi; Tsuda, Katsutoshi; Michiyoshi, Itaru

doi:10.1007/978-3-642-82112-7_25

Cited by 16 publications

(13 citation statements)

References 9 publications

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“…The relative error is always lower than 5 %. The diameter and length of the sensitive element of the probe (70 µm, 1.25 mm), associated with the non-negligible mean liquid velocity, allowed correct piercing of the bubbles, so that interactions between the probe and the bubbles were negligible Serizawa, Tsuda & Michiyoshi 1983). The passing of a bubble over the film causes a sudden change in heat transfer, so that the associated portion of the signal has no meaning and must be removed from the signal (figure 5a).…”

Section: Measuring Methodsmentioning

confidence: 99%

Measurement of interstitial velocity of homogeneous bubbly flows at low to moderate void fraction

Roig

Tournemine

2007

J. Fluid Mech.

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We develop a new methodology to examine the conditional and unconditional vertical velocity induced by high-Reynolds-number bubbles rising in a uniform flow, at low to moderate void fraction α (up to 15%). These statistics provide a local description of the perturbation of the liquid velocity around a test bubble in the swarm. In particular, the attenuation of the length of the wakes with increasing void fraction is measured for a large range of void fraction. The strong attenuation of the wakes is related to wake intermingling mechanisms. The methodology also enables a definition of the interstitial liquid flow. The velocity of the fluid averaged over all the interstitial volume far away from the bubbles is introduced. It is a useful concept, in particular to define the relative velocity, or for drift models. Our experimental results allow a discussion of the predictions of irrotational drift models. For low void fraction (α≤2%), potential flow models provide practical estimates of the interstitial velocity field. At higher void fractions, the effect of vorticity is important. A simple phenomenological model is proposed to include the effect of the flow generated by the bubble wakes.

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Section: Measuring Methodsmentioning

confidence: 99%

Measurement of interstitial velocity of homogeneous bubbly flows at low to moderate void fraction

Roig

Tournemine

2007

J. Fluid Mech.

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“…3.2. Bubble-probe interaction The interaction between a hot-film probe and bubbles had already been investigated by several workers (Delhaye 1969;Bremhorst & Gilmore 1976;Serizawa, Tsuda & Michiyoshi 1983;Farrar & Bruun 1989;Bruun 1995). However, the case in which bubbles rise upstream has, to our knowledge, not yet been considered.…”

Section: Calibrationmentioning

confidence: 99%

The effect of bubbles on developed turbulence

2005

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Hot-film anemometry measurements are performed in a fully developed turbulent bubbly flow. For the bubble detection in the signal, both a threshold method and a new pattern recognition algorithm are employed. The measurements are carried out with gas fractions up to 3% and a mean water velocity of 0.20 m s-1, corresponding to a Reynolds number of about 9x10 4. The typical bubble radius is 1–2 mm, corresponding to 10–20 Kolmogorov length scales. In this regime, a ‘bubblance’ parameter b which compares the kinetic energy originating from the rising bubbles with that of the turbulence fluctuations is smaller than 1. Probability distribution functions, structure functions (with and without the extended self-similarity (ESS) method), and spectra of the water velocity time series are calculated. Both our results for the turbulent energy spectra and the second-order structure functions show qualitative agreement with numerical results by Massitelli, Lohse & Toschi (Phys. Fluids, vol. 15 (2003), p. L5), i.e. a more pronounced energy enhancement on small scales than on large scales owing to the presence of bubbles, leading to a less steep slope in the spectrum as compared to the Kolmogorov -5/3 law. These results are robust, i.e. do not depend on details of the bubble detection scheme

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“…Serizawa et al [12] performed an optical analysis of the interactions between a wire and rising bubbles. The wire is stretched over the diameter of a pipe and positioned normally to the main direction of liquid flow.…”

Section: An Overviewmentioning

confidence: 99%

“…The splitting of bubbles by the wire was only observed with bubbles larger than d B = 3.0 mm and, according to the work of Bremhorst and Gilmore [2], with cylindrical sensors and bubble diameters smaller than the total length of the sensor. To classify possible interactions Serizawa et al [12] proposed so-called bubble-wire interaction maps, depending on the velocity of the fluid and the diameters of the bubbles and the sensors.…”

Section: An Overviewmentioning

confidence: 99%

Investigations of static and dynamic interactions between bubbles and X-hot-film probes

Benk¹,

Schmidt²,

Loth³

2001

Meas. Sci. Technol.

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Very few investigations of bubbly two-phase flows have used X-hot-film probes for the measurement of the turbulence field in the continuous phase. Therefore the interactions between the sensors of the X probe and the bubbles are not well known and thus can lead to errors in the determination of turbulence parameters. To gain understanding of the interaction, investigations of static and dynamic bubble-sensor interactions were carried out. In the static investigations a probe that is moved through stagnant water interacts with a bubble that is fixed to a small nozzle. These experiments help us to understand signals for situations in which the liquid and the bubble move with the same speed. In this case, the so-called post-signal occurring at the exit of the sensor penetration through the bubble is caused by the deformation of the bubble surface by the sensor and its prongs rather than by the flow field. In the dynamic investigations the probe is fixed in a vertical flow and it interacts with single bubbles of a bubble stream, as is the case in any two-phase flow situation. A bubble-probe interaction map is proposed that classifies the behaviour into four different modes of interaction. In both series of measurements, various parameters characterizing bubble signals were determined. A synchronized video system is used for visual investigations of deformations of the bubble surface. The results will be used for the future development of a so-called bubble elimination algorithm that is used for filtering the bubble signals out of the two-phase signal.

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Real-Time Measurement of Two-Phase Flow Turbulence Using a Dual-Sensor Anemometry

Cited by 16 publications

References 9 publications

Measurement of interstitial velocity of homogeneous bubbly flows at low to moderate void fraction

Measurement of interstitial velocity of homogeneous bubbly flows at low to moderate void fraction

The effect of bubbles on developed turbulence

Investigations of static and dynamic interactions between bubbles and X-hot-film probes

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