Premixed flame propagating into a narrow channel at a high speed, part 1: Flame behaviors in the channel

1985 ◽  
Vol 60 (3) ◽  
pp. 245-255 ◽  
Author(s):  
Norimasa Iida ◽  
Osamu Kawaguchi ◽  
G.Takeshi Sato
Keyword(s):  
High Speed ◽  
Narrow Channel ◽  
Premixed Flame

Effects of Curved Section on Gas-Liquid Two-Phase Flow in Milli-Channel

2013 ◽  
Author(s):  
Kazuki Takeda ◽  
Shinpei Okamoto ◽  
Kenji Yoshida ◽  
Isao Kataoka
Keyword(s):  
Pressure Loss ◽  
High Speed ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Narrow Channel ◽  
Phase Flow ◽  
Straight Section ◽  
Industrial Products ◽  
Two Phase ◽  
Curved Section

In recent years, we can easily find the gas-liquid two-phase flow in narrow channel which has straight section and curved section in many industrial products. In order to improve the performance of these industrial products, it is important to clarify the effects of curved section on gas-liquid two-phase flow behavior in narrow channel. In this study, we have measured the pressure loss precisely on straight section and curved section in milli-channel respectively. From the measured pressure loss, we evaluated the mean pressure loss and its intensity. Flow visualization by using high-speed video camera was additionally performed to make clear the relation between modification of pressure loss and flow pattern in curved section. As a result, effects of curved section on gas-liquid two-phase flow in narrow channel were evaluated.

High-Speed 4D Flame-Flow Measurements of a Bluff-Body Stabilized Premixed Flame

2020 ◽  
Author(s):  
Jonathan Reyes ◽  
Kareem A. Ahmed ◽  
Brynmor Davis ◽  
Darin A. Knaus ◽  
Daniel Micka
Keyword(s):  
High Speed ◽  
Bluff Body ◽  
Premixed Flame ◽  
Flow Measurements

Taylor dispersion and thermal expansion effects on flame propagation in a narrow channel

2014 ◽  
Vol 754 ◽  
pp. 161-183 ◽  
Author(s):  
P. Pearce ◽  
J. Daou
Keyword(s):  
Activation Energy ◽  
Thermal Expansion ◽  
Peclet Number ◽  
Propagation Speed ◽  
Narrow Channel ◽  
Variable Density ◽  
Taylor Dispersion ◽  
Premixed Flame ◽  
Asymptotic Results ◽  
Péclet Number

AbstractWe investigate the propagation of a premixed flame subject to thermal expansion through a narrow channel against a Poiseuille flow of large amplitude. This is the first study to consider the effect of a large-amplitude flow, characterised by a Péclet number of order one, $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\mathit{Pe}=O(1)$, on a variable-density premixed flame in the asymptotic limit of a narrow channel. It is also the first study on Taylor dispersion in the context of combustion. The relationship between the propagation speed and Péclet number is investigated, with the effect of large flame-front thickness $\epsilon $ and activation energy $\beta $ studied asymptotically in an appropriate distinguished limit. The premixed flame for $\epsilon \to \infty $, with $\mathit{Pe}=O(1)$, is found to be governed by the equation for a planar premixed flame with an effective diffusion coefficient. In this case the premixed flame can be considered to be in the Taylor regime of enhanced dispersion due to a parallel flow. The infinite activation energy limit $\beta \to \infty $ is taken to provide an analytical description of the propagation speed. Corresponding results are obtained for a premixed flame in the constant-density approximation. The asymptotic results are compared to numerical results obtained for selected values of $\epsilon $ and $\beta $ and for moderately large values of the Péclet number. Physical reasons for the differences in propagation speed between constant- and variable-density flames are discussed. Finally, the asymptotic results are shown to agree with those of previous studies performed in the limit $\mathit{Pe}\to 0$.

Experimental Investigation on the Effect of Bubble Behavior on Flow Boiling Pressure Drop in Narrow Channel

2012 ◽  
Author(s):  
Deqi Chen ◽  
Ren Song ◽  
Liang-ming Pan
Keyword(s):  
Experimental Investigation ◽  
Pressure Drop ◽  
Void Fraction ◽  
High Speed ◽  
Channel Wall ◽  
Flow Boiling ◽  
Narrow Channel ◽  
High Speed Camera ◽  
Bubble Behavior ◽  
Channel Dimension

Bubble behavior in narrow channel can be quite different with that in conventional channel. When the bubble reaches a size which is comparable with the channel dimension, the bubble is confined by the channel wall. This influences the bubble evolution significantly in the narrow channel. Then the characteristics of pressure drop in the narrow channel is affected significantly. In order to investigate the effect of bubble behavior on flow boiling pressure drop, a visual study was carried out with a high speed camera (5,000 frame per second was used) to record the bubble behavior. It is found that the OSV (Onset of Significant Vapor) emerges much earlier in narrow channel when comparing with that in conventional channel. A revised correlation for prediction of the real void fraction is proposed based on the experimental investigation. It is also found that the bubble behavior affects the pressure drop in narrow channel significantly, and the channel will be blocked easily when the confined vapor cluster appears. The pressure drop, however, dose not increase linearly with increasing void fraction, and the minimum pressure drop occurs with 60% void fraction. With increasing void fraction, the bubble behavior is more intense and turbulent, which induces more severe fluctuation in pressure drop.

scholarly journals Particle pair dispersion and eddy diffusivity in a high-speed premixed flame

2020 ◽  
Author(s):  
Ryan Darragh ◽  
Colin A.Z. Towery ◽  
Alexei Y. Poludnenko ◽  
Peter E. Hamlington
Keyword(s):  
High Speed ◽  
Eddy Diffusivity ◽  
Premixed Flame ◽  
Particle Pair

Premixed flame ignition in high-speed flows over a backward facing step

2021 ◽  
Vol 229 ◽  
pp. 111398
Author(s):  
Paul Pouech ◽  
Florent Duchaine ◽  
Thierry Poinsot
Keyword(s):  
High Speed ◽  
Premixed Flame ◽  
Backward Facing Step ◽  
Flame Ignition ◽  
High Speed Flows

219 High-Speed and Magnifying Observations of Burning Processes of Micro PET Particles Frying Trough a Two-Dimensional Premixed Flame

2006 ◽  
Vol 2006.16 (0) ◽  
pp. 200-203
Author(s):  
Takanori TOMATSU ◽  
Yuki KATO ◽  
Ryuji YAMAKITA ◽  
Yojiro ISHINO ◽  
Norio OHIWA
Keyword(s):  
High Speed ◽  
Premixed Flame ◽  
Two Dimensional

The Design of Nuclear Noise Frequency Spectrum Analysis System and Helium Bubble Movement Behavior Computation for Narrow Channel Core

2018 ◽  
Author(s):  
Herong Zeng ◽  
Baoxin Yuan
Keyword(s):  
Frequency Spectrum ◽  
High Speed ◽  
Research Work ◽  
Reactor Core ◽  
Narrow Channel ◽  
Movement Behavior ◽  
Waveform Generator ◽  
Helium Bubble ◽  
Noise Frequency ◽  
Analysis System

This paper designs a measure and analysis system of nuclear noise frequency spectrum for narrow channel research reactor core. Based on high-speed synchronization DAQ which is PXI-1031, the hardware design has been carried out. By using Labview, the data acquisition and analysis code has been developed. In order to verify the function of nuclear noise frequency spectrum measure and analysis system, firstly, through using arbitrary waveform generator which is Fluke-282, two sine signals have been tested. Secondly, by using history operation datum, the prompt neutron decay constant has been measured and analyzed. The simulation experimental and operational datum results show that such measure and analysis system of nuclear noise frequency spectrum is successful and reliable design, which can meet the design requirements. Finally, the preliminary research work between helium bubble and its responding frequency for narrow channel core has just started to monitor safety operation or carry out fault diagnosis.

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