Propagation of Premixed Flame Kernels in High Speed Channel Flows with Moderate Turbulence

2015 ◽  
Author(s):  
Nathan R. Grady ◽  
Robert W. Pitz ◽  
Suresh Menon ◽  
Bradley A. Ochs ◽  
David E. Scarborough ◽  
...  
Keyword(s):  
High Speed ◽  
Channel Flows ◽  
Premixed Flame

scholarly journals Flow Structures of the Air-Water Layer in the Free Surface Region of High-Speed Open Channel Flows

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Feng Jiang ◽  
Weilin Xu ◽  
Jun Deng ◽  
Wangru Wei
Keyword(s):  
Free Surface ◽  
Layer Thickness ◽  
High Speed ◽  
Open Channel ◽  
Water Layer ◽  
Channel Flows ◽  
Flow Structures ◽  
Air Velocity ◽  
Open Channel Flows ◽  
The Relationship

In hydraulic engineering, intense free surface breakups have been observed to develop in high-speed open channel flows, resulting in a mixed air-water layer near the free surface that grows with the development of self-aeration. This region is characterized by a substantial number of droplets coexisting with an induced air layer above. Little information about this droplet layer is currently available and no practicable approach has been proposed for predicting the parameters of the induced air layer based on the related flow structures in the droplet layer. In this research, laboratory experiments were accordingly conducted to observe the detailed droplet layer development in terms of layer thickness, droplet size, and frequency distributions under comparative flow conditions. Based on the simplified droplet layer roughness determined using the experimentally measured mean droplet size, the classical power-law of boundary layer theory was applied to provide an analytical solution for the air velocity profile inside the air layer. The relationship of air layer growth to droplet layer thickness, which is a key factor when determining the air velocity distribution, was also established, and the analytical results were proven to be in reasonable agreement with air velocity profiles presented in the literature. By determining the relationship between droplet layer properties and air velocity profiles, the study establishes a basis for the improved modeling of high-speed open channel flows.

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

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

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

scholarly journals Effect of finite Weissenberg number on turbulent channel flows of an elastoviscoplastic fluid

2021 ◽  
Vol 927 ◽  
Author(s):  
Daulet Izbassarov ◽  
Marco E. Rosti ◽  
Luca Brandt ◽  
Outi Tammisola
Keyword(s):  
Drag Reduction ◽  
High Speed ◽  
Weissenberg Number ◽  
Channel Flows ◽  
Viscoplastic Flow ◽  
Turbulent Structures ◽  
Turbulent Dissipation ◽  
Flow Equations ◽  
Turbulent Channel Flows ◽  
Nonlinear Elastic

Direct numerical simulations are carried out to study the effect of finite Weissenberg number up to $Wi=16$ on laminar and turbulent channel flows of an elastoviscoplastic (EVP) fluid, at a fixed bulk Reynolds number of $2800$ . The incompressible flow equations are coupled with the evolution equation for the EVP stress tensor by a modified Saramito model that extends both the Bingham viscoplastic and the finite extensible nonlinear elastic-Peterlin (FENE-P) viscoelastic models. In turbulent flow, we find that drag decreases with both the Bingham and Weissenberg numbers, until the flow laminarises at high enough elastic and yield stresses. Hence, a higher drag reduction is achieved than in the viscoelastic flow at the same Weissenberg number. The drag reduction persists at Bingham numbers up to 20, in contrast to viscoplastic flow, where the drag increases in the laminar regime compared with a Newtonian flow. Moreover, elasticity affects the laminarisation of an EVP flow in a non-monotonic fashion, delaying it at lower and promoting it at higher Weissenberg numbers. A hibernation phenomenon is observed in the EVP flow, leading to large changes in the unyielded regions. Finally, plasticity is observed to affect both low- and high-speed streaks equally, attenuating the turbulent dissipation and the fragmentation of turbulent structures.

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

Frictional drag reduction promoted by generating void waves in high-speed turbulent channel flows

2019 ◽  
Vol 2019.24 (0) ◽  
pp. A122
Author(s):  
Taiji TANAKA ◽  
Hyun Jin PARK ◽  
Yuji TASAKA ◽  
Yuichi MURAI ◽  
Chiharu KAWAKITA
Keyword(s):  
Drag Reduction ◽  
High Speed ◽  
Channel Flows ◽  
Frictional Drag ◽  
Turbulent Channel Flows

Repetitive bubble injection promoting frictional drag reduction in high-speed horizontal turbulent channel flows

2021 ◽  
Vol 239 ◽  
pp. 109909
Author(s):  
Taiji Tanaka ◽  
Yoshihiko Oishi ◽  
Hyun Jin Park ◽  
Yuji Tasaka ◽  
Yuichi Murai ◽  
...  
Keyword(s):  
Drag Reduction ◽  
High Speed ◽  
Channel Flows ◽  
Frictional Drag ◽  
Turbulent Channel Flows
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