scholarly journals Transient Ignition of Premixed Methane/Air Mixtures by a Pre-chamber Hot Jet: a DNS Study

2021 ◽  
Author(s):  
Cheng Chi ◽  
Abouelmagd Abdelsamie ◽  
Dominique Thévenin
Keyword(s):  
Jet Flow ◽  
Turbulent Jet ◽  
Characteristic Time Scale ◽  
Ignition Process ◽  
Main Chamber ◽  
Physicochemical Interactions ◽  
Flame Development ◽  
Turbulent Jet Flow ◽  
Ignition Threshold ◽  
Local Enrichment

AbstractThe present study investigates the transient processes controlling ignition by a hot jet issued from a pre-chamber. Direct numerical simulations (DNS) have been performed to study the characteristics of the turbulent jet flow and of the associated flame during the whole ignition process, quantifying the relevant physicochemical interactions between pre-chamber and main chamber. Thanks to a detailed analysis of the DNS results, the transient ignition is found to consist of three main sequential processes: (1) near-orifice local ignition in the main chamber; (2) further flame development supported by the jet flow; and (3) global ignition and propagation of a self-sustained flame in the main chamber, independently from the hot jet. The characteristic time-scale of the hot jet as well as jet-induced effects (local enrichment, supply of radicals and heat) are found to be essential for successful ignition in the main chamber. A more intense turbulence in the main chamber appears to support local ignition. However, it also induces local quenching, thus delaying global ignition. An ignition threshold based on a critical Damköhler number is a promising concept, but is not sufficient to describe the process in all its complexity.

scholarly journals The Turbulent Jet from a Series of Holes in Line

1964 ◽  
Vol 15 (1) ◽  
pp. 1-28 ◽  
Author(s):  
R. Knystautas
Keyword(s):  
Jet Flow ◽  
Turbulent Jet ◽  
Two Dimensional ◽  
Turbulent Jet Flow ◽  
Similar Density

SummaryThe possibility of obtaining two-dimensional turbulent jet flow from a series of closely-spaced uniform holes in line has been investigated both theoretically and experimentally. The case studied was that of a jet discharging into still fluid of similar density at incompressible speeds. Such a quasi-two-dimensional jet is a particular example of a multiple-interfering jet group.

scholarly journals A theoretical model of a wake of a body towed in a stratified fluid at large Reynolds and Froude numbers

2006 ◽  
Vol 13 (3) ◽  
pp. 247-253 ◽  
Author(s):  
Y. I. Troitskaya ◽  
O. A. Druzhinin ◽  
D. A. Sergeev ◽  
V. V. Papko ◽  
G. N. Balandina
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Momentum Transfer ◽  
Hydrodynamic Instability ◽  
Jet Flow ◽  
Stratified Fluid ◽  
Turbulent Jet ◽  
Wake Flow ◽  
Mean Flow ◽  
Turbulent Jet Flow

Abstract. The objective of the present paper is to develop a theoretical model describing the evolution of a turbulent wake behind a towed sphere in a stably stratified fluid at large Froude and Reynolds numbers. The wake flow is considered as a quasi two-dimensional (2-D) turbulent jet flow whose dynamics is governed by the momentum transfer from the mean flow to a quasi-2-D sinuous mode growing due to hydrodynamic instability. The model employs a quasi-linear approximation to describe this momentum transfer. The model scaling coefficients are defined with the use of available experimental data, and the performance of the model is verified by comparison with the results of a direct numerical simulation of a 2-D turbulent jet flow. The model prediction for the temporal development of the wake axis mean velocity is found to be in good agreement with the experimental data obtained by Spedding (1997).

Analysis of Coupled CFD-DEM Simulations in Dense Particle-Laden Turbulent Jet Flow

2020 ◽  
Author(s):  
Dustin Weaver ◽  
Sanja Miskovic
Keyword(s):  
Experimental Data ◽  
Particle Flux ◽  
Axial Direction ◽  
Jet Flow ◽  
Turbulent Jet ◽  
Sufficient Information ◽  
Dense Particle ◽  
Dem Simulations ◽  
Mesh Resolution ◽  
Turbulent Jet Flow

Abstract In this paper, coupled CFD-DEM simulations of dense particle-laden jet flow are performed using CFDEM® coupling interface that couples LAMMPS-based LIGGGHTS® DEM engine with OpenFOAM CFD framework. Suspensions of mono-sized spherical glass particles with 80 microns diameter and a mass loading of 0.23 and 0.86 are considered. Three different CFD meshes are used with an average mesh resolution dimension of 3.06, 2.67, and 1.86 particle diameters and it is determined that mesh resolution does not change results for void fraction calculation (using the divided model) of the CFD-DEM equations. Samples of particle flux are taken at 0.1, 10, and 20 nozzle diameters along the axial direction of the jet region. The numerical results for particle flux are compared with a well cited experimental data found in literature. The CFD-DEM simulations in turbulent jet flow are found to be highly sensitive to initial particle velocity inputs but the experimental data provide sufficient information to produce comparable results.

Dissipation element analysis of scalar field in turbulent jet flow

2012 ◽  
Vol 37 ◽  
pp. 57-64 ◽  
Author(s):  
A.M. Soliman ◽  
Mohy S. Mansour ◽  
Norbert Peters ◽  
Mohamed H. Morsy
Keyword(s):  
Scalar Field ◽  
Jet Flow ◽  
Turbulent Jet ◽  
Element Analysis ◽  
Turbulent Jet Flow
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