Numerical Simulation of Turbulence-Chemical Interaction Models on Combustible Particle MILD Combustion

2014 ◽  
Vol 1070-1072 ◽  
pp. 1752-1757
Author(s):  
Bin Xian Shen ◽  
Wei Qiang Liu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Chemical Interaction ◽  
Fluid Dynamic ◽  
Mixture Fraction ◽  
Equilibrium Mixture ◽  
Interaction Models ◽  
Concept Model ◽  
Mild Combustion ◽  
Kinetic Mechanisms

Typical combustible particle coal has been analyzed by using turbulence-chemistry interaction models to realize which models are more accurate and reasonable on pulverized coal MILD combustion. Three turbulence-chemistry interaction models are examined: the Equilibrium Mixture Fraction/PDF (PDF), the Eddy Break Up (EBU), the Eddy Dissipation Concept (EDC). All of three models can give a suitable prediction of axial velocity on combustible particle coal MILD combustion because turbulence-chemistry interaction models have little influence on flow field and flow structure. The Eddy Dissipation Concept model (EDC), based on advanced turbulence-chemistry interaction with global and detailed kinetic mechanisms can produce satisfactory results on chemical and fluid dynamic behavior of combustible particle coal MILD combustion, especially on temperature and species concentrations.

Numerical Simulation of Flow Field Characteristics of Free Falling Particle Plume Affected by Particle Diameter and Density

2014 ◽  
Vol 894 ◽  
pp. 163-166 ◽  
Author(s):  
Ze Qin Liu ◽  
Ling Yu Liu ◽  
Xiao Jian Li
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Particle Density ◽  
Fluid Dynamic ◽  
Particle Diameter ◽  
Ambient Air ◽  
Two Phase ◽  
Flow Field Characteristics ◽  
Computational Fluid Dynamic Software ◽  
Free Falling

The study of flow field characteristics of free falling particle plume is part of the basic application research of gas-solid two phase flow. The Computational Fluid Dynamic Software FLUENT was adopted in this paper. The numerical simulation was carried out to study the influence of particle diameter and particle density to the particle flow field characteristics of free falling particle plume. The results of the numerical simulation showed that, with the increasing of particle diameter and the increasing of particle density, the disturbance of ambient air to the particle plume decreased, and the entrainment ability of particle plume to the ambient air was diminished.

Ignition, lift-off, and soot formation studies in n-dodecane split injection spray-flames

2017 ◽  
Vol 18 (10) ◽  
pp. 1077-1087 ◽  
Author(s):  
Ahmed Abdul Moiz ◽  
Khanh D Cung ◽  
Seong-Young Lee
Keyword(s):  
Numerical Simulation ◽  
Computational Fluid Dynamic ◽  
Soot Formation ◽  
Fluid Dynamic ◽  
Mixture Fraction ◽  
Air Entrainment ◽  
Flame Stabilization ◽  
Propagation Mechanism ◽  
Constant Density ◽  
Lift Off

A close-coupled double injection strategy with two 0.5-ms injections separated by a 0.5-ms dwell is implemented. Studies are performed in a constant volume pre-burn type combustion vessel over two ambient temperatures (900 and 800 K) at constant density (22.8 kg/m3) with 15% O2 by volume in the ambient. The aim of this work is to investigate the establishment and dependence of ignition delay and flame stabilization on the ambient temperature conditions especially for the main injection, and thereby investigating eventual soot production. Simultaneous schlieren and planar laser -induced fluorescence experiments as well as three-dimensional Reynolds-averaged numerical simulation computational fluid dynamic modeling with chemical kinetics in every computational fluid dynamic cell were performed. It was observed experimentally that at 900 K, the second injection is injected in a high-temperature combustion recessed ambient of the first injection whereas at 800 K it is injected in a low temperature, possibly reactive species environment. It was found from Reynolds-averaged numerical simulation modeling that combustion recession at 900 K in the present case entails rich presence of hydroxyl radical species and also the ambient of 800 K is source of reactive radicals like peroxides, leading to acceleration of main ignition. Flame stabilization of the second injection occurs closer to the injector due to short ignition delays with flame being sustained in the fuel–air premixing zone. Flame stabilization of the second injection was found to follow a premixed flame propagation mechanism. Investigation in mixture fraction and temperature space of pilot-main spray combustion revealed that the lower lift-off of main results in lower air-entrainment which causes richer ignition of main resulting in quicker and higher soot formation. The effect of the second injection in enhancing the oxidation of soot from the first injection by inducing enhanced mixing was also revealed.

scholarly journals Numerical Simulation of Characteristics of Spray Flow Field on the Conical Surface

2020 ◽  
Vol 1670 ◽  
pp. 012030
Author(s):  
Shiming Chen ◽  
GuichunYang ◽  
Shuang Zhou ◽  
Wenzhuo Chen ◽  
Jinfa Guan ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Conical Surface

scholarly journals Coupled Fluid–Solid Numerical Simulation for Flow Field Characteristics and Supporting Performance of Flexible Support Cylindrical Gas Film Seal

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 97
Author(s):  
Junfeng Sun ◽  
Meihong Liu ◽  
Zhen Xu ◽  
Taohong Liao ◽  
Xiangping Hu ◽  
...  
Keyword(s):  
Flow Field ◽  
Film Thickness ◽  
Fluid Dynamic ◽  
Structural Characteristics ◽  
Structural Parameters ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
High Rotational Speed ◽  
Flexible Support ◽  
Flow Field Characteristics

A new type of cylindrical gas film seal (CGFS) with a flexible support is proposed according to the working characteristics of the fluid dynamic seal in high-rotational-speed fluid machinery, such as aero-engines and centrifuges. Compared with the CGFS without a flexible support, the CGFS with flexible support presents stronger radial floating characteristics since it absorbs vibration and reduces thermal deformation of the rotor system. Combined with the structural characteristics of a film seal, an analytical model of CGFS with a flexible wave foil is established. Based on the fluid-structure coupling analysis method, the three-dimensional flow field of a straight-groove CGFS model is simulated to study the effects of operating and structural parameters on the steady-state characteristics and the effects of gas film thickness, eccentricity, and the number of wave foils on the equivalent stress of the flexible support. Simulation results show that the film stiffness increases significantly when the depth of groove increases. When the gas film thickness increases, the average equivalent stress of the flexible support first decreases and then stabilizes. Furthermore, the number of wave foils affects the average foils thickness. Therefore, when selecting the number of wave foils, the support stiffness and buffer capacity should be considered simultaneously.

scholarly journals Influence of Vortex Finder Structure on Separation Performance of Double-Overflow Three-Product Hydrocyclones

Separations ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 79
Author(s):  
Yuekan Zhang ◽  
Jiangbo Ge ◽  
Lanyue Jiang ◽  
Hui Wang ◽  
Junru Yang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Experimental Research ◽  
Separation Efficiency ◽  
Structural Parameters ◽  
Separation Performance ◽  
Insertion Depth ◽  
Flow Field Characteristics ◽  
Vortex Finder ◽  
Fine Classification

In view of the difficulty of traditional hydrocyclones to meet the requirements of fine classification, a double-overflow three-product (internal overflow, external overflow and underflow) hydrocyclone was designed in this study. Numerical simulation and experimental research methods were used to investigate the effects of double-overflow flow field characteristics and structural parameters (i.e., internal vortex finder diameter and insertion depth) on separation performance. The research results showed that the larger the diameter of the internal vortex finder, the greater the overflow yield and the larger the cut size. The finest internal overflow product can be obtained when the internal vortex finder is 30 mm longer than the external vortex finder. The separation efficiency is highest when the internal vortex finder is 30 mm shorter than the external vortex finder.

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