Numerical Study of Combustion in a Porous Medium With Liquid Fuel Injection

2017 ◽  
Author(s):  
Arash Mohammadi ◽  
Mona Benhari ◽  
Mehrdad Nouri Khajavi
Keyword(s):  
Porous Medium ◽  
Free Volume ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Soot Formation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Nitrogen Monoxide ◽  
Maximum Pressure ◽  
Fluid Temperature

Porous medium (PM) has potential advantage to enhance evaporation of droplets in liquid-fuel burners, low emissions and minimize instabilities of combustion. This paper represents the numerical study of liquid-fuel injection, evaporation, and combustion inside constant-volume chemically inert PM. It stabilizes lean combustion and decreases emissions. Three-dimensional numerical results were obtained based on a modified KIVA-3V code. Diesel fuel is directly injected into chamber for two cases, free volume and PM reactor. With high initial temperature, fast evaporation and self-ignited occur. The results for specified conditions were compared with experimental data in literature. Effects of injection on mixture formation was investigated. Distribution of diesel vapor, fluid and solid temperature of PM in a cutting plane, were shown. Diagram of diesel vapor, CO, NO, Soot, solid and fluid temperature versus time for different mass of injected fuel, were presented. Also, results of diesel vapor, pressure and temperature in free volume and PM reactor have compared. The results show considerable reduction in maximum pressure and temperature, carbon monoxide, nitrogen monoxide and soot formation in PM reactor in comparison with free volume.

Simulation of Combustion in a Porous Reactor

2014 ◽  
Author(s):  
Arash Mohammadi ◽  
Mona Benhari
Keyword(s):  
Diesel Engines ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Numerical Study ◽  
Direct Injection ◽  
Nitrogen Monoxide ◽  
High Porosity ◽  
Lean Mixture ◽  
Cold Condition ◽  
Reduce Emissions

Development of IC engines with low emissions and low fuel consumption causes interest in direct injection engine, especially diesel engines that work with lean mixture. This goal may be achieved with separation of mixture formation and combustion processes, in diesel engines. A practicable way to reach this target is the use of porous medium (PM) inside the combustion chamber. The PM has benefits to enhance the evaporation of droplets in liquid-fuel burners, reduce emissions and minimize instabilities. This paper represents the numerical study of liquid-fuel injection and combustion inside constant-volume chemically inert PM to stabilize lean mixture. 3D numerical results have obtained based on a modified version of KIVA-3V code. Diesel was directly sprayed inside hot and high pressure PM chamber. Complete evaporation and self-ignited was achieved due to the initial temperature of PM. The results in an especial condition have compared with an experimental data in the literature. Effect of injection in cold condition has investigated. Contours of diesel vapor, fluid and solid temperature of PM in a cross section, have shown. Also, effects of pore density on a constant high-porosity PM and mass of spray fuel were studied. The results show considerable reduction in carbon monoxide, nitrogen monoxide and elimination of soot.

Arc Behavior Numerical Analysis in GMAW Welding Deposition-Based Rapid Forming

2014 ◽  
Vol 488-489 ◽  
pp. 285-288
Author(s):  
Feng Liang Yin ◽  
Sheng Zhu ◽  
Hong Wei Liu ◽  
Lei Guo
Keyword(s):  
Heat Flux ◽  
Fluid Flow ◽  
Weld Pool ◽  
Numerical Study ◽  
Three Dimensional ◽  
Radial Distance ◽  
Maximum Pressure ◽  
Forming Process ◽  
Arc Behavior ◽  
Gmaw Welding

Metal fluid flow in weld pool would influence final quality of forming part in GMAW welding deposition-based rapid forming process. To numerical study fluid flow in weld pool, heat and force effects on weld pool surface must been made clear firstly. A three-dimensional numerical model has been built to study arc behavior in GMAW welding deposition-based rapid forming process. Solving the model, heat flux and pressure distributions on the cathode were derived. Calculated results show that heat flux from the arc to the cathode is related to arc temperature nearly above the cathode, and is not monotonous about radial distance within 2 mm distance away from arc axis. A maximum pressure with a value of 800 Pa happens at 1mm away from arc axis.

scholarly journals Numerical Study of Natural Convection Heat Loss from Cylindrical Solar Cavity Receivers

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
M. Prakash
Keyword(s):  
Natural Convection ◽  
Cylindrical Cavity ◽  
Numerical Study ◽  
Three Dimensional ◽  
Working Fluid ◽  
Helical Coil ◽  
Fluid Temperature ◽  
Medium Temperature ◽  
Inclination Angles ◽  
Temperature Levels

The numerical study of the natural convection loss occurring from cylindrical solar cavity receivers is reported in this communication. These cavity receivers can be used with solar dish concentrators for process heat applications at medium temperature levels. Three cylindrical cavity receivers of diameter 0.2, 0.3, and 0.4 m with aspect ratio equal to one and opening ratios of 1 and 0.5 are used for the analysis. Fluent CFD software is used for the analysis of the three-dimensional (3D) receiver models. In this study the receiver tubes within the cylindrical cavity are modeled as a helical coil similar to those existing in actual systems. The flow of the working fluid within the helical coil is also modeled. The simulations are performed for fluid inlet temperatures of 150°C and 250°C and for receiver inclination angles of 0 (sideways-facing cavity), 30, 45, 60, and 90 degree (vertically downward-facing receiver). It is found that the convective loss increases with increasing mean fluid temperature and decreases with, increase in receiver inclination. The convective loss is found to increase with, opening ratio. These observations are true for all cavity receivers analysed here. A Nusselt number correlation involving Rayleigh numbers, receiver inclinations, and opening ratios is proposed for the convective loss.

scholarly journals Numerical study of the effects of natural convection in a thermoacoustic configuration

2019 ◽  
Vol 20 (8) ◽  
pp. 807
Author(s):  
Omar Hireche ◽  
Catherine Weisman ◽  
Diana Baltean-Carlès ◽  
Virginie Daru ◽  
Yann Fraigneau
Keyword(s):  
Porous Medium ◽  
Natural Convection ◽  
Numerical Study ◽  
Three Dimensional ◽  
Boussinesq Approximation ◽  
Acoustic Resonator ◽  
Operating Conditions ◽  
Temperature Fields ◽  
Convection Flow ◽  
Conductivity Anisotropy

This study focuses on natural convection flows within a cylindrical guide containing a porous medium. This configuration is applicable to standing-wave thermoacoustic engines, usually composed of an acoustic resonator where a (short) stack (or porous medium) is inserted, with a heat exchanger placed at one of its ends. The resulting horizontal temperature gradient, when high enough, triggers the onset of an acoustic wave. Natural convection effects are usually neglected in thermoacoustics so that axisymmetry is often assumed. Here a 3D numerical study of natural convection flow is performed using a finite volume code for solving mixed Navier-Stokes and Darcy-Brinkman equations under Boussinesq approximation. The influence of the porous medium’s physical characteristics (permeability, thermal conductivity, anisotropy) on the flow and temperature fields is investigated. It is shown that such flows are fully three-dimensional and therefore can modify significantly starting as well as steady operating conditions of the thermoacoustic engine.

Three-Dimensional Double Diffusion Mixed Convection in Rectangular Channel Filled with Porous Medium

2010 ◽  
Vol 297-301 ◽  
pp. 1010-1015 ◽  
Author(s):  
Omar Rahli ◽  
Rachid Bennacer ◽  
K. Bouhadef ◽  
Djamel Eddine Ameziani ◽  
Elhem Ghorbel
Keyword(s):  
Porous Medium ◽  
Mixed Convection ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Three Dimensional ◽  
Double Diffusion ◽  
Porous Region ◽  
Rectangular Channels ◽  
Porous Block ◽  
Rayleigh Benard

This paper presents a numerical study of mixed convection heat and mass transfer in horizontal rectangular channels partially filled with porous medium. The main contribution of this research is to characterize how the porous block will create a heterogeneity that will induce a change on the Poiseuille-Rayleigh-Benard (PRB) fluid circulation dynamics. For a broad range of dimensionless parameters, which control the mixed convection, we show that the effect of the insertion of the porous block changes the thermal and solutal boundary layers; we find that the exchanges are intensified near the sidewalls in the porous region compared to upstream and downstream of the porous medium; and inversely in the core region. We describe, also, the onset of the longitudinal rolls at both upstream and downstream of the porous region. And finally, we compared the heat transfer, for different positioning of the porous medium with the purely fluid mixed convection.

A Numerical Study of the Effect of Injection Velocity on Fuel Droplets Sizing in a Three-Dimensional Side-Dump Combustor

2011 ◽  
Vol 52-54 ◽  
pp. 2045-2050 ◽  
Author(s):  
Mohammad Mahdi Doustdar ◽  
Mohammad Mojtahedpoor
Keyword(s):  
Mass Fraction ◽  
Fuel Injection ◽  
Numerical Study ◽  
Air Flow ◽  
Three Dimensional ◽  
Injection Velocity ◽  
Fuel Vapor ◽  
Design Work ◽  
Fuel Droplets ◽  
Dump Combustor

The effects of injection velocity on propulsive droplets sizing and efficient mass fraction in a three dimensional side-dump combustor with dual opposite curved side-inlet duct are numerically investigated in the present paper. The mass of fuel vapor inside the flammability limit is named efficient mass fraction. The air flow comes from side-inlet ducts into the cylindrical combustor and four nozzles which are located in the top of the cylinder have the duties of fuel injection. The injection velocity is varied as 20, 40, 60 and 80 [m/s] respectively to examine its effects on propulsive droplets sizing and efficient mass fraction which provides worthwhile information for the combustor design work. As well, by increasing entrance air flow velocity from 35 to 100 and 280[m/s] correspondingly, these computations are repeated. To fulfill the calculations a modified version of KIVA-3V code which is a transient, three-dimensional, multiphase, multicomponent code for the analysis of chemically reacting flows with sprays, is used.

scholarly journals Numerical study on effects of chamber design and multi-inlet on storm geyser

2021 ◽  
Vol 83 (6) ◽  
pp. 1286-1299
Author(s):  
Jiachun Liu ◽  
Shuangqing Zhang ◽  
Biao Huang ◽  
David Z. Zhu
Keyword(s):  
Peak Pressure ◽  
Numerical Study ◽  
Three Dimensional ◽  
Mitigation Measures ◽  
Maximum Pressure ◽  
Rapid Urbanization ◽  
Inflow Condition ◽  
Entrapped Air ◽  
Mitigation Methods ◽  
Dynamics Models

Abstract Storm geysers increasingly occur in sewer systems under climate change and rapid urbanization. Mitigation measures are in great demand to avoid safety problems. In this study, three-dimensional computational fluid dynamics models of single-inlet and multi-inlet systems were established to investigate geysering induced by rapid filling and assess the effectiveness of potential mitigation methods. The modeling results suggest that increasing the capacity of the downstream pipe before the inflow front reaches the chamber can effectively reduce the maximum geyser pressure. The peak pressure can be significantly mitigated when the chamber size is designed with care and the drop height between the upstream and downstream pipes is reduced. A diversion deflector with air vents and an orifice plate at the riser top end can alleviate the maximum pressure by about 65% with about 75% of the entrapped air being released. The peak pressure during the geyser event in the multi-inlet model is less than that of a single-inlet model under the same total inflow condition, but more water can be released.

scholarly journals Numerical Study of Evaporation Modelling for Different Fuels at High Operating Conditions in a Diesel Engine

2021 ◽  
Vol 12 (1) ◽  
pp. 8
Author(s):  
Ali Raza ◽  
Sajjad Miran ◽  
Tayyab Ul Islam ◽  
Kishwat IJaz Malik ◽  
Zunaira-Tu-Zehra ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Numerical Study ◽  
Droplet Diameter ◽  
Operating Conditions ◽  
Injection System ◽  
Diesel Fuels ◽  
Fuel Droplets ◽  
Engine Cylinder

A fuel injection system in a diesel engine has different processes that affect the complete burning of the fuel in the combustion chamber. These include the primary and secondary breakups of liquid fuel droplets and evaporation. In the present paper, evaporation of two different diesel fuels has been modelled numerically. Evaporation of n-heptane and n-decane is governed by the conservation equations of mass, energy, momentum, and species transport. Results have been plotted by varying the droplet diameter and temperature. It was observed that droplet size, temperature of droplets, and ambient temperature have notable effect on the evaporation time of diesel fuel droplets in the engine cylinder.

scholarly journals Numerical Analysis of Thermochemical Nonequilibrium Flows in a Model Scramjet Engine

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 606
Author(s):  
Seoeum Han ◽  
Sangyoon Lee ◽  
Bok Jik Lee
Keyword(s):  
Numerical Simulations ◽  
Test Section ◽  
Thermal Equilibrium ◽  
Fuel Injection ◽  
Numerical Study ◽  
Three Dimensional ◽  
Reservoir Conditions ◽  
Nonequilibrium States ◽  
Computational Fluid Dynamics Cfd ◽  
Inflow Conditions

This numerical study was conducted to investigate the flow properties in a model scramjet configuration of the experiment in the T4 shock tunnel. In most numerical simulations of flows in shock tunnels, the inflow conditions in the test section are determined by assuming the thermal equilibrium of the gas. To define the inflow conditions in the test section, the numerical simulation of the nozzle flow with the given nozzle reservoir conditions from the experiment is conducted by a thermochemical nonequilibrium computational fluid dynamics (CFD) solver. Both two-dimensional (2D) and three-dimensional (3D) numerical simulations of the flow in a model scramjet were conducted without fuel injection. Simulations were performed for two types of inflow conditions: one for thermochemical nonequilibrium states obtained from the present nozzle simulation and the other for the data available using the thermal equilibrium and chemical nonequilibrium assumptions. The four results demonstrate the significance of the modelling approach for choosing between 2D or 3D, and thermal equilibrium or nonequilibrium.

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