Coupling LES with soot model for the study of soot volume fraction in a turbulent diffusion jet flames at various Reynolds number configurations

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohamed Ibrahim N.H. ◽  
M. Udayakumar ◽  
Sivan Suresh ◽  
Suvanjan Bhattacharyya ◽  
Mohsen Sharifpur
Keyword(s):  
Reynolds Number ◽  
Nucleation Rate ◽  
Volume Fraction ◽  
Soot Volume Fraction ◽  
Surface Oxidation ◽  
Surface Growth ◽  
Nitrogen Diffusion ◽  
Coagulation Rate ◽  
Content Type ◽  
Jet Flame

Purpose This study aims to investigate the insights of soot formation such as rate of soot coagulation, rate of soot nucleation, rate of soot surface growth and soot surface oxidation in ethylene/hydrogen/nitrogen diffusion jet flame at standard atmospheric conditions, which is very challenging to capture even with highly sophisticated measuring systems such as Laser Induced Incandescence and Planar laser-induced fluorescence. The study also aims to investigate the volume of soot in the flame using soot volume fraction and to understand the global correlation effect in the formation of soot in ethylene/hydrogen/nitrogen diffusion jet flame. Design/methodology/approach A large eddy simulation (LES) was performed using box filtered subgrid-scale tensor. A filtered and residual component of the governing equations such as continuity, momentum, energy and species are resolved and modeled, respectively. All the filtered and residual components are numerically solved using the ILU method by considering PISO pressure–velocity solver. All the hyperbolic flux uses the QUICK algorithm, and an elliptic flux uses SOU to evaluate face values. In all the cases, Courant–Friedrichs–Lewy (CFL) conditions are maintained unity. Findings The findings are as follows: soot volume fraction (SVF) as a function of a flame-normalized length for three different Reynolds number configurations (Re = 15,000, Re = 8,000 and Re = 5,000) using LES; soot gas phase and particulate phase insights such as rate of soot nucleation, rate of soot coagulation, rate of soot surface growth and soot surface oxidation for three different Reynolds number configurations (Re = 15,000, Re = 8,000 and Re = 5,000); and soot global correction using total soot volume in the flame volume as a function of Reynolds number and Froude number. Originality/value The originality of this study includes the following: coupling LES turbulent model with chemical equilibrium diffusion combustion conjunction with semi-empirical Brookes Moss Hall (BMH) soot model by choosing C6H6 as a soot precursor kinetic pathway; insights of soot formations such as rate of soot nucleation, soot coagulation rate, soot surface growth rate and soot oxidation rate for ethylene/hydrogen/nitrogen co-flow flame; and SVF and its insights study for three inlet fuel port configurations having the three different Reynolds number (Re = 15,000, Re = 8,000 and Re = 5,000).

Impact of Soot Radiative Properties, Pressure and Soot Volume Fraction on Radiative Heat Transfer in Turbulent Sooty Flames

2020 ◽  
Author(s):  
Kevin Torres Monclard ◽  
Olivier Gicquel ◽  
Ronan Vicquelin
Keyword(s):  
Heat Transfer ◽  
Thermal Radiation ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Volume Fraction ◽  
Soot Volume Fraction ◽  
Turbulent Flames ◽  
Radiative Properties ◽  
Jet Flame ◽  
Soot Particles

Abstract The effect of soot radiation modeling, pressure, and level of soot volume fraction are investigated in two ethylene-air turbulent flames: a jet flame at atmospheric pressure studied at Sandia, and a confined pressurized flame studied at DLR. Both cases have previously been computed with large-eddy simulations coupled with thermal radiation. The present study aims at determining and analyzing the thermal radiation field for different models from these numerical results. A Monte-Carlo solver based on the Emission Reciprocity Method is used to solve the radiative transfer equation with detailed gas and soot properties in both configurations. The participating gases properties are described by an accurate narrowband ck model. Emission, absorption, and scattering from soot particles are accounted for. Two formulations of the soot refractive index are considered: a constant value and a wavelength formulation dependency. This is combined with different models for soot radiative properties: gray, Rayleigh theory, Rayleigh-Debye-Gans theory for fractal aggregates. The effects of soot radiative scattering is often neglected since their contribution is expected to be small. This contribution is determined quantitatively in different scenarios, showing great sensitivity to the soot particles morphology. For the same soot volume fraction, scattering from larger aggregates is found to modify the radiative heat transfer noticeably. Such a finding outlines the need for detailed information on soot particles. Finally, the role of soot volume fraction and pressure on radiative interactions between both solid and gaseous phases is investigated.

scholarly journals Effects of Fuel Molecular Weight on Emissions in a Jet Flame and a Model Gas Turbine Combustor

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Anandkumar Makwana ◽  
Suresh Iyer ◽  
Milton Linevsky ◽  
Robert Santoro ◽  
Thomas Litzinger ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Volume Fraction ◽  
Soot Formation ◽  
Premixed Flames ◽  
Soot Volume Fraction ◽  
Spatial Development ◽  
Gas Turbine Combustor ◽  
Jet Flames ◽  
Jet Flame ◽  
Model Gas Turbine Combustor

The objective of this study is to understand the effects of fuel volatility on soot emissions. This effect is investigated in two experimental configurations: a jet flame and a model gas turbine combustor. The jet flame provides information about the effects of fuel on the spatial development of aromatics and soot in an axisymmetric, co-flow, laminar flame. The data from the model gas turbine combustor illustrate the effect of fuel volatility on net soot production under conditions similar to an actual engine at cruise. Two fuels with different boiling points are investigated: n-heptane/n-dodecane mixture and n-hexadecane/n-dodecane mixture. The jet flames are nonpremixed and rich premixed flames in order to have fuel conditions similar to those in the primary zone of an aircraft engine combustor. The results from the jet flames indicate that the peak soot volume fraction produced in the n-hexadecane fuel is slightly higher as compared to the n-heptane fuel for both nonpremixed and premixed flames. Comparison of aromatics and soot volume fraction in nonpremixed and premixed flames shows significant differences in the spatial development of aromatics and soot along the downstream direction. The results from the model combustor indicate that, within experiment uncertainty, the net soot production is similar in both n-heptane and n-hexadecane fuel mixtures. Finally, we draw conclusions about important processes for soot formation in gas turbine combustor and what can be learned from laboratory-scale flames.

scholarly journals Numerical study of heat transfer in 90° bend tube by AI2O3 nano fluids using fluid injection

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hadi Mahdizadeh ◽  
Nor Mariah Adam
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Volume Fraction ◽  
Fluid Injection ◽  
Content Type ◽  
Nano Fluid ◽  
The Impact

Purpose This paper aims to investigate increasing heat transfer in bend tube 90° by fluid injection using nano fluid flow that was performed by expending varying Reynolds number. This paper studies the increased heat transfer in the bent tube that used some parameters to examine the effects of volume fraction, nanoparticle diameter, fluid injection, Reynolds number on heat transfer and flow in a bend pipe. Design/methodology/approach Designing curved tubes increases the thermal conductivity amount between fluid and wall. It is used the finite volume method and simple algorithms to solve the conservation equations of mass, momentum and energy. The results showed that the nanoparticles used in bent tube transfusion increase the heat transfer performance by increasing the volume fraction; it has a direct impact on enhancing the heat transfer coefficient. Findings Heat transfer coefficient enhanced 1.5% when volume fraction increased from 2 % to 6%, the. It is due to the impact of nanoparticles on the thermal conductivity of the fluid. The fluid is injected into the boundary layer flow due to jamming that enhances heat transfer. Curved lines used create a centrifugal force due to the bending and lack of development that increase the heat transfer. Originality/value This study has investigated the effect of injection of water into a 90° bend before and after the bend. Specific objectives are to analyze effect of injection on heat transfer of bend tube and pressure drop, evaluate best performance of mixing injection and bend in different positions and analyze effect of nano fluid volume fraction on injection.

Heat transfer and entropy generation analysis of Cu-water nanofluid in a vertical channel

2018 ◽  
Vol 15 (5) ◽  
pp. 604-613
Author(s):  
Essma Belahmadi ◽  
Rachid Bessaih
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Mixed Convection ◽  
Friction Factor ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Vertical Channel ◽  
Simple Algorithm ◽  
Content Type

Purpose The purpose of this study is to analyze heat transfer and entropy generation of a Cu-water nanofluid in a vertical channel. The channel walls are maintained at a hot temperature Tw. An up flow penetrates the channel at a uniform velocity v0 and a cold temperature T0 (T0 < Tw). The effects of Reynolds number Re, Grashof number Gr and solid volume fraction ϕ on streamlines, isotherms, entropy generation, friction factor, local and mean Nusselt numbers are evaluated. Design/methodology/approach The Cu-water nanofluid is used in this study. The software Ansys-fluent 14.5, based on the finite-volume method and SIMPLE algorithm, is used to simulate the mixed convection problem with entropy generation in a vertical channel. Findings The results show that the increase of Reynolds and Grashof numbers and solid volume fraction improves heat transfer and reduces entropy generation. Correlations for the mean Nusselt number and friction factor in terms of Reynolds number and solid volume fraction are obtained. The present results are compared with those found in the literature, which reveal a very good agreement. Originality/value The originality of this work is to understand the heat transfer and entropy generation for mixed convection of a Cu-water nanofluid in a vertical channel.

Water–copper nanofluid flow in flat and ribbed microchannels: numerical modeling and optimization

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alireza Dibaji ◽  
Seyed Amin Bagherzadeh ◽  
Arash Karimipour
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Slip Velocity ◽  
Volume Fraction ◽  
Optimal Decision ◽  
Function Estimation ◽  
Slip Coefficient ◽  
Parametric Function ◽  
Content Type ◽  
High Reynolds

Purpose This paper aims to simulate the nanofluid forced convection in a microchannel. According to the results, at high Reynolds numbers and higher nanofluid volume fractions, an increase in the rib height and slip coefficient further improved the heat transfer rate. The ribs also affect the flow physics depending on the Reynolds number so that the slip velocity decreases with increasing the nanofluid volume fraction and rib height. Design/methodology/approach Forced heat transfer of the water–copper nanofluid is numerically studied in a two dimensional microchannel. The effects of the slip coefficient, Reynolds number, nanofluid volume fraction and rib height are investigated on the average Nusselt number, slip velocity on the microchannel wall and the performance evaluation criterion. Findings In contrast, the slip velocity increases with increasing the Reynolds number and slip coefficient. Afterwards, a non-parametric function estimation is performed relying on the artificial neural network. Originality/value Finally, the Genetic Algorithm was used to establish a set of optimal decision parameters for the problem

Instability of hydromagnetic Couette flow for hybrid nanofluid through porous media with small suction and injection effects

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Pascalin Tiam Kapen ◽  
Cédric Gervais Njingang Ketchate ◽  
DIdier Fokwa ◽  
Ghislain Tchuen
Keyword(s):  
Magnetic Field ◽  
Reynolds Number ◽  
Porous Media ◽  
Stability Analysis ◽  
Volume Fraction ◽  
Temporal Stability ◽  
Darcy Number ◽  
Hybrid Nanofluid ◽  
Content Type ◽  
The Magnetic Field

Purpose This paper aims to investigate a linear and temporal stability analysis of hybrid nanofluid flow between two parallel plates filled with a porous medium and whose lower plate is fixed and the upper plate animated by a uniform rectilinear motion. Design/methodology/approach The nanofluid is composed of water as a regular fluid, silver (Ag) and alumina (Al2O3) as nanoparticles. The mathematical model takes into account other effects such as the magnetic field and the aspiration (injection/suction). Under the assumption of a low magnetic Reynolds number, a modified Orr–Sommerfeld-type eigenvalue differential equation governing flow stability was derived and solved numerically by Chebyshev’s spectral collocation method. The effects of parameters such as volume fraction, Darcy number, injection/suction Reynolds number, Hartmann number were analyzed. Findings It was found the following: the Darcy number affects the stability of the flow, the injection/suction Reynolds number has a negligible effect, the volume fraction damped disturbances and the magnetic field plays a very important role in enlarging the area of flow stability. Originality/value The originality of this work resides in the linear and temporal stability analysis of hydromagnetic Couette flow for hybrid nanofluid through porous media with small suction and injection effects.

Effects of Fuel Molecular Weight on Emissions in a Jet Flame and a Model Gas Turbine Combustor

2017 ◽  
Author(s):  
Anandkumar Makwana ◽  
Suresh Iyer ◽  
Milton Linevsky ◽  
Robert Santoro ◽  
Thomas Litzinger ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Volume Fraction ◽  
Premixed Flames ◽  
Soot Volume Fraction ◽  
Spatial Development ◽  
Inlet Temperature ◽  
Gas Turbine Combustor ◽  
Jet Flames ◽  
Jet Flame ◽  
Model Gas Turbine Combustor

The objective of this study is to understand the effects of fuel volatility on soot emissions. The effect of fuel volatility on soot is investigated in two experimental configurations: a jet flame and a model gas turbine combustor. The jet flame experiment provides information about the effects of fuel on the spatial development of aromatics and soot in an axisymmetric, co-flow, laminar flame at atmospheric pressure. The data from the model gas turbine combustor illustrate the effect of fuel volatility on net soot production under conditions similar to an actual engine at cruise, operated at 5 atm, an inlet temperature of 560 K, and an inlet global equivalence ratio of 0.9 to 1.8. Two fuels with different boiling points are investigated: n-heptane/n-dodecane mixture and n-hexadecane/n-dodecane mixture. The n-hexadecane has a boiling point of 287° C as compared to 216° C for n-dodecane and 98° C for n-heptane. The jet flames investigated are non-premixed and premixed flames (jet equivalence ratios of 24 and 6) in order to have fuel rich conditions similar to those in the primary zone of an aircraft engine combustor. The results from the jet flames indicate that the peak soot volume fraction produced in the n-hexadecane fuel is slightly higher as compared to the n-heptane fuel for both non-premixed and premixed flames. The comparison of aromatics and soot volume fraction in non-premixed and premixed flames shows significant differences in the spatial development of aromatics and soot along the downstream direction. The results from the model combustor indicate that, within experiment uncertainty, the net soot production is similar in both n-heptane and n-hexadecane fuel mixtures. In comparing the results from these two burner configurations, we draw conclusions about important processes for soot formation in gas turbine combustors and what can be learned from laboratory-scale flames.

Effect of replacing nanofluid instead of water on heat transfer in a channel with extended surfaces under a magnetic field

2019 ◽  
Vol 29 (4) ◽  
pp. 1249-1271 ◽  
Author(s):  
Saeed Aghakhani ◽  
Behzad Ghasemi ◽  
Ahmad Hajatzadeh Pordanjani ◽  
Somchai Wongwises ◽  
Masoud Afrand
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Lower Wall ◽  
Parallel Plates ◽  
Content Type ◽  
Extended Surfaces

PurposeThe purpose of this study is to conduct a numerical analysis of flow and heat transfer of water–aluminum oxide nanofluid in a channel with extended surfaces in the presence of a constant magnetic field. The channel consists of two parallel plates and five obstacles of constant temperature on the lower wall of the channel. The upper wall and the inlet and outlet lengths of the lower wall are insulated. A uniform magnetic field of the magnitude B0 is located beneath the obstacles. The nanofluid enters the channel with a uniform velocity and temperature, and a fully developed flow leaves the channel.Design/methodology/approachThe control volume-based finite difference and the SIMPLE algorithm were used for numerical solution. In addition to examining the effect of the Reynolds number, the effects of Hartman number, the volume fraction of nanoparticles, the height of obstacles, the length of obstacles and the distance between the obstacles were investigated.FindingsAccording to the results, the heat transfer rate increases with an increasing Reynolds number. As the Hartmann number increases, the heat transfer rate increases. The heat transfer rate also increases with an increase in the volume fraction of nanoparticles. The mean Nusselt number is reduced by an increasing height of obstacles. An increase in the distance between the obstacles in the presence of a magnetic field does not have a significant impact on the heat transfer rate. However, the heat transfer rate increases in the absence of a magnetic field, as the distance between the obstacles increases.Originality/valueThis paper is original and unpublished and is not being considered for publication elsewhere.

Deconvolution of Temperature and Soot Volume Fraction in a Turbulent Ethylene Flame by Inverse Spectral Radiation Analysis

Volume 4 ◽  
2004 ◽  
Author(s):  
Yuan Zheng ◽  
Jay P. Gore
Keyword(s):  
Volume Fraction ◽  
Soot Volume Fraction ◽  
Turbulent Flames ◽  
Gradient Algorithm ◽  
Spectral Radiation ◽  
Jet Flame ◽  
Ethylene Flame ◽  
Simultaneous Reconstruction ◽  
Local Mean ◽  
Good Agreement

We report a new non-intrusive diagnostics technique for the simultaneous reconstruction of temperature (T) and soot volume fraction (fv) profiles in axi-symmetric turbulent luminous flames. Line-of-sight spectral radiation intensities (Iλ) for one diametric and nine chord-like radiation paths from a representative horizontal plane of a turbulent ethylene jet flame were measured by a fast infrared array spectrometer. By inverse analysis of the measured mean Iλ at four wavelengths where continuum radiation from soot particles dominates, four local scalar statistics, including mean and root-mean-square (rms) of T and fv, were de-convoluted. Powell’s conjugate-gradient algorithm and Brent’s line minimization algorithm were adopted in solving the present four-variable inverse problem. The calculated mean Iλ matched the experimental data very well within a 3% difference in general. The reconstructed local mean/rms T and fv distributions were in reasonably good agreement with sampling data from similar turbulent flames.

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