One-dimensional turbulence model simulations of autoignition of hydrogen/carbon monoxide fuel mixtures in a turbulent jet

2011 ◽  
Vol 158 (2) ◽  
pp. 327-344 ◽  
Author(s):  
Kamlesh G. Gupta ◽  
Tarek Echekki
Keyword(s):  
Carbon Monoxide ◽  
Turbulence Model ◽  
Turbulent Jet ◽  
Model Simulations ◽  
One Dimensional ◽  
Fuel Mixtures

Pollutant emission from a heat station supplied with agriculture biomass and wood pellet mixture

2012 ◽  
Vol 33 (2) ◽  
pp. 231-242 ◽  
Author(s):  
Marek Juszczak ◽  
Katarzyna Lossy
Keyword(s):  
Carbon Monoxide ◽  
Pollutant Emission ◽  
Heat Output ◽  
Wood Pellets ◽  
Wood Pellet ◽  
Carbon Monoxide Concentration ◽  
Heat Efficiency ◽  
Air Stream ◽  
Fuel Mixtures ◽  
Lower Carbon

Pollutant emission from a heat station supplied with agriculture biomass and wood pellet mixtureTests for combustion of hay and sunflower husk pellets mixed with wood pellets were performed in a horizontal-feed as well as under-feed (retort) wood pellet furnace installed in boilers with a nominal heat output of 15 and 20 kW, located in a heat station. During the combustion a slagging phenomenon was observed in the furnaces. In order to lower the temperature in the furnace, fuel feeding rate was reduced with unaltered air stream rate. The higher the proportion of wood pellets in the mixture the lower carbon monoxide concentration. The following results of carbon monoxide concentration (in mg/m3presented for 10% O2content in flue gas) for different furnaces and fuel mixtures (proportion in wt%) were obtained: horizontal-feed furnace supplied with hay/wood: 0/100 - 326; 30/70 - 157; 50/50 - 301; 100/0 - 3300; horizontal-feed furnace supplied with sunflower husk/wood: 50/50 - 1062; 67/33 - 1721; 100/0 - 3775; under-feed (retort) furnace supplied with hay/wood: 0/100 - 90; 15/85 - 157; 30/70 - 135; 50/50 - 5179; under-feed furnace supplied with sunflower husk/wood: 67/33 - 2498; 100/0 - 3128. Boiler heat output and heat efficiency was low: 7 to 13 kW and about 55%, respectively, for the boiler with horizontal-feed furnace and 9 to 14 kW and 64%, respectively, for the boiler with under-feed furnace.

A Study of a Sharp 90 Degree Curved Flow

1992 ◽  
Author(s):  
R. H. Kim
Keyword(s):  
Turbulence Model ◽  
Ideal Gas ◽  
Radius Of Curvature ◽  
Dimensional Theory ◽  
One Dimensional ◽  
Algebraic Stress Model ◽  
Finite Difference Technique ◽  
Curved Tube ◽  
Kinetic Energy Loss ◽  
The Ideal

Abstract An investigation of air flow along a 90 degree elbow-like tube is conducted to determine the velocity and temperature distributions of the flow. The tube has a sharp 90 degree turn with a radius of curvature of almost zero. The flow is assumed to be a steady two-dimensional turbulent flow satisfying the ideal gas relation. The flow will be analyzed using a finite difference technique with the K-ε turbulence model, and the algebraic stress model (ASM). The FLUENT code was used to determine the parameter distributions in the passage. There are certain conditions for which the K-ε model does not describe the fluid phenomenon properly. For these conditions, an alternative turbulence model, the ASM with or without QUICK was employed. FLUENT has these models among its features. The results are compared with the result computed by using elementary one-dimensional theory including the kinetic energy loss along the passage of the sharp 90 degree curved tube.

scholarly journals Assessment of CFD turbulence models for free surface flow simulation and 1-D modelling for water level calculations over a broad-crested weir floodway

Water SA ◽  
2019 ◽  
Vol 45 (3 July) ◽  
Author(s):  
Ahmed M Helmi
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Water Level ◽  
Dimensional Analysis ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Cfd Simulations ◽  
One Dimensional ◽  
The Mean ◽  
The One

Floodways, where a road embankment is permitted to be overtopped by flood water, are usually designed as broad-crested weirs. Determination of the water level above the floodway is crucial and related to road safety. Hydraulic performance of floodways can be assessed numerically using 1-D modelling or 3-D simulation using computational fluid dynamics (CFD) packages. Turbulence modelling is one of the key elements in CFD simulations. A wide variety of turbulence models are utilized in CFD packages; in order to identify the most relevant turbulence model for the case in question, 96 3-D CFD simulations were conducted using Flow-3D package, for 24 broad-crested weir configurations selected based on experimental data from a previous study. Four turbulence models (one-equation, k-ε, RNG k-ε, and k-ω) ere examined for each configuration. The volume of fluid (VOF) algorithm was adopted for free water surface determination. In addition, 24 1-D simulations using HEC-RAS-1-D were conducted for comparison with CFD results and experimental data. Validation of the simulated water free surface profiles versus the experimental measurements was carried out by the evaluation of the mean absolute error, the mean relative error percentage, and the root mean square error. It was concluded that the minimum error in simulating the full upstream to downstream free surface profile is achieved by using one-equation turbulence model with mixing length equal to 7% of the smallest domain dimension. Nevertheless, for the broad-crested weir upstream section, no significant difference in accuracy was found between all turbulence models and the one-dimensional analysis results, due to the low turbulence intensity at this part. For engineering design purposes, in which the water level is the main concern at the location of the flood way, the one-dimensional analysis has sufficient accuracy to determine the water level.

Laser Velocimeter Measurements in Highly Turbulent Recirculating Flows

1984 ◽  
Vol 106 (2) ◽  
pp. 173-180 ◽  
Author(s):  
W. H. Stevenson ◽  
H. D. Thompson ◽  
R. R. Craig
Keyword(s):  
Turbulent Flows ◽  
Turbulence Model ◽  
Quantitative Description ◽  
Sudden Expansion ◽  
Laser Doppler Velocimeter ◽  
Bias Error ◽  
Mean Velocity ◽  
One Dimensional ◽  
Numerical Predictions ◽  
Velocity Bias

This paper presents the results of an extensive study of subsonic separated flows using a laser Doppler velocimeter. Both a rectangular rearward facing step and cylindrical (axisymmetric) sudden expansion geometry were studied. The basic objectives were to resolve the question of whether a velocity bias error does, in fact, occur in LDV measurements in highly turbulent flows of this type and, if so, how it may be eliminated; map the velocity field (mean velocity, turbulence intensity, Reynolds stress, etc.) including the entire recirculation zone; and compare experimental results with numerical predictions based on the k-ε turbulence model. Measurements were carried out using a one-dimensional LDV operating in forward scatter with signal processing by means of a commercial counter-type processor. Results obtained show that velocity bias does occur in turbulent flows and that it can be overcome by proper data acquisition procedures. The results also indicate that the important mean velocity and turbulence quantities can be obtained with reasonable accuracy using a one-dimensional LDV system. Although the k-ε turbulence model provides a good qualitative picture of the flow field, it does not yield a completely adequate quantitative description. Results obtained here illustrate the discrepancies to be expected and provide a basis for further model development.

scholarly journals Numerical investigation of turbulent-jet primary breakup using one-dimensional turbulence

2017 ◽  
Vol 89 ◽  
pp. 241-254 ◽  
Author(s):  
A. Movaghar ◽  
M. Linne ◽  
M. Oevermann ◽  
F. Meiselbach ◽  
H. Schmidt ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Turbulent Jet ◽  
One Dimensional ◽  
Primary Breakup

Hybrid Turbulence Model Simulations of Partially Stalled Airfoil Flow

AIAA Journal ◽  
2016 ◽  
Vol 54 (4) ◽  
pp. 1220-1234 ◽  
Author(s):  
A. Gross ◽  
H. F. Fasel
Keyword(s):  
Turbulence Model ◽  
Model Simulations ◽  
Airfoil Flow

Soot Formation Reaction Effect in Modeling Thermal Partial Oxidation of Jet-A

2014 ◽  
Author(s):  
Richard Scenna ◽  
Ashwani K. Gupta
Keyword(s):  
Experimental Data ◽  
Carbon Monoxide ◽  
Partial Oxidation ◽  
Kinetic Models ◽  
Soot Formation ◽  
Radical Formation ◽  
Fuel Reforming ◽  
Chemical Modeling ◽  
Formation Reaction ◽  
One Dimensional

The results obtained from the modeling of thermal partial oxidation of kerosene based Jet-A fuel are presented using one dimensional chemical modeling. Two detailed kinetic models for alkenes chemistry ranging between C8 to C16 were evaluated and compared against experimental data of thermal partial oxidation of Jet-A fuel. The key difference between these two kinetic models was the inclusion of model for soot formation reactions. Chemical modeling was performed using dodecane to represent Jet-A fuel. The results showed that the model with soot reactions was significantly more accurate in predicting reformate products from Jet-A. In particular, the formation of carbon monoxide, methane and acetylene closely followed the experimental data with the model that included soot formation reactions. The results revealed that the soot formation reactions promoted the smaller hydrocarbons to decompose via the alternate kinetic pathways and from additional radical formation. The results also reveal that the inclusions of soot formation reactions are critical in the modeling of thermal partial oxidation of fuels for fuel reforming.

Lean Premixed Combustion of Carbon-Monoxide-Hydrogen-Methane Fuel Mixtures Using Porous Inert Media

2005 ◽  
Author(s):  
S. K. Alavandi ◽  
A. K. Agrawal
Keyword(s):  
Carbon Monoxide ◽  
Flame Temperature ◽  
Carbon Foam ◽  
Premixed Combustion ◽  
Nox Emissions ◽  
Lean Premixed Combustion ◽  
Lean Premixed ◽  
Porous Inert Media ◽  
Fuel Mixtures ◽  
Coated Carbon

Lean premixed combustion of carbon monoxide (CO), hydrogen (H2), and methane (CH4) fuel mixtures with air was investigated experimentally. Combustion at atmospheric pressure was stabilized within porous inert medium made of silicon-carbide coated carbon foam with 4 pores per centimeter. CH4 in the fuel was varied from 100% to 0% (by volume), with the remaining fuel containing equal amounts of CO and H2. Experiments at a fixed air flow rate were conducted by varying the adiabatic flame temperature and fuel composition. Profile of CO and NOx emissions in the axial and transverse directions were taken to identify the post-combustion zone and uniformity of combustion. At a given flame temperature, fuels with CO/H2 produced lower CO and NOx emissions compared to those for CH4. The temperature at the lean blow off limit was significantly lower (compared to CH4) if the fuel contained CO and H2, each greater than 35% by volume.

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