Effects of Flow Field on Combustion Characteristics of Confined Jet Nonpremixed Flames

2007 ◽  
Author(s):  
Susumu Noda ◽  
Yuzuru Nada ◽  
I. Gede Parwatha ◽  
Shingo Fukushige
Keyword(s):  
Flow Characteristics ◽  
Flow Fields ◽  
Nonpremixed Flames ◽  
Air Velocity ◽  
Velocity Difference ◽  
Flame Stretch ◽  
Inner Diameter ◽  
Jet Nonpremixed Flames ◽  
Cylindrical Furnace ◽  
Emission Index

Confined flames are widely used in the industrial field. The flame characteristics can be strongly dominated by the combination of a burner and furnace geometries, which were not paid much attention before. In the present study, flow fields in confined flames are discussed in terms of the flame characteristics. The flow characteristics of confined flames have been investigated for propane nonpremixed flames in cylindrical furnaces. The effects of the inner diameter of the cylindrical furnace D1, the turbulence at the flame boundary, and the global equivalence ratio φ are examined in terms of the relation between the emission of NOx and the flow fields. The emission index of NOx, EINOx, decreases roughly with these parameters. The decrease in EINOx is thought to be related to the dilution of mixtures by the burned gas and the flame stretch. The dilution is attributable to vortices formed at the bottom of the furnace, and the flame stretch is attributable to the air velocity difference ΔUa created by two air nozzles. In the present study, it was found that the increases in D1, ΔUa, and φ enlarge and strengthen recirculation vortices to dilute the flame.

Magnetophoresis Effects on the Flow Characteristics of Oil-Based Ferrofluids in Rectangular Enclosures

2015 ◽  
Vol 15 (10) ◽  
pp. 7451-7456
Author(s):  
Hyeon-Seok Seo ◽  
Jin-Hyo Boo ◽  
Youn-Jea Kim
Keyword(s):  
Magnetic Fields ◽  
Permanent Magnet ◽  
Flow Characteristics ◽  
Flow Fields ◽  
Working Fluid ◽  
Magnetic Flux Density ◽  
Magnetic Field Direction ◽  
Analysis Model ◽  
Rectangular Enclosure ◽  
Flow Phenomena

This study numerically investigated the flow characteristics in a rectangular enclosure filled with oil-based ferrofluid (EFH-1, Ferrotec.) under the influence of external magnetic fields. The rectangular enclosure contained obstacles with different shapes, such as a rectangle and a triangle mounted on the top and bottom wall surfaces. In order to generate external magnetic fields, a permanent magnet was located in the lower part of the rectangular enclosure, and its direction was selected to be either horizontal or vertical. Our results showed that the ferrofluid flow fields were affected by the applied external magnetic field direction and eddy flow phenomena in the working fluid were generated in the vicinity of high magnetic flux density distributions, such as at the edge of the permanent magnet. It was also confirmed that the magnetophoretic force distributions in the analysis model played a significant role in the development of the ferrofluid flow fields.

scholarly journals Investigation of droplet nucleation in CCS relevant systems: Progress in the design and testing of the mixture preparation device

2019 ◽  
Vol 213 ◽  
pp. 02092
Author(s):  
Václav Vinš ◽  
Miroslav Čenský ◽  
Jan Hrubý ◽  
Jiří Hykl
Keyword(s):  
Capillary Flow ◽  
Flow Characteristics ◽  
Capillary Tubes ◽  
Expansion Chamber ◽  
Pressure Transducers ◽  
Flow Parameters ◽  
Droplet Nucleation ◽  
Mixture Preparation ◽  
Inner Diameter ◽  
And Performance

The study presents progress in the development of mixture preparation device (MPD) representing an important part of the larger experimental setup intended for investigation of homogeneous droplet nucleation in CO2-rich systems. MPD allows for accurate adjustment of flow parameters, i.e. temperature, pressure, and flow rate, of CO2 in either superheated vapor or supercritical fluid phases and of other gas components such as argon or nitrogen. Through accurate settings of flow rates of individual components, the mixture composition can continuously be defined. MPD is going to be connected to the expansion chamber, where the droplet nucleation will experimentally be observed. In this work, CO2-branch, i.e. the core part of MPD, was modified and tested. Several components, e.g., pressure transducers and safety valve, had to be calibrated and adjusted to assure well-defined and safe operation. Most attention was paid to the design and performance of throttling capillary tubes installed in thermostatic bath, which define final flow parameters of CO2 coming from the CO2 branch. The flow characteristics of two capillary tubes with lengths of 7.8 and 4.0 m and inner diameter 0.1 mm were measured and compared to the predictions of a numerical model. The 1-D model of isothermal capillary flow was found to provide quite good agreement with the measured data.

Large Eddy Simulations of Film Cooling Flow Fields From Cylindrical and Shaped Holes

2008 ◽  
Author(s):  
D. H. Leedom ◽  
S. Acharya
Keyword(s):  
Film Cooling ◽  
Flow Characteristics ◽  
Flow Fields ◽  
Large Eddy Simulations ◽  
Delivery Tube ◽  
Asymmetric Flow ◽  
Specific Mass ◽  
Cooling Flow ◽  
Large Eddy ◽  
Coolant Delivery

Large Eddy Simulations (LES) of cylindrical, laterally diffused, and console holes are performed, and the resulting flow field data is presented. The motivation for performing LES is to enable more accurate simulations and to obtain a better understanding of the flow physics associated with complex hole shapes. The simulations include the coolant delivery tube and the feeding plenum chamber, and are performed for a specific mass flow rate of coolant per unit width of blade. A crossflow inlet is used on the plenum, and the resulting asymmetric flow characteristics are investigated. Coolant delivery tube flow fields are investigated in detail. Results show qualitative agreement with reported trends of improved film coverage with diffused and console holes.

Moisture Dependent Dynamic Flow Properties of Coconut Flours

2016 ◽  
Vol 12 (6) ◽  
pp. 577-585 ◽  
Author(s):  
M. R. Manikantan ◽  
R. P. Kingsly Ambrose ◽  
Sajid Alavi
Keyword(s):  
Moisture Content ◽  
Normal Stress ◽  
Flow Characteristics ◽  
Coconut Oil ◽  
Friction Angle ◽  
Wall Friction ◽  
Flow Properties ◽  
Dynamic Flow ◽  
Virgin Coconut Oil ◽  
Air Velocity

Abstract The dynamic flow properties of two important coproducts of virgin coconut oil (VCO) i. e. coconut milk residue flour (MRF) and VCO cake flour (CF) were studied. The basic flowability energy of CF was higher than MRF and increased with moisture content. The change in compressibility and shear stress, with applied normal stress and moisture content, indicated that these powders are highly cohesive. For both flours, the energy required to make the powder flow increased with moisture at all experimental air velocity. Moisture did not significantly influence the cohesion and unconfined yield strength of MRF, whereas for CF there was significant effect due to the presence of moisture. The wall friction angle of both the flours increased significantly with moisture and decreased with applied normal stress. The results from this study indicated that, both CF and MRF at around 4.00 % moisture content had better flow characteristics than at higher moisture levels.

scholarly journals Two-Phase Flow Characteristics on The Extensive Expansion Channel

2017 ◽  
Vol 16 (2) ◽  
Author(s):  
Latif Ngudi Wibawanto ◽  
Budi Santoso ◽  
Wibawa Endra Juwana
Keyword(s):  
Flow Pattern ◽  
Homogeneous Model ◽  
Flow Characteristics ◽  
Flow Equation ◽  
Pressure Recovery ◽  
Sudden Expansion ◽  
Air Velocity ◽  
Two Phase ◽  
Model Flow ◽  
Two Phases

This research was conducted to find out the flow characteristic of two phases through channel with sudden expansion in the form of change of flow pattern and pressure recovery. The test was conducted with variation of superficial velocity of water 0.2-1.3 m / s and superficial air velocity of 0.2-1.9 m / s resulting in pattern of three flow patterns ie bubble, plug, and slug. The expansion channel resulted in some changes to the flow pattern that originally plugs in the upstream channel into bubble in the downstream channel and the slug becomes plug. Pressure recovery experimental results were compared with the homogeneous model flow equation and Wadle correlation, the two correlations had predictions with standard deviation values of 0.32 and 0.43.

scholarly journals Air flow characteristics of a room with air vortex diffuser

2018 ◽  
Vol 240 ◽  
pp. 02002 ◽  
Author(s):  
Marek Borowski ◽  
Marek Jaszczur ◽  
Daniel Satoła ◽  
Michał Karch
Keyword(s):  
Air Flow ◽  
Ventilation System ◽  
Flow Characteristics ◽  
Comfort Level ◽  
Translational Velocity ◽  
Comfort Zone ◽  
Air Velocity ◽  
Velocity Decay ◽  
Different Diameters ◽  
Comfort Criteria

The air diffuser is a very important component of any ventilation system, and the comfort level of ventilated space occupants depend among many other factors on properly designed and choice of diffusers. At present a large number of diffusers are produced to meet a different kind of requirements. One of the most efficient and very popular types of the diffuser is the vortex diffuser in which air flow has angular as well as translational velocity components. This paper investigates experimentally airflow characteristics of vortex ceiling diffuser and its effect on airflow in a ventilated space. Two thermal comfort criteria namely: mean age of the air and ventilation effectiveness have been used to predict the comfort zone inside the room. Effect of supply air velocity on the flow field is investigated and hence the on comfort and energy consumption. The results show that significant amount of energy can be saved by using vortex diffuser in reference to the other diffusers type. The values of the velocity decay coefficient were compared for different diameters of vortex diffuser.

Investigation of Cycle-to-Cycle Variation of In-Cylinder Engine Swirl Flow Fields Using Quadruple Proper Orthogonal Decomposition

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Penghui Ge ◽  
David L. S. Hung
Keyword(s):  
Proper Orthogonal Decomposition ◽  
High Speed ◽  
Combustion Process ◽  
Flow Characteristics ◽  
Propagation Speed ◽  
Fuel Mixture ◽  
Flow Fields ◽  
Swirl Flow ◽  
Orthogonal Decomposition ◽  
Proper Orthogonal

It has been observed that the swirl characteristics of in-cylinder air flow in a spark ignition direct injection (SIDI) engine affect the fuel spray dispersion and flame propagation speed, impacting the fuel mixture formation and combustion process under high swirl conditions. In addition, the cycle-to-cycle variations (CCVs) of swirl flow often degrade the air–fuel mixing and combustion quality in the cylinder. In this study, the 2D flow structure along a swirl plane at 30 mm below the injector tip was recorded using high-speed particle image velocimetry (PIV) in a four-valve optical SIDI engine under high swirl condition. Quadruple proper orthogonal decomposition (POD) was used to investigate the cycle-to-cycle variations of 200 consecutive cycles. The flow fields were analyzed by dividing the swirl plane into four zones along the measured swirl plane according to the positions of intake and exhaust valves in the cylinder head. Experimental results revealed that the coefficient of variation (COV) of the quadruple POD mode coefficients could be used to estimate the cycle-to-cycle variations at a specific crank angle. The dominant structure was represented by the first POD mode in which its kinetic energy could be correlated with the motions of the intake valves. Moreover, higher order flow variations were closely related to the flow stability at different zones. In summary, quadruple POD provides another meaningful way to understand the intake swirl impact on the cycle-to-cycle variations of the in-cylinder flow characteristics in SIDI engine.

Analysis of the Flow Characteristics of Multiphase Flow Fields in the Mixing Agitator

2014 ◽  
Vol 580-583 ◽  
pp. 3167-3170
Author(s):  
Xiao Bing Wang
Keyword(s):  
Multiphase Flow ◽  
Flow Characteristics ◽  
Flow Fields ◽  
Agitation Rate ◽  
Fluid Shear ◽  
Eddy Simulation ◽  
Spiral Vortex ◽  
Large Eddy ◽  
Circular Flows ◽  
Solid Liquid

The numerical simulation for the flow characteristics of multiphase flow fields in the multiple-blade mixing agitator is carried out by means of combining of the large eddy simulation (LES) and multiphase flow model. Then the flow pattern changes and material mixing rule at different speed conditions are analyzed. The result shows that complicated circular flows form among the four groups of blades in the axial cross section. In the mixing process, the upper solid-liquid mixture is transported to the bottom of the agitator under the action of gravity and fluid shear. Finally it mainly distributes at the agitator walls and the inverted cone manifold in the center of the agitating shaft. With the gradually increasing in the agitation rate, there are a large amount of vortex structures near the blade. Then spiral vortex distribution areas are formed.

Experimental Study of the Real Gas Flow in Microtubes

2012 ◽  
Vol 496 ◽  
pp. 347-350
Author(s):  
Qing Min Zhao ◽  
Xiang An Yue ◽  
Fei Wang
Keyword(s):  
High Pressure ◽  
Gas Flow ◽  
Flow Characteristics ◽  
Low Pressure ◽  
Real Gas ◽  
The Real ◽  
Gas Seepage ◽  
Theoretical Predictions ◽  
Inner Diameter ◽  
Microscale Effect

The flow characteristics of nitrogen in microtubes with diameters of 14.9, 10.1, 5.03 and 2.05μm are investigated experimentally under high pressure conditions. The results show that the high pressure flow characteristics of nitrogen in microtube with the diameter of 14.9μm are in accordance with the classical fluid mechanics theory. However, with the decrease of the inner diameter of microtube, gas flow shows an apparent microscale effect and the results depart from the theoretical predictions of the conventional theory, moreover the smaller the diameter, the stronger the microscale effect. Besides, the high pressure microscale effect can not be characterized by the Knudsen number, which is proposed for studying rarefaction effect at low-pressure. Because of the existence of high-pressure microscale effect, it is inappropriate to study the real gas seepage characteristic in reservoir through the flow experiment at low pressure.

The Flow Conditions to Move Different Plastic Particles in Dilute Pneumatic Conveying

2011 ◽  
Vol 148-149 ◽  
pp. 932-937
Author(s):  
Rungtawan Wiwattanasirikul ◽  
Purimpat Sujumnongtokul
Keyword(s):  
Unit Length ◽  
Positive Pressure ◽  
Pneumatic Conveying ◽  
Flow Conditions ◽  
Test Rig ◽  
Air Velocity ◽  
Two Phase ◽  
Inner Diameter ◽  
Minimum Velocity ◽  
Total Test

In this research, positive-pressure high velocity pneumatic conveying has been tested to determine the flow conditions such as minimum velocity, solid mass flow rate, and pressure drop per unit length of polypropylene (PP), recycled polyethylene (recycled PE), high-density polyethylene (HDPE), and low-density polyethylene (LDPE). The conveying efficiency (η ) of such two-phase flow was also experimentally investigated. During the course of the experimental conduct, the material sphericity ranged from 73.2 to 84.4 %. True density ranged from 904.5 to 1305.7 kg/m3, and bulk density covered the range of 493.7 to 783.4 kg/m3 .The tests were carried out on a pneumatic conveying test rig using a PVC pipes of 0.079-m inner diameter and total test length of 8.57 m. The results showed the minimum conditions to move the particles in dilute phase. For the conveying efficiency (η), the efficiency varies reversely with the air velocity in exponential function.

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