Study on ventilation performance of lateral exhaust hood under the influence of two high-temperature buoyant jets

2020 ◽  
Vol 177 ◽  
pp. 106849 ◽  
Author(s):  
Yanqiu Huang ◽  
Ke Lu ◽  
Junwei Guo ◽  
Yi Wang ◽  
Chunxiao Zhao ◽  
...  
Keyword(s):  
High Temperature ◽  
Exhaust Hood ◽  
Buoyant Jets ◽  
Ventilation Performance

scholarly journals Flow-Field Characteristics of High-Temperature Annular Buoyant Jets and Their Development Laws Influenced by Ventilation System

2013 ◽  
Vol 2013 ◽  
pp. 1-11
Author(s):  
Yi Wang ◽  
Yanqiu Huang ◽  
Jiaping Liu ◽  
Hai Wang ◽  
Qiuhan Liu
Keyword(s):  
High Temperature ◽  
Flow Field ◽  
Cross Section ◽  
Flow Rate ◽  
Ventilation System ◽  
Volumetric Flow Rate ◽  
Outer Diameter ◽  
Exhaust Hood ◽  
Buoyant Jets ◽  
Flow Field Characteristics

The flow-field characteristics of high-temperature annular buoyant jets as well as the development laws influenced by ventilation system were studied using numerical methods to eliminate the pollutants effectively in this paper. The development laws of high-temperature annular buoyant jets were analyzed and compared with previous studies, including radial velocity distribution, axial velocity and temperature decay, reattachment position, cross-section diameter, volumetric flow rate, and velocity field characteristics with different pressures at the exhaust hood inlet. The results showed that when the ratio of outer diameter to inner diameter of the annulus was smaller than 5/2, the flow-field characteristics had significant difference compared to circular buoyant jets with the same outer diameter. For similar diameter ratios, reattachment in this paper occurred further downstream in contrast to previous study. Besides, the development laws of volumetric flow rate and cross-section diameter were given with different initial parameters. In addition, through analyzing air distribution characteristics under the coupling effect of high-temperature annular buoyant jets and ventilation system, it could be found that the position where maximum axial velocity occurred was changing gradually when the pressure at the exhaust hood inlet changed from 0 Pa to −5 Pa.

Lateral ventilation performance for removal of pulsating buoyant jet under the influence of high-temperature plume

2019 ◽  
Vol 29 (4) ◽  
pp. 543-557 ◽  
Author(s):  
Yi Wang ◽  
Lei Cao ◽  
Yanqiu Huang ◽  
Yingxue Cao
Keyword(s):  
High Temperature ◽  
Ventilation System ◽  
Capture Efficiency ◽  
Buoyant Jet ◽  
Buoyant Jets ◽  
Future Design ◽  
Two Factors ◽  
Building Ventilation ◽  
Ventilation Performance ◽  
Instantaneous Increase

Lateral exhaust systems have commonly been applied to capture polluted buoyant jets in many industrial processes, such as casting and metallurgy. Compared with the normal conditions of design manuals, the capture efficiency of a lateral exhaust hood (LEH) is often weakened by two factors in actual processes: the unsteady buoyant jet released from the operating surface, and the plume formed above a high-temperature workpiece placed between the LEH and the operating surface. In this study, through experiments and numerical simulations, a pulsatile phenomenon was found in the velocity and concentration distribution of the unsteady buoyant jet. Results show that the contaminate escape ratio is pulsatile; it rises with the instantaneous increase in the buoyant jet velocity and gradually decreases to a constant value. This study not only reveals the air distribution of pulsating buoyant jet but also analyses the effect of the pulsating buoyant jet and high-temperature plume on lateral ventilation system capture efficiency and provides a possible guidance for future design of new building ventilation technologies.

Study on limit flow ratio method for a lateral exhaust hood above high-temperature buoyant jets

2020 ◽  
Vol 54 ◽  
pp. 101969 ◽  
Author(s):  
Yanqiu Huang ◽  
Ke Lu ◽  
Yi Wang ◽  
Chuang Jiang ◽  
Lei Cao ◽  
...  
Keyword(s):  
High Temperature ◽  
Ratio Method ◽  
Flow Ratio ◽  
Exhaust Hood ◽  
Buoyant Jets

Reduced-scale experimental investigation on ventilation performance of a local exhaust hood in an industrial plant

2015 ◽  
Vol 85 ◽  
pp. 94-103 ◽  
Author(s):  
Yanqiu Huang ◽  
Yi Wang ◽  
Li Liu ◽  
Peter V. Nielsen ◽  
Rasmus L. Jensen ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Industrial Plant ◽  
Exhaust Hood ◽  
Ventilation Performance ◽  
Reduced Scale

Isothermal free jets in high-temperature surroundings

2011 ◽  
Vol 225 (8) ◽  
pp. 1913-1918 ◽  
Author(s):  
M A Azim
Keyword(s):  
High Temperature ◽  
Dynamical Behaviour ◽  
Flow Dynamics ◽  
Governing Equations ◽  
Buoyant Jet ◽  
Buoyant Jets ◽  
Free Jets ◽  
Tridiagonal Matrix Algorithm ◽  
Negatively Buoyant ◽  
Negatively Buoyant Jets

Two types of isothermal free jets, named positively and negatively buoyant, have been studied numerically to discern the effect of surrounding temperatures on their flow dynamics. Turbulence closure in those jets was achieved by standard k - ε model. The governing equations were solved using Implicit θ-Scheme and Tridiagonal Matrix Algorithm. Calculations were made for the jets having constant temperature at 20 °C and by varying surrounding temperatures from 20°C to 1000°C. It is clear that negatively buoyant jets but not the positively buoyant jets are nearly invariant to the change in surrounding temperatures compared to non-buoyant jet. Change in fluid dynamical behaviour of positively buoyant jets due to surrounding temperature change seems promising as it may offer the advantages of fuel jets in high-temperature air combustion.

Near- and Far-Field Properties of High-Temperature Turbulent Buoyant Jets

2017 ◽  
Author(s):  
Nicholas T. Wimer ◽  
Caelan Lapointe ◽  
Torrey R. Hayden ◽  
Jason D. Christopher ◽  
Alexei Poludnenko ◽  
...  
Keyword(s):  
High Temperature ◽  
Far Field ◽  
Buoyant Jets

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

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