scholarly journals Spray Structure and Characteristics of a Pressure-Swirl Dust Suppression Nozzle Using a Phase Doppler Particle Analyze

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1127
Author(s):  
Junpeng Wang ◽  
Cuicui Xu ◽  
Gang Zhou ◽  
Yansong Zhang
Keyword(s):  
Particle Size ◽  
Velocity Distribution ◽  
Droplet Size ◽  
Three Dimensional ◽  
Calibration Data ◽  
Dust Suppression ◽  
Dust Fall ◽  
Spray Structure ◽  
Spray Field ◽  
Pressure Swirl

In order to understand the characteristics of the spray field of a dust suppression nozzle and provide a reference for dust nozzle selection according to dust characteristics, a three-dimensional phase Doppler particle analyzer (PDPA) spray measurement system is used to analyze the droplet size and velocity characteristics in a spray field, particularly the joint particle size–velocity distribution. According to the results, after the ejection of the jet from the nozzle, the droplets initially maintained some velocity; however, the distribution of particles with different sizes was not uniform. As the spray distance increased, the droplet velocity decreased significantly, and the particle size distribution changed very little. As the distance increased further, the large droplets separated into smaller droplets, and their velocity decreased rapidly. The distributions of the particle size and velocity of the droplets then became stable. Based on the particle size-velocity distribution characteristics, the spray structure of pressure-swirl nozzles can be divided into five regions, i.e., the mixing, expansion, stabilization, decay, and rarefied regions. The expansion, stabilization, and decay regions are the effective dust fall areas. In addition, the droplet size in the stabilization region is the most uniform, indicating that this region is the best dust fall region. The conclusions can provide abundant calibration data for spray dust fall nozzles.

Three-Dimensional Velocity and Droplet Size Measurements of Spray Flow (Keynote Paper)

2003 ◽  
Author(s):  
Yoshio Zama ◽  
Masaaki Kawahashi ◽  
Hiroyuki Hirahara
Keyword(s):  
Velocity Distribution ◽  
Droplet Size ◽  
Measurement Technique ◽  
Three Dimensional ◽  
High Density ◽  
Dimensional Structure ◽  
Practical Application ◽  
Droplet Motion ◽  
Observation Area ◽  
Spray Field

The present investigation describes an application of a novel technique of simultaneous measurement of droplet size and three-dimensional components of velocity in a high density spray with swirl. The spray has a complicated and three-dimensional structure caused by mixing with surrounding airflow entrained by high speed fuel jet issuing from a nozzle. The breakup process of fuel film to fine-droplet-cloud, the droplet size dispersion and the velocity distribution of droplets are important factors in practical application of fuel spray for combustors. The conventional technique can be applied to local measurement of droplet speed and size. Recent methods, based on optical and image processing techniques, provide measurement of the velocity and droplet size distribution in observation area or volume. Maeda et al. proposed an excellent measurement technique of the size and the velocity distribution of droplet in spray based on interferometric laser imaging in which the fringe pattern is generated at the out of focus plane by interference between 0th order and 1st order refractions of droplet illuminated by high power laser light sheet. And also, in this technique, the separation of overlapping droplets image has been successfully done by optical method. As a practical application, the size and velocity distributions of droplets in a high density spray without swirl have been measured by this technique. In general, the droplet motion in a spray field is highly three-dimensional. Especially, a spray generated by a swirl nozzle shows complicated droplet motion in the three-dimensional field. In order to analyze the configuration of a complicated spray field, three-dimensional velocity measurement of droplets must be required. In the present paper, a combined measurement technique of the size and three velocity components of droplets in three-dimensional spray field based on doublet imaging technique of droplets and stereoscopic PIV method has been developed. And its feasibility and applicability was confirmed by practical application to measurements of spray fields induced by a swirl jet nozzle using in gas turbine.

scholarly journals Analysis of internal flow and outlet velocity characteristics associated with dust suppression nozzles and their impact on spray field

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983630
Author(s):  
Cuicui Xu ◽  
Yansong Zhang ◽  
Qingguo Yao ◽  
Shichuan Zhang
Keyword(s):  
Velocity Distribution ◽  
Internal Flow ◽  
Boundary Region ◽  
Fluid Density ◽  
Dust Suppression ◽  
Solid Cone ◽  
Spray Field ◽  
The Relationship ◽  
Nozzle Structure

In order to understand the relationship between nozzle structure and spray field, the present paper conducts velocity-based parametric study on two types of dust suppression nozzles, focusing on the link among nozzle structure, velocity distribution, and the resulting spray field. The simulation investigation indicates that the increase of flow velocity mainly occurs in the convergence section and the outlet region of a nozzle, with its magnitude dictated by the convergence angle, ratio of inlet to outlet diameter, and the length–diameter ratio of the outlet. Based on the velocity distribution characteristic of axis direction and radial direction near different nozzles’ outlet, one can predict that fluid density is higher in the central axis region and lower in the boundary region in spray field with cylindrical outlet, which can form a “solid cone” shape and stable spray. In the case where the nozzle outlet has “dash” type, one can find that the spray field, which associated with this type of nozzle, is a fan-shaped, with the fluid density fluctuating up and down. The above hypothesis has been corroborated by the spray experiments which have been conducted here. The simulation results concerning the internal flow field in dust suppression nozzles can provide guidance over the nozzle design and the parametric optimization and are of great significance to enhance the atomization quality of spray field.

scholarly journals Hemp (Cannabis sativa L.) Seed Protein–EGCG Conjugates: Covalent Bonding and Functional Research

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1618
Author(s):  
Xin-Hui Pang ◽  
Yang Yang ◽  
Xin Bian ◽  
Bing Wang ◽  
Li-Kun Ren ◽  
...  
Keyword(s):  
Particle Size ◽  
Fluorescence Spectroscopy ◽  
Cannabis Sativa ◽  
Three Dimensional ◽  
Epigallocatechin Gallate ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Particle Size Data ◽  
Covalently Bonded ◽  
Covalently Linked

In order to make HPI have a wide application prospect in the food industry, we used EGCG to modify HPI. In this study, we prepared different concentrations (1, 2, 3, 4, and 5 mM) of (−)-epigallocatechin gallate (EGCG) covalently linked to HPI and use methods such as particle size analysis, circular dichroism (CD), and three-dimensional fluorescence spectroscopy to study the changes in the structure and functional properties of HPI after being covalently combined with EGCG. The particle size data indicated that the covalent HPI-EGCG complex was larger than native HPI, and the particle size was mainly distributed at about 200 μm. CD and three-dimensional fluorescence spectroscopy analyses showed that the conformation of the protein was changed by conjugation with EGCG. The β-sheet content decreased from 82.79% to 66.67% after EGCG bound to the protein, and the hydrophobic groups inside the protein were exposed, which increased the hydrophobicity of the protein and changed its conformation. After HPI and 1 mM of EGCG were covalently bonded, the solubility and emulsifying properties of the covalent complex were improved compared with native HPI. These results indicated that HPI-EGCG conjugates can be added in some foods.

scholarly journals Numerical Study toward Optimization of Spray Drying in a Novel Radial Multizone Dryer

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1233
Author(s):  
Umair Jamil Ur Rahman ◽  
Artur Krzysztof Pozarlik ◽  
Thomas Tourneur ◽  
Axel de Broqueville ◽  
Juray De Wilde ◽  
...  
Keyword(s):  
Spray Drying ◽  
Droplet Size ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Three Dimensional ◽  
Droplet Size Distribution ◽  
Vortex Chamber ◽  
Temperature Pattern ◽  
Multiphase Model ◽  
Drying Technology

In this paper, an intensified spray-drying process in a novel Radial Multizone Dryer (RMD) is analyzed by means of CFD. A three-dimensional Eulerian–Lagrangian multiphase model is applied to investigate the effect of solids outlet location, relative hot/cold airflow ratio, and droplet size on heat and mass transfer characteristics, G-acceleration, residence time, and separation efficiency of the product. The results indicate that the temperature pattern in the dryer is dependent on the solids outlet location. A stable, symmetric spray behavior with maximum evaporation in the hot zone is observed when the solids outlet is placed at the periphery of the vortex chamber. The maximum product separation efficiency (85 wt %) is obtained by applying high G-acceleration (at relative hot/cold ratio of 0.75) and narrow droplet size distribution (45–70 µm). The separation of different sized particles with distinct drying times is also observed. Smaller particles (<32 µm) leave the reactor via the gas outlet, while the majority of big particles leave it via the solids outlet, thus depicting in situ particle separation. The results revealed the feasibility and benefits of a multizone drying operation and that the RMD can be an attractive solution for spray drying technology.

scholarly journals A Fast Two-Dimensional Numerical Method for the Wake Simulation of a Vertical Axis Wind Turbine

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 49
Author(s):  
Zheng Yuan ◽  
Jin Jiang ◽  
Jun Zang ◽  
Qihu Sheng ◽  
Ke Sun ◽  
...  
Keyword(s):  
Velocity Distribution ◽  
Numerical Method ◽  
Three Dimensional ◽  
Particle Method ◽  
Vortex Method ◽  
Vertical Axis ◽  
Two Dimensional ◽  
Vertical Axis Wind Turbine ◽  
Wake Effect ◽  
Array Design

In the array design of the vertical axis wind turbines (VAWT), the wake effect of the upstream VAWT on the downstream VAWT needs to be considered. In order to simulate the velocity distribution of a VAWT wake rapidly, a new two-dimensional numerical method is proposed, which can make the array design easier and faster. In this new approach, the finite vortex method and vortex particle method are combined to simulate the generation and evolution of the vortex, respectively, the fast multipole method (FMM) is used to accelerate the calculation. Based on a characteristic of the VAWT wake, that is, the velocity distribution can be fitted into a power-law function, a new correction model is introduced to correct the three-dimensional effect of the VAWT wake. Finally, the simulation results can be approximated to the published experimental results in the first-order. As a new numerical method to simulate the complex VAWT wake, this paper proves the feasibility of the method and makes a preliminary validation. This method is not used to simulate the complex three-dimensional turbulent evolution but to simulate the velocity distribution quickly and relatively accurately, which meets the requirement for rapid simulation in the preliminary array design.

scholarly journals Three-dimensional Simulation and Analysis of Spray Structure inVertical MOCVD Reaction Chamber

2020 ◽  
Vol 585 ◽  
pp. 012183
Author(s):  
Liu Changjiang ◽  
Li Zhiming ◽  
Guo Runqiu ◽  
Feng Lansheng ◽  
YangShun Tao
Keyword(s):  
Three Dimensional ◽  
Reaction Chamber ◽  
Spray Structure ◽  
Dimensional Simulation

Experimental and Numerical Investigation of Air-Particle Two-Phase Flow in Centrifugal Separator

2000 ◽  
Author(s):  
H. J. Kang ◽  
B. Zheng ◽  
C. X. Lin ◽  
M. A. Ebadian
Keyword(s):  
Velocity Distribution ◽  
Separation Efficiency ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Tangential Direction ◽  
Cylinder Surface ◽  
Centrifugal Separator ◽  
Two Phase ◽  
Dust Collection ◽  
Numerical Solver

Abstract The velocity distributions inside a centrifugal separator with outside and inside diameters of 152.4 mm (6″) and 76.2 mm (3″), respectively, have been investigated experimentally and numerically to obtain optimum separation efficiency. Two 12.7 mm (1/2-inch) holes were drilled on the external surface of the separator to measure the velocity distribution in the separator. Two direction velocities (tangential direction along the cylinder surface and axial along the vertical direction) were measured to compare with the numerical simulation results. A 6060P Pitot probe was employed to obtain the velocity distribution. The dust samples (a mixture of steel particle and dust) from the dust collection box were analyzed using a Phillips XL30 Scanning Electron Microscope. FLUENT code is used as the numerical solver for this fully three-dimensional problem. The fluid flow in the separator is assumed to be steady and incompressible turbulent flow. The standard k–ε model was employed in this study. Non-uniform, unstructured grids are chosen to discretize the entire computation domain. Almost 100,000 cells are used to discretize the whole separator. The constant velocity profile is imposed on the inlet plane. The pressure boundary condition is adopted at outlet plane. Comparing the velocity distribution and separation efficiency from the experiment and the numerical modeling shows that the experimental results and the estimated data agree fairly well and with a deviation within ±10%.

Experimental Study of Superheated Kerosene Jet Fuel Sprays From a Pressure-Swirl Nozzle

2017 ◽  
Author(s):  
Shaji S. Manipurath
Keyword(s):  
Laser Sheet ◽  
Cone Angle ◽  
Test Facility ◽  
Chamber Pressure ◽  
Engine Fuel ◽  
Fuel Temperature ◽  
Solid Cone ◽  
Spray Cone ◽  
Spray Structure ◽  
Pressure Swirl

The development of higher thermal stability fuels and the development of onboard fuel deoxygenation systems may permit the preheating of fuel up to about 755 K before the onset of pyrolysis. At a sufficiently high fuel temperature for a given combustion chamber pressure, the flash vaporization of liquid or supercritical state fuel can ensue upon injection into the chamber. The performance of standard aviation turbine engine fuel nozzles, designed for mechanically breaking up liquid sprays, may thus be significantly altered by the employment of severely preheated fuel. An evaluation of heated and superheated Jet A-1 sprays from a pressure-swirl atomizer was implemented in a purpose-built test facility. Laser sheet imaging of the spray yielded simultaneous axial cross-sectional maps of Mie-scatter and fluorescence signals. In addition, particle image velocimetry was also used to measure the spray droplet velocity-field. The results indicated that increasing the fuel’s dimensionless level of superheat ΔT* from −1.8 to 0.6 yielded significant changes in the spray structure; specifically, finer droplet sizes, a more uniform dropsize distribution across the spray, increased spray cone angle till about ΔT* = −0.8 followed by a contraction thereafter, marginally increased spray penetration, and significantly higher localised near nozzle tip droplet velocities. The measurements supported the hypothesis that the initial hollow-cone spray structure evolves to a near solid-cone structure with a central vapour core as the fuel is superheated.

scholarly journals Numerical Simulation and Analysis on Spray Drift Movement of Multirotor Plant Protection Unmanned Aerial Vehicle

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2399 ◽  
Author(s):  
Fengbo Yang ◽  
Xinyu Xue ◽  
Chen Cai ◽  
Zhu Sun ◽  
Qingqing Zhou
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Droplet Size ◽  
Wind Field ◽  
Flow Model ◽  
Two Phase Flow ◽  
Plant Protection ◽  
Three Dimensional ◽  
Phase Flow ◽  
Two Phase

In recent years, multirotor unmanned aerial vehicles (UAVs) have become more and more important in the field of plant protection in China. Multirotor unmanned plant protection UAVs have been widely used in vast plains, hills, mountains, and other regions, and become an integral part of China’s agricultural mechanization and modernization. The easy takeoff and landing performances of UAVs are urgently required for timely and effective spraying, especially in dispersed plots and hilly mountains. However, the unclearness of wind field distribution leads to more serious droplet drift problems. The drift and distribution of droplets, which depend on airflow distribution characteristics of UAVs and the droplet size of the nozzle, are directly related to the control effect of pesticide and crop growth in different growth periods. This paper proposes an approach to research the influence of the downwash and windward airflow on the motion distribution of droplet group for the SLK-5 six-rotor plant protection UAV. At first, based on the Navier-Stokes (N-S) equation and SST k–ε turbulence model, the three-dimensional wind field numerical model is established for a six-rotor plant protection UAV under 3 kg load condition. Droplet discrete phase is added to N-S equation, the momentum and energy equations are also corrected for continuous phase to establish a two-phase flow model, and a three-dimensional two-phase flow model is finally established for the six-rotor plant protection UAV. By comparing with the experiment, this paper verifies the feasibility and accuracy of a computational fluid dynamics (CFD) method in the calculation of wind field and spraying two-phase flow field. Analyses are carried out through the combination of computational fluid dynamics and radial basis neural network, and this paper, finally, discusses the influence of windward airflow and droplet size on the movement of droplet groups.

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