Begell House Inc.
Atomization and Sprays
AAS
1044-5110
2
4
1992
PHASE-SHIFT DOPPLER ANEMOMETER MEASUREMENTS OF DIESEL SPRAY BEHAVIOR IN OPEN COMBUSTION CHAMBERS
367-383
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M. M.
Elkotb
Mechanical Power Department, Faculty of Engineering, Cairo University, Giza, Egypt
O. M. F.
Elbahar
Mechanical Power Department, Faculty of Engineering, Cairo University, Giza, Egypt
T. I.
Sabry
Mechanical Power Department, Faculty of Engineering, Menoufia University, Shebin El-Kom, Egypt
S. A.
Wilson
Crop Protection Research & Development, Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, USA; and Mechanical Power Department, Faculty of Engineering, Menoufia University, Shebin El-Kom, Egypt
Local measurements of particle size distribution and droplet velocity were conducted inside diesel sprays injected into an open combustion chamber. The measurements were conducted using a phase-shift Doppler anemometer having a dynamic size range of 30. The intermittency of the injection process in diesel engines was taken into account. The results obtained indicate that the radial distributions of droplet size and velocity at a given axial distance from the injection nozzle are not uniform. Furthermore, swirl has a profound effect on the local values of droplet size and velocity distributions.
ACCOUNTING FOR DEPTH OF FIELD IN SIZING SPHERICAL PARTICLES BY IMAGING
385-409
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Douglas
Talley
USAF Research Lab, CA, USA
M.
Hassani
Department of Mechanical Engineering and Applied Mechanics, The University of Michigan, Ann Arbor, Michigan, 48109
A general approach to correcting for depth-of-field effects in sizing spherical particles by imaging is presented, and shown to reduce to two other well-known but heretofore apparently unrelated methods as special cases. The approach is adaptable to a wide variety of conditions by means of functions that are measured during calibration. Most generally, correcting for depth-of-field effects requires traversing the object plane through the particle field. However, conditions are identified that allow proper corrections to be made without having to move the object plane. The dynamic range of an instrument as a function of distance from the object plane, or the dynamic envelope, measured during calibration will not necessarily be the same as the one actually realized in measurement, which can be significantly different. This must be taken into account as part of the measurement process.
EFFECT OF NOZZLE CONFIGURATION ON THE ATOMIZATION OF A STEADY SPRAY
411-426
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Takao
Karasawa
Department of Mechanical Engineering, Faculty of Engineering, Gunma University, Gunma, Japan
Masaki
Tanaka
Department of Mechanical Engineering, Faculty of Engineering, Gunma University, Kiryu, Gunma 376, Japan
Kazuhiro
Abe
Fuji Heavy Industry, Ohta, Gunma 373, Japan
Seiichi
Shiga
Monodzukuri Research Organization,
Department of Mechanical Engineering, Faculty of Engineering, Gunma University Kiryu, Gunma, Japan
Toshio
Kurabayashi
Department of Mechanical Engineering, Hiroshima Institute of Technology, Hiroshima, Hiroshima 731-51, Japan
The purpose of this study was to obtain the relationship between the droplet size of a spray, the nozzle hole configuration represented by the nozzle length/diameter ratio (L/D), and the shape of the inlet of the nozzle hole in a steady spray in the range of diesel injection pressures, and to obtain a possible mechanism of the nozzle hole configuration effect. It is shown that the droplet size is insensitive to the L/D for less than a certain value, for a simple straight nozzle, and is apparently affected by the shape of the inlet. However, the inlet shape effect is not substantial, because it disappears when the virtual injection velocity obtained on the basis of the contraction coefficient of the nozzle is applied instead of the mean injection velocity obtained from the nominal nozzle diameter. These conclusions were derived from various lands of experiments using several types of nozzles and different kinds of measurements. A possible mechanism is presented that can explain most of the results.
NUMERICAL PREDICTION OF NONEVAPORATING AND EVAPORATING FUEL SPRAYS UNDER NONREACTIVE CONDITIONS
427-443
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X.-Q.
Chen
Section of Applied Thermodynamics, Department of Mechanical Engineering, Instituto Superior Técnico/Technical University of Lisbon, Lisbon, Portugal
Jose C. F.
Pereira
IDMEC, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
Numerical calculations of nonevaporating and evaporating sprays are reported and compared with experimental results that hare been previously reported in the literature. The Eulerian formulation for the gas field equations and the Lagrangian formulation for the droplet field equations are used together with the stochastic approach accounting for the effect of turbulence on the droplet motion. A numerical procedure using multicomputational domains is applied to cover the physical space until the required locations. The air entrainment at the free boundary of the jet spray is implicitly calculated in the solutions. All the spray predictions are compared against experimental data. It is shown that the predicted results satisfactorily follow the experimental measurements.
MEASUREMENTS AND PREDICTIONS OF A LIQUID SPRAY FROM AN AIR-ASSIST NOZZLE
445-462
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Daniel L.
Bulzan
NASA Lewis Research Center, Cleveland, Ohio 44135
Yeshayahou
Levy
Faculty of Aerospace Engineering, Technion - Israel Institute of Technology, Haifa, Israel
Suresh
Aggarwal
Department of Mechanical and Industrial Engineering University of Illinois at Chicago
Susheel
Chitre
The University of Illinois at Chicago, Chicago, Illinois 60680
Droplet size and velocity and gas velocity were measured in a water spray using a two-component phase/Doppler particle analyzer. Л complete set of measurements was obtained at axial locations from 5 to 50 cm downstream of the nozzle. The nozzle used was a simple axisymmetric air-assist nozzle. The sprays produced using the atomizer were extremely fine. Sauter mean diameters were less than 20 μ;m at all locations. Measurements were obtained for droplets ranging from 1 to 50 μ;m. The gas phase was seeded with micrometer-sized droplets, and droplets having diameters of 1.4 μ;m and less were used to represent gas-phase properties. Measurements were compared with predictions from a multiphase computer model. Initial conditions for the model were taken from measurements at 5 cm downstream. Predictions for both the gas phase and the droplets showed relatively good agreement with the measurements.
ATOMIZATION, CHARGE, AND DEPOSITION CHARACTERISTICS OF BIPOLARLY CHARGED AIRCRAFT SPRAYS
463-481
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B. H.
Kim
Department of Mechanical Engineering, Texas A&M University, College Station, Texas 77843
A. R.
McFarland
Department of Mechanical Engineering, Texas A&M University, College Station, Texas 77843
Kenneth D.
Kihm
Texas A&M University College Station, TX; and Micro/Nano-Scale Fluidics and Energy Transport Laboratory, University of Tennessee, Mechanical, Aerospace and Biomedical Engineering Department, Knoxville TN 37996-2210, USA
Atomization, charge, and deposition characteristics of a bipolar-charged electrostatic aircraft spray system were studied. The system used serrated spinner cup atomizers with tap water as the atomized fluid. Despite the well-known advantages of electrostatic sprays, electrical discharge from excessive buildup of residual charge on the aircraft skin has been a major problem in utilizing electrostatic systems for aircraft spraying. The idea of bipolar electrostatic charging has been investigated, and the results show that the bipolar charging could effectively abate the residual charge buildup. In addition, the deposition efficiency of aircraft sprays could be fairly significantly enhanced, Atomization and charging behaviors of the atomizer were studied under a laboratory simulation using a laser diffraction droplet sizing technique and a Faraday cage collector, respectively. The deposition characteristics were investigated by carrying out a field experiment with an aircraft spray system and a water-sensitive dye paper sampling technique. Droplet patterns on exposed dye papers were digitized and processed to obtain the droplet diameters and other statistical data. Compared with corresponding electrically neutral sprays, the average SMD of bipolar-charged sprays was increased by over 10%, with a noticeable decrease in the number of small droplets and an increase in large drops. The effect should reduce the drift problem of aircraft sprays. The total deposition mass was also increased by more than 45% when the spray was charged with dual polarities.
Contents, Index to Volume 2
483-490
10.1615/AtomizSpr.v2.i4.70