Begell House Inc.
Atomization and Sprays
AAS
1044-5110
24
2
2014
DEVELOPMENT OF A MATHEMATICAL MODEL AND 3D NUMERICAL SIMULATION OF THE INTERNAL FLOW IN A CONICAL SWIRL ATOMIZER
97-114
Julio Roman
Ronceros Rivas
Universidad Peruana de Ciencias Aplicadas
Amilcar Porto
Pimenta
Instituto Tecnologico de Aeronautica, Comando Geral de Tecnologia Aeroespacial, Sao Jose dos Campos, SP, Brazil, 12228-900
Gustavo A. Ronceros
Rivas
Instituto Tecnologico de Aeronautica, Comando Geral de Tecnologia Aeroespacial, Sao Jose dos Campos, SP, Brazil, 12228-900
The purpose of this paper is to summarize important aspects related to the study of the mathematical model of internal flow and the nominal performance main parameters of the conical swirl atomizer similar to that used in the JT8 Pratt & Whitney engine. The mathematical proposed model is composed of the inviscid fluid theory of Abramovich and incompressible friction theory of Kliachko, applied to the complexity of the geometry of the inlet channels, such as the irregular cross-section area and nontangential nature with respect to the swirl chamber (geometric characteristics of the conical swirl atomizer). Computational fluid dynamics (CFD) provides additional information on internal flow characteristics of swirl atomizers, the main difficulty of which is the precise control of liquid/air. It was found that by using the volume of fluid (VoF) method and k-epsilon turbulence model (implemented in software Fluent 6.3.26), an understanding of physical phenomena can be obtained as well as better visualization of the air core and hollow-cone spray angle of the atomizer, where the computational domain is composed for three-dimensional structured grids. Experimental data and numerical simulation were used for validation of this mathematical model. These results provide elementary and worthwhile information for the practical design of swirl atomizers, in addition to cost reduction before the combustion testing phase.
SPRAY DROPLET CHARACTERIZATION INSIDE A GLASS COLUMN THROUGH DENSE WALL FLOW
115-128
Yash S.
Tamhankar
School of Chemical Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, USA
J. R.
Whiteley
School of Chemical Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, USA
M. R.
Resetarits
Fractionation Research Incorporated, Stillwater, Oklahoma 74074, USA
C. P.
Aichele
School of Chemical Engineering, Oklahoma State University, Stillwater, Oklahoma 74078, USA
Spray absorption efficiency is a function of the surface area of drops, interaction between the drops, oscillations, coalescence, and breakup. Knowledge of drop size distributions is critical for estimating the total surface area of drops and hence the rate of absorption. This paper illustrates a unique facility designed to measure drop size and velocity distributions using a phase Doppler interferometer (PDI) through dense wall flow. A novel eyepiece insert facilitated PDI measurements through liquid films running down the inner wall of the glass chamber. Measurement data with water as the test fluid with and without countercurrent gas flow is presented.
RESPONSE OF LIQUID JET TO MODULATED CROSSFLOW
129-154
Jinkwan
Song
Combustion Research Laboratory, School of Aerospace Systems, University of Cincinnati, Cincinnati, Ohio 45221, USA
Chandrasekar
Ramasubramanian
Combustion Research Laboratory, School of Aerospace Systems, University of Cincinnati, Cincinnati, Ohio 45221, USA
Jong Guen
Lee
Department of Aerospace Engineering and Engineering Mechanics University of
Cincinnati, Cincinnati, Ohio 45221-0070, USA
Experimental results on the response of spray formed by the liquid (Jet A) jet injection into a crossflow (air) is presented with a special emphasis on its response to the modulating crossflow. The pressure of the chamber is up to 3.5 atm, and the corresponding Weber number is up to 510. The spray of a liquid jet for steady and oscillating crossflow is characterized. The flow field at the injector location in the crossflow direction is determined using particle image velocimetry for the oscillating as well as steady crossflow case. Planar Mie scattering measurement is used to characterize the response of spray formed under oscillating crossflow, and supplementary phase-averaged phase Doppler particle analyzer (PDPA) measurements are used to understand the response behavior. The global response of spray to the oscillating crossflow is characterized using the planar Mie scattering imaging. It shows that few differences exist in the heights of the maximum-pixel intensity trajectory for the nonoscillating and oscillating crossflow conditions and the trajectory under oscillating crossflow is lower than that of steady crossflow, suggesting the oscillating crossflow affects the atomization (i.e. the oscillating crossflow enhances the atomization process, results in smaller droplets and penetrates less transversely). The response of spray to the oscillating crossflow characterized in terms of the spray transfer function (STF) shows that the gain of the STF increases linearly (at least monotonically) as the liquid−air momentum flux ratio increases but does not change as much with respect to the change of Weber number for a fixed liquid−air momentum flux ratio. This also indicates that the liquid jet atomization under oscillating crossflow is enhanced much more with the increase of liquid−air momentum flux ratio than with the increase of Weber number. The phase-averaged PDPA measurements confirm that the oscillating crossflow indeed enhances the atomization process in that the oscillating crossflow results in a relatively greater number of smaller droplets and mean droplet size.
LINEAR STABILITY ANALYSIS OF AN ELECTRIFIED VISCOELASTIC LIQUID SHEET IN A VISCOUS GAS MEDIUM
155-179
Run-ze
Duan
School of Energy and Power Engineering, Beijing University of Aeronautics and Astronautics, Beijing, China, 100191
Zhi-ying
Chen
School of Energy and Power Engineering, Beihang University, Beijing 100191, China
Lei
Li
School of Energy and Power Engineering, Beijing University of Aeronautics and Astronautics, Beijing, China, 100191
A linear analysis is carried out to investigate the instability behavior of a viscoelastic planar liquid sheet moving through a viscous gas in an electric field. The inner liquid is assumed to have a high electric conductivity and the outer gas is assumed to an insulating dielectric. The liquid and gas velocity profiles are taken to account. The governing equations of the sinuous and varicose disturbances for electrified viscoelastic liquid sheets have been solved using the Chebyshev spectral collocation method. The corresponding numerical results are compared with those of the electrified Newtonian liquid sheets, which reveals that the disturbance growth rate on the electrified viscoelastic liquid sheets is greater than that on electrified Newtonian ones with the identical zero shear viscosity. The maximum growth rate and dominant wave number of disturbance waves in the sinuous and varicose modes have been obtained. The influences of the electrical Euler number, liquid Reynolds number, and other rheological parameters on the instability of the electrified viscoelastic sheets have been investigated. It is concluded that the disturbance growth rate of sinuous mode is greater than that of the varicose mode. The increase of the electrical Euler number, liquid Reynolds number, and gas−liquid density ratio can accelerate the breakup of viscoelastic liquid sheets. The increase of time constant ratio and the ratio of the distance between the horizontal electrode and liquid sheet to the liquid sheet thickness would dampen the break-up process.
COMPARISON OF DROP SIZE DATA FROM GROUND AND AERIAL APPLICATION NOZZLES AT THREE TESTING LABORATORIES
181-192
Bradley K.
Fritz
USDA-ARS-Aerial Application Research Unit, College Station, Texas, USA
W. Clint
Hoffmann
USDA-ARS-Aerial Application Research Unit, College Station, Texas, USA
Greg R.
Kruger
University of Nebraska-Lincoln, North Platte, Nebraska 75289
Ryan S.
Henry
University of Nebraska-Lincoln, North Platte, Nebraska 75289
Andrew
Hewitt
Lincoln Agritech, Lincoln University, Christchurch, New Zealand and The University of Queensland, Gatton, Australia 7640
Zbigniew
Czaczyk
Poznan University of Life Sciences, Institute of Agricultural Engineering, Wojska Polskiego 28, PL60-637 Poznan, Independent Consultant, os. B. Chrobrego 13/154, 60-681 Poznan, Poland
Spray drop size is a critical factor in the performance of any agrochemical solution and is a function of spray solution, nozzle selection, and nozzle operation. Applicators generally select a particular nozzle based on the drop size reported by manufacturers and researchers. Like most population sampling methods, the accurate measurement of spray drop sizing is a function of sampling methodology, accuracy of the measurement, and inferences about a total population from a subset. Studies were conducted to determine the repeatability and accuracy of spray drop size from a standardized set of spray nozzles at three different application technology research laboratories (USDA-ARS in College Station, Texas; University of Nebraska-Lincoln in North Platte, Nebraska; and University of Queensland, Gatton in Gatton, Australia). To minimize differences in drop size measurements between laboratories, the same set of nozzles was used at each location. The three laboratory measurements of drop size varied by less than 5% except for the measurement of the very largest drops in a spray plume. Day-to-day differences in drop size measurements within each lab were also found to be around 5%. This work shows that through careful monitoring of spray pressure, air speed, and measurement distance, very close agreement in drop size measurements can be obtained between different facilities.