Begell House Inc.
Atomization and Sprays
AAS
1044-5110
30
2
2020
VOLUME OF FLUID SIMULATION OF SHEET FORMATION AND PRIMARY BREAKUP OF NON-NEWTONIAN PROPELLANTS IN A PINTLE INJECTOR WITH VARIABLE INJECTION AREAS
75-95
10.1615/AtomizSpr.2020031413
Kanmaniraja
Radhakrishnan
Graduate School, Department of Aerospace and Mechanical Engineering, Korea
Aerospace University, Goyang, Gyeonggi-do, 10540, Republic of Korea
Jaye
Koo
School of Aerospace and Mechanical Engineering, Korea Aerospace University,
Goyang, Gyeonggi-do, 10540,
Dept. of Aeronautical & Mech. Engrg., Hankook Aviation Univ., Republic of Korea
Yongseok
Hwang
Agency for Defense Development, Daejeon, 34060, Republic of Korea
gelled hydrogen peroxide
gelled kerosene
volume of fluid (VOF) approach
pintle injector
Two-dimensional axisymmetric large eddy simulation was conducted to model the sheet formation and primary breakup of gelled kerosene and gelled hydrogen peroxide in a pintle injector. This was done by varying the pintle opening distance. To simulate a hollow conical gelled hydrogen peroxide sheet from the center gap and the sheet breakup by the gelled kerosene from the annular gap, volume of fluid (VOF) simulation was employed. Here, the viscosity was considered as a function of the shear rate. The power law expression for hydrogen peroxide and the Herschel-Bulkley extended expression for kerosene were used as the user-defined function codes. The variations of the breakup length, wavelength, and the amplitude of the formed sheet due to disturbance waves using VOF simulation with varied pintle opening distances were studied. The viscosity distributions due to the shear rate of the gel flow and the velocity at the exit of the injector were plotted to investigate the gel flow behavior.
MOMENTUM ANALYSES FOR DETERMINATION OF DROP SIZE AND DISTRIBUTIONS DURING SPRAY ATOMIZATION
97-109
10.1615/AtomizSpr.2020033955
T.-W.
Lee
Department of Mechanical and Aerospace Engineering, School of Engineering for Matter, Transport and Energy (SEMTE), Arizona State University, Tempe, AZ 85287, USA
J. E.
Park
Mechanical and Aerospace Engineering, School for Engineering of Matter,
Transport, and Energy (SEMTE), Arizona State University,
Tempe, AZ 85287-6106, USA
Hana
Bellerova
Heat Laboratory, Brno University of Technology, Brno, Czech Republic
Milan
Hnizdl
Heat Laboratory, Brno University of Technology, Brno, Czech Republic
Miroslav
Raudensky
Heat Transfer and Fluid Flow Laboratory, Faculty of Mechanical Engineering, Brno University of
Technology, Technicka 2, Brno, 616 69, Czech Republic
spray atomization
momentum conservation
Sauter mean diameter
drop size distribution
We consider the momentum effects on drop size and distributions during spray atomization. By adding the liquid and gas momentum analysis to conservation equations for mass and energy, we construct a formulation for determination of the spray drop size, number density, and liquid/gas velocities during spray atomization. In this approach, the aerodynamic drag is approximately parameterized by the drag coefficient, and viscous dissipation with dimensional scaling. This allows us to calculate the spray drop size and distributions from the injection parameters. The formulation also yields a broad dynamic perspective of spray atomization in which the liquid momentum undergoes deceleration due to drag and the drop size is the result of attendant energy transfer from the liquid kinetic to surface tension energy. Momentum adds a key component to the analysis of spray atomization leading to some useful relationships between the drop size and velocities. In this work, we present some methods for the use of momentum analyses for determination of drop size and distributions in various spray injection geometries.
EXPERIMENTAL STUDY ON THE EFFECT OF CAVITATION ON PRESSURE FLUCTUATIONS IN OPTICAL DIESEL NOZZLES AND SPRAY CHARACTERISTICS
111-129
10.1615/AtomizSpr.2020034273
Tianyi
Cao
Institute for Energy Research, Jiangsu University, Zhenjiang, China; School of Energy and Power Engineering, Jiangsu University, Zhenjiang, China
Zhixia
He
Institute for Energy Research, Jiangsu University, Zhenjiang 212013, China
Liang
Zhang
Institute for Energy Research, Jiangsu University, Zhenjiang, China; School of Energy and Power Engineering, Jiangsu University, Zhenjiang, China
Wei
Guan
Institute for Energy Research, Jiangsu University, Zhenjiang 212013, China; School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, China
Qian
Wang
School of Energy and Power Engineering, Jiangsu University, Zhenjiang,
212013, China
diesel injector nozzle
visualization experiment
string cavitation
pressure fluctuations
spray characteristics
The influence of the cavitation effect on the diesel engine nozzle is based on the following aspects: flow and spray characteristics, cavitation erosion on the nozzle wall, and pressure fluctuations of diesel fuel in the system. The first two have been extensively studied, but the research on the third one is rather limited. In this article, the synchronous acquisition, data processing system of cavitation, pressure fluctuations of diesel fuel, and spray characteristics inside the transparent nozzle were examined, then the direct correspondence among pressure fluctuations and cavitation phenomenon was explored. Experimental studies under steady injection pressure and fixed needle lift show that: during the process of transforming hole-to-hole string cavitation to needle-originated string cavitation, the pressure fluctuation amplitude increases significantly. String cavitation under low pressure is easily converted into geometry-induced cavitation due to morphological instability, which has a large disturbance to the spray cone angle. String cavitation under high pressure is more intense with the pressure fluctuation is relatively large and its intensity is weaker than the geometry-induced cavita-tion intensity under the same pressure; however, both the pressure fluctuation amplitude and spray cone angle are much larger. The peak pressure of string cavitation is higher than that of geometry-induced cavitation. In the process of the disappearance, fracture, and fusion of string cavitation, the pressure fluctuation amplitude increases significantly. The results of this experiment play a crucial role in the effective control of pressure fluctuations in the system.
SPH SIMULATIONS OF DROP IMPACT ON HEATED WALLS AND DETERMINATION OF IMPACT CRITERIA
131-152
10.1615/AtomizSpr.2020032857
Yaoyu
Pan
Department of Mechanical Engineering, Iowa State University, Ames, Iowa
50011, USA
Xiufeng
Yang
Department of Mechanical Engineering, Iowa State University, Ames, Iowa
50011, USA
Song-Charng
Kong
Texas Tech University
Chol-Bum M.
Kweon
Propulsion Division, DEVCOM, Army Research Laboratory, APG, MD 21005, USA
drop impact
smoothed particle hydrodynamics
wall film
splashed mass
The outcomes of fuel drop impact on a combustion chamber wall will affect the fuel-air mixture distribution and subsequent combustion performance of an internal combustion engine. In this paper, the process offuel drop impact on a solid dry surface was simulated, using a numerical method based on smoothed particle hydrodynamics (SPH). This method was first validated using experimental data on the impact regimes of ethanol drops and n-heptane drops on a heated surface. Various impact outcomes: deposition, contact-splash, bounce, and film-splash, were predicted successfully. Then, the impact process of iso-octane drops on a solid surface under engine-relevant conditions was studied. Numerical results show that the splash threshold will decrease as the wall temperature increases. A variety of impact regimes were identified and the impact outcomes in each regime were analyzed. Based on the simulation results, the splashed mass ratio will increase as the kinetic energy of the incident drop and the wall temperature increase. The impact outcomes were found to be similar if the wall temperature is higher than the drop's Leidenfrost temperature. The effect of wall temperature on the impact outcomes was characterized and incorporated into the model. The proposed drop/wall interaction model, derived from the present SPH study, can be readily implemented for engine spray/wall impingement simulation.