Begell House Inc.
Atomization and Sprays
AAS
1044-5110
19
4
2009
AN EXPERIMENTAL STUDY ON SPRAY TRANSIENT CHARACTERISTICS IN FUEL CONTAINING CO2
311-320
10.1615/AtomizSpr.v19.i4.10
Jin
Xiao
Key Laboratory of Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Minhang District, 200240 Shanghai, People's Republic of China
Zhen
Huang
Key Laboratory of Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Minhang District, 200240 Shanghai, People's Republic of China
Ma
Junjun
Key Laboratory of Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University, P.R. China
Qiao
Xinqi
Key Laboratory of Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University, P.R. China
Spray of fuel containing CO2 is a method of twin-fluid spray that involves dissolving CO2 gas into liquid fuel before it is ejected from the injector. The technique of dissolving CO2 gas into liquid fuel is essentially different from other methods of twin-fluid spray and leads to significant improvements in performance in terms of smaller drop sizes and lower injection pressures. This paper presents an experimental study on the process of injecting a bubble jet of transient spray with fuel containing CO2 using high-speed imaging technology. Experiments were performed under atmospheric conditions with a diesel hole-type nozzle. The effect of injection pressure on the bubble jet atomization process was evaluated, especially in the early stage of injection. The transient characteristics of spray, such as spray angle and spray tip penetration, were also investigated. The images clearly display the developing process of the spray. New insight into the process of bubble jet injection of fuel containing CO2 spray was obtained, and a possible mechanism to explain the phenomena was proposed.
EXPERIMENTAL STUDY ON SPRAY AND MIXTURE PROPERTIES OF THE GROUP-HOLE NOZZLE FOR DIRECT-INJECTION DIESEL ENGINES, PART I: A COMPARATIVE ANALYSIS WITH THE SINGLE-HOLE NOZZLE
321-337
10.1615/AtomizSpr.v19.i4.20
Jian
Gao
Department of Mechanical System Engineering, University of Hiroshima, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
Yuhei
Matsumoto
Department of Mechanical System Engineering, University of Hiroshima, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
Keiya
Nishida
Department of Mechanical System Engineering, University of Hiroshima, 1-4-1
Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan
The group-hole nozzle is regarded as a promising instrument to facilitate better fuel atomization and evaporation for direct-injection diesel engine applications. This work, and the accompanying paper, present an experimental study of spray and mixture properties of the group-hole nozzle by means of the ultraviolet-visible laser absorption-scattering (LAS) imaging technique. In this paper (Part I), study is focused on the spray behavior of the group-hole nozzle with close and parallel orifices, in comparison with the conventional single-hole nozzle. Experiments for nonevaporating and evaporating sprays were designed to clarify the effect of the group-hole nozzle. As a result: (1) Due to the minimization of the nozzle orifice used with nonevaporating sprays, the group-hole nozzle concept displays the potential to produce better fuel atomization and it does not adversely affect spray spatial distribution. (2) Under evaporation conditions, the peak equivalence ratio of the vapor phase is increased using the group-hole nozzle. Mixture properties (including mass of ambient gas entrained, mass of fuel vapor, and evaporation ratio) can also be improved with the group-hole nozzle, which is helpful in forming a leaner, more homogeneous fuel-gas mixture; this is especially evident at high injection pressure. Despite the potential to improve atomization and evaporation using the group-hole nozzle, no significant difference was detected between the two nozzles used in this work. In a second publication (Part II), another two series of group-hole nozzles will be analyzed to investigate the effects of nozzle specifications on spray and mixture properties by extending the LAS technique to a nonaxisymmetric spray analysis.
EXPERIMENTAL STUDY ON SPRAY AND MIXTURE PROPERTIES OF THE GROUP-HOLE NOZZLE FOR DIRECT-INJECTION DIESEL ENGINES, PART II: EFFECTS OF INCLUDED ANGLE AND INTERVAL BETWEEN ORIFICES
339-355
10.1615/AtomizSpr.v19.i4.30
Keiya
Nishida
Department of Mechanical System Engineering, University of Hiroshima, 1-4-1
Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan
Jian
Gao
Department of Mechanical System Engineering, University of Hiroshima, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
Yuhei
Matsumoto
Department of Mechanical System Engineering, University of Hiroshima, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
The research reported in this article is an experimental investigation on the effects of nozzle specifications on spray and mixture properties of the group-hole nozzle by varying the included angle and interval between orifices. Since the group-hole nozzle spray loses its axisymmetry in the divergent angle and large interval cases, the original ultraviolet-visible laser absorption-scattering (LAS) imaging technique was first extended to simultaneous measurement of the total masses, as well as the mass distributions of vapor/liquid phases per projection area perpendicular to the laser beam in a nonaxisymmetric evaporating spray. Two major aspects of group-hole nozzle specifications have been investigated in this work. The results suggest that: (1) Increasing the divergent angle between orifices results in shorter spray tip penetration, larger spray cone angle, and significant increase in mass of fuel vapor, indicating the evaporation improvement. (2) In the case of group-hole nozzle with relatively large interval between orifices used in this study, the decreased penetration, larger spray cone angle, and reduced mass ratio of fuel vapor can be found. It is considered to be contributed to by the combined effect of direct droplets collision in the overlapping part of the two jets and the droplets collision and coalescence in the stagnation region inside the fuel spray.
EXPERIMENTAL DATA AND NUMERICAL SIMULATION OF COMMON-RAIL ETHANOL SPRAYS AT DIESEL ENGINE-LIKE CONDITIONS
357-386
10.1615/AtomizSpr.v19.i4.40
P.
Spiekermann
Institut für Technische Verbrennung, RWTH Aachen University, Templergraben 64, 52056 Aachen, Germany
S.
Jerzembeck
Institut für Technische Verbrennung, RWTH Aachen University, Templergraben 64, 52056 Aachen, Germany
C.
Felsch
Institut für Technische Verbrennung, RWTH Aachen University, Templergraben 64, 52056 Aachen, Germany
S.
Vogel
Institut für Technische Verbrennung, RWTH Aachen University, Templergraben 64, 52056 Aachen, Germany
M.
Gauding
Institut für Technische Verbrennung, RWTH Aachen University, Templergraben 64, 52056 Aachen, Germany
Norbert
Peters
Department of Combustion Technology RWTH Aachen University Templergraben 64, 52056 Aachen, Germany
Common-Rail ethanol sprays are experimentally investigated in a high-pressure vessel for pressures up to 50 bar and temperatures up to 800 K. Mie, Shadow, and Raman optical measurement techniques are used for the spray investigations. The experimental setup and the measurement techniques are described in detail. Detailed experimental results are presented for various vessel conditions. This includes liquid and gaseous penetration, spray angle of liquid and gaseous phase, liquid and vapor fuel mass fraction, liquid and vapor temperature, as well as Sauter mean radius. The experimental results provide a considerable dataset for numerical validation purposes. In addition to the experimental investigations, numerical simulations are carried out applying the commonly used discrete droplet model (DDM). A short review of the DDM including its inherent submodels is presented along with the simulation setup. Selected experimental results (liquid and gaseous penetration, liquid and vapor fuel mass fraction, liquid and vapor temperature, and Sauter mean radius) are compared to corresponding results obtained from the spray simulations to evaluate the performance of the DDM approach.
SPRAY CHARACTERISTICS OF ARTIFICIAL AEROSOL CLOUDS IN A LOW-SPEED ICING WIND TUNNEL
387-405
10.1615/AtomizSpr.v19.i4.50
Laszlo E.
Kollar
CIGELE/INGIVRE, University of Québec at Chicoutimi, 555 Boulevard de l'Université, Chicoutimi, Québec G7H 2B1, Canada
This article investigates liquid water content (LWC) and its uniformity in supercooled aerosol clouds produced in a low-speed horizontal icing wind tunnel used for simulating atmospheric icing. The dependence of LWC obtained at mid-height of the tunnel test section on thermodynamic parameters of the air stream and on dynamic parameters applied to the nozzle system is determined empirically for two types of nozzles. The investigation reveals that LWC increases with air velocity, reaches a maximum at a low airspeed (below 30 m/s), and decreases as was observed at high airspeeds used for modeling aircraft icing (up to 160 m/s) only after passing this maximum. This complex behavior is explained by the concurrence of two processes: the vertical separation of droplets of different size due to the effect of gravity, and the vertical and transverse shrinkage of the aerosol cloud co-occurring with its streamwise expansion.