Begell House Inc.
Atomization and Sprays
AAS
1044-5110
23
7
2013
STATIC AND DYNAMIC DROP FORMATION ON DOWNWARD-FACING NOZZLES
567-587
10.1615/AtomizSpr.2013006471
Mathias
Etzold
FMP TECHNOLOGY GMBH, Am Weichselgarten 34, 91058 Erlangen, Germany
Franz
Durst
FMP TECHNOLOGY GMBH, Am Weichselgarten 34, 91058 Erlangen, Germany
U.
Acikel
FMP TECHNOLOGY GMBH, Am Weichselgarten 34, 91058 Erlangen, Germany
R.
Gautam
FMP TECHNOLOGY GMBH, Am Weichselgarten 34, 91058 Erlangen, Germany
Michael
Zeilmann
FMP TECHNOLOGY GMBH, Am Weichselgarten 34, 91058 Erlangen, Germany
drop formation
Static drop formation on downward-facing nozzles was investigated, numerically and experimentally. A representation of the variation of the contact angle with respect to nozzle diameter and increasing drop volume, during quasistatic drop formation, was determined and experimentally verified. The condition for the formation of single drops is given. It is pointed out that this limit exists for dynamic drop formation on downward-facing nozzles. This formation is treated in an integral manner and the results are presented in an Ohnesorge−Reynolds diagram. The latter diagram is explained in detail, since it allows a generalization of the authors' experimental results. Experiments and corresponding theoretical results are described and show very good agreement.
EXPERIMENTAL INVESTIGATION OF DYNAMICS AND ATOMIZATION OF A LIQUID FILM FLOWING OVER A SPINNING DISK
589-603
10.1615/AtomizSpr.2013006704
Martin
Freystein
Institute for Technical Thermodynamics, TU Darmstadt, 64287 Darmstadt, Germany
T.
Borsdorf
Institute for Technical Thermodynamics, TU Darmstadt, 64287 Darmstadt, Germany
Tatiana
Gambaryan-Roisman
Faculty of Mechanical and Process Engineering,
Technische Universität Darmstadt,
Petersenstr. 30, 64287, Darmstadt, Germany
Peter
Stephan
Institute for Technical Thermodynamics, Technische Universität Darmstadt,
Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany
rotary atomization
spinning disk
film flow
One of the most commonly used methods of liquid atomization is the rotary atomization. In this process a radially spreading thin liquid film is created on a surface of a rotating disk, due to centrifugal forces. The liquid flows over the disk edge and disintegrates. The liquid film is mostly wavy. The radially propagating waves induce fluctuations resulting in an expansion of the drop size distribution after atomization. An experimental apparatus has been built to investigate the effect of the film dynamics on the atomization process. A water jet is impinging at the center of a rotating disk made of stainless steel. The local instantaneous film thickness is measured using a confocal chromatic sensoring technique. The drop sizes are determined using the shadowgraphy method. The film flow on the rotating disk has been investigated in a wide range of parameters. The strongly wavy structure of the film flow has been observed for all sets of parameters. The development of waves depends on the nozzle-to-disk distance. The radial distribution of the time-averaged film thickness over the disk surface agrees fairly well with the correlations found in the literature. First results of the drop size distribution show a bimodal distribution for low liquid mass flow rates.
EXPERIMENTAL STUDY ON TRANSCRITICAL SPRAY OF LIQUID AVIATION KEROSENE
605-621
10.1615/AtomizSpr.2013007793
Haoyi
Song
School of Power and Energy, Northwestern Polytechnical University, Xian, 710072, China
Wei
Fan
School of Power & Energy, Northwestern Polytechnical University, Xi'an,
710072, China
Zhencen
Fan
School of Power and Energy, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
Le
Jin
School of Power and Energy, Northwestern Polytechnical University, Xian, 710072, China
transcritical
supercritical
aviation kerosene
spray pattern
breakup length
High-speed photography was used to study the transcritical spray of liquid aviation kerosene into supercritical environments. The transcritical spray patterns under different conditions were investigated, and the reason spray patterns and breakup length vary was analyzed. It was discovered that ambient temperature and Reynolds number dominate the transcritical injection patterns, and the ambient temperature influences the injection patterns most under transcritical conditions while the Reynolds number is the most important parameter when ambient pressure is subcritical. It was also shown that the "continuous mist" form emerges when the ambient pressure is larger than 2 MPa and the Reynolds number is larger than 5400, and this pattern is unique to transcritical injection. An empirical formula that can predict the breakup length of transcritical injection well was obtained via modifying the previous formula and fitting the experimental data.
ANALYZING THE CYCLE-TO-CYCLE VARIATIONS OF PULSING SPRAY CHARACTERISTICS BY MEANS OF THE PROPER ORTHOGONAL DECOMPOSITION
623-641
10.1615/AtomizSpr.2013007851
Hao
Chen
Tula Technology, Inc.
David L. S.
Hung
University of Michigan-Shanghai Jiao Tong University Joint Institute,
Shanghai Jiao Tong University, 800 Dongchuan Rd., Shanghai, 200240, China
Min
Xu
School of Mechanical Engineering, Shanghai Jiao Tong University, National Engineering Laboratory for Automotive Electronic Control Technology, Shanghai 200240, China
Jie
Zhong
University of Michigan-Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240, China
cycle-to-cycle variation
pulsing spray characteristics
proper orthogonal decomposition
This paper presents a novel approach to analyze the cycle-to-cycle variations of pulsing spray characteristics. The purpose is to quantify the cycle-to-cycle variations of the macroscopic characteristics of spark-ignition direct-injection (SIDI) fuel injector spray, so that improvements of air-fuel mixture formation can be made to enhance the combustion efficiency and reduce emissions of SIDI engines. The experiments were carried out using an eight-hole SIDI fuel injector under a controlled ambient environment with an extended range of test conditions. Using a strobe light as an illumination source, multiple cycles of macroscopic spray structure images at a fixed injection delay time were taken by a CCD camera. The proper orthogonal decomposition (POD) technique was implemented to analyze the cycle-to-cycle characteristics of spray variation. In addition, the effects of injection pressure, ambient pressure, and fuel type on spray variation were also investigated. POD analysis reveals that the mode 1 pattern captured the ensemble-averaged spray shape, the mode 2 pattern provided quantification of spatial fuel distribution variations of different cycles of spray, and higher mode patterns further quantified the finer details of the variations surrounding the well-atomized periphery of the spray structure. POD analysis also quantitatively confirms that better-atomized sprays led to slightly higher variations of finer structures along the spray boundary. Overall, this study demonstrates that POD analysis can be used as a novel approach to quantify the cycle-to-cycle variation of pulsing spray characteristics.
EXPERIMENTAL INVESTIGATION OF THE ATOMIZATION CHARACTERISTICS OF ANTICORROSION WAX
643-662
10.1615/AtomizSpr.2013007919
Sanghoon
Lee
Graduate School, Hanyang University, Seoul 133791, Republic of Korea
Sungwook
Park
School of Mechanical Engineering, Hanyang University, Seoul 133791, Republic of Korea
anticorrosion wax
SMD (Sauter mean diameter)
atomization characteristics
We investigated the spray characteristics of continuous-flow nozzles using anticorrosion wax. Based on particle image velocimetry (PIV) and phase Doppler particle analyzer (PDPA) experiments during spray injection, we calculated the velocity field of the entire spray and analyzed the atomization processes. All experiments were performed under ambient conditions (atmospheric pressure and room temperature) with an injection pressure of 10 MPa. For the PIV experiment, a frequency-doubled Nd:YAG laser having 25 mJ/pulse energy and a time interval of 30 s and a CCD camera synchronized with the laser pulse were used. The captured images from the CCD camera were processed using Matlab software to increase the image quality prior to applying a PIV algorithm. In this process, the intensities of each pair of consecutive images were harmonized, and droplet edge enhancement was also carried out. In addition, in order to investigate the droplet atomization processes, a PDPA system was employed to measure the distribution of droplet diameter and velocity during the spray injection at a distance of 20 mm, 40 mm, and 60 mm from the nozzle. The wax spray had a cone angle of 33.2° at an injection pressure of 10 MPa. Larger droplets of higher velocity were observed in the region of the nozzle, but as the droplets proceeded in the axial direction, smaller droplets of lower velocity were observed. Most of the droplets in the spray had a velocity between 40 and 60 m/s. By comparing the Sauter mean diameter (SMD) profiles and velocity distributions at distances of 20, 40, and 60 mm from the nozzle, droplet atomization was found to be markedly affected by distance. That is, as distance increases, the droplets tend to be smaller and of lower velocity due to loss of momentum. Comparing the droplet velocity distributions obtained by the PIV and PDPA, similar trends are observed at a distance of 20 mm, such as the maximum velocity value of 78 m/s and symmetric distribution of the peak value. Also, we confirmed that the PDPA result showed more detailed information regarding velocity distribution.