• Title/Summary/Keyword: 분무특성

Search Result 1,452, Processing Time 0.028 seconds

The Study on the Spray Characteristics of Supercritical Spray (초임계상태 분무의 분무 특성에 관한 연구)

  • Park, C.J.
    • Journal of ILASS-Korea
    • /
    • v.4 no.3
    • /
    • pp.8-14
    • /
    • 1999
  • The characteristics of the breakup process in supercritical spray is investigated during the injection of supercritical sulfur hexafluoride into dissimilar gases at supercritical pressures and subcritical temperature of the injected fluid. The visualization techniques used are backlighting and shadowgraph methods. The spray angles are measured and the breakup and mixing process are observed at near and supercritical conditions. The results show that spray angles are decreased with the in..ease of the ratio of density $(\frac{\rho_f}{\rho_g})$. At the supercritical temperature, the spray angles in atomization region are kept nearly constant such as the typical spray angle in gas injection. The mixing process is changed radically at the temperature where $\frac{d\rho}{dT}=\frac{1}{2}[\frac{d\rho}{dT}]_{max}$ at given pressure.

  • PDF

Investigation on Injection Rate and Microscopic Spray Characteristics of Fine Bubble Diesel Fuel (미세버블 디젤 연료의 분사율과 미시적 분무특성에 대한 연구)

  • Chen, Hai-Lun;Lee, Seungwoo;Kim, Kihyun
    • Journal of ILASS-Korea
    • /
    • v.25 no.1
    • /
    • pp.15-20
    • /
    • 2020
  • This study aims to investigate injection rate and microscopic spray characteristics of diesel fuel containing fine air bubble (FBD). fine bubble was generated by cavitation theory using bubble generator. Fuel spray was injected into constant volume chamber and visualized by high speed camera. The injection rate data was acquired with bosch tube method. Injection rate of finebubble diesel was very similar with that of diesel. It showed slightly faster injection start by 5 ㎲ attributed to the low viscosity characteristics. In microscopic spray visualization, fine bubble diesel spray showed unsymmetric spray shape compared with diesel spray. It also showed very vigorous spray atomization performance during initial spray development. Improved atomization was also attributed to the low viscosity and surface tension of finebubble diesel fuel.

Spray Patterns and Atomization Characteristics of Viscoelastic Fluid with Impinging Jet (점탄성 유체에 따른 충돌분무의 분무패턴 및 미립화 특성)

  • Lee, Mun Hee;Hong, Jung Goo
    • Journal of ILASS-Korea
    • /
    • v.24 no.3
    • /
    • pp.145-151
    • /
    • 2019
  • Viscoelastic fluid is used in various industrial sites because its cost reduction and environmental benefits by preventing formation of fine droplets that scattered around. However, viscoelastic fluids, unlike newtonian fluids, contain a shear thinning characteristic that decrease in viscosity as shear rate increases and elastic characteristic, making it difficult to predict spray breakup process. In this study we made three test fluids. Boger fluid with viscoelastic characteristics, and two newtonian fluids, were prepared to exclude shear thinning characteristics and study the effects of elastic characteristic only. Flow visualization, spray angle, and SMD were measured for three test fluids using laboratory scale impinging jet test apparatus. As a result, it was confirmed that Boger fluid, unlike the newtonian fluid, was not formed fine droplets that scattered around and the breakup process appeared differently. In addition, SMD was found to be large in Boger fluid, and the SMD according to pressure was confirmed that there is no significant difference.

Experimental and Numerical Analysis of DME Spray Characteristics in Common-rail Fuel System (커먼레일 연료시스템에서의 DME 분무 특성에 대한 실험과 해석적 연구)

  • Jeong, Soo-Jin;Park, Jung-Kwon;Lee, Sang-In;Lim, Ock-Taeck
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.36 no.12
    • /
    • pp.1151-1159
    • /
    • 2012
  • Spray visualization and computer simulation of a DME injector have been conducted to investigate the enlarged injection hole diameter effect. To increase the reliability of the computational result, simulation results have been compared with the visualization test results, and the behaviors of a DME spray under various high-pressure and -temperature conditions have been computed. This study shows a discrepancy of 3.57% between the experimental and the computational results of penetration length for an injection pressure of 35 MPa and ambient pressure of 5 MPa. When simulating the engine conditions, the maximum penetration length of a fully developed DME spray is 42 mm when the temperature to pressure ratio is 300 K/MPa. The DME spray behavior is dominantly affected by the ambient pressure under the condition that the ratio is less than 300 K/MPa, and by the ambient temperature under the condition that the ratio is more than 300 K/MPa.

Effect of Injector Cooling on Ignition of Cryogenic Spray (분사기 냉각이 초저온 분무의 점화에 미치는 영향)

  • Kim, Do-Hun;Lee, Jin-Hyuk;Koo, Ja-Ye
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.40 no.3
    • /
    • pp.222-229
    • /
    • 2012
  • The cooling of a injector effects on the vapor pressure of cryogenic oxidizer spray, and it decides the phase transition point at the ignition process, when the combustion chamber pressure increases drastically. The phase transition of oxidizer spray affects the ignition characteristics, and several ignition tests with the LOx/$GCH_4$ uni-element coaxial swirl injector was performed in the different initial temperatures of oxidizer injector, in order to investigate the effect of injector cooling on the ignition transient characteristics. At the transition point of oxidizer phase, where the combustion chamber pressure increased over the LOx vapor pressure, the temporary quenching phenomenon of the flame occurred. The lower temperature of chilled down injector and tubing tends to move up the phase transition earlier.

Spray Characteristics of a Movable Pintle Injector with Pintle Tip Shape (가변 핀틀 인젝터에서 핀틀 팁 형상에 따른 분무특성 연구)

  • Nam, Jeongsoo;Lee, Keonwoong;Park, Sunjung;Huh, Hwanil;Koo, Jaye
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.47 no.9
    • /
    • pp.658-664
    • /
    • 2019
  • In the development of the liquid rocket engine using the pintle injector, spray characteristics such as spray angle, droplet size, and distribution of the droplets are dominant parameters. Three different kind of multi hole type pintle tip and a continuous type pintle tip were designed. In the case of multi hole pintle tip, SMD result did not have a significant difference depending on the number of holes. In analysis with visualization images, however, the droplets were uniformly distributed as the number of holes increased. Liquid droplets from continuous type pintle tip were finely atomized and dispersed uniformly than those from multi-hole type pintle tip. In addition, the thrust control by adjusting the liquid injection area of the pintle is suitable for the continuous type, which is easier to face-shutoff rather than the multi hole type. The spray angle of each pintle tip according to TMR was measured to derive a specific tendency and corresponding empirical formula.

Spray-Dried Powder Preparation and Physicochemical Properties of Green Coffee Bean Extracts (커피 생두 추출물을 이용한 분무건조 분말의 제조 및 물리화학적 품질특성)

  • Kim, Ju-Hyeon;Hong, Joo-Heon
    • Journal of Chitin and Chitosan
    • /
    • v.23 no.4
    • /
    • pp.234-243
    • /
    • 2018
  • In this study, the physicochemical properties of freeze dried (FD) and spray dried powders (SD-MD10, SD-MD20, SD-CD10, SD-CD20) from green coffee bean extract were investigated. Yields were 91.46% for FD powder and 71.63~87.98% for SD powders, respectively. The moisture content of SD powders (1.39~1.86%) was lower than that of FD powder (3.19%). L, a and b value of SD powders were higher than of FD powder. The particle size of the FD powder ($147.67{\mu}m$) was higher than that of the SD powders ($54.23{\sim}66.07{\mu}m$). The water absorption index of the SD powders (0.51-0.59) were lower than that of the FD powder (0.72). The water solubility index of the SD powders, 77.26-90.07%, was higher than that of the FD powder (70.07%). The total phenolic and flavonoid contents of SD-CD10 were 20.67 g/100 g and 8.92 g/100 g, respectively. The chlorogenic acid content of SD-CD10 (12.04 g/100 g) was higher than other SD powders. The DPPH and superoxide radical scavenging activities of SD-CD10 at $1,000{\mu}g/mL$ were 88.02% and 86.89%, respectively. The SD-CD10 was better than other SD powders on protective effects against oxidative stress in L-132 cells (87.33%). In conclusion, we provided experimental evidence that spray-dried powder of green coffee bean extracts have potential as functional food materials.

Effect of Nozzle Hole Number on Fuel Spray and Emission Characteristics of High Pressure Diesel Injector (고압 디젤 인젝터 노즐 홀 수가 연료 분무 및 배기 특성에 미치는 영향)

  • Chon, Mun Soo
    • Journal of ILASS-Korea
    • /
    • v.17 no.4
    • /
    • pp.210-215
    • /
    • 2012
  • This paper This paper presents effect of nozzle hole number on spray characteristics and engine performance. Experiments were conducted to measure spray penetration and SMD distributions using a spray visualization system and PDPA (phase Doppler particle analyzer) system. In addition, engine performance and emission characteristics were measured using a single cylinder engine and emssion measurement systems. Results showed that 8-hole-injector exhibits improved spray performances. Furthermore, soot emission was decreased with 8-hole-injector, compared to that of 6-hole-injector.

Spray characteristics of twin-fluid atomization using external-mixing sonic nozzles (외부혼합형 음속노즐을 사용한 2유체 미립화의 분무특성)

  • Park, Byeong-Gyu;Lee, Jun-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.21 no.1
    • /
    • pp.132-139
    • /
    • 1997
  • Spray characteristics of external mixing sonic twin-fluid atomization nozzles are investigated experimentally. Particle sizes are measured by the Fraunhofer diffraction method using the Malvern particle analyzer, and their radial distributions are obtained using the tomographical transformation technique. The spatial distribution of SMD shows that the drop size increases in the radial direction at a fixed liquid flow rate, and the distribution is getting uniform rapidly as the atomizing gas pressure increases. The SMD decreases as the liquid flow rate increases at a fixed GLR. It is found that the atomization efficiency of the flush type sonic nozzle is superior to that of protrusion type. The effect of laser beam diameter of the particle analyzer on the spatial SMD distribution is minor at present experimental conditions.

Comparison of LPG/Diesel Sprays in high Pressure Injection System (고압 LPG/디젤연료의 분무특성 비교)

  • 박권하
    • Proceedings of the Korean Society of Marine Engineers Conference
    • /
    • 2000.05a
    • /
    • pp.77-85
    • /
    • 2000
  • LPG gains many advantages of a high octane number low emissions and low cost over conventional fuel. The fuel has been naturally used in engines to save running cost but the first generation fuel feeding system was not satisfied with stringent requirement for exhaust emissions, A liquid direct injection system into a cylinder has been suggested as a next generation system to maximize a fuel economy as well as to reduce emissions. In this paper LPG sprays are compared with diesel sprays in a high pressured surrounding condition in order to understand the high pressure spray characteristics, The spray images show that LPG spray penetrates further soon after the injection then the sprays stays in a distant. it may explain the flashing effect of LPG.

  • PDF