• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.717-722
• /
• 2003

The aspect ratio is the main parameter which governs the outer flow pattern and nozzle performance. And in this study, some flow characteristics with the variation of nozzle aspect ratios such as mean pressure distributions along the center line of the outer flow, flow coefficients and the diffusion angles have been experimentally investigated. Through the experimental analysis, the higher aspect ratio was known to decrease the jet kinetic energy because of the friction losses at the outer of nozzle. As the result, it is found that the nozzle performance depends mainly on the aspect ratio of nozzle.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
• /
• pp.583-586
• /
• 2017

마이크로 터보제트엔진을 이용하여 S형상 배기노즐의 플룸의 적외선 신호 특성을 이해하기 위하여 적외선 신호 특정 연구를 수행하였다. 엔진 배기노즐은 원형노즐과 가로세로비가 5인 사각형 노즐 그리고 가로세로비가 5.2인 S형상의 배기노즐을 제작하여 실험을 수행하였다. 배기가스에서 방출되는 적외선 신호는 가로세로비가 클수록 적외선 신호의 크기가 점차 감소하는 경향을 보였고 배기노즐의 형상이 S형상의 경우 사각형 노즐 보다 적외선 신호가 28.4% 감소하는 것을 확인하였다.

• 대한기계학회논문집B
• /
• 제28권11호
• /
• pp.1459-1466
• /
• 2004

The purpose of this study is to investigate the effect of swirler angle and the aspect ratio of swirl chamber of nozzle on the characteristics of single and twin spray. The characteristics of sprays have been investigated by measuring the spray angle, droplet size and velocity. Visualization of spray was conducted to obtain the spray angle and breakup process. The spray characteristics such as droplet size and velocity were measured by Phase Doppler Anemometry(PDA). It was found that the spray angle was increased with increasing the swirler angle. For both sprays, the axial velocity and SMD were decreased with increasing the swirler angle. It was also shown that the axial velocity and SMD were decreased with increasing the aspect ratio of swirl chamber, but for the twin spray, the axial velocity and SMD were not influenced significantly by the changing the aspect ratio of swirl chamber. The effect of swirler angle on the spray characteristics was greater than the aspect ratio of swirl chamber for single spray. The nozzle pitch was one of the important factors affecting the spray characteristics of twin spray.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2002년도 학술대회지
• /
• pp.233-236
• /
• 2002

The high-pressurized spray nozzle is used f3r special washing and cutting with strong impact force. The performance of this nozzle, which focused on spray penetration and radial dispersion, was mainly investigated to maximize the momentum and minimize the flow loss. Hence, our experimental research was conducted by changing the aspect ratio ranging from 0 to 3 with nozzle outlet of 1.1. The spray trajectory far high-pressurized water was experimentally investigated using PDPA diagnostics, which was available at spray downstream region. As the spray at upstream near the nozzle exit did not show the improved disintegration. The results showed empirical correlation with regard to non-dimensional axial velocity distribution, spray penetration, and radial spreading rate with photographic visualization.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.2031-2036
• /
• 2003

High-pressurized jet is widely using in industrial works. however, few papers studied on the performances or characteristics on that kind of nozzles. And in this study, some flow characteristics with the variation of nozzle aspect ratios such as mean velocity distributions, momentum variations along the center line have been experimentally investigated. As the results, some semi-empirical correlations of profiles of pressure and mean velocity distributions, momentum conservations with the nozzle aspect ratios are formulated. It is expected that these empirical formula can be applied for the random estimations of nozzle performances.

• 한국분무공학회지
• /
• 제8권4호
• /
• pp.39-45
• /
• 2003

The Objective of this study is to investigate the effect of internal swiller angle and swirl chamber aspect ratio of nozzle on spray characteristics for application of spray system in micro fabrication process. The macro-spray characterictics such as the spray angle and breakup process were obtained by photographs illustrating atomization. The micro-spray characteristics such as droplet size and axial velocity were measured by using PDA with swirler angle and swirl chamber aspect ratio. The swiller angles were $13.5^{\circ},\;27^{\circ},\;and\;40.5^{\circ}$. The swirl chamber aspect ratios were 1.2, 1.6, and 2.0. It was found that the smaller swirl chamber aspect ratio was, the larger axial velocity and drop size were.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
• /
• pp.682-685
• /
• 2017

본 연구는 비원형 Effervescent Type 이유체 노즐의 분사 특성을 조사하기 위한 실험적 연구를 수행하였다. 이를 위해 거의 동일한 노즐 출구 면적으로 가공한 2종류의 비원형 노즐 (E1, E2)과 1종류의 원형 노즐 (C)을 대상으로 비교 실험을 진행하였다. 이때 노즐에 장착된 Aerorator는 노즐 출구 면적과의 Aspect Ratio를 맞추기 위해 지름이 다른 3종류를 사용하였다. 따라서 각 노즐마다 3가지의 Aspect Ratio에 따라 3번의 실험을 진행하였으며, 전체 총 9종의 실험이 진행되었다. 실험은 Liquid의 유량을 고정시킨 후, 유입되는 Air의 양을 제어하며 진행하였으며, 노즐 내부 압력과 액적의 크기 (SMD)를 측정하고 노즐에서 분사 이미지를 촬영하였다. 이를 통해 3종의 노즐의 유량 계수를 압력 분무방정식과 Jedelsky 방정식을 비교 계산하였고, Jedelsky 방정식이 약 4배 정도 더 큰 값을 갖는 것을 확인하였다. 노즐에서 분사되는 SMD는 원형보다 비원형에서 더 작은 값을 갖는 것으로 나타났으며, 이는 유량 계수 값의 차이 의해 야기된 것으로 예상된다.

• 대한기계학회논문집A
• /
• 제25권4호
• /
• pp.564-573
• /
• 2001

The mechanical properties of short carbon/glass fiber reinforced polypropylene are experimentally measured as functions of fiber content and nozzle diameter. Also, these properties are compared with the survival rate of reinforced fibers and fiber volume fraction using image analysis after pyrolytic decomposition. The survival rate of fiber aspect ratio as well as fiber volume fraction is influenced by injection processing condition, the used materials and mold conditions such as diameter of nozzle, etc. In this study, the survival rate of fiber aspect ratio is investigated by nozzle size variations in injection/mold sides. It is found that the survival rate of glass fiber is higher that the survival rate of glass fiber is higher than that of carbon fiber. Both tensile modulus and strength of short-fiber reinforced polypropylene are improved s the fiber volume fraction and nozzle diameter are increased.

• 대한기계학회논문집
• /
• 제16권6호
• /
• pp.1156-1162
• /
• 1992

본 연구에서는 종횡비가 다른 3가지의 날카로운 모서리를 가진 타원 슬롯노즐 (AR=1,2,4)을 풍동 수축부 끝에 장착하여 타원제트의 유동특성 및 축교차현상을 3-D LDV 시스템을 이용하여 조사하였다.

• 한국분무공학회지
• /
• 제10권4호
• /
• pp.1-7
• /
• 2005

The purpose of this study is to investigate the effect of swirler vane angle and the aspect ratio of swirl chamber of nozzle on the characteristics of single spray. The characteristics of sprat's have been investigated by measuring the spray angle, droplet size and velocity Visualization of spray was conducted to obtain the spray angle and breakup process. The spray characteristics such as droplet size and velocity were measured by Phase Doppler Anemometry(PDA). It was found that the spray angle was increased with increasing the swirler angle. For both sprays, the axial velocity and SMD were decreased with increasing the swirler vane angle. It was also shown that the axial velocity and SMD were decreased with increasing the aspect ratio of swirl chamber The effect of vane angle un the spray characteristics was greater than the aspect ratio of swirl chamber for single spray.