• 한국분무공학회지
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• 제2권3호
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• pp.8-16
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• 1997

Ta investigate characteristics and spray of emulsified fuet we are mixed water with diesel oil using ultrasonic energy fuel feeding system. Separation ratio of emulsified fuel was shown good condition that of water content is small and longer ultrasonic energy adding time. Viscosity of emulsified fuel increased 79% with addition to water content and surface tension increased 1.6% in comparision to pure diesel oil. The SMD of emulsified fuel adding ultrasonic energy decreased with 3% in comparision to pure diesel oil. With increasing 5, 10% water content the SMD decreased 15.6, 20.1% in comparision to pure diesel oil. The mind-explosion was investigated with 4step.

• 한국자동차공학회논문집
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• 제10권5호
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• pp.90-97
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• 2002

The interaction between airflow and liquid phase LfG (Liquefied Petroleum Gas) sprays was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of flow inside intake port of LPG engines with liquid injection system. The spray developments in flowing fields with the mean velocities of 5.4, 21.5 and 42.4m/s were identified by spray visualization techniques such as Mie scattering and shadowgraph. The microscopic visualization using a telescopic lens system was performed to investigate the shape and size of liquid droplets in the spray. PDA measurement was used to get 1-dimensional velocity and diameter of liquid droplets. The fast co-flows make the spray field be compact and be lead upward to the injection direction. SMD of the spray was smaller at the fast flowing field. Spray width got bigger and SMD of the spray was smaller with higher injection pressure.

• 한국안전학회지
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• 제16권2호
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• pp.13-21
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• 2001

The effect of water spray for the fire sprinkler depends on droples distribution over maximum possible floor area. The present study are carried out for the characteristics of water spray and droplets experimentally and numerically km two fire sprinkler heads which are CHM head and CHl heal CHl head is self-production and CHl head is widely used up to date. As the result of using CHM head, water spray and droplets are distributed over large area because CHM head has smooth surface and non-flamed shape. When the pressure of fire sprinkler head is low, SMD(sauter mean diameter) is large and when the pressure of fire sprinkler head is high, SMD is small.

• Journal of Mechanical Science and Technology
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• 제17권5호
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• pp.766-775
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• 2003

The intermittent spray characteristics of a multi-hole diesel nozzle with a 2-spring nozzle holder were investigated experimentally. Without changing the total orifice exit area, the hole number of the multi-hole nozzle varied from 3 (d$\_$n/=0.42 mm) to 5 (d$\_$n/=0.32 mm). The time-resolved droplet diameters of the spray including the SMD (Saute. mean diameter) and the AMD (arithmetic mean diameter), injected intormittently from the multi-hole nozzles into still ambient ai., were measured by using a 2-D PDPA (phase Doppler particle analyze.). The 5-hole nozzle spray shows the smaller spray cone angle, the decreased SMD distributions and the small difference between the SMD and the AMD, compared with that of the 3-hole nozzle spray. From the SMD distributions with the radial distance, the spray structure can be classified into the three regions : (a) the inner region showing the high SMD distribution , (b) the mixing flow region where the shea. flow structure would be constructed : and (c) the outer region formed through the disintegration processes of the spray inner region and composed of fine droplets. Through the SMD distributions along the spray centerline, it reveals that the SMD decreases rapidly after showing the maximum value in the vicinity of the nozzle tip. The SMD remains the constant value near the Z/d$\_$n/=166 and 156.3 for the 3-hole and 5-hole nozzles, which illustrate that the disintegration processes of the 5-hole nozzle spray proceed more rapidly than that of the 3-hole nozzle spray.

• 한국항공우주학회지
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• 제47권3호
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• pp.204-211
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• 2019

희박연료 직접분사(Lean Direct injection(LDI)) 가스터빈 연소기에 대한 이상유동 특성을 해석하였다. LDI 연소기에 적용된 환형분사기(hollow-cone spray injector)의 분열을 모사하기 위해 분열모델(Linearized Instability Sheet Atomization(LISA), Aerodynamically Progressed Taylor Analysis Breakup(APTAB)을 적용하였다. 침투깊이와 평균입도(Sauter Mean Diameter(SMD))를 통해 분열모델을 검증하였으며, LDI 연소기에 적용하여 이상유동특성을 분석하였다. 스월인젝터로 인해 Precessing Vortex Core(PVC)가 발생하였으며, 액적들이 PVC를 따라 미립화되는 것을 확인하였다. SMD 결과를 통해 PVC가 회전하는 영역의 외곽으로 즉, 빠른 속도 영역에 액적들이 분포하며, 스톡스수(Stokes number)는 1보다 작다.

• 대한기계학회논문집B
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• 제23권1호
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• pp.92-103
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• 1999

The fuel spray behavior in the intake port of an electronic control port irijection gasoline engine has a strong influence on engine performance, exhaust emission and fuel consumption. Thus, in this study, fuel spray behavior and flow characteristics of the air assist gasoline spray injected into a suction flow in a simulated rectangular intake port have boon investigated. Macro-behavior of spray characteristics was investigated by means of visualization and the measurements of SMD and velocity were made by PDPA. For analysis the flow field with droplets size, droplets are classified five droplets size groups. As a result, the normal distance of suction flow increasing, the relatively large droplets distribution and SMD increase because small droplets easily follow suction flow. Near impinging wail, after impinging against the wall, secondary atomized small droplets of D < $30{\mu}m$ bound from the wall. And the increasement of suction flow progress to the large droplets of D > $100{\mu}m$ distribution. Therefore, SMD are apparently increased near impinging wall, Z/d = 9.0.

• 한국분무공학회지
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• 제17권1호
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• pp.35-44
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• 2012

To improve the mixing and atomizing performance at the center region of the conventional coaxial shear injector spray, the concept of a coaxial porous injector was invented. This novel injection concept for liquid rocket engines utilizes the Taylor-Culick flow in the cylindrical porous tube. The 2-dimensional injector, which can be converted in three injection configurations, was fabricated, and several cold flow tests using water-air simulant propellant was performed. The hydraulic characteristics and the effects of a gas flow condition on the spray pattern and the Sauter mean diameter (SMD) was analyzed for each configuration. The atomizing mechanism of coaxial porous injector was different with the coaxial shear injector, and it was explained by the momentum of the gas jet, which is injected normally against the center liquid column, and by the secondary disintegration at the wavy interface of liquid jet, which was generated at the recessed region. The SMD of 2D coaxial porous injector, which has higher gas momentum, was measured and it shows better atomizing performance at the center and outer side of spray than the 2D coaxial shear injector.

• 한국추진공학회지
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• 제12권1호
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• pp.29-36
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• 2008

APU 가스터빈에 적용되는 연료노즐의 분무특성을 확인하였다. 분무시험은 항공기의 비행조건에 따라 4개의 작동조건에 대하여 수행하였으며 각 분무조건은 지상에서의 무부하 및 통합부하 조건과 고도 20,000 feet에서의 무부하 및 통합부하에 대해서 실험을 수행하였다. 분무특성은 레이저 빔을 이용한 가시화와 PDPA 시스템을 이용하여 SMD 및 속도측정을 수행하였으며 노즐출구에서 $20{\sim}100\;mm$지점에서 측정하였다. 연구결과 20,000 feet 무부하 조건의 경우 $90{\sim}95\;{\mu}m$ 정도의 SMD를 나타내었고 지상무부하의 경우 약 $60{\sim}75\;{\mu}m$로 측정되었으며 20,000 feet 통합부하의 경우 약 $55{\sim}65\;{\mu}m$ 지상 통합부하의 경우 $30{\sim}70\;{\mu}m$의 값을 나타내었다. 20,000 feet 무부하의 경우 화염 불안정이 발생할 가능성이 있으므로 연료분무입자의 크기를 감소하는 다양한 노력이 요구된다.

• 한국분무공학회지
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• 제1권3호
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• pp.51-59
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• 1996

An experiment was carried out on the structure of twin spray from pressurize-swirl nozzles, in order to investigate the effect of different size of spray nozzles on the characteristics of the overlap of two single sprays, for example, mean diameter, number density, and spatial distribution of flow rate. Using image processing method, the distributions of size and velocity of droplets of a single spray and twin spray were measured and compared to investigate the overlapping effect of two identical sprays. Comparing experimental results from a twin-spray with those from two-single sprays shows that the flow rate distribution of the twin-spray was concentrated around the midst of the overlapping region of two sprays. In this region, Sauter mean diameter (SMD) did not change much in the twin spray from 6032 nozzles, but it was smaller by 10 micrometers in the twin-spray than two-single sprays from 60063 nozzles. In spite of large difference in Weber numbers of the colliding sprays between the 60063 and 6032 nozzles, the phenomena did not have a big change in the overlapping region of twin spray. This shows that in the collision between droplets from two single spray in the overlapping region to cause the disruption of droplets, the size distribution of spray droplets was also important as well as Weber number.

• 한국분무공학회지
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• 제26권1호
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• pp.18-25
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• 2021

The objective of this study is to investigate the effect of cryogenic intake air temperature on the injected fuel droplet behavior in a compression ignition engine under the different start of energizing timing. To achieve this, the intake air temperatures were changed from -18℃ to 18℃ in steps of 9℃, and the result of fuel evaporation rate, Sauter mean diameter, and equivalence ratio distributions were compared. When the intake air temperature decreased in steps of 9℃, less fuel was evaporated by about 3.33% because the cylinder temperature was decreased. In addition, the evaporated fuel amount was increased with retarding the start of energizing timing because the cylinder temperature raised. However, the difference was decreased according to the retarded start of energizing timing because the cylinder pressure was also increased at the start of fuel injection. The equivalence ratio was reduced by 5.94% with decreasing the intake air temperature. In addition, the ignition delay was expected to longer because of the deteriorated evaporation performance and the reduced cylinder pressure by the low intake air temperature.