• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.219-227
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• 1998

This paper describes the fuel spray characteristics of gasoline port injectors such as the breakup procedures of liquid fuel, breakup and extinction behaviors of fuel spray at nozzle tip, time history of SMD and velocity distribution of fuel spray in the direction of fuel stream. Pintle-type gasoline fuel injector was used to analyze mentioned spray characteristics. In order to visualize the fuel spray behaviors and to measure the droplet mean diameter and velocities of spray droplets, the Schlieren method, digital image processing and auto-correlation PIV were applied in this study. In addition, the spray characteristics according to the variation of time were considered. The results of fuel spray show that the liquid sheet breakup starts at 10mm downstream actively. The flying time is approximately 4msec between 50mm and 80mm down the nozzle tip. Also, SMD of fuel spray, the number of droplets and fuel velocity distribution at each point of downstream are discussed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.125-128
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• 2008

Atomization characteristics of small LRE-injector spray are investigated by using dual-mode phase Doppler anemometry (DPDA). Velocity, size, number density, and volume flux were measured at various injection pressures along the radial distance to make a close inquiry into spatial distribution characteristic of spray droplets. As the injection pressure increases, the velocity, turbulence intensity, number density, and volume flux of spray droplets become higher, whereas the droplet size ($D_{10}$ or $D_{32}$) gets smaller. Also, velocity and volume flux are proportional to Sauter mean diameter (SMD, $D_{32}$).

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.1
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• pp.26-33
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• 2007

The intake swirl motion, as one of dominant effects for an engine combustion. is very effective for turbulence enhancement during the compression process in the cylinder of 2-valve engine. Because the combustion flame speed is determined by the turbulence that is mainly generated from the mean flow of the charge air motion in intake port system. This paper describes the experimental results of swirl flow and combustion characteristics by using the oil spot method and back-scattering Laser Doppler velocimeter (LDV) in 2-valve single cylinder transparent LPG engine using the liquid phase LPG injection. For this. various intake port configurations were developed by using the flow box system and swirl ratios for different intake port configurations were determined by impulse swirl meter in a steady flow rig test. And the effects of intake swirl ratio on combustion characteristics in an LPG engine were analyzed with some analysis parameters that is swirl ratio. mean flow coefficient, swirl mean velocity fuel conversion efficiency. combustion duration and cyclic variations of indicated mean effective pressure(IMEP). As these research results, we found that the intake port configuration with swirl ratio of 2.0 that has a reasonable lean combustion stability is very suitable to an $11{\ell}$ heavy-duty LPG engine with liquid phase fuel injection system. It also has a better mean flow coefficient of 0.34 to develope a stable flame kernel and to produce high performance. This research expects to clarify major factor that effects on the design of intake port efficiently with the optimized swirl ratio for the heavy duty LPG engine.

• Journal of Industrial Technology
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• v.6
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• pp.19-31
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• 1986

The residence time distribution of liquid flow in a 4.0cm diameter column packed with porous $Al_2O_3$ spheres of 0.37cm diameter were measured with pulse injections of a tracer under cocurrent trickling flow conditions. The mean residence time of liquid flow and liquid hold-up calculated by the transient curve of tracer were unaffected by gas flow rates under experimental ranges of liquid flow rates from 2.4 to $4.5(kg/m^2\;sec)$ and gas flow rates from 0 to $0.13(kg/m^2\;sec)$. The axial dispersion coefficient of liquid stream and apparent diffusivity of tracer in a micropore of solid particle were estimated from the response curve of tracer. The calculated Peclet No. were increased in ranges of 68-to 82 with a increasing of liquid mass velocity, and the external effective contacting efficiency between liquid and solid which can be expressed. by $(D_i)_{app}/D_i$ varied in ranges of 0.54 to 0.68 depending on the liquid flow rates. The gas to liquid(water) volumetric mass transfer coefficient were determined from desorption experiments with oxygen at $25^{\circ}C$ and 1 atm. The measured mass transfer coefficients were increased with liquid flow rates and the effect of gas flow rates on the mass transfer coefficient was insignificant.

• Journal of ILASS-Korea
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• v.1 no.1
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• pp.21-27
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• 1996

This experimental study was to investigate spray angles and drop sizes in an external mixed twin-fluid swirl jet nozzle. Twin-fluid swirl jet nozzle with swirlers designed four swirl angles such as $0^{\circ},\;22.5^{\circ},\;45^{\circ},\;64.2^{\circ}$ was employed. A PDA system was utilized for the measurement of drop size and mean velocity. Water and air were used as the working fluids in this experiment. The mass flow rate of water was fixed as 0.03 kg/min, and air flow rates were controlled to have the air/liquid mass ratio from 1.0 to 6.0. As a result, swirl angle controlled to spray angles and drop sizes. It was found that swirl angle was increased with spray angle and with decreased SMD. However, the effect of swirl angle was reduced at large air/liquid mass ratio(Mr=6.0).

• Journal of ILASS-Korea
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• v.4 no.4
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• pp.24-29
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• 1999

In the pressure swirl atomizer, the liquid is injected through tangential passages into a swirl chamber, from which it emerges with both tangential and axial velocity components to form a thin conical sheet at the nozzle exit. This sheet rapidly attenuates, finally disintegrating into ligaments and then drops. The purpose of this study is to measure the spray characteristics according to variation of viscosity of the spray produced by the pressure swirl atomizer. The nozzle tested here were especially designed for this investigation. The discharge coefficient is determined by measuring the volume flow rate with a flow meter and the cone angle of the liquid sheets issuing from the nozzle is obtained from series of photographs of the sheet for various liquid viscosity and injection pressure. And mean drop size is measured by image processing method. It is found that the geometrical characteristics of the nozzle and the variation of viscosity were the influential parameters to determine the spray characteristics such as the cone angle, discharge coefficients and SMD.

• Bulletin of the Korean Chemical Society
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• v.18 no.5
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• pp.478-484
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• 1997

In a recent paper[Bull. Kor. Chem. Soc. 17, 735 (1996)] we reported results of molecular dynamic (MD) simulations for the thermodynamic and structural properties of liquid n-alkanes, from n-butane to n-heptadecane, using three different models. Two of the three classes of models are collapsed atomic models while the third class is an atomistically detailed model. In the present paper we present results of MD simulations for the dynamic properties of liquid n-alkanes using the same models. The agreement of two self-diffusion coefficients of liquid n-alkanes calculated from the mean square displacements (MSD) via the Einstein equation and the velocity auto-correlation (VAC) functions via the Green-Kubo relation is excellent. The viscosities of n-butane to n-nonane calculated from the stress auto-correlation (SAC) functions and the thermal conductivities of n-pentane to n-decane calculated from the heat-flux auto-correlation (HFAC) functions via the Green-Kubo relations are smaller than the experimental values by approximately a factor of 2 and 4, respectively.

• International Journal of Automotive Technology
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• v.5 no.1
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• pp.17-22
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• 2004

An experimental investigation was conducted to study the characteristics of turbulent swirling flow in an axisymmetric annuli. The swirl angle measurements were performed using a flow visualization technique using smoke and dye liquid for Re=60,000-80,000. Using the two-dimensional Particle Image Velocimetry method, this study found the time-mean velocity distribution and turbulence intensity in water with swirl for Re=20,000, 30,000, and 40,000 along longitudinal sections. There were neutral points for equal axial velocity at y/(R-r)=0.7-0.75, and the highest axial velocity was recorded near y/(R-r)=0.9. Negative axial velocity was observed near the convex tube along X/(D-d)=3.0-18.0 for Re=20,000.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.251-253
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• 2017

Numerical study of air-blast type injector for low emission aircraft engines was conducted. Volume-of-fluids approach was used to track interface of fuel and air. Primary atomization of fuel stream was visualized, and thickness and mean velocity at the injector exit was calculated. Liquid fuel injected from fuel slots joined together as a thin film on preflimer surface, and interacted with swirling air. As instability on the fuel surface increased, separation of fuel as ligaments and droplets occured. The film thickness and velocity were used to as fuel injection boundary condition for reactive flow simulation. Primary reaction zone was formed in vicinity of the fuel nozzle, creating a stable flame inside the combustor.

• Journal of the Korean Society of Visualization
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• v.8 no.4
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• pp.60-65
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• 2010

A focus is given to the breakup behavior of spray droplets issuing from a nonimpinging-type injector. The analysis has been carried out experimentally by means of the dual-mode phase Doppler anemometry (DPDA). Spray characteristic parameters in terms of axial velocity, mean diameter, velocity fluctuation, and span (width of the size distribution) of droplets are measured down the geometric axis of a nozzle orifice and on the plane normal to the spray stream with the injection pressure variations. As the injection pressure increases, the velocity and its fluctuation become higher, whereas the droplet sizes get smaller. It is also shown that the magnitudes of those parameters are smoothed out by dispersion when the droplets move downstream as well as outwardly. The atomization process is significantly influenced by the injection pressure rather than the traveling distance in the experimental condition presented.