• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.354-358
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• 2007

An experimental study was performed to understand spray characteristics of the slinger injector. system for the micro turbojet engine. In this fuel injection system, fuel is sprayed and atomized in the combustor by centrifugal forces of engine shaft. This experimental apparatus consist of a high speed rotating Spindle, slinger injector, pressure tank and acrylic case. The droplet size and velocity were measured by PDPA(Phase Doppler Particle Analyzer) and spray was visualized by using Nd-Yag laser-based flash photography. From the test results, the droplet size(SMD) is largely affected to rotational speed, mass flow rate and the number of injection orifice. From the this experimental study, we could understand the spray characteristics of the slinger injection system and obtain the optimum shape of the slinger injector nozzle which is suitable for the micro turbojet engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.40-47
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• 2010

This study deals with the investigation about the effect of the pilot and split injection strategies on the spray-atomization characteristics of biodiesel fuel derived from a soybean oil. Experimental results were compared with the calculation results obtained from the numerical analysis. Fuel properties of biodiesel according to the variation of the fuel temperature were inserted to the fuel library in the KIVA code. The amount of fuel injection is divided into equal mass for each split and main injection. In this work, the pilot injection strategy can be achieved by the amount of fuel injection shortly before the start of the main injection. A spray tip penetration, radial distance and spray area were measured for the analysis of macroscopic spray characteristics. In addition, the local and overall droplet size distribution were calculated by using KIVA-3V code to study the effect of split and pilot injection on the atomization performance under high ambient pressure. From these studies, the experimental results showed the multiple injection induced the decrease of the spray tip penetration due to the reduction and division of the spray momentum compared to single injection. In the atomization performance, the droplet size increased in the case of the multiple injection a little. Moreover, the SMD slightly increased as the fuel droplets goes through the axial direction. The spray behavior of numerical results were well predicted the experimental multiple spray characteristics of biodiesel fuel.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1121-1129
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• 1988

An economic and efficient system for measuring drop sizes was developed. Pattern recognition technique was used with conventional oil-bath sampling and photographic method. The system was designed to measure and count relatively large number of drops in a very short time, and also to filter out abnormal images such as drops in contact or overlap as well as odd-shaped foreign materials. In this measuring system, most important error originates from the process of converting the original image to the binary image. If the photograph contains a large number of spray drops, the relative size of the pixel to the drops is not infinitesimally small; thus the proper choice of threshold level to convert the original image to the binary image becomes very important. In present case, most of the images lay in one of the two separate bands of brightness level and the arithmetic mean of the most popular brightness levels from each band was chosen as the threshold level. Present image processing system reduces the subjective error by the observers in counting and measuring drops and turns out to be substantially effective. The processing time can be further reduced by improving the hardware system concerned with the digital image coding.

• Journal of the Korean Society of Visualization
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• v.21 no.1
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• pp.94-102
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• 2023

Three design parameters were considered in this study: outlet nozzle angle (30°, 60°, 80°), neck length (1 mm, 3 mm), and flow rate (0.5, 0.6, 0.7, 0.8 lpm). A neck diameter of 0.5 mm induced cavitation flow at a venture nozzle. A secondary transparent chamber was connected after ejection to increase bubble duration and shape visibility. The bubble size was estimated using a Gaussian kernel function to identify bubbles in the acquired images. Data on bubble size were used to obtain Sauter's mean diameter and probability density function to obtain specific bubble state conditions. The degree of bubble generation according to the bubble size was compared for each design variable. The bubble diameter increased as the flow rate increased. The frequency of bubble generation was highest around 20 ㎛. With the same neck length, the smaller the CV number, the larger the average bubble diameter. It is possible to increase the generation frequency of smaller bubbles by the cavitation method by changing the magnification angle and length of the neck. However, if the flow rate is too large, the average bubble diameter tends to increase, so an appropriate flow rate should be selected.

• Applied Chemistry for Engineering
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• v.32 no.5
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• pp.562-568
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• 2021

An O/W (oil in water) emulsion, wheat germ oil raw material, was produced by using natural wheat germ oil and composite sugar-ester. The effects of variables such as the hydrophile-lipophile balance (HLB) value, added emulsifier amount, and emulsification time on the average particle size, emulsification viscosity and ESI of O/W wheat germ oil emulsion were investigated. The parameters of the emulsification process produced by the central composite design model of the response surface methodology (CCD-RSM), which is a reaction surface analysis method, were simulated and optimized. The optimum process conditions obtained from this paper for the production of O/W wheat germ oil emulsion were 8.4, 6.4 wt%, 25.4 min for the HLB value, amount of emulsifier, and emulsion time, respectively. The predicted reaction values by CCD-RSM model under the optimum conditions were 206 nm, 8125 cP, and 98.2% for mean droplet size (MDS), viscosity, and ESI, respectively, based on the emulsion after 7 days. The MDS, viscosity and ESI of the emulsion obtained from actual experiments were 209 nm, 7974 cP and 98.7%, respectively. Therefore, it was possible to design an optimization process for evaluating the stability of the emulsion of wheat germ oil raw material by CCD-RSM.

• Journal of Hydrogen and New Energy
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• v.28 no.3
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• pp.300-307
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• 2017

This study is to investigate particle size and velocity profile of gasoline port injector using Phase Doppler Particle Analyzer (PDPA). In this experiment, a GV 250 Delphi port injector used for motorcycles was used for liquid injection. The injector consists of four holes and has a static flow rate of 2.13 g/s. The fuel used in the injection was N-heptane, which is similar to gasoline, as an alternative fuel. The test fuel was injected at an atmospheric temperature of $20^{\circ}C$ and an open atmosphere of 1 atm. The injection time was 10 ms and the injection pressure was 3.5 bar in PDPA experiment. The experimental target position was fiexd at 30, 50 and 75 mm from the nozzle tip and data were collected for a total of 10,000 samples. The experimental results show that the length diameter (D10), the Sauter mean diameter ($D_{32}$), and the mean droplet velocity (MDV) are $45-54{\mu}m$, $99-115{\mu}m$ and 15-21 m/s, respectively.

• Journal of ILASS-Korea
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• v.1 no.2
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• pp.66-73
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• 1996

The present study investigates experimentally the characteristics of liquid jet, which is, the spray flow in the normal direction of the air stream under the flow conditions of air velocity $110\sim125m/s$. The present study adopts with the flow visualization technique using a short duration light bulb and the image processing analyse with CCD camera. Two types of injector were used: one is a flat plate type, and the other is backward facing step type, which height are 5, 8, 10mm. Dispersion of liquid jet can be represented by gray level of CCD camera. In the upstream of liquid jet, the backward facing step shows better liquid jet penetration. However, in the downstream. mean droplet size for backward facing step injector is smaller than that for flat plate injector

• Journal of the korean Society of Automotive Engineers
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• v.7 no.4
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• pp.57-66
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• 1985

This paper deals with an experimental study on a liquid atomization to investigate the break- up mechanism of a liquid film flow which is formed by a high speed air flow in parallel direction and an atomization characteristics of a liquid film flow in order to provide the basic data for the development of the twin fluid atomizer. Authors had built the simplified, transparent new devices which can form a uniform thickness of liquid film and an electrical measuring circuit of the liquid film thickness. By introducing the new devices and the measuring circuit, the time variation of a liquid film thickness the mean diameter of the droplets, the droplet size distribution, the degree of the dispersion and the atomization rate of a liquid film are measured experimentally. As the analysis of the study, it can be said the experimental investigation will fairly contribute for further study in this field of study.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.52-58
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• 1998

The spray characteristics of air-assisted fuel injection and its effects on the engine combustion was investigated in this study. The atomization characteristics of a Bosch fuel injector inserted into the air-assist adapter were measured using particle motion analysis system. Droplet size decreased with air supplied and fine spray with below $60\mu\textrm{m}$ of SMD was acquired under the conditions of air-assist pressure over 0.5bar. The lean combustion performance of a 1.8L DOHC engine equipped with air-assist adapters was tested on the dynamometer. When the assistant air pressure is 1.0bar, lean limit recorded the highest value, and CO, HC emissions were decreased at the pressure over 1.0bar.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.3
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• pp.102-108
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• 1992

To clarify the structure of a diesel spray, a transient non-evaporating diesel spray injected under different ambient pressure and different injection pressure was studied. Spray tip penet- ration and spray angle were measured by taking the high speed shadowgraph of spray and Sauter mean Diameter(SMD) was also measured by light scattering technique at different positions along the spray axis and at different time from the start of injection. The effects of the operating parameters on the spray shape and SMD were investigated. By increasing the injection pressure, the spray tip penetration and the spray angle increased and the change of the ambient pressure also resulted in the considerable change in the shape of the spray. The analysis of SMD measurement showed that the atomization is a process that continues in sp- ace and time. As the injection pressure increases SMD decreases rapidly and with the increa- se of the ambient pressure the atomization process ends faster than the lower ambient press- ure and at lower pressure the atomization process continues to much farther downstream and far afterward.