• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.37-40
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• 2009

This study was performed to design of $H_2O_2$/Kerosene catalyst ignition injector and cold flow test to measure the mass flow rate and spray angle. Mass flow rate and spray angle were measured by designed injector through cold flow test. Result of test kerosene mass flow rate was measured 12.88 g/s and 40 deg of spray angle at pressure drop 3 bar as same as design point. And hydrogen peroxide was measured 94.39 g/s at pressure drop 1 bar smaller than design point.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.8-22
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• 1995

Three dimensional numerical study of non-evaporating and evaporating spray characteristics was performed in a quiescent and motoring condition of direct injection diesel engine. The calculation parameter was breakup model. The breakup models used were Reitz & Diwakar model and TAB model. The modified k-${\varepsilon}$ turbulence model considering the compressibility effect due to the compression and expansion of piston was used. The calculation results of the spray tip penetration and tip velocity using the TAB model showed similar trends comparing with the experimental data. Although the evaporation rate was not nearly affected with the breakup model at the higher injection pressure, in the low injection case, the evaporation rate result using the TAB model became higher than that of R&D model. The evaporation rate was increased with the injection pressure due to the vigorous interaction with the gas field.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.4
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• pp.444-453
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• 2014

A throttleable rocket engine enables operational possibilities such as the docking of spacecraft, maneuvering in a certain orbit and landing on a planet's surface, altitude control, and entrance to atmosphere-less planets. Thus, throttling methods have long been researched. However, dual-manifold injectors, which represent one throttling method, have been investigated less than others. In this study, dual-manifold and single-manifold injectors were compared to determine the characteristics of dual-manifold injectors. Also, the effects of gas injection were investigated with various F/O ratios. To investigate the characteristics, mass flow rate, spray pattern, spray angle, and droplet size were measured. The spray angle and droplet size were captured by indirect photography. About 30 images were taken to assess the spray patterns and spray angle. Also, 700 images were analyzed to understand the droplet distribution and targeting area, moving to the right from the centerline with 1.11-cm intervals. The droplet size was obtained from an image processing procedure. From the results, the spray angle showed two transition regions, due to swirl momentum in the swirl chamber regardless of the F/O ratio. The droplet size showed similar trends in both dual-manifold and single-manifold injectors except in the low mass flow rate region. In the case of the dual- manifold injector, the spray cone was not fully developed in the low mass flow rate region due to low angular momentum in the swirl chamber.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.662-669
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• 1994

In the combustion system, the optimum spray conditions reduce the pollutant emission of exhaust gas and enhance the fuel efficiency. The spray characteristics-the drop size, the drop velocity, the number density and the mass flux, become increasingly important in the design of combustor and in testifying numerical simulation of spray flow in the combustor. The purposes of this study are to clarify the spray characteristics of twin-fluid nozzle and to offer the data for combustor design and the numerical simulation of a spray flow. Spatial drop diameter was measured by immersion sampling method. The mean diameter, size distribution and uniformity of drop were analyzed with variations of air/liquid mass flow ratio. The results show that the SMD increases with the liquid supply flow rate and decreases with the air supply velocity. The radial distribution of SMD shows the larger drops can diffuse farther to the boundary of spray. And the drop size range is found to be wider close to the spray boundary where the maximum SMD locates.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.2 s.233
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• pp.279-286
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• 2005

This study presents experimental results on the heat transfer coefficients in the film boiling region of spray cooling for actual metallurgical process. In this study, the heat flux distributions of a two dimensional dilute spray impinging on a hot plate were experimentally investigated. A stainless steel block was cooled down from intial temperature of about $800^{\circ}C$ by twin fluid (air-water) flat spray. It was found from the experimental results that the heat transfer area was classified into the stagnation region and wall-flow region. In the stagnation region, the experimental data of local heat transfer coefficient was closely correlated with the local droplet-flow-rate supplied from the spray nozzle directly. Thus, the local heat transfer coefficients are in good agreement with the predicted values from the correlations proposed by our previous study. In wall-flow region, however, remarkable differences are observed between experimental data and predicted values because the number of rebound droplets increase with increasing the distance from the stagnation point.

• Journal of the Korean Chemical Society
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• v.64 no.5
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• pp.259-266
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• 2020

The main purpose of this study is to examine the different physicochemical properties of spray-dried products. The carrier agents and powders after the spray-drying process were analyzed for encapsulation yield, moisture content, color parameters, total polyphenol content (TPC), antioxidant capacity (AC), bulk density, flowability, wettability, hygroscopicity, water solubility index (WSI), particle size and microstructure. The spray-drying process was carried out with different carrier agents including maltodextrin (MD) and the combination of maltodextrin and gum arabic (MD-GA) with MA/GA ratio of 70/30, dried at the inlet/outlet air temperature of 160 ℃/70 ℃, 4 bar, airflow rate of 70 ㎥·h^-1 and feed flow rate of 750 mL·h^-1. The results showed that the different carrier agents have significant influences on the physicochemical properties of the powder produced by the spray-drying method. In there, while the values of recovery efficiency and flowability of spray-dried products from MD are higher than those of spray-dried products from MD-GA combination, the opposite is true for the values of TPC, AC, bulk density and wettability, whereas hygroscopicity and WSI values are equally represented in both products.

• Journal of ILASS-Korea
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• v.15 no.3
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• pp.115-123
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• 2010

The purpose of this study is to compare and to investigate spray characteristics of dimethyl ether (DME) and diesel fuel in the various injection pressures, ambient pressures, and the energizing durations. For the analysis of the spray characteristics, the spray visualization system including the high speed camera and the spray image analyzer is installed. The spray characteristics such as the spray development process, spray tip penetraion and the spray cone angle are analyzed from the spray images. It was revealed that the spray characteristics of DME and diesel fuels are mainly affected by the injection conditions. However, in the region after the end of the injection, the spray tip penetration was affected by the fuel properties such as the fuel density, the surface tension, and the viscosity. DME fuel has generally a short tip penetration and a wide cone angle. In the elevating conditions of the ambient gas pressure, the spray cone angle of DME fuel converged to high value when comparing diesel fuel in advance. Also, the increasing rate of the spray tip penetration in DME fuel is significantly decreased from 0.7 ms of the energizing duration (diesel : 0.9 ms).

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.786-791
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• 2003

We have studied on the main causes of pressure drop in the paint hose under the spraying with airless spray pump and suggest calculation method for selecting the optimum pressure drop during the spraying. Among many factors contributing the pressure drop during the airless spraying procedure of paint, some of the key factors and the correct method for checking pressure loss between airless pump and spray gun are addressed. We have developed pressure loss calculation method which depending on hose length and diameter, viscosity and flow rate in the painting hose during the spraying. also we have developed calculation equation for the expected spray tip flow rate which depending on pressure and specific gravity and tip size.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.10
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• pp.886-893
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• 2000

A good understanding of the heat transfer distribution is very important to suppress the deformation of steel products. In this study, the local heat transfer coefficients are experimentally investigated to understand the heat transfer distribution of thick steel plates with even flat spray nozzle. The steel slabs are cooled down from the initial temperature of about $1000^{\circ}C$ , and the local heat transfer coefficients and surface temperatures are calculated from the measured temperature-time history. The results show that the local heat transfer coefficients of spray cooling are dominated by the local droplet flow rate, and in proportion to becoming more distant from the center of heat transfer surface, the local heat transfer coefficients decrease with the decrease of the local droplet flow rate.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.76-84
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• 2010

The aim of this study is to analyze the effect of the ethanol blending in diesel-ethanol blended fuels on the spray and combustion characteristics in a common-rail four-cylinder diesel engine. For the analysis of the spray characteristics, the spray images were obtained using a high speed camera with metal-halide lamps. From these spray images, the macroscopic spray characteristics such as the spray tip penetration and spray cone angle were investigated. Also, the combustion characteristics including the combustion pressure and the rate of heat release were studied with the analysis of the exhaust emissions in diesel-ethanol blended fuel driven diesel engine. It can be confirmed from the experiment on spray characteristics of diesel-ethanol blended fuels that the increased ethanol blending ratio induced the decrease of the spray tip penetration after the end of the injection. The spray cone angle slightly increased by the blending of ethanol fuel. In the experiment on atomization characteristics, the ethanol blending caused the improvement of the diesel atomization performance. On the other hand, at the same engine load condition, the increase of the ethanol blending ratio lead to lengthen the ignition delays, and to decrease the peak combustion pressure and the rate of heat release. Totally, the combustion and emission characteristics of ULSD and DE10 showed similar characteristics. However, in the case of DE20, CO and HC rapidly increased, and $NO_x$ decreased. It can be believed that 20% ethanol disturbed the combustion of diesel-ethanol blended fuel due to the low cetane number and evaporation.