Spray Behavior Characteristics Research Articles

Spray-Behavior Characteristics based on Change in Flow-Path Shape of Nozzle Tip

Spray-Behavior Characteristics based on Change in Flow-Path Shape of Nozzle Tip

Internal Cavitating Flow and External Spray Behavior Characteristics According to Length-to-Width Ratio of Transparent Nozzle Orifice

The purpose of this study is to investigate effects of length-to-width (L/W) ratio on cavitation flow inside a transparent acrylic nozzle orifice, and its effects on spray angle. Three visualization nozzles with different geometries (L/W = 2.0, 2.67, and 4.0) are used, and the working fluid is water. In order to visualize the development process of cavitation, the injection pressure of the working fluid is changed, and a high-speed camera is used with a metal-halide lamp. From experiments and analysis, some important facts are determined. As the injection pressure increases, the cavitation length and thickness increase linearly until the hydraulic flip occurs. Although the cavitation width varies according to the orifice width, the maximum cavitation thickness relative to the orifice width is almost constant at approximately 25% ∼ 30%. When the nozzle shape ratio increases, the discharge coefficient tends to increase because of the decrease in friction area. When entering the hydraulic flip region, the discharge coefficient decreases due to the reduction of the exit section area. The spray angle is affected by the cavitation number, cavitation length, cavitation thickness, and Reynolds number. The higher the injection pressure, the higher the turbulence intensity, and the greater the instability of the fluid flow.

Study on in-nozzle flow and spray behavior characteristics under various needle positions and length-to-width ratios of nozzle orifice using a transparent acrylic nozzle

This study visualizes and analyzes the changes in cavitation flow and spray characteristics that depend on the needle position and length-to-width ratios of the nozzle. We tested five needle positions that simulated the eccentricity of the needle. The length-to-width ratios were set at 2.0 and 2.67. The width of the nozzle was taken as 3 mm and 4 mm, and the length of the nozzle was fixed at 8 mm. The cross section of the test nozzles was rectangular. The injection pressure was set at 1–4 bar in 0.1 bar increments, and the inside of the nozzle was visualized using shadow graphic visualization. The flow rate of the fluid, the injection pressure applied to the inside of the nozzle, and the material properties of the fluid were measured in terms of the Reynolds number, the cavitation number, and the discharge coefficient, respectively. We analyzed the spray angle, cavitation length, and cavitation width inside the nozzle from the captured images by using image processing, as well as the correlations between the spray angle and cavitation length and width.

연료분사시기와 압력이 함정용 디젤연료의 분무 및 연소특성에 미치는 영향

The objective of this work focuses on the analysis of injection rate and macroscopic spray behavior characteristics with injection pressures as well as combustion and exhaust emission characteristics with injection timing and injection pressure by using a common rail single-cylinder diesel engine. The injection rate was measured by applying the Bosch method, and macroscopic spray behavior characteristics were analyzed with a constant-volume vessel and a high-speed camera. In addition, combustion and emission characteristics were analyzed in a common-rail single-cylinder diesel engine with precise control of fuel injection timing and pressure. For injection pressures of 30MPa and 50MPa, the injection rate was higher at 50 MPa, and the spray development (penetration) was also higher in the same elapsed time. The peak in-cylinder pressure and rate of heat release showed a tendency to decline as injection timing was delayed, and the peak in-cylinder pressure and rate of heat release were slightly higher for higher injection pressures. Higher injection pressures also reduced the mean effective pressure, while the indicated mean effective pressure and torque increased as injection timing was delayed to TDC. Nitrogen oxides had a peak level at injection timings of (30MPa) and (50MPa); carbon monoxide emissions were reduced by delaying injection timing from .

에멀젼연료 충돌분무의 거동특성에 관한 연구

In this study, to investigate the effect of spray behavior characteristics, we induce the mixing ratio of emulsified fuel using impinging spray. We formulate the emulsified fuel by mixing diesel and hydrogen peroxide(). We set the temperature of the heating plate to , , and , and set the injection pressures to 400, 600, 800, and 1000bar. The surfactants for the emulsified fuel mixture, which were mixed span80 and tween80 was mixed as 9:1, were fixed to 3% of the total volume of the emulsified fuel. We set the mixing ratio of in the emulsified fuel as emulsified fuel(EF)0, EF2, EF12, and EF22. Further, we visualize the evaporation impinging spray using the Schlieren method. Based on the results of this study, we found that a higher temperature and injection pressure of the heating plate impingement led to the active diffusion of the fuel vapor, which promoted emulsified fuel evaporation. When the emulsified fuel is utilized in an actual engine, because of the temperature-drop effect of the combustion chamber, which is due to the evaporation of in fuel and faster mixture formation is expected to decrease the engine emissions.

Experimental and numerical analysis of breakup process of biodiesel fuel spray

In this study, the experiments and the numerical analysis were performed in order to compare the spray behavior characteristics of diesel and biodiesel, which was intend to compare the spray tip penetration, the spray cone angle and the average droplet diameter. Diesel, palm oil biodiesel, waste cooking oil biodiesel, and soybean oil biodiesel were used for preparing blended fuel, and the ratios of the blended fuel were varied in the BD(Biodiesel)3~BD100 range. The injection pressures (Δpinj) was considered as an experimental variable and was set to 500 bar, 1000 bar, 1500 bar, and 1600 bar by setting injection duration to 500 μs. In the numerical analysis, the initial droplet diameter was set equally with the diameter of hole, and overall numerical analysis condition was based on the experiments. Consequently, it was found that the change of average droplet diameter did not show the large difference according to fuel mixing ratio, and then the spray tip penetration highly depends on the spray pressure rather than the mixing ratio of the fuels.

증발장에서 에멀젼연료의 거동특성에 관한 연구

본 논문은 에멀젼연료(Diesel/H₂O₂)에 있어 과산화수소의 혼합비가 혼합연료 액적증발 및 분무거동 특성에 미치는 영향을 연구하였다. 연료혼합을 위한 계면활성제는 span 80, tween 80을 9:1로 혼합하여 에멀젼연료 총 부피의 3%로 고정 혼합하였다. 또한 과산화수소의 혼합비율은 계면활성제의 혼합비를 고려하여 EF (Emulsified Fuel)0, EF2, EF12, EF22, EF32 및 EF42로 설정하였다. 에멀젼연료 액적의 증발특성을 관찰하기 위해 가열판에 액적 방울을 투하시켜 액적이 증발하는 현상을 산란광 및 쉴리렌기법을 통하여 촬영하였다. 또한 혼합비 변화에 따른 혼합연료의 분무거동특성을 해석하기 위하여 혼합연료 EF0~EF22를 선택하여 150℃로 유지된 정적용기에서 증발자유분무 거동해석 실험을 실시하였다. 그 결과 과산화수소의 혼합비율이 EF0보다 높은 EF22 에멀젼연료의 자유분무성장이 연료 속에 혼합된 과산화수소의 증발촉진으로 인하여 보다 신속하였다.

Study of behavior characteristics of diesel fuel spray according to breakup models

The atomization of the injection fuel in the diesel engine directly affects on the combustion process of engine, and as a result, it is the main factor that determines the operating performance of the engine. In this study, the breakup process of the droplets by the atomization of the injected was investigated, using the breakup models (Reitz&Diwakar, CAB, ETAB and TAB) included in the commercial numerical analysis program. In order to select the optimum model for the droplet breakup interpretation, the results of spray tip penetration, Sauter mean diameter (SMD) and momentum length obtained as each breakup model were compared with the experimental data. In the case of changing of the spray tip penetration as the research results, TAB model was measured the shorter compared to the experimental measurements, and other models showed the similarity with the experimental value. In the case of SMD analysis, the use of Reitz&Diwakar model showed the best results. In addition, the frequency of breakup which is the microscopic spray behavior characteristics considering the impact of the coefficient of contraction in the nozzle was investigated in order to determine the diameter of initial particle in the fuel injection necessary to the numerical analysis. As a result, it was found that there is suitable initial droplet diameter in numerical analysis, in the case of nozzle-hole diameter 0.12mm of this study, it was the most appropriate that the diameter of the initial particle for the numerical analysis is about 0.06mm.

바이오디젤 연료 분무의 거동특성 연구

Diesel engine is most suitable one for biodiesel fuel because the compression-ignition diesel engine has desirable fuel consumption due to higher thermal efficiency and in addition, the improvement of the fuel consumption also leads to a reduction of <TEX>$CO_2$</TEX> emission and then it does not need to have spark-ignition system, which means that there is less charge on the technic and complexity. In this study, the spray behavior characteristics of the vegetable palm oil were analyzed by using a common-rail injection system of commercial diesel engine and the results were compared with those obtained for the diesel fuel. The injection pressures and blend ratios of palm oil and diesel(BD3, BD5, BD20, BD30, BD50, and BD100) were the main parameters. The experiments were conducted for different injection pressures: 500bar, 1000bar, 1500bar, and 1600bar by setting injection duration to <TEX>$500{\mu}s$</TEX>. Consequently, it was found that there is no significant difference in the macro characteristics of the spray behavior(spray penetration and spray angle) in response to change in the blend ratio of palm oil and diesel at a fixed injection pressure. In particular, all experiments showed the spray angle about <TEX>$12^{\circ}{\sim}13^{\circ}$</TEX>.

에멀젼연료의 분무거동특성에 관한 기초연구

본 연구는 에멀젼연료(diesel/H2O2 )의 분무거동특성에 관한 기초 연구로서 에멀젼연료를 제조하여 분무거동특성에 영향을 주는 연료의 물성치(점도, 표면장력, 밀도)와 연료액적 증발특성을 조사하였다. 또한 에멀젼연료와 디젤연료의 거시적 분무거동특성인 분무선단도달거리, 분무각을 비교 분석하였다. 에멀젼연료의 교반 조건은 디젤 연료와 계면활성제 span 80, tween 80을 각각 9:1로 혼합한 유화제를 제작하여 사용 하였으며 과산화수소의 혼합비율은[EF(Emulsified Fuel)2, EF12, EF22, EF32, EF42, EF52, EF62, EF72, EF82, EF92]로 설정하였고, 분사압력은 400bar, 600bar, 800bar 및 1000bar로 설정하였다. 본 연구의 결과로서 연료의 점도는 과산화수소의 혼합비율이 증가할수록(EF52까지) 점도가 증가하나, 그 이후부터는 점도가 낮아져 기존의 디젤연료와 같은 점도를 가지게 된다. 이는 디젤의 혼합비율이 큰 EF52까지는 교반 시 수중유형(Water in Oil)이 생성되나 과산화수소의 혼합비율이 큰(EF52 이상) 에멀젼연료에서는 유중수형(Oil in Water)이 생성되기 때문이다. 또한 혼합비 변화에 따른 분무거동의 특성(분무선단도달거리, 분무각)의 변화는 크지 않았다.

디젤-가솔린 혼합연료의 혼합안정성 및 거시적인 분무 특성에 관한 실험적 연구

The study is to investigate the mixing stability, fuel properties, and macroscopic spray characteristics of diesel-gasoline blended fuels in a common-rail injection system of a diesel engine. The test fuels were mixed diesel with gasoline fuel, which were based volume fraction of gasoline from 0 to 100% in 20% intervals. In order to analyze the blended effect of gasoline to diesel fuel, the properties of test fuels such as density, viscosity, and surface tension were measured. In addition, the spray behavior characteristics were studied by investigating the spray tip penetration and spray angle using a spray images through a spray visualization system. It was revealed that the density, kinematic viscosity and surface tension of diesel-gasoline blending fuels were decreased with the increase of gasoline fuel. The injection quantity of test fuels were almost similar level at short energizing duration condition. On the other hand, the increase of energizing duration shows the decrease of injection quantity compared to short energizing duration. The test blending fuels have similar growth in Spray tip penetration and Spray cone angle.

바이오연료의 엔진 적용을 위한 분무거동 기초연구(팜유-점성고려)

디젤엔진은 바이오연료 적용을 위한 엔진으로서 가솔린엔진과 비교해 사용연료가 바이오연료와 유사한 높은 세탄가를 가지며, 가솔린엔진과 달리 점화계통 장치의 불필요 등 기존 엔진의 개조비용 등에서 유리한 장점이 있다. 따라서 본 연구에서는 상용 디젤 엔진의 커먼레일 분사시스템을 사용하여 바이오연료인 식물성 팜유의 분무거동특성을 해석하고, 그 결과를 기존의 디젤엔진 연료인 경유와 비교?분석하였다. 실험변수로서는 분사압력과 경유에 대한 바이오디젤 연료의 혼합비율(BD3, BD5, BD20, BD30, BD50, BD100)을 달리하였다. 분사압력은 500bar, 1000bar, 1500bar 및 1600bar로 설정하고 분사기간은 500μs로 동일하게 하였다. 본 연구의 결과로서, 분사압력이 동일한 경우 사용한 바이오디젤 연료의 혼합비 변화에 대한 거시적 분무거동특성(분무선단도달거리 및 분무각)의 변화는 뚜렷하지 않았다. 특히 분무각의 경우 본 연구의 모든 실험조건에 있어서 약 15°의 값을 나타내었다.

분사 조건이 다공형 GDI 인젝터의 분무 거동에 미치는 영향

The purpose of this study is to investigate the overall spray behavior characteristics for various injection conditions in a gasoline direct injection(GDI) injector with multi-hole. The spray characteristics, such as the spray penetration, the spray angle, and the injection quantity, were studied through the change of the injection pressure, the ambient pressure, and the energizing duration in a high-pressure chamber with a constant volume. The n-heptane with 99.5% purity was used as the test fuel. In a constant volume chamber, the injected spray was visualized by the spray visualization system, which consisted of the high-speed camera, the metal-halide lamp, the injector control device, and the image analysis system with the image processing program. It was revealed that the injection quantity was mainly affected by the difference between the injection pressure and the ambient pressure. For low injection pressure conditions, the injection quantity was decreased by the increase of the ambient pressure, while it nearly maintained regardless of the ambient pressure at high injection pressure. According to the increase of the ambient pressure in the constant volume chamber, the spray development became slow, consequently, the spray tip penetration decreased, and the spray area increased. In additions, the circular cone area decreased, and the vortex area increased.

Mixing Stability and Spray Behavior Characteristics of Diesel−Ethanol−Methyl Ester Blended Fuels in a Common-Rail Diesel Injection System

The purpose of this study is to investigate the mixing stability, fuel properties, and spray-atomization characteristics of diesel−ethanol blended fuels in a common rail diesel injection system. In...

Effect of Bioethanol−Biodiesel Blending Ratio on Fuel Spray Behavior and Atomization Characteristics

The aim of this work is to investigate the effect of the bioethanol addition on the spray behavior and atomization characteristics of biodiesel fuel. Spray behavior characteristics were studied by analyzing the spray tip penetration, spray centroid, and spray cone angle. In addition, the spray tip penetrations estimated by theoretical and empirical equations were compared with the experimental results. Droplet size and axial velocity were investigated for analyzing the fuel atomization characteristics. Bioethanol fuel was blended with biodiesel fuel derived from soybean oil in a volumetric ratio from 10 to 30% in 10% intervals. It was revealed that the blending ratio of bioethanol fuel had little effect on the spray tip penetration. The spray cone angle of blended fuels was increased by adding the bioethanol fuel. When the ambient gas temperature increased, the spray tip penetration of an undiluted biodiesel fuel increased due to the decrease in ambient gas density. However, the spray tip penetration of b...

The experimental study of atomization characteristics of gasoline spray impinging on glow plug

In order to reduce the exhaust emissions of a spark ignition engine, it is important not only to improve the catalyst conversion efficiency, but also to directly reduce the engine-out exhaust emissions during a cold starting of the engine and warm up periods. The purpose of this study is to evaluate feasibility of a glow plug for an early fuel evaporator. In order to promote atomization, gasoline is injected on the glow plug with room temperature (20°C) and high temperature (250°C). To analyze the spray behavior characteristics, a PMAS is used to measure the SMD and the dropsize distribution of an impinging spray and a free spray. Results show that the evaporation rate of the impinging spray on the high temperature surface of the glow plug was higher than that of the free spray on the room temperature surface.