Exciplex Fluorescence Method Research Articles

Quantitative Analysis of Vapor Formation Process in Gasoline Spray in Evaporation Field with Laser Induced Exciplex Fluorescence Method (LIEF Method)

Quantitative Analysis of Vapor Formation Process in Gasoline Spray in Evaporation Field with Laser Induced Exciplex Fluorescence Method (LIEF Method)

Quantitative analysis of vapor concentration in unsteady evaporating gasoline spray with LIEF method (2nd Report：Analysis of mixture-liquid two-phase characteristics)

This paper reports the quantitative analysis of vapor concentration in the mixture-liquid two-phase region with Laser Induced Exciplex Fluorescence（LIEF）for the unsteady evaporating gasoline type spray. These methods were used to analyze the mixture-liquid two-phase characteristics in the process of mixture formation. The exciplex fluorescence method, developed by Melton, is a method to optically separate the fluorescence of the liquid and vapor phases, but quantitative analysis of vapor concentration in the mixture-liquid two-phase e region is difficult due to fluorescence cross talk. In this study, the quantitative analysis of vapor concentrations using the average temperature of mixing was used to quantify the vapor concentrations in the mixture-liquid two-phase region by image processing that considers the fluorescence cross talk between the liquid and vapor phases. As a result, the vapor concentration, the temperature of the mixture, and the concentration distribution of the liquid phase in the mixture-liquid two-phase region of the spray cross section were obtained. Based on these results, the correlation diagram between vapor concentration and fluorescence intensity of the liquid phase and the relative frequency distribution of vapor concentration were calculated. A comparison was made between the characteristic values of the fuel and the temperature under the experimental conditions. It was found that the spray consisted mainly of a region where the liquid phase was almost absent and dilute vapors were formed, and a region where the liquid phase was present and formed dense vapors. The same analysis was performed to evaluate the process of vaporization of the spray mixture at different times from the start of injection.

Quantitative Evaluation of Gasoline Spray in Evaporation Fields Using Laser Induced Exciplex Fluorescence Method

Quantitative Evaluation of Gasoline Spray in Evaporation Fields Using Laser Induced Exciplex Fluorescence Method

An Advanced Method for Behavior-Characteristics Analysis of Diesel Fuel Spray

In order to control emissions from engine, it is necessary to understand the mixture formation process of diesel spray. In this study, analysis of diesel fuel(n-Tridecane, C13H28) spray under a high temperature and pressure was performed by a general-purpose program, ANSYS CFX release 11.0, and the results of these are compared with experimental results of diesel fuel spray using the Exciplex Fluorescence Method. The simulation results of diesel spray is analyzed by using the combination of Large-Eddy Simulation(LES) and Lagrangian Particle Tracking(LPT), and then injection pressure was selected as an analysis parameter. Consequently, it was found that the experimental results and the numerical results are consistent with each other, and then in order to investigate the behavior characteristics of evaporative diesel spray, the effectiveness of the use of CFX of commercial code is definitely validated.

주위조건 변화에 대한 증발 디젤분무 거동특성 연구

디젤자유분무 Diesel-Free Spray( ), 증발분무 Abstract To analyze the mixture formation process of evaporating diesel spray is important for emissions reduction in actual engines. Then the effects of change in density of ambient gas on spray structure in high temperature and pressure field have been investigated in this study. The ambient gas density was changed from ρa=5.0kg/m 3 to ρa=12.3kg/m 3 with CVC(Constant Volume Chamber). Also, simulation study by modified KIVA-II code was conducted and compared with experimental results. The ambient temperature and injection pressure are kept as 700K and 72MPa, respectively. The images of liquid and vapor phase in the evaporating free spray were simultaneously taken by exciplex fluorescence method. As experimental results, with increasing ambient gas density, the tip penetration of the evaporating free spray decreases due to the increase in the drag force from ambient gas. The spatial structure of a diesel spray can be verified as 2-regions consisted of liquid with momentum decrease and vapor with large-scale vortex. The calculated results obtained by modified KIVA-II code show good agreements with experimental results.

비정상 증발디젤분무의 측정과 그 응용해석

The characteristics of combustion process in an internal combustion engine are affected by the mixing process between injected fuel and ambient gas. Therefore, it is necessary to understand the mixture formation process of diesel spray. In this study, the spray structure was visualized by the exciplex fluorescence method, which can provide the simultaneous 2-D images of vapor and liquid phase in inner spray. For accurate investigation, the liquid-phase images were recorded with a 35mm still camera and CCD camera. Consequentially, it could be confirmed that the high-concentration vapor phase is formed in the region of spray tip and the edge of the liquid phase where droplets exist in the evaporating diesel spray, and the formed vapor is spread by diffusion. Also, the distribution of vapor is determined by the motion of droplets that exist in the edge of the liquid phase and the spray-tip region.

A study of the mixture formation process of a diesel spray under phase change

The purpose of this study was to analyze the structure and to clarify the mixture formation process within evaporative diesel spray. Liquid fuel was injected from a single-hole nozzle (l/d=1.0mm/0.2mm) into a constant-volume vessel under high pressure and temperature in order to visualize the spray phenomena. An exciplex fluorescence method was applied to the evaporative fuel spray to measure and investigate both the liquid and the vapor phase of the injected spray. The region of interest in this experiment was downstream towards the end of the spray. For accurate investigation, images of the liquid and vapor phase regions were recorded with a 35mm still camera and CCD camera, respectively. For the case of the evaporative fuel spray, the images showed that within the region of liquid phase very small droplets could be found outside of the spray and larger droplets at the spray’s tip. This can be explained through the droplet classification defined byStokes number (stk) (Chung et al., 1990). From the 2-dimensional analysis results of the heterogeneous distribution of the inner spray, a 3-dimensional analysis was attempted by using the offset incidence of the laser beam from the spray’s center axis. Finally, in order to quantify the mixture’s state change within the vapor phase region of the injected spray, images analysis were carried out based on the entropy of statistical thermodynamics.

연료의 임계조건을 고려한 디젤 액상분무거동에 관한 연구

In this study the penetration distance of liquid phase fuel(i.e. liquid phsae length) was investigated in evaporative field. An exciplex fluorescence method was applied to the evaporative fuel spray to measure and investigate both the liquid and the vapor phase of the injected spray. For accurate investigation, images of the liquid and vapor phase regions were recorded using a 35㎜ still camera and CCD camera, respectively. Liquid fuel was injected from a single-hole nozzle (l/d=1.0㎜/0.2㎜) into a constant-volume chamber under high pressure and temperature in order to visualize the spray phenomena. Experimental results indicate that the liquid phase length decreased down to a certain constant value in accordance with increase in the ambient gas density and temperature. The constant value, about 40㎜ in this study the, is reached when the ambient density and temperature of the used fuel exceed critical condition.

An analysis on structure of impinging and free diesel spray with exciplex fluorescence method in high temperature and pressure field

Because an injected spray development process consists of impinging and free spray in the diesel engine, it is needed to analyze the impinging spray and free spray, simultaneously, in order to study the diesel spray behavior. To dominate combustion characteristics in diesel engine is interaction between injected fuel and ambient gas, that is, process of mixture formation. Also it is very important to analyze liquid and vapor phases of injected fuel on the investigation of mixing process, respectively and simultaneously. Therefore, in this study, the behavior characteristics of the liquid phase and the vapor phase of diesel spray was studied by using exciplex fluorescence method in high temperature and injection pressure field. Finally, it can be confirmed that the distribution of vapor concentration is more uniform in the case of the high injection than in that of the low injection pressure.

A study on the behavior of evaporating diesel spray using LIEF measurement and kiva code

The effects of change in injection pressure on spray structure in high temperature and pressure field have been investigated. The analysis of liquid and vapor phases of injected fuel is important for emissions control of diesel engines. Therefore, this work examines the evaporating spray structure using a constant volume vessel. The injection pressure is selected as the experimental parameter, is changed from 400 bar to 800 bar by using a common rail injection system. Also, we conducted simulation study by modified KIVA-II code. The results of simulation study are compared with experimental results. The images of liquid and vapor phase for free spray were simultaneously taken by exciplex fluorescence method. As experimental results, the vapor concentration of injected fuel is leaner due to the increase of atomization in the case of the high injection pressure than in that of the low injection pressure. The calculated results obtained by modified KIVA-II code show good agreements with experimental results.

분위기 조건에 따른 GDI 엔진용 인젝터의 분무거동 및 증발특성에 대한 수치적 해석

The purpose of this study is to improve the prediction ability of the atomization and vaporization processes of GDI spray. Several models have been introduced and compared. The atomization process was modeled using hybrid breakup model that is composed of Linearized Instability Sheet Atomization (LISA) model and Aerodynamically Progressed TAB (APTAB) model. The vaporization process was modeled using Spalding model and Abramzon ＆ Sirignano model. Exciplex fluorescence method was used for comparing calculated with experimental results. The experiment and computation were performed at the ambient pressure of 0.1 MPa, 0.5 MPa and 1.0 MPa and the ambient temperature of 293k and 473k. Comparison of calculated and experimental spray characteristics was carried out and the calculated results of GDI spray showed good agreement with experimental results.

A study on the behavior characteristics of diesel spray by using a high pressure injection system with common rail apparatus

The effects of change in injection pressure on spray structure in high temperature and pressure field have been investigated. The analysis of liquid and vapor phases of injected fuel is important for emissions control of diesel engines. Therefore, this work examines the evaporating spray structure using a constant volume vessel. The injection pressure is selected as the experimental parameter, is changed from 22 MPa to 112 MPa using a high pressure injection system (ECD-U2). Also, we conducted simulation study by modified KIVA-II code. The results of simulation study are compared with experimental results. The images of liquid and vapor phase for free spray were simultaneously taken by exciplex fluorescence method. As experimental results, the vapor concentration of injected fuel is leaner due to the increase of atomization in the case of the high injection pressure than in that of the low injection pressure. The calculated results obtained by modified KIVA-II code show good agreements with experimental results.

A study on the mixture formation process of evaporating diesel spray by offset incidence laser beam

This paper analyzes heterogeneous distribution of branch-like structure at the downstream region of the spray. The liquid and vapor phase of the spray are obtained using a 35mm still camera and CCD camera in order to investigate spray structure of evaporating diesel spray. There have been many studies conducted on diesel spray structure but have yet only focused on the analyses of 2-D structure. There are a few information which is concerned with 3-D structure analysis of evaporating spray. The heterogeneous distribution of droplets in inner spray affects the mixture formation of diesel spray and the combustion characteristics of the diesel engines. In this study, the laser beam of 2-D plane was used in order to investigate 3-D structure of evaporating spray. The incident laser beam was offset on the central axis of the spray. From the analysis of images taken by offset laser beam, we will examine the formation mechanism of heterogeneous distribution of the diesel spray by vortex flow at the downstream of the spray. The images of liquid and vapor phase of free spray are simultaneously taken through an exciplex fluorescence method. Through this, the branch-like structure consisting of heterogeneous distribution of the droplets forms high concentrated vapor phase at the periphery of droplets and at the spray tip.

직분식 가솔린기관 내에서 피스톤 형상이 연료혼합기 거동에 미치는 영향

This study was performed to investigate the behavior of vapor phase of fuel mixtures with different piston bowl shapes(F, B and R-type) in a optically accessible engine. The images of liquid and vapor phases were captured in the motoring engine using exciplex fluorescence method. Fuel was injected into atmospheric nitrogen to prevent quenching phenomenon by oxygen. Injection pressure was 5.1MPa. Two dimensional spray fluorescence image of vapor phase was acquired to analyze spray behaviors and fuel distribution inside of cylinder. Four injection timings were set at BTDC 90, 80, 70, and 60. With a fuel injection timing of BTDC 90, fuel-rich mixture level in the center region was highest in a B-type piston. With a fuel injection timing of BTDC 60, R-type piston was best. R-type piston shape was suitable under enhanced swirl ratio and late injection condition and B-type piston shape was right in a weak swirl ratio. It was found that the piston bowl shape affected the mixture stratification inside of cylinder.

1221 液化CO_2混合燃料の噴霧構造に関する研究(OS-3 新燃料システム)

In the diesel engines, the trade-off relations for reducing both Soot and NO emissions cannot be avoid. In this study, it is proposed that a concept on simultaneous reduction of NO and Soot emissions in Diesel engine exhaust by use of the Diesel fuel oil (n-Tridecane) mixed with liquefied CO_2. The combustion process inside the S.I. engines and diesel engines seems to be affected mixture formation process of the injected or charged fuels. In addition, the spray structure of the liquefied CO_2 mixed fuel is difference from the spray structure of the diesel fuel. Therefore, in this paper, to be clarified the mixture formation process of the liquefied CO_2 mixed fuel, the vapor concentration distribution of n-Tridecane in liquefied CO_2 mixed fuel were observed by exciplex fluorescence method. And vaporization process of CO_2 in liquefied CO_2 mixed fuel were evaluated by measuring spray momentum.

Exciplex蛍光法を用いた非定常蒸発ディーゼル噴霧の測定とその応用解析

Exciplex蛍光法を用いた非定常蒸発ディーゼル噴霧の測定とその応用解析

Analysis of Spray Flame Structure in a Hot Air Stream by Exciplex Fluorescence Method.

Analysis of Spray Flame Structure in a Hot Air Stream by Exciplex Fluorescence Method.

Development behavior of vaporizing sprays from a high-pressure swirl injector using exciplex fluorescence method

The effects of ambient conditions on vaporizing sprays from a high-pressure swirl injector were investigated by an exciplex fluorescence method. Dopants used were 2% fluorobenzene and 9% DEMA (diethyl-methyl-amine) in 89% solution of hexane by volume. In order to examine the behavior of liquid and vapor phases inside of vaporizing sprays, ambient temperatures and pressures similar to engine atmospheres were set. It was found that the ambient pressure had a significant effect on the axial growth of spray, while ambient temperature had a great influence on the radial growth. The spatial distribution of vapor phase at temperatures above 473K became wider than that of liquid phase after half of injection duration, From the analysis of the area ratio for each phase, the middle part (region II) in the divided region was the region which liquid and vapor phases intersect. For liquid phase, fluorescence-intensity ratio was greatly changed at lms after the start of injection. However, the ratio of vapor phase was nearly uniform in each divided region throughout the injection.

C502 Exciplex蛍光法を用いた非定常蒸発ディーゼル噴霧の解析

The characteristics of combustion process in an internal combustion engine are affected by the mixing process between injected fuel and ambient gas. Therefore, it is necessary to understand the mixture formation process of diesel spray. In this study, the spray structure was visualized by the exciplex fluorescence method, which provides the simultaneous 2-D images of vapor and liquid phase in the spray, in order to discuss the mixture formation process of diesel spray. In addition, the vapor concentration using Lambert-Beer's law was quantitatively obtained from the fluorescence intensity measured in the spray. The fractal analysis to 2-D images measured by exciplex fluorescence method was carried out for turbulence analysis.

Measurement of Distribution and Concentration of Vapor/Liquid Phases in Gasoline Direct Injection Spray Using Exciplex Fluorescence Method

Measurement of Distribution and Concentration of Vapor/Liquid Phases in Gasoline Direct Injection Spray Using Exciplex Fluorescence Method