연료분무 및 연소 1 : 직접 분사식 압축착화 엔진에서 가솔린과 디젤의 분무 및 연소 특성 가시화

김기현 ( Ki Hyun Kim ),김동훈 ( Dong Hoon Kim ),정용진 ( Yong Jin Jung ),배충식 ( Choong Sik Bae ) 한국액체미립화학회 2012 한국액체미립화학회 학술강연회 논문집 Vol.2012 No.-

Direct visualization of spray and combustion was performed using gasoline and diesel fuel in a compression ignition engine at low load condition. Identical fuel injection system using common rail was applied to both gasoline and diesel. A constant volume chamber and an optical engine were used for spray visualization under non-evaporating and evaporating condition, respectively. Liquid penetration length and spray cone angle were measured and analyzed in the spray visualization. Under non-evaporating condition, both gasoline and diesel spray showed increased liquid penetration length with increased injection pressure. There was no significant difference between gasoline and diesel spray in liquid penetration length. However, spray angle was somewhat wider for gasoline spray compared to diesel spray. It was attributed to gasoline`s low density and viscosity. Wider spray angle implies that the gasoline spray would have more potential to undergo improved mixing process which consists of vigorous atomization and evaporation process. Under evaporating condition, there was significantly different phenomenon in liquid penetration length and spray angle between two fuels. Firstly, gasoline spray showed much shorter liquid penetration length than that of diesel spray. It was resulted from gasoline`s superior volatility in addition to gasoline`s enhanced atomization and mixing characteristics compared to diesel. Secondly, spray angle was narrower for gasoline spray than diesel spray. It was opposite trend compare with the result from non-evaporating condition. Vigorous mixing and evaporation process occurred at the boundary of the gasoline spray since the distillation temperature range of gasoline is much lower than diesel. Liquid penetration length was decreased with retarded injection timing for both fuels since both cylinder pressure and cylinder temperature was increased as injection timing was retarded. Separately, it was observed that maximum liquid penetration length was maintained at almost constant regardless of injection pressure for both gasoline and diesel.

Experimental Investigation on the Spray and Heat Transfer Characteristics in the Cryogen Spray with the Expansion-Chambered Nozzle

( Xinsheng Wang ),( Bin Chen ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

Cryogen spray cooling (CSC) is commonly applied in laser dermatology to protect epidermis from thermal damage. Many efforts have been conducted to improve the cooling capacity of CSC, among which the use of expansion-chambered nozzles is simple and with great potential. This study examined the influence of expansion-chambered nozzle structure including the ratio of the two orifice diameter and expansion chamber volume on the R134a and R404A spray cooling. Fifteen transparent expansion-chambered nozzles with expansion chamber aspect ratio of 1, diameter of expansion chamber ranges from 5 mm to 10 mm and the ratio of the two orifice diameter ranges from 0.6 to 1.4 as well as the straight-tube nozzle were compared. The internal flow pattern inside the expansion chamber, spray pattern and surface heat transfer characteristics of cryogen spray using different nozzles were investigated. It was found that the spray radius was declined when the expansion-chambered nozzles were used, and the spray radius showed a negative relation with the expansion chamber volume and positive relation with the ratio of two orifice diameters. The introduction of expansion-chambered nozzle could effectively improve the spray cooling capacity, and the minimum average surface temperature during the full developed period of spray could be reached by the nozzle with expansion chamber diameter of 5 mm and ratio of two orifice of 0.6 was adopted for both R134a spray and R404A spray.

Experimental and Numerical Study on Effects of Wall Impingement on Spray and Combustion Characteristics in a Diesel Engine

Liu, Yu,Chung, S.S.,Ha, J.Y. Institute for Liquid Atomization and Spray Systems 2010 한국액체미립화학회지 Vol.15 No.3

The spray-wall impingement in diesel engines is important to mixture preparation, engine performance and pollutant emissions. The purpose of this paper is to study the effects of spray-wall impingement on fuel distribution, combustion and emission characteristics by using both experimental and numerical methods. To investigate the spray-wall impingement process, an impingement-chamber was designed and a visualization experiment system was also developed. The images of impinged spray and free spray were digitally recorded with an intensified CCD camera. To investigate the fuel distribution, combustion and emission characteristics of impinged spray in a real diesel engine, the fuel injection and combustion processes of an engine with impingement-chamber were simulated by CFD software. Equivalence ratio distribution results were obtained to understand the fuel distribution characteristics of the impinged spray. Some combustion and emission characteristics were also acquired and the results showed that ignition delay of impinged spray was shorter than that of free spray; NO emission of the impinged spray was significantly less than that of free spray, but soot emission of impinged spray was more than that of the free spray. This study found that the diesel engine with spray-wall impingement has significant potential to reduce NO emission.

스월형 및 팬스프레이형 고압직분식 가솔린 분사기의 상온 평판에서의 분무 충돌 특성에 관한 연구

김종민(Chongmin Kim),강신재(Shin Jae Kang),김만영(Man Young Kim) 한국자동차공학회 2006 한국 자동차공학회논문집 Vol.14 No.2

The behavior of spray impinging on the inclined constant temperature flat plate was experimentally investigated. To clarify the wall effect of a high pressure DISI injector, a relative angle of the inclined wall to a spray axis was varied. Spray penetration along the wall was observed optically and it was compared with that of a Fan spray type and Swirl type spray. To evaluate various spray motion quantitatively, a spray path penetration which describe the development of a spray tip along the wall was newly introduced. To observe the structure of an impinging spray, it was visualized by a controlled stroboscope light and its visualized image was captured on an CCD camera. Using the digital image of impinging spray H<SUB>χ</SUB> and R<SUB>χ</SUB> was extracted to clarify the structure of impinging spray. The main parameter of the relative position of the wall was the inclined angle which was defined as the angle was varied from 0˚(vertical impingement) to 60˚ at the same condition.

Atomization characteristics of hairspray with various design parameters of spray vessel

( Huijun Kim ),( Junkyu Park ),( Sungwook Park ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

This study was conducted to analyze the spray characteristics of aerosol sprays depending on various nozzle design parameters. In this study, actuator, valve geometry and propellant/product ratio were selected as variables for spray experiment. In aerosol spray vessels, product and liquefied propellant are present together. Therefore, product fluid was atomized by flash-boiling of propellant induced by sudden pressure drop. The atomization performance of a hair spray can be evaluated by SMD and droplet distribution. Droplet diameter and velocity are measured via PDPA(Phase Doppler Particle Analyzer) and macroscopic spray characteristics such as spray development and cone angle were investigated through spray visualization. ICCD (Intensified Charge Coupled Device) camera and Nd:YAG laser was used to take spray internal structure. Experimental results show how nozzle parameter affects spray characteristics. Image processing was done with MATLAB program to analyze captured image from ICCD camera. Actuator mainly affected spray cone angle rather than atomization characteristics. For example, increasing actuator orifice nozzle diameter and impellers made spray cone angle larger. Conversely, the valve design had an effect to atomization characteristics such as droplet diameter and propellant/product ratio affected both spray cone angle and atomization characteristics. In particular, the increase in vapor phase tap of valve and propellant/product ratio had a dramatic impact on the reduction in SMD.

분무 가시화를 통한 직분사 시스템에서 n-heptane및 propane의 분무발달특성 비교

박준규,박성욱 한국분무공학회 2023 한국액체미립화학회지 Vol.28 No.1

In this study, spray characteristics of n-heptane and propane were investigated under different injection pressure using various imaging techniques such as Mie-scattering, DBI (diffuse back-illumination), and Schlieren imaging techniques. NI compact RIO system was used to control a test injector. Spray penetration length, length-to-width ratio and number of black pixels were calculated by using MATLAB software to compare spray characteristics of each fuel. Longer spray penetration length and higher length-to-width ratio were observed in propane spray because of flash boiling caused by high saturated vapor pressure. Spray collapse occurred in propane spray due to the high plume-to-plume interaction. Moreover, rapid evaporation occurred in propane spray, so that nozzle tip wetting could not be observed. Rapid evaporation of propane also caused fewer residual droplets compared to n-heptane spray. Therefore, propane is advantageous in reducing the generation of soot emission from large droplets that are not atomized. However, additional evaluation should be conducted considering combustion efficiency and the possibility of deposits by nozzle tip icing during fuel injection.

인젝터 설계변수 및 분사조건에 따른 분무타겟팅 지점의 측정 및 예측

상몽소,Bo Zhou,박수한 한국분무공학회 2023 한국액체미립화학회지 Vol.28 No.1

In the cylinder of gasoline direct injection engines, the spray targeting from injectors is of great significance for fuel consumption and pollutant emissions. The automotive industry is putting a lot of effort into improving injector targeting accuracy. To improve the targeting accuracy of injectors, it is necessary to develop models that can predict the spray targeting positions. When developing spray targeting models, the most used technique is computational fluid dynamics (CFD). Recently, due to the superiority of machine learning in prediction accuracy, the application of machine learning in this field is also receiving constant attention. The purpose of this study is to build a machine learning model that can accurately predict spray targeting based on the design parameters of injectors. To achieve this goal, this study firstly used laser sheet beam visualization equipment to obtain many spray cross-sectional images of injectors with different parameters at different injection pressures and measurement planes. The spray images were processed by MATLAB code to get the targeting coordinates of sprays. A total of four models were used for the prediction of spray targeting coordinates, namely ANN, LSTM, Conv1D and Conv1D & LSTM. Features fed into the machine learning model include injector design parameters, injection conditions, and measurement planes. Labels to be output from the model are spray targeting coordinates. In addition, the spray data of 7 injectors were used for model training, and the spray data of the remaining one injector were used for model performance verification. Finally, the prediction performance of the model was evaluated by R2 and RMSE. It is found that the Conv1D&LSTM model has the highest accuracy in predicting the spray targeting coordinates, which can reach 98%. In addition, the prediction bias of the model becomes larger as the distance from the injector tip increases.

직접분사식 LPG 엔진의 분무특성에 관한 연구

김윤호(Yun Ho Kim),김명윤(Myung Yoon Kim),전학식(Hak Sik Jeon),이창식(Chang Sik Lee) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

This work is to investigate the spray characteristics and visualization of spray developing on the LPG direct injection engine. The spray visualization and spray development process are carried out by using the visualized single cylinder engine. The injection mass of fuel is increased in accordance with the increase of elapsed time alter the start of injection. The macroscopic behaviors of the fuel spray show that the spray tip penetrations of LPG spray is longer than that of gasoline spray. Also the behaviors of in-cylinder flow and LPG spray in the combustion chamber are visualization cylinder of its engine.

Spray Characteristics of Dimethyl Ether(DME) Fuel Compared to Various Diesel Fuels

Lee, Seang-Wock,Kim, Duk-Sang,Cho, Yong-Seok The Institute for Liquid Atomization and Spray Sys 2008 한국액체미립화학회지 Vol.13 No.2

It is recognized that alternative fuel such as dimethyl ether (DME) has better combustion polluting characteristics than diesel fuel, even though the cetane number of DME is almost the same as that of diesel. Characteristics of DME spray were observed experimentally under various ambient conditions using a constant volume chamber and a common-rail injection system. N-dodecane and LPG fuel sprays were also observed under same conditions of DME spray. Using spray images from backlight scattering and Mie scattering, characteristics of fuel sprays such as penetration and spray volume were visualized and quantitatively measured. The measurements showed that the penetration of early period decreased remarkably, because evaporation of alternative fuels became prosperous by the influence of flash boiling phenomenon under the condition of the low temperature and pressure compared with n-dodecane. The penetration of DME and LPG spray received the influence of temperature more largely in comparison with low density, because the specific surface area increased by atomizing in high density.

연료분사 노즐 형상이 선박용 중형 디젤 엔진의 NOx에 미치는 영향 연구

윤욱현(Wook-Hyeon Yoon),김병석(Byong-Seok Kim),류승협(Sung-Hyup Ryu),김기두(Ki-Doo Kim),하지수(Ji-Soo Ha) 한국마린엔지니어링학회 2005 한국마린엔지니어링학회 학술대회 논문집 Vol.2005 No.-

Multi-dimensional combustion analysis and experiment has been carried out to investigate the effects of the injector nozzle hole diameter and number on the NOx formation and fuel consumption in HYUNDAI HiMSEN engine. The behavior of spray and combustion phenomena in diesel engine was examined by FIRE code. Wave breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation. Wallfilm model suggested by Mundo, et al. and auto-ignition model suggested by Theobald and Cheng were adopted to investigate the spray-wall interaction characteristics and ignition delay. The information of spray angle and spray tip penetration length was extracted from fuel spray visualization experiment and the fuel injection rate profile was extracted from fuel injection system experiment as an input and verification data for the combustion analysis. Next, the nine different nozzle configurations were simulated to evaluate the effect of injector hole diameter and number on the NOx formation and fuel consumption.