Spray distortion effect on particulate emission in stratified combustion of n-butane

( Sangjae Park ),( Jinyoung Jung ),( Choongsik Bae ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

To obtain spray robustness for fuel injection directly in engine cylinders, typical hollow cone injectors are used in several direct injection engine, especially for advanced gasoline direct injection engine. In terms of lean stratified combustion, the robustness would be major factor for mixture formation process, which has significant impact on particulate matter emission. Dedicated injector nozzle design for gasoline fuel showed small sensitiveness for spray structure of the injected fuel, but if other fuel, such as liquefied petroleum gas, a typical with high vapor pressure, is used with same injector, the spray structures were distorted from typically designed spray configuration. Intuitively, spray tip vortexes were formed near to injector tip compared to liquid fuel spray, and they showed shorter liquid penetration than those of liquid fuel spray. But, in terms of inner structure of hollow cone spray, there are more severe distortion those of outer surface, due to the overlap of inner vortexes. The overlap could affect whole spray structure by filling the hollow space with fuel cloud, so that the vapor cloud of fuel behaved as a typical kind of full cone spray. These phenomena caused deterioration of mixture formation between surrounding air and fuel vapor, which could affect particulate formation within the combusted by ignitor. These effects were not majorly observed in particulate mass emission, but in particulate number emission the large difference could be observed by that effect. These distortion could be evaluated indirectly by observing side structure of spray, in these case, larger mixing time causes more particulate emission, contradictively.

DIESEL SPRAY CHARACTERISTICS AND ITS COMBUSTION

Masataka ARAI 한국자동차공학회 2005 한국자동차공학회 Workshop Vol.2005 No.-

Spray formation mechanism of a diesel spray and its combustion process were reviewed. Spray formation mechanism of the diesel spray was controlled by a cavitation inside an injection nozzle. The Sauter mean diameter of a diesel spray became small when the cavitation occurred in the nozzle and it resulted in a complete spray. The empirical equations of the Sauter mean diameter were shown with the discussion of the cavitation. The spray tip penetrations of free and wall impingement sprays were introduced with the equations. The spray tip penetration was discussed with air entrainment process. Impingement spray was discussed with penetration and adhering fuel on the wall. High pressure injection spray was introduced with its spray characteristics. Spray-to spray interaction was clearly shown by many photographs to propose a new spray system. Evaporation process on an impingement wall was duscused. Ignition delay and the empirical equations of it were reviewed. The ignition delay was greatly affected by the spray movement and surrounding conditions. Wall and residual gas effects on the ignition delay were reviewed. The OH flame kernel and hot flame kernel observed at the ignition of impingement spray were explained. Alos, effect of injection pressure and effect of wall impingement on flame development process was explained.

A study on the macroscopic spray behavior and atomization characteristics of biodiesel and dimethyl ether sprays under increased ambient pressure

Kim, H.J.,Park, S.H.,Lee, C.S. Elsevier Scientific Pub. Co 2010 Fuel processing technology Vol.91 No.3

The aim of this work is to investigate the spray behaviors of biodiesel and dimethyl ether (DME) fuels using image processing and atomization performance analysis of the two fuel sprays injected through a common-rail injection system under various ambient pressure conditions in a high pressure chamber. In order to observe the biodiesel and DME fuel spray behaviors under various ambient pressures, the spray images were analyzed at various times after the start of energization using a visualization system consisting of a high speed camera and two metal halide light sources. In addition, a high pressure chamber that can withstand a pressure of 4MPa was used for adjusting the ambient pressure. From the spray images, spray characteristics such as the spray tip penetration, cone angle, area, and contour plot at various light intensity levels were analyzed using image conversion processing. Also, the local Sauter mean diameters (SMD) were measured at various axial/radial distances from the nozzle tip by a droplet measuring system to compare the atomization performances of the biodiesel and DME sprays. The results showed that the ambient pressure had a significant effect on the spray characteristics of the fuels at the various experimental conditions. The spray tip penetration and spray area decreased as the ambient pressure increased. The contour plot of the biodiesel and DME sprays showed a high light intensity level in the center regions of the sprays. In addition, it was revealed that the atomization performance of the biodiesel spray was inferior to that of the DME spray at the same injection and ambient conditions.

분무응용 기술 : 바이오 디젤의 수평분무 이미지 분석

윤석주 ( Suckju Yoon ),황창영 ( Changyeong Hwang ) 한국액체미립화학회 2015 한국액체미립화학회 학술강연회 논문집 Vol.2015 No.-

This paper presents the possibility of bio-diesel which has high viscosity and oxygenated fuel by gun-type burner. The experiments were carried out for the comparison of the spray characteristics of the kerosene, lard, and soybean fuel injected from the pressure swirl nozzle of gun-type burner. The spray images were acquired by the high speed camera and changes of injection pressures and blending rate. In the horizontality direction spray different from vertical direction spray, the flow of single spray in downstream was found. This flow was appeared by the generation of primary spray and secondary spray. The primary spray has an influence of initial spray condition and secondary spray was shown by correlation of primary spray and nearby air.

High-Speed PIV Evaluation of Fuel Sprays under Superheated Conditions

( Ming Zhang ),( Min Xu ),( Yu Yin Zhang ),( Gao Ming Zhang ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-

Spray structure, distribution, and atomization process of the superheated sprays are dramatically influenced by the degree of the fuel superheating. The fuel spray flow field can provide detailed information about such influence due to the fuel superheating. It is anticipated that the fuel spray flow field depends on the superheat degree, which is carefully examined using high-speed PIV in this study. The fuel droplet velocities are measured within the lower number density regions of the spray generated from a multi-hole injector. The spray structure is characterized by spray penetration, maximum spray width and spray angle derived from the spray laser-sheet images. These characteristics are correlated with the spray velocity vector field to analyze the driving force of the spray transformation. The results illustrate that, as the superheat degree increases, the spray velocities in both radial and axial directions vary dramatically accompanied by the unexpected transformations of the spray structure, such as transforming from separate plumes to a collapsed form. The superheat degree is the predominant factor influencing break-up, atomization, and structure of the superheated sprays.

압력선회노즐에서 물-기름 유화연료의 분무특성

임정현 ( J. H. Rhim ),노수영 ( S. Y. No ) 한국액체미립화학회 2000 한국액체미립화학회지 Vol.5 No.1

The beneficial aspects of applying emulsion fuels to combustion systems may be due to the changes of fuel properties which lead to the enhanced atomization characteristics. The spray characteristics of water/oil emulsified fuel injected from the pressure-swirl(simplex) atomizer using for oil burner were investigated. Four different water contents from 10 to 40 % by volume at 10% increment were prepared by mixing with the different contents of surfactants. Total amount of surfactant used was varied from 1 to 3 % by volume. This study demonstrates the influence of water and surfactant contents of emulsified fuel, injection pressure on the spray characteristics, i.e. Sauter mean diameter(SMD) and spray angle. The drop size distribution of the emulsified fuel spray was measured with a Malvem particle sizer. In order to measure the spray angle, the digital image processing was employed by capturing multiple images of the spray with 3-CCD digital video camera. It was evident that the addition of water and surfactant changes fuel properties which are the key parameters influencing the atomization of the spray. The increase in surfactant content results in the decrease of SMD and the increase in spray angle. The droplets decease with increase in injection pressure, but the influence of injection pressure in this experimental condition was less important than expected. The more viscous fuel with the increase of water content exhibits the larger droplets in the centerline of the spray, and the less viscous fuel in the outer edges of the spray. The increase in axial position from the nozzle causes the spray angle to decrease. The spray angle decreases with increase in water content. This is due to increase in viscosity with increase in water content.

Experiment and CFD Calculation of Flat Wall Impinging Fuel Spray in High-Pressure Cross-Flow Ambient Injected by VCO Nozzle for DISI Engine

( Zhanbo Si ),( Nagisa Shimasaki ),( Keiya Nishida ),( Youichi Ogata ),( Chenglong Tang ),( Zuohua Huang ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

The fuel spray injected into a direct injection (DI) engine is strongly affected by both the in-cylinder air flow and the piston cavity wall impingement. The combined effect of the air flow and the wall impingement plays an important role on the spray development, mixture formation and subsequent combustion. In this study, the effects of the parallel cross-flow and the flat wall impingement were investigated on the spray development and dispersion. The spray was injected by a valve covered orifice (VCO) nozzle under various cross-flow velocities and ambient pressures. Tomographic images of the spray in a vertical and several horizontal planes were taken by a high-speed video camera and a continuous wave laser sheet. Moreover, the experiment results were compared with simulation which was calculated by the validated spray models based on the CONVERGE software. The results show that with increasing the cross-flow velocity, the spray tip penetration is decreased slightly before the impingement while the spray tip penetrates further in the cross-flow downstream direction after the impingement. The high ambient pressure tend to compress the spray profiles. Additionally, under the condition of the similar fuel injection and cross-flow momentum flux ratio, the distortion curves of the sprays in the cross flow upstream side agree well with each other whereas the spray dispersion in the downstream side is affected by the cross flow velocity. In the vertical plane along the flat wall, the head vortex is generated at the spray tip. With the head vortex growing, the surrounding air is significantly entrained into the spray. In the horizontal plane, an empty belt is observed near the head vortex core region. The quantitative analysis shows that the high velocity of the cross-flow favors the spray breakup and dispersion, leading to a larger head vortex and a wider spray angle.

ATOMIZATION PROCESS OF DIESEL FUEL SPRAY IN THE INITIAL STAGE OF INJECTION

KO K. N.,LEE C. S.,HUH J. C. The Korean Society of Automotive Engineers 2005 International journal of automotive technology Vol.6 No.1

An experimental investigation has been carried out to reveal the atomization process of the diesel fuel spray. The spray injected through a single hole nozzle was taken by a camera on the opposite side of a stroboscope for macroscopic observation or a nanolite for microscopic observation. The effect of nozzle aspect ratio was analyzed with disintegration phenomena of the diesel spray. Based on the enlarged spray photograph, atomization process was observed in detail and further the spray cone angle was measured under various ambient pressures. The result shows that atomization of diesel spray in early stage of injection is mainly progressed in the vicinity of spray periphery region except the region close to the nozzle exit and spray head region. The spray cone angle is nearly constant under the pressurized condition, while it decreases with elapsing time under the atmospheric condition.

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.

살포 시스템에 의한 살균제 Dithianon의 감귤 잎 부착량 및 농작업자 노출량 비교

김민석(Min-Seok Kim),홍수명(Su-Myeong Hong),현재욱(Jae-Wook Hyun),황록연(Rok-Yeon Hwang),권혜영(Hye-Young Kwon),이효섭(Hyo-Sub Lee),문병철(Byeong-Chul Moon) 한국농약과학회 2017 농약과학회지 Vol.21 No.2

Recently, orchard control is equipped with automated facilities in order to labor-saving and control diseases caused by insects and pests. However, citrus orchards are small citrus trees and high in planting density. Therefore, Therefore, the automated facilities suitable for citrus orchards are needed because the automated facilities used in other orchards are not suitable. The purpose of this study is to determine the applicability of miniaturized speed spray compared to engine type spray used in citrus orchards. This experiment sprayed dithianon with engine type spray, speed spray and compared the amount of adhesion by a spray system using citrus leaves and water sensitive paper. The operator protective clothing was used to determine the operator exposure. The adhesion of citrus leaves was 2.13 μg/㎠ for engine type spray, 2.59 μg/㎠ for speed spray. The operator exposure was 0.38 μg/㎠ for speed spray and 2.10 μg/㎠ for engine type spray. In the citrus plant, spraying a speed spray showed a higher deposition amount than that of the engine type spray. The exposure of the speed spray was lower than that of the engine type spray.