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분사 압력 변화에 따른 농업용 노즐의 분무 및 미립화 특성
상몽소,박수한,Chang, Mengzhao,Park, Suhan 한국분무공학회 2021 한국액체미립화학회지 Vol.26 No.4
Spray drift of agricultural nozzles has become a big issue because it causes low precision targeting and environmental pollution. In order to reduce the spray drift, study spray characteristics of agricultural nozzles is virtually important. In this study, shadowgraph and Mie-scattering visualization techniques were used to study the macroscopic spray and atomization characteristics of an agricultural nozzle. PDPA was used to measure the atomization characteristics of spray. The injection pressure is set to 1 bar, 3 bar and 5 bar, which covers the working range of the nozzle. For the PDPA experiment, 75 points were measured in an area of 160 mm × 120 mm at 10 mm intervals directly below the nozzle to grasp the overall atomization characteristics of the spray. It was found that the spray width and sheet width showed a linear correlation. As the injection pressure increased, the sheet expansion in the 0-degree direction and the sheet swing in the 90-degree direction jointly promoted the breakup of the sheet. In addition, the area close to the central axis had a large droplet velocity, and since a large droplet velocity promoted atomization of spray, the area close to the central axis had a smaller spray droplet diameter than the left and right regions.
플래시 보일링 조건에서 다공형 직접분사식 인젝터의 분무 및 미립화 특성 연구
상몽소(Mengzhao Chang),박수한(Suhan Park) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.6
연료의 분무 및 미립화 특성은 엔진 성능 개선 및 배기 배출물 저감에 매우 중요한 역할을 한다. 활발한 액적 분열 활동으로 인해 작고 균일한 연료 분무가 형성된다면 연소실 내에서의 분무 증발이 가속화하고, 균일한 공기-연료 혼합기를 형성할 수 있어 엔진의 연소과정을 최적화할 수 있다[1, 2]. 연구자들은 분무 미립화 특성을 개선하기 위해 500 bar 이상의 (초)고압분사, 가열된 연료의 분사 등 다양한 분사 기술 및 전략을 개발하고 있다. 본 연구에서는 실제 엔진 운전조건에서 발생하는 플래시보일링 조건을 모사하기 위해 연료 온도를 20 ℃와 120 ℃로 설정하여 과냉 (sub-cooled) 및 과열(super-heated)조건에서 다공형 직접 분사식 인젝터 (multi-hole direct injection injector, GDI)의 분무 미립화 특성을 비교 및 분석하였다. 분무 전체의 미립화 및 균일도를 파악하기 위해 인젝터 30mm 아래의 평면에서 2mm 간격으로 약 100 개의 측정 지점을 설정하고 위상 도플러 입자 분석기(phase Doppler particle analyzer, PDPA)를 이용하여 액적의 속도 및 크기를 측정하였다. 실험장치의 개략도 및 상세 정보는 아래의 그림과 표에 나타내었다. [그림 본문 참조]
쉴리렌 가시화방법을 이용한 E85 연료의 기상 분무 특성 연구
상몽소 ( Mengzhao Chang ),박정현 ( Jeonghyun Park ),박수한 ( Suhan Park ) 한국액체미립화학회 2018 한국액체미립화학회 학술강연회 논문집 Vol.2018 No.-
The objective of this study is to evaluate the gas phase spray characteristics of a gasoline direct injection (GDI) injector using E85 fuel according to the increase of injection pressure and chamber ambient temperature. The gas phase spray images are obtained from Schlieren spray visualization system including point light source, concave mirror, knife edge, high speed camera and image storage device. The gas phase spray characteristics such as spray angle, spray tip penetration, and spray area, are obtained through the image processing using MATLAB. From the experiment and analysis, it was found that increasing injection pressure produced larger vapor phase spray penetration and spray angle, while ambient temperature had no important effect on vapor phase spray penetration and spray angle
쉴리렌 가시화 기법을 이용한 E85 연료의 액상 및 기상 분무 비교
박수한,상몽소,Park, Suhan,Chang, Mengzhao 한국교통대학교 융복합기술연구소 2018 융ㆍ복합기술연구소 논문집 Vol.8 No.1
The purpose of this study is to investigate the liquid- and vapor-phase spray characteristics, such as spray tip penetration and spray angle using gasoline direct injection (GDI) injector with multi-hole. The vapor-phase spray was captured by the Schlieren visualization system, which consists of high-speed camera, LED lamp, concave mirrors, and knife-edge. The liquid-phase spray was visualized by Mie-scattering techniques. Both spray images of vapor- and liquid-phase were visualized under 373 K of ambient temperature, 1 bar of ambient pressure, and 100/200 bar of injection pressure. The energizing duration was fixed at 1.5 ms. From the analysis of experimental results, it revealed that the increased injection pressure induced an early vaporization due to the improvement of droplet atomization. The spray tip penetration and spray angle in vapor-phase were higher than those in liquid-phase. The difference in the spray tip penetration between vapor- and liquid-spray gradually increased with the time elapsed after the injection. Even with the spray angle characteristics, it was found that the difference between the spray angle of liquid and vapor spray gradually grew after they entered steady-state conditions.
노즐 홀 직경에 따른 단공 GDI 인젝터의 분무 특성 연구 - (2) 분무 균일도 및 미립화 특성 비교
박정현 ( Jeonghyun Park ),노승천 ( Seungcheon Ro ),상몽소 ( Mengzhao Chang ),박수한 ( Suhan Park ) 한국분무공학회 2020 한국액체미립화학회지 Vol.25 No.4
A single spray plume is the basic unit of the entire spray plume and is an important factor in understanding the spray characteristics. However, since the multi-hole GDI injector has a narrow spray angle, the superposition of the spray plumes occurs severely. Therefore, the spray uniformity and the spray atomization characteristics of a single spray plume were analyzed in this study using a single-hole GDI injector. Five single-hole GDI injectors with different nozzle hole diameters were used in the experiment. The uniformity of the spray was evaluated through the analysis of the spray pattern images. In addition, the atomization characteristics were compared using the diameter distribution of the spray droplets obtained using PDPA. As a result, the larger diameter of the nozzle hole, the less uniformity of the spray, and the injection pressure did not have a significant effect on the spray uniformity. It is judged that the surface roughness of the injector has a greater effect on spray uniformity than the diameter of the nozzle hole. Also, the size of the spray droplets increased sharply when the diameter of the nozzle hole was 230 μm.