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LDV를 이용한 토크 컨버터 내 유동의 실험적 분석(Ⅱ)
유성출,조장현 한국기계기술학회 2019 한국기계기술학회지 Vol.21 No.4
LDV(laser Doppler velocimetry) measurements were conducted at a total of four planes at 0.4 speed ratio. The speed ratio of 0.4 is 1600rpm of impeller and 633rpm of turbine speed. Even at the speed ratio 0.4, fluid flow at the gap region between the impeller and turbine and impeller exit was leaving the impeller and flowing up behind the turbine, and flows were affected by the turbine blade as it passed, negatively effecting converter efficiency. In the gap region, fluctuations make a clear sinusoidal trend unclear. The rise and fall of the flow rates in a broad sense, indicate a dependency based on the passage of the turbine blade in front of the impeller passage exit but a sinusoidal trend is not evident from this data.
유성출 한국기계기술학회 2018 한국기계기술학회지 Vol.20 No.6
LDV(laser Doppler velocimetry) measurements were conducted on the exit region of the impeller passage and the gap between the impeller and turbine blades under 0.8 speed ratio. The 0.8 speed ratio has an impeller speed of 2000rpm and a turbine speed of 1600rpm. A periodic variation of the mass flow rate is present in many of the measurements made. The frequency of this variation is the same as the frequency of the turbine blades passing the impeller passage exit. It is found that the instantaneous position of the turbine had effect on fluid flow inside the impeller passage and gap region. This study would aid in the construction of higher accuracy CFD models of this complex turbomachinery device.
유성출,Yoo, Seoung-Chool The Institute for Liquid Atomization and Spray Sys 2000 한국액체미립화학회지 Vol.5 No.1
This study presents the flow visualization results, velocity and turbulence intensity measurements made within an air filter cover and entry region of a mass air flow sensor (MAFS) which is used in an induction system of 3.8L engine. Flow structure in two air filter cover assemblies were examined. The first was a clear plastic replica of the production cover while the second was a modified clear plastic cover with a geometry configured to reduce fluctuations. High speed flow visualization and laser doppler velocimetry (LDV) systems were used to reveal and analyze the flow field characteristics encountered in the sensor design process under steady flow conditions. A 40-watt copper vapor laser was used as a light source. Its beam is focused down to a sheet of light approximately 1.5mm thick. The light scattered off the particles was recorded by a 16mm high speed rotating prism camera at 5000 frames per second. A comparison of the flow patterns and LDV measurements in the original and modified air filter covers is presented to illustrate the controlling effect of the cover design on the turbulence structure formation near the bypass and on the sensor output signal. In both axial and radial planes of the main passage it was found that the turbulence flow pattern is remarkably influenced by the air filter cover and main passage configuration.
난류 드래그 저감을 위한 벽면의 형상 변화에 관한 연구
유성출 한국기계기술학회 2020 한국기계기술학회지 Vol.22 No.3
The production of turbulence near a wall is the governing mechanism of the turbulent drag from external flow around bodies and in internal flows involving turbulence. The pocket is closely associated with the occurrence of the large Reynolds stress producing motions, and therefore implicitly involved with the turbulence production process. Within the wall region, hot-wire measurements show that a strong vortex forms within the pockets. This vortex is the rearrangement of existing sublayer vorticity and its amplification. The work in this area has been applied to the prediction and reduction of drag. The study is focused on the time scale of the pockets. The relationship between pocket time scale and modified wall has been found. By changing the upstream boundary condition at the wall the time scale of pockets were increased.
벽면의 형상 변화에 의한 난류 드래그 관련 Pocket Length Scale 저감연구
유성출,조장현 한국기계기술학회 2019 한국기계기술학회지 Vol.21 No.6
The flow-surface interaction and resulting pockets is the case of a turbulence boundary layer. Conditionally sampled hot-wire measurements within the wall region show that a strong vortex forms within the pocket, bordering the upstream portion, which stay in the wall region. This vortex is the result of the rearrangement of existing sublayer vorticity and its amplification. The work in this area has been applied to the prediction and reduction of drag. The study is focused on determining change in the length scale of the pockets. An important relationship between pocket and modified wall has been found. By changing the upstream boundary condition at the wall, the length scale of pockets were decreased.
유성출 한국기계기술학회 2018 한국기계기술학회지 Vol.20 No.4
Fluid motion within the internal combustion engine cylinder plays a major role in controlling the fuel/air mixing and combustion processes in spark-ignition engines, and the combustion processes in compressionignition engines. In-cylinder flow is quite unstable and varies from one cycle to another. Various methods of in-cylinder flow measurement and fuel/air mixing characterization have been developed during the past few decades. In particular, laser based flow diagnostic techniques have been utilized for this purpose. This study will focus on the quantification of spark-ignition engine in-cylinder flow using the laser based flow diagnostic techniques. The measurement methods, including high speed flow visualization and laser Doppler velocimetry (LDV), will be discussed.
실린더 내 유동해석에 레이저 기반 유동 진단기술 적용을 위한 실험용 Four-valve SI 기관의 설계 및 제작기술 개발
유성출 한국기계기술학회 2018 한국기계기술학회지 Vol.20 No.3
An AVL research engine, type 520, is modified to adapt to the 3.5L four-valve SI engine. With these given engine configurations, a test rig is constructed which allows easy changing of the different pistons and engine heads with a motoring capacity up to 3500 rpm. Nearly complete optical access to the inside of the cylinder is obtained by installing a transparent quartz cylinder on an AVL single cylinder engine. To avoid lubrication and to minimize scratches in the quartz cylinder the piston rings are made of Rulon-LD. With this experimental engine, researches for the in-cylinder flow characteristics by changing the induction system have been carried out using the laser based flow diagnostic techniques. In accordance with the previous result, it is evident that larger sized particles would be required in order to observe the flow characteristics of interest. The flow visualization taken with microballoon particles shows significant improvement. This provide detailed information.
Intake System이 Four-valve SI 기관 연소실 내 난류 운동에너지에 미치는 영향
유성출 한국기계기술학회 2017 한국기계기술학회지 Vol.19 No.6
The effects of intake system on turbulent kinetic energy for the in-cylinder flow of a four-valve SI engine were studied. For this study, the same head, cylinder, and the piston were used to examine turbulence characteristics in two different intake systems. In cylinder flow measurements were conducted using three dimensional LDV system. The measurement method, which simultaneously collects 3-D velocity data, allowed a evaluation of turbulent kinetic energy inside a cylinder. High levels of turbulent kinetic energy were found inregions of high shear flow, attributed to the collisions of intake flows. These specific results support the more general conclusion that the slightly offset direction of the intake system produced higher in-cylinder velocities on the +x-axis side of the cylinder which caused some asymmetric flow patterns about the z-axis. Higher levels of turbulent kinetic energy prevailed in zones of mean velocity collisions and regions where significant directional changes in the mean velocity patterns occurred.
유성출 한국해양교통학회 2022 한국해양교통학회 학술대회자료집 Vol.2022 No.2
1. 해양교통수단으로써 연안여객선의 중요성 증대 (1) 2020. 10. 8. 대중교통으로 인정(2) 연안 여객선 해양사고 증가(3) 코로나 팬더믹 이후 여객선 이용객 증가 2. 다른 시서물 및 교통시설과의 비교안전공학적 분석(1) 여객선 비상훈련의 법원(2) 다중이용시설 및 철도의 비상대응 훈련(3) 산업안적공학의 위험예지훈련에 적용한 여객선 비상대응훈련 3. 비상훈련적합증서 기초모형 설계(1) 안전관리적합증서 등 다른 유사한 제도 벤치마킹하여, (2) 안전한 해양교통을 위하여 연안여객선 비상훈련 적합증서 제도화 기초 모형 설계(3) 비상훈련 관련 빅데이터 관리를 통한 교육 및 훈련 발전 방향 모색