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스트레칭 분리 영역을 포함한 새로운 액적 충돌 모델의 개발
고권현(Gwon Hyun Ko),유홍선(Hong Sun Ryou) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
The present article proposes a new droplet collision model including the stretching separation regime and the formation of satellite droplets. The new model consists of a several equations to calculate the post-collision characteristics of colliding droplets and satellite droplets. These equations are derived from the energy balance of droplets between before and after collision. For binary collision of water droplets, the new model shows good agreement with experimental data for the number of satellite droplets. Nevertheless, it is thought that, in order to guarantee the generality of the new model, the improvements should be performed to consider the effects of the bouncing and the reflexive separation, which is essential process in the collision of hydrocarbon droplets.
극초고압 조건에서 디젤 분무 특성에 미치는 액적 항력 모델의 영향
고권현 ( Gwon Hyun Ko ),이성혁 ( Seong Hyuk Lee ),유홍선 ( Hong Sun Ryou ),이종태 ( Jong Tai Lee ) 한국분무공학회 2004 한국액체미립화학회지 Vol.9 No.3
N/A The present article investigates the influence of droplet drag models on predictions of diesel spray behaviors under ultra-high injection pressure conditions. To consider drop deformation and shock disturbance, this study introduces a new hybrid model in predicting drag coefficient from the literature findings. Numerical simulations are first conducted on transient behaviors of single droplet to compare the hybrid model with earlier conventional model. Moreover, using two different models, extensive numerical calculations are made for diesel sprays under ultra-high pressure sprays. It is found that the droplet drag models play an important role in determining the transient behaviors of sprays such as spray tip velocity and penetration lengths. Numerical results indicate that this new hybrid model yields the much better conformity with measurements especially under the ultra-high injection pressure conditions.
포스터 전시회 : 미세물분무의 작동에 대한 FDS 예측 성능 평가
고권현 ( Gwon Hyun Ko ),노경철 ( Kyoung Chul Ro ),김성찬 ( Sung Chan Kim ),이성혁 ( Seong Hyuk Lee ),유홍선 ( Hong Sun Ryou ) 한국액체미립화학회 2012 한국액체미립화학회 학술강연회 논문집 Vol.2012 No.-
In this study, the prediction performance of FDS has been estimated on the suppression of diesel pool fires by water mist. A downward-directed nozzle produces a fine water spray over small-scale opposed diesel pool fires located at the center of compartment. At FDS simulation, the water mist injection conditions are tuned to mimic the droplet size and velocity measured at the experiment. The predicted temperature distribution of flame shows good agreements with the measurement before and after water mist activation
[디젤엔진부문] 공동 현상 모델이 디젤분무의 예측에 미치는 영향에 대한 수치 해석적 연구
고권현(Gwon-Hyun Ko),유홍선(Hong Sun Ryou),이성혁(Seong Hyuk Lee) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The aim of this article is to investigate an importance of cavitation effect on numerical calculation for high-pressure diesel sprays. The nozzle flow model was used to take account of nozzle inlet configurations, cavitation effect, injection flow rate and chamber conditions. The KH/RT model published recently was also adopted for atomization and breakup processes. The numerical calculations were carried out for non-evaporative diesel sprays under different ambient conditions and the predicted results were compared with experimental data. The tip penetration and Sauter Mean Diameter(SMD) with considering the cavitation effect were in better agreement with experimental data than those obtained without considering the cavitation effect. In addition, the results showed that the cavitation could cause the increase of the atomization of liquid jet, resulting in producing smaller SMDs
고온 벽면에 충돌하는 분무 액적의 액막형성 및 열전달에 대한 수치해석 연구
고권현(Gwon Hyun Ko),손소연(So Yeon Son),노경철(Kyoung Chul Ro),유홍선(Hong Sun Ryou) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
The main purposes of this article are modeling the heat transfer process of liquid film produced by spraying droplets and analyzing the characteristics of impinging sprays on the hot surface. The Eulerian-Lagrangian approach is used for the interaction between gas phase and sprays with several sub-models. A new model is proposed for the liquid film formation and its heat transfer, and it is coupled with our previous model for spray/wall interaction. The new model is derived from mass, momentum, and energy conservation considering the liquid film formation by impinging droplets and spreading by successive addition of impinging droplets with the heat transfer to surrounding gas phase and wall surface. To assess the new model, numerical results using the new model are compared with experimental data. The liquid film dynamics and heat transfer by impinging fuel spray on heated wall are analyzed and the limitations of the present model are discussed.
[디젤엔진부문] 공기보조 분무에서 분산 모델들의 적용에 대한 수치 해석적 연구
고권현(Gwon-hyun Ko),유홍선(Hong Sun Ryou),이성혁(Seong Hyuk Lee) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
A numerical study was performed for applications of earlier published breakup models to air-assisted liquid drop atomization. In this paper, the Taylor analogy breakup (TAB) model, the surface wave instability (WAVE) model, and the drop drag WAVE (DDW) model were used to simulate breakup processes for liquid drops. Liquid drops was injected into high-speed gas flows with various Weber numbers, taken as 72. 148. and 270, at room temperature. At high Weber number, all models showed good agreement with experimental results for parent drop trajectories. For all ranges of Weber number, the TAB model underestimated drop sizes, but the WAVE relatively showed good results. It was thought that the DDW model was acceptable for the computation of liquid drop breakup in air-assisted sprays.<br/> <br/>