• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.919-924
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• 2000

Spray impingement model and fuel film formation model were developed and incorporated into the computational fluid dynamics code, STAR-CD. The spray/wall interaction process were modelled by considering the change of behaviour with surface temperature condition and fuel film formation. We divided behaviour of fuel droplets after impingement into stick, rebound and splash using Weber number and parameter K. Spray impingement model accounts for mass conservation, energy conservation and heat transfer to the impinging droplets. A fuel film formation model was developed by Integrating the continuity, the Navier-Stokes and the energy equations along the direction of fuel film thickness. The validation of the model was conducted using diesel spray experimental data and gasoline spray impingement experiment. In all cases, the prediction compared reasonably well with experimental results. Spray impingement model and fuel film formation model have been applied to a direct injection diesel engine combustion chamber.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3467-3472
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• 2007

The effects of the wall geometry on the spray-wall impingement process of a hollow-cone fuel spray emerging from a high-pressure swirl injector of the Gasoline Direct Injection (GDI) engine were investigated by means of a numerical method. The ized Instability Sheet Atomization (LISA) & Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model for spray atomization process and the Gosman model were applied to model the atomization and wall impingement process of the spray. The calculation results of spray characteristics, such as a spray development process and a radial distance after wall impingement, compared with the experimental ones by the Laser Induced Exciplex Fluorescence (LIEF) technique. It was found that the radial distance of the cavity angle of 90$^{circ]$ after wall impingement was the shortest and the ring shaped vortex was generated near the wall after spray-wall impingement process.

• Journal of Mechanical Science and Technology
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• 제16권3호
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• pp.376-385
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• 2002

Spray impingement and fuel film formation models with cavitation have been developed and incorporated into the computational fluid dynamics code, STAR-CD. The spray/wall interaction process was modeled by considering the effects of surface temperature conditions and fuel film formation. The behavior of fuel droplets after impingement was divided into rebound, spread and splash using the Weber number and parameter K(equation omitted). The spray impingement model accounts for mass conservation, energy conservation, and heat transfer to the impinging droplets. The fuel film formation model was developed by integrating the continuity, momentum, and energy equations along the direction of fuel film thickness. Zero dimensional cavitation model was adopted in order to consider the cavitation phenomena and to give reasonable initial conditions for spray injection. Numerical simulations of spray tip penetration, spray impingement patterns, and the mass of film-state fuel matched well with the experimental data. The spray impingement and fuel film formation models have been applied to study spray/wall impingement in high-speed direct injection diesel engines.

• 대한기계학회논문집B
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• 제25권2호
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• pp.187-194
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• 2001

Spray impingement and fuel film formation models were developed and incorporated into the computational fluid dynamics code. STAR-CD. The spray/wall interaction process was modeled by considering the change of behaviour with surface temperature conditions and the fuel film formation. We divided the behaviour of fuel droplets after impingement into rebound, spread and splash using the Weber number and the parameter K. The Spray impingement model accounts for mass conservation, energy conservation and heat transfer to the impinging droplets. The fuel film formation model was developed by integrating the continuity, Navier-Stokes and energy equations along the direction of fuel film thickness. Validation of the models was conducted using previous diesel spray experimental data and the present experimental results for the gasoline spray impingement. In all the cases, the prediction compared reasonably well with the experimental results. The spray impingement and fuel film formation models have been applied to the spray/wall impingement in high speed direct injection diesel engines.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.75-80
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• 2001

The present article deals with the numerical calculations for the inter-spray impingement of two diesel sprays under the conditions of high injection pressure. The Wave model involving the cavitation effect inside the nozzle was used for describing the atomization process. In particular, a hybrid model for drop collision was newly suggested in this study and compared with the O'Rourk's model, which has been widely used for diesel sprays. The impingement angles of 60 and 90 degrees were considered for simulation of non-evaporative diesel sprays. The calculated results for tip penetration were compared with experimental data and the Sauter Mean Diameter(SMD) characteristic was analyzed. It was concluded that the hybrid model slightly shows better agreement with experimental data than the O'Rourke's model. However, the more elaborate study should be needed for better understanding of spray-to-spray impingement phenomena.

• 한국자동차공학회논문집
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• 제16권2호
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• pp.166-174
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• 2008

Numerical study on the impingement process and the fuel film formation of the hollow-cone fuel spray was conducted under vaporization condition, and the effect of the wall cavity angle on spray-wall impingement structure was investigated. A detailed understanding of this phenomena will help in designing injection systems and controlling the strategies to improve engine performance and exhaust emissions of the Gasoline Direct Injection (GDI) engine. The improved Abramzon model was used to model the spray vaporization process and the Gosman model was adopted for modeling of spray-wall impingement process. The calculated results of the spray-wall impingement process were compared with experimental results. The velocity field of the ambient gas, the Sauter Mean Diameter (SMD) and the generated fuel film on the wall, which are difficult to obtain by the experimental method, were also calculated and discussed. It was found that the radial distance after the wall impingement and the SMD decreased with increasing the cavity angle and the temperature.

• 한국자동차공학회논문집
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• 제15권4호
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• pp.124-131
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• 2007

The numerical study on behavior of impinging spray from high-pressure swirl injector under various ambient temperatures was performed by using spray vaporization model and spray-wall impingement model implemented in modified KIVA code, and these spray models were estimated by comparison with experimental results. To compute the spray-wall impingement process, the Gosman model, which is based on the droplet behavior after impingement determined by experimental correlations, was used. The modified Abramzon and Sirignano model, that includes the effects of variable thermodynamic properties and non-unitary Lewis number in the gas film, was adapted for spray vaporization process. The exciplex fluorescence measurements were also conducted for comparison. The experimental and numerical analysis were carried out at the ambient pressures of 0.1 MPa and at the ambient temperature of 293 K and 473 K, and the spray characteristics, such as spray-wall impingement process, gas velocity field, SMD and vapor concentration, were acquired. It was found that the impinging spray develops active and SMD is small at vaporization conditions.

• 한국자동차공학회논문집
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• 제6권3호
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• pp.97-105
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• 1998

High pressure injection is recently used to reduce the emissions and increase the power of DI diesel engine. This high pressure injection makes the spray strike the cylinder wall. This spray/wall impingement is known to affect the emission and performance of DI diesel engine such that it is very important to know the spray/wall impingement process. In this study, multidimensional computer program KIVA-II was used to clarify the effect of spray wall impingement by different injection spray angle with the spray/wall impingement model consiedering rebound and slide motion and also the improved submodel for liquid breakup, drop distortion model.

• 대한기계학회논문집B
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• 제23권1호
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• pp.69-81
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• 1999

In this research computational methods for the droplet atomization and spray wall impingement are studied for the non-evaporating diesel fuel spray. The TAB(Taylor Analogy Breakup) model and Wave model are compared with experiments in order to describe droplet atomization process. The Watkins model and O'Rourke model are compared to simulate the spray wall impingement. As a result, It is found that the application of the Wave model has a good agreement with the experimental data in the case of high pressure injection. With regard to wall Impingement phenomena, it is found that the Watkins model is appropriate to the high temperature cylinder wall condition, while the O'Rourke model is appropriate to cold starting problem.

• Journal of Mechanical Science and Technology
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• 제20권8호
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• pp.1101-1117
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• 2006

In the present article, recent progress of spray-wall interaction research has been reviewed. Studies on the spray-wall interaction phenomena can be categorized mainly into three groups: experiments on single drop impact and spray (multiple-drop) impingement, and development of comprehensive models. The criteria of wall-impingement regimes (i.e., stick, rebound, spread, splash, boiling induced breakup, breakup, and rebound with breakup) and the post-impingement characteristics (mostly for splash and rebound) are the main subjects of the single-drop impingement studies. Experimental studies on spray-wall impingement phenomena cover examination of the outline shape and internal structure of a spray after the wall impact. Various prediction models for the spray-wall impingement phenomena have been developed based on the experiments on the single drop impact and the spray impingement. In the present article, details on the wall-impingement criteria and post-impingement characteristics of single drops, external and internal structures of the spray after the wall impact, and their prediction models are reviewed.