• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.3467-3472
• /
• 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.

• Environmental Engineering Research
• /
• v.21 no.4
• /
• pp.365-372
• /
• 2016

The effects of hydrodynamics and alum dose on particle growth were investigated by monitoring particle counts in a rapid mixing process. Experiments were performed to measure the particle growth and breakup under various conditions. The rapid mixing scheme consisted of the following operating parameters: Velocity gradient (G) ($200-300s^{-1}$), alum dose (10-50 mg/L) and mixing time (30-180 s). The Poisson regression model was applied to assess the effects of the doses and velocity gradient with mixing time. The mechanism for the growth and breakup of particles was elucidated. An increase in alum dose was found to accelerate the particle count reduction. The particle count at a G value of $200s^{-1}$ decreased more rapidly than those at $300s^{-1}$. The growth and breakup of larger particles were more clearly observed at higher alum doses. Variations of particles due to aggregation and breakup of micro-flocs in rapid mixing step were interactively affected by G, mixing time and alum dose. Micro-flocculation played an important role in a rapid mixing process.

• Journal of ILASS-Korea
• /
• v.10 no.1
• /
• pp.35-42
• /
• 2005

The present study has numerically and experimentally investigated the spray behavior of liquid jet injected in subsonic cross-flow. The corresponding spray characteristics are correlated with jet operating parameters. The spray dynamics are known to be distinctly different in the three regimes: the column, the ligament and the droplet regimes. The behaviors of column, penetration and breakup of liquid jet have been studied. Numerical and physical models are base on a modified KIVA code. The primary atomization is represented by a wave model base on the KH(Kelvin-Helmholtz) instability that is generated by a high interface relative velocity between the liquid and gas flows. In odor to capture the spray trajectory, CCD camera has been utilized. Numerical and experimental results indicate that the breakup point is delayed by increasing gas momentum ratio and the penetration decreases by increasing Weber number.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.5
• /
• pp.659-669
• /
• 1997

The effects of exhaust gas recirculation on diesel engine combustion and soot/NOx emissions are numerically studied. The primary and secondary atomization is modelled using the wave instability breakup model. Autoignition of a diesel spray is modelled using the Shell ignition model. Soot formation is kinetically controlled and soot oxidation is represented by a model which account for surface chemistry. The NOx formation is based on the extended Zeldovich NOx model. Effects of injection timing and concentration of $O_{2}$ and CO$_{2}$ on the pollutant formation and the combustion process are discussed in detail.

• Journal of ILASS-Korea
• /
• v.4 no.1
• /
• pp.1-12
• /
• 1999

• Journal of ILASS-Korea
• /
• v.4 no.2
• /
• pp.1-9
• /
• 1999

• Journal of ILASS-Korea
• /
• v.4 no.3
• /
• pp.1-7
• /
• 1999

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.3
• /
• pp.204-211
• /
• 2019

The analysis on two-phase flow in a Lean Direct Injection(LDI) combustor has been investigated. Linearized Instability Sheet Atomization(LISA) and Aerodynamically Progressed Taylor Analogy Breakup(APTAB) breakup models are applied to simulate the droplet breakup process in hollow-cone spray. Breakup model is validated by comparing penetration length and Sauter Mean Diameter(SMD) of the experiment and simulation. In the LDI combustor, Precessing Vortex Core(PVC) is developed by swirling flow and most droplets are atomized along the PVC. It has been confirmed that all droplets have Stokes number less than 1.0.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.11 no.5
• /
• pp.37-50
• /
• 2007

This study investigated the characteristics of spray generated by a liquid coaxial swirl injector used in a combustor of the liquid rocket engine. The linear stability analysis considered long and short wave was introduced in liquid sheet breakup. Through the hydrodynamic analysis the initial liquid sheet thickness spray angle and injection velocity were predicted. To evaluate the effect of turbulence model standard $k-{\varepsilon}$ and RNC $k-{\varepsilon}$ model were applied to numerical calculation and it was known that RNC $k-{\varepsilon}$ model was more applicable to predict spray characteristics. On the basis of this evaluation validation of the developed model was performed with swirl injector installed in LPRE and the predicted results of breakup length, spray angle, and SMD agreed well with experiments qualitatively and quantitatively.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.3
• /
• pp.97-105
• /
• 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.