• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.651-663
• /
• 2017

Experimental results of $30^{\circ}-15^{\circ}$ nozzles were compared with numerically calculated convective heat transfer coefficients using FLUENT, Boundary Layer Integration Method and Bartz predictions. Also, the convective heat transfer coefficients were calculated by using FLUENT and boundary layer integration method for NASA HIPPO nozzles according to the characteristics of combustion gas and the correlation between pressure and pressure was compared. Finally, thermal analysis of NASA HIPPO nozzle was performed to compare the ablation thickness and char depth according to the combustion gas characteristics.

• Journal of the Korean Society of Safety
• /
• v.29 no.4
• /
• pp.91-96
• /
• 2014

This research deals with the combustion experiment of pine trees, which are the most representative species in Korea. Experimental data are compared with theoretical ones using Fire Simulation Program(FDS). It is considered that horizontal/vertical temperature distribution and radiant heat influence on adjacent areas in fire scenes. The linear function for separation distance to temperature was drawn by applying Stefan-Boltzmann's law; $y=112.13133{\times}({\sigma}T^4)^{-0.52916}$ for calculating the separation distance. In combustion experiment, the radiant heat came to $1.4{\sim}1.5kW/m^2$ in case of the separation distance by one meter. The numerical values mean that human body show the critical level of pain after one minute without a protective equipment.

• KEPCO Journal on Electric Power and Energy
• /
• v.5 no.2
• /
• pp.103-111
• /
• 2019

The combined cycle plant is an integration of gas turbine and steam turbine, combining the advantages of both cycles. It recovers the heat energy from gas turbine exhaust to use it to generate steam. The heat recovery steam generator plays a crucial role in combined cycle plants, providing the link between the gas turbine and the steam turbine. Simulation of the performance of the HRSG is required to study its effect on the entire cycle and system. Computational fluid dynamics has potential to become a useful to validate the performance of the HRSG. In this study a solver has been implemented in the open source code, OpenFOAM, for combustion simulation in the heat recovery steam generator. The solver is based on the steady laminar flamelet model to simulate detailed chemical reaction mechanism. Thereafter, the solver is used for simulation of HRSG system. Three cases with varying fuel injections and gas turbine exhaust gas flow rates were simulated and the results were compared with measurements at the system outlet. Predicted temperature and emissions and those from measurements showed the same trend and in quantitative agreement.

• 한국연소학회:학술대회논문집
• /
• 2005.10a
• /
• pp.170-178
• /
• 2005

Multi-hole type oxygen combustion burner was developed for industrial gasification and smelting furnace. We investigated characteristics of flame, radiation transfer, and soot emission in the convectional oxygen burner with respect to the feeding condition of fuel and oxygen. Regarding the results of the conventional burner, we designed new burners which have larger fuel consumption rate and radiation heat transfer. We changed the size and hole number and shape of the exit plane of the burner. In addition, the performance of the burner was tested with respect to the feeding condition of the fuel and air: Normal Diffusion flame(NDF) and Inverse Diffusion Flame(IDF). We investigated the flame configuration, radiation heat transfer, and soot formation by using a CCD camera, heat flux meter, and Laser Induced Incadescence(LII), respectively. The stable operating condition was obtained by the flame configuration and the flame of the burner which has dented exit plane was more stable in whole operating conditions. The characteristics of radiative heat transfer were sensitive to the feeding condition of reactants and the flame of 75% primary oxygen and 25% secondary oxygen of the IDF case shows maximum radiation heat transfer. The soot volume fraction of the flame was measured in the axial direction of the flame and the amount of soot volume fraction is proportion to the radiation heat transfer. As a result, we can get the optimal operating condition of the newly designed burner which enhances the characteristics of flame stabilization and radiation heat transfer.

• 한국연소학회:학술대회논문집
• /
• 2014.11a
• /
• pp.179-182
• /
• 2014

A comparative DNS study of the ignition characteristics of dual-fueled reactivity controlled compression ignition (RCCI) and stratification charge compression ignition (SCCI) is investigated using a 116-species reduced primary reference fuel (PRF) mechanism. In the RCCI combustion, two PRF fuels (n-heptane and iso-octane) with opposite autoignition characteristics are separatedly supplied and in-cylinder blended such that spatial variations in fuel reactivity, fuel concentration and temperature are achieved. In the SCCI combustion, however, just a single fuel (PRF50) is used such that only fuel concentration and temperature inhomoginieties are obtained. Because three factors, rather than only two as in SCCI combustion, govern the overall RCCI combustion, combustion timing and combustion duration or heat release rate of RCCI combustion are flexibly and effectively controlled. It is found that the overall RCCI combustion occurs much earlier and its combustion duration is longer compared to SCC combustionI. Moreover, the negative temperature coefficient (NTC) has a positive effect on enhancing RCCI combustion by inducing a shorter combustion timing and a longer combustion duration as a result of the occurrence of a predominant low-speed deflagration-combustion mode.

• Journal of the Korean Society of Combustion
• /
• v.14 no.3
• /
• pp.29-36
• /
• 2009

Simulation is performed to analyze the characteristics of turbulent spray combustion in a diesel engine condition. An extended Conditional Moment Closure (CMC) model is employed to resolve coupling between chemistry and turbulence. Relevant time and length scales and dimensionless numbers are estimated at the tip and the mid spray region during spray development and combustion. The liquid volume fractions are small enough to support validity of droplets assumed as point sources in two-phase flow. The mean scalar dissipation rates (SDR) are lower than the extinction limit to show flame stability throughout the combustion period. The Kolmogorov scales remain relatively constant, while the integral scales increase with decay of turbulence. The chemical time scale decreases abruptly to a small value as ignition occurs with subsequent heat release. The Da and Ka show opposite trends due to variation in the chemical time scale. More work is in progress to identify the spray combustion regimes.

• Journal of the Korean Society of Combustion
• /
• v.15 no.4
• /
• pp.53-57
• /
• 2010

The purpose of the present work is to investigate the effect of gasoline-premixing on a combustion and emissions characteristics in a compression ignition engine. For studying combustion characteristics, a combustion pressure and rate of heat release (ROHR) were measured using a single-cylinder DI compression ignition engine with a common-rail injection system and premixed fuel injection system. In addition, exhaust emissions characteristics were studied using emission analyzers and smoke meter. The experimental results showed that the case of gasoline-premixing had longer ignition delay and lower combustion pressure compared to the cases of diesel direct injection. Furthermore, premixed gasoline-air mixture reduced NOx emissions due to low peak of ROHR.

• Journal of the Korean Society of Combustion
• /
• v.16 no.1
• /
• pp.52-57
• /
• 2011

The present study describes the characteristics of combustion and exhaust emissions in compression ignition engines using diesel-gasoline dual fuel. For investigating combustion characteristics, diesel fuel was injected directly in a single-cylinder compression ignition engine with a common-rail injection system and gasoline fuel was injected into a premixed chamber installed in an intake port. In order to investigate exhaust emission characteristics, exhaust gas was measured by emission analyzer and smoke meter. The experimental results showed that cases of diesel-gasoline dual fuel combustion exhibited extended ignition delay and reduced peak combustion pressure compared to those of directly injected diesel fuel cases. Furthermore, premixed gasoline-air mixture reduced NOx emissions due to low peak of rate of heat release(ROHR).

• Journal of the Korean Society of Combustion
• /
• v.13 no.3
• /
• pp.24-32
• /
• 2008

Steady Laminar Flamelet Model (SLFM) calculation is performed to compare the turbulent combustion characteristics of air combustion and oxy-combustion with $CO_2$ recirculation. Radiative heat loss is considered by the optically thin limit assumption. For more realistic simulation the first-order conditional moment closure(CMC) model is applied to SANDIA PILOTED FLAME D again for the oxidants of air and mixture of $O_2$ and $CO_2$. The chemical kinetic machanism for methane is GRI Mech 3.0. Results show that oxy flames are much more stable than air flames, while comparable stability is maintained with 65% $CO_2$ recirculation. The comparable peak temperature is maintained with 80% $CO_2$ recirculation. Higher the temperature, higher the fractions of intermediate species, CO and OH, due to dissociation.

• 한국연소학회:학술대회논문집
• /
• 2012.11a
• /
• pp.291-294
• /
• 2012

The research and development status of combustion chamber of liquid rocjet engine for Korea Space Launch Vehicle(KSLV-II) are briefly described. The cold and hot firing tests of uni-element injector, the performance/heat flux measurement/hot firing tests of subscale combustion chamber and the performance/stability rating/regenerative cooling/hot fire tests of 30ton-class combustion chamber were successfully performed. Based on these results, the research and development of combustion chamber for 75ton-class liquid rocket engine are underway.