• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.391-398
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• 2008

LES analysis was conducted with in-house CFD code to investigate the turbulence evolution and interaction due to turbulence ring and splash plate in the gas generator. Though chemical reaction was not accounted for, the results can be useful in determining the turbulence characteristics generated by ring and plate. The calculation results show that the installation of turbulence ring can introduce additional turbulences and improve turbulent mixing in the downstream flow. However, the addition of splash plate in the downstream of TR brings totally different shape of perturbation energy and enstrophy distribution for turbulent mixing. This enhancement can be done by the formation of the intensively strong vorticity production and mixing behind the plate. Pressure drop was found to be a reasonable level of about 1% or less of initial pressure in all calculation cases. Also, calculation results revealed that the variation of TR shape and intrusion length did not change the characteristics of turbulent mixing in the chamber. Even though the effect of installation location of splash plate on the turbulent mixing is not investigated yet, calculation results conclude the addition of splash plate leads to the increase in turbulent mixing with an acceptable pressure drop.

• 한국추진공학회지
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• 제22권6호
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• pp.72-83
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• 2018

본 연구에서는 단일 전단 동축 분사기를 이용한 수소 로켓 연소기의 전산유체 해석을 수행하였다. 2차원 축대칭 형상에서 난류연소 해석을 위해 hybrid RANS/LES 난류모델을 적용하였다. 적합한 해석기법을 찾기 위해 3가지 화학 반응기구, 3가지 고해상도 기법 및 3단계 격자해상도 조합을 비교하였다. 벽면 열유속을 실험결과와 비교하여 해석 성능을 살펴보았으며, 유동장 결과 분석으로 동축 분사기를 가지는 로켓 연소기의 난류연소특성을 살펴볼 수 있었다.

• Journal of Mechanical Science and Technology
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• 제16권11호
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• pp.1550-1557
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• 2002

Diode laser sensor for measuring gas temperature and species concentration in combustion chamber was developed using 2.0 tim distributed feed back lasers. To evaluate the measurement sensitivity of diode laser sensor system, CO2 survey spectra near 2.0 Um were measured and compared with the calculated one. This diode laser absorption sensor was applied to measure gas temperatures in a premixed flat flame of CH$_4$-air mixture. Experimental results were in good agreement with the values by an R-type thermocouple within 6.12%. In addition, successful demonstration of measurement of gas temperature and species concentration in a soot flame showed the promising possibility of diode laser absorption sensors for practical combustion system with non-intrusive method.

• 한국자동차공학회논문집
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• 제10권1호
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• pp.115-124
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• 2002

The optimum design of auto-catalyst needs a good compromise between the pressure drop and flow distribution in the monolith. One of the effective methods to achieve this goal is to use the concept of radially variable cell density. However, there has been no study of evaluating the usefulness of this method on light-off catalyst. We have computationally investigated the effectiveness of variable cell density technique applied to the light-off catalyst using a three-dimensional integrated CFD model. in which transient chemical reacting calculations are involved. Computed results show that variable cell density technique can reduce the accumulated emissions of CO and HC during the early 100sec of FTP cycle by 86.78 and 80.87%, respectively, The effect of air-gap between the monoliths has been also examined. It is found that air-gap has a beneficial effect on reducing pressure drop and cold-start emissions.

• 한국연소학회지
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• 제6권2호
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• pp.23-28
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• 2001

In the present work, the effect of PDF selection and intermittency on the result of the numerical simulation are examined by the simulation of a turbulent methane-air jet diffusion flame. As to the PDFs, beta-function and clipped Gaussian are considered. Results for the pure mixing jet are compared with experimental results. Then, the turbulent flame is calculated for the same conditions and the results obtained for the several models are compared. It is found that the clipped Gaussian distribution coupled with consideration of intermittency recovers the experimental data very well. As to the reacting flow results, the main overall properties of the turbulent jet diffusion flame such as maximum flame temperature are less affected by the choice of the PDF. Flame height and NO emissions, on the contrary, appear to be significantly influenced.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.269-272
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• 2005

Due to the high density and heating value, liquid fuel is attractive for ramjet propulsion system. Liquid fuel requires time to evaporation and mix with incoming air before ignition; insufficient evaporation and mixing result in low combustion efficiency and instability. So the numerical studies are conducted to investigate the spray and combustion characteristics of a liquid-fueled dump type Integrated Rocket Ramjet combustor. The governing equations are solved by means of a finite-volume using time derivative preconditioning method for chemical reacting flow. The liquid phase is treated by solving Lagrangian equations of motion and transport for the life histories of a statistically significant sample of individual droplets.

• 한국연소학회지
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• 제15권4호
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• pp.43-52
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• 2010

A non-intrusive measurement, Planar Laser Induced Fluorescence was employed to visualize and measure the fuel distribution of the non-reacting field at the burner exit of gas turbine combustor. Measurement techniques, image processing method and quantification procedure were presented. Also, concentration measurement with gas analyzer was carried out to verify the propriety of PLIF result. The PLIF result coincides well with gas analyzer measurement result. PLIF test result for several other conditions are mentioned as well.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제21회 추계학술대회 논문집
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• pp.204-207
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• 2003

The present paper reports high-fidelity simulation of direct initiation processes of cylindrical detonation waves by concentrated energy deposition. The goal is to understand the underpinning mechanisms in failed or successful detonation initiation processes. We employed the Space-Time CESE method to solve the reacting flow equations, including realistic finite-rate chemistry model of the nine species and twenty-four reactions for H$_2$-O$_2$-Ar mixtures. Detailed results of sub-critical, critical. and supercritical initiation process are reported.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.175-178
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• 2008

예조건화 기법을 이용하여 AP/HTPB 연료를 사용하는 내삽 노즐에 대한 수치해석을 실시하여 실험데이터와 비교해 보았다. 내부 현상을 파악하기 위해서 고체연료가 regression 되는 현상을 묘사하여 시간에 따른 온도,압력등의 변화를 확인해 보았다.

• 대한기계학회논문집
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• 제18권9호
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• pp.2431-2442
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• 1994

In this paper the efficient space marching Viscous Shock Layer and Parabolized Navier-Stokes method have been applied to study the complex 3-D hypersonic equilibrium chemically reacting flowfilelds over sphere-cone($10^{\circ}$) vehicle at low angles of attack($0^{\circ}~5^{\circ}), Mach 20, and an altitude of 35km. The current bluntbody/afterbody space marching numerical method predicts the complex flowfields accurately and efficiently even on a small computer. The shock thickness from equilibrium air model is thinner than that from the perfect gas model. The windside wall heat-transfer rate, pressure and skin friction force were increased significantly when compared with those of leeside. The CA, CN, CM were increased almost linearly with the angle of attack in this region. The wall pressure, heat transfer, skin friction and axial force coeffient from equilibrium model were much higher than those from perfect gas model. The center of pressure moved forward with the increase of angle of attack.