• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.77-80
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• 2013

An analytical study on performance of superdetonative mode ram accelerator was conducted for understanding the S225 experimental result of ISL. It would be noticeable that ISL S225 experimental result could be analytically simulated with the assumptions of inlet shockwave, equilibrium combustion chemistry, temperature dependent specific heat, and C-J oblique detonation in superdetonative operation mode. As result, the S225 experiment could be affected by heat of aluminum. Also, this study showed that the improper assumption, like isentropic assumption on shockwave, or constant specific heat on combustion, might cause misunderstanding about experimental result.

• Journal of the Korean Society of Combustion
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• v.12 no.4
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• pp.31-38
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• 2007

An numerical study was conducted on superdetonative mode ram accelerator with length extended combustor. The computation condition was based on ISL's RAMAC30 II S225 experiment. For 50% length increased combustor, flame is not sustained. For the case of 60% and 70% increase, flame is successfully sustaind. But detonation wave is oscillating and acceleration is fluctuating. Extention of combustor is helpful for sustaing detonation wave but it may cause unstart.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.126-129
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• 2007

An numerical study was conducted on superdetonative mode ram accelerator with extended combustor. The computation case was based on ISL's RAMAC30 II experiment. For 50% length increased combustor, flame is not sustained. For the case of 60% and 70% increase, flame is successfully sustaind. But detonation wave is oscillating and acceleration is fluctuating. Increasing of combustor length is helpful for sustaing detonation wave but it may cause unstart.

• Journal of the Korean Society of Combustion
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• v.19 no.1
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• pp.1-10
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• 2014

An analytical study on performance evaluation of superdetonative mode ram accelerator was conducted for understanding the experimental result. The quasi-one dimensional continuum, momentum, energy equations were solved under the assumption of inviscid flow. It would be noticeable that experimental result could be analytically simulated with the assumptions of inlet shockwave, temperature dependent specific heat, and additional aluminum combustion due to ablation of aluminum projectile in superdetonative operation mode. The acceleration of ram accelerator was comparable to experimental result with the consideration of the additional aluminum combustion energy by ablation of projectile. As result, the experimental result with the aluminum projectile could be affected by heat of aluminum.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.244-247
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• 2008

Based on ISL' S225 superdetonative mode ram accelerator, numerical simulation is conducted for strong mixture cases ($2H_2+O_2+3CO_2,\;2H_2+O_2+2.5CO_2$). For 3.0CO2 case, projectile is not acclerated, but 2.5CO2 case has sucessful acceleration. It shows that superdetonative mode ram accelerator can be operated when using mixture which strong enough to ignition.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.519-524
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• 2008

A numerical study is conducted to investigate propulsion performance enhancement based on S225 experiment case of ISL(French-German Research Institute of Saint-Louis)'s superdetonative ram accelerator. For govern equation, multi-species Navier-Stokes equation coupled with Baldwin-Lomax turbulence modeling is used. Govern equation is discretized by Roe's FDS and integrated by LU-SGS time integration. Detailed chemical reaction about $H_2/O_2/CO_2$ for high pressure is considered. $2H_2+O_2+2.5CO_2$ mixture was used for propellant gas. For the same over-driven factor, the launching speed of computation was faster than one of S225. Another configuration and condition of S225 was applied. A flame structure is very different from S225. For strong mixture case, it shows ignition by viscous effect. Acceleration and speed increment is higher than S225 computation and experiment. By using more strong mixture, propulsion performance was enhanced.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.3
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• pp.358-365
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• 2016

In this study, one-dimensional analysis under the assumption of an inviscid flow was conducted for the experiment initiated by the French-German Research Institute of Saint-Louis (ISL) in order to investigate the energy effect of aluminum combustion. Previous theoretical analysis based on the assumptions of isentropic compression and a constant specific heat derived by ISL claimed that the experiment was not affected by the heat of aluminum combustion. However, rigorous analysis in present investigation that considered the average properties behind the shock wave compression and temperature-dependent specific heat showed that the S225 experiment was partially affected by the aluminum combustion. The increase in heat due to aluminum combustion was estimated from the rigorous analysis.

• Journal of the Korean Society of Combustion
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• v.1 no.1
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• pp.83-91
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• 1996

A numerical study is carried out to examine the ignition and propagation process of detonation wave in SCRam-accelerator operating in superdetonative mode. The time accurate solution of Reynolds averaged Navier-Stokes equations for chemically reacting flow is obtained by using the fully implicit numerical method and the higher order upwind scheme. As a result, it is clarified that the ignition process has its origin to the hot temperature region caused by shock-boundary layer interaction at the shoulder of projectile. After the ignition, the oblique detonation wave is generated and propagates toward the inlet while constructing complex shock-shock interaction and shock-boundary layer interaction. Finally, a standing oblique detonation wave is formed at the conical ramp.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.2
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• pp.82-91
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• 1999

Projectile shapes of the superdetonative ram accelerator have great effects on shock structures, detonation wave formation, and ram acceleration characteristics. In this study, cone-cylinder-cone, a baseline projectile configuration of the superdetonative combustion mode, double-cone configurations and power-law shape, have been numerically investigated to analyze the effect of the front/rear configuration changes, on the flow field around the projectile, detonation wave formation process, and projectile acceleration characteristics. Hence, a ram projectile configuration with conspicuously improved acceleration characteristics has been proposed by adjusting the double cone angle and height. The results provide useful information for the ram accelerator design optimization study.

• Journal of computational fluids engineering
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• v.5 no.2
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• pp.55-63
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• 2000

In this paper, the numerical study has been done for the improvement of the superdetonative ram accelerator performance and for the design optimization of the system. The objective function to optimize the premixture composition is the ram tube length, required to accelerate projectile from initial velocity V/sub 0/ to target velocity V/sub e/. The premixture is composed of H₂, O₂, N₂ and the mole numbers of these species are selected as design variables. RSM(Response Surface Methodology) which is widely used for the complex optimization problems is selected as the optimization technique. In particular, to improve the non-linearity of the response and to consider the accuracy and the efficiency of the solution, design space stretching technique has been applied. Separate sub-optimization routine is introduced to determine the stretching position and clustering parameters which construct the optimum regression model. Two step optimization technique has been applied to obtain the optimal system. With the application of stretching technique, we can perform system optimization with a small number of experimental points, and construct precise regression model for highly non-linear domain. The error compared with analysis result is only 0.01% and it is demonstrated that present method can be applied to more practical design optimization problems with many design variables.