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91 results on '"Kang, Sang Hun"'

12. Phase transition between pressure and heat release oscillations in hybrid rocket combustion

Author

Kang， Sang Hun, Lee， Changjin, and Choi Hyo Sang

Subjects
Phase difference, 0209 industrial biotechnology, Phase transition, Materials science, business.product_category, Mechanical Engineering, Direct numerical simulation, 02 engineering and technology, Mechanics, Combustion, Vortex, Physics::Fluid Dynamics, 020303 mechanical engineering & transports, 020901 industrial engineering & automation, 0203 mechanical engineering, Rocket, Mechanics of Materials, Low frequency instability, Physics::Chemical Physics, business, Equivalence ratio
Abstract

To understand the initiating mechanism of low frequency instability (LFI) in hybrid rocket combustion, numerical calculation was performed using a direct numerical simulation (DNS). Special attention was paid to the effect of the equivalence ratio on the shift in the phase difference between pressure (p’) and heat release oscillations (q’). A change in the equivalence ratio was considered by varying the temperature and composition of the combustion gas that entered into the post combustion chamber. In the obtained results, additional combustion was successfully simulated along with a vortex generation over the backward step, and combustion pressure and heat release oscillations were clearly reproduced as small vortices that move downward. In addition, the obtained results confirmed that the phase difference between pressure and heat release oscillations shifted because of the changes in the propagation speed of the pressure wave when the temperature of the combustion gas changes.

Published
2019

20. Oscillating Boundary Layer in Hybrid Rocket Combustion

Author

KIM, Jina, KANG, Sang Hun, and LEE, Changjin

Subjects
HYBRID ROCKET PROPULSION, BOUNDARY LAYERS
Abstract

The resonance of thermal lags of solid fuel with heat transfer oscillations in the boundary layer flow is the primary mechanism of exciting low frequency instability (LFI) in hybrid rocket combustion. Recent studies reported that swirl injection seems to stabilize combustion by suppressing boundary layer oscillations. This study focused on the experimental investigation of how the boundary layer is perturbed and it leads to the LFI. Also the appearance of temporal stabilization of combustion between two consecutive LFIs was investigated in terms of boundary layer oscillation. Special attentions were also made to monitor the overall behavior of oscillating boundary layer and the occurrence of the LFI as swirl intensity increased. Fluctuating boundary layer was successfully captured by visualized images and POD (Proper Orthogonal Decomposition) analysis. In the results, oscillating boundary layer became stabilized as the swirl intensity increases. And the coupling strength between high frequency p\', q\' diminished and periodical amplification of RI (Rayleigh Index) with similar frequency band of thermal lag was also decayed. Results confirmed that oscillating axial boundary layer triggered by periodic coupling of high frequency p\', q\' is the primary mechanism to excite thermal resonance with thermal lag characteristics of solid fuel. Numerical simulation also confirmed that transitioning to a positive coupling of high frequency p\', q\' is the mechanism responsible for exciting boundary layer oscillation.

Published
2019
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44. Protective effect of Bojungbangdocktang on cisplatin-induced cytotoxicity and apoptosis in MCF-10A breast endothelial cells

Author

Kang, Sang-Hun, primary, Lee, Hyo-Jung, additional, Jeong, Soo-Jin, additional, Kwon, Hee-Young, additional, Kim, Ji-Hyun, additional, Yun, Sun-Mi, additional, Kim, Jin-Hyung, additional, Lee, Hyo-Jeong, additional, Lee, Eun-Ok, additional, Ahn, Kwang Seok, additional, Ahn, Kyoo Seok, additional, and Kim, Sung-Hoon, additional

Published
2009
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