http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
엇갈린 V-형 리브가 부착된 냉각유로에서의 열유동 수치해석
명현국(H.K. Myong),김광용(K.Y. Kim) 한국전산유체공학회 2008 한국전산유체공학회지 Vol.13 No.4
The present study numerically simulates the flow and heat transfer characteristics of rib-induced secondary flow in a square cooling channel with staggered V-shaped ribs, extruded on both walls. The rib pitch-to-height ratio (p/h) varies from 2.8 to 10 with the rib-height-to-hydraulic diameter ration (h/D<SUB>h</SUB>) of 0.07 and the Reynolds number of 50,000. Shear stress transport (SST) turbulence model is used as a turbulence model. Computational results show that complex secondary flow patterns are generated in the channel due to the snaking flow in the streamwise direction for all tested cases. In the range of p/h=5 to 10 the staggered V-shaped rib gives about 3 times higher heat transfer augmentation than the reference smooth pipe with high heat transfer on both front side and the area around the leading edge of the ribs, while the former cases give about 18 times higher streamwise pressure drop than the latter ones. However, for the thermal performances, based on the equal pumping power condition, the case of p/h=2.8 gives the best result among three cases, mainly due to relatively low streamwise pressure drop, although it gives relatively low heat transfer augmentation.
Ahmed body 주위의 난류유동장 해석에 대한 난류모델의 평가
명현국(H.K.Myong),박희경(H.K.Park) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.11_2
A numerical simulation has been carried out for three-dimensional turbulent flows around an Ahmed body. The full Navier-Stokes equation is solved with the SIMPLE method in general<br/> curvi I inear coordinates system.. Several k-ε turbulence mode I s wi th two convective difference<br/> schemes are evaluated for the performance such as drag coefficient, velocity and pressure fields. The results of simulation prove that the RNG k-ε model with a quadratic upwind difference scheme predicts fairely well the tendency of velocity and pressure fields and gives more reliable drag coefficient.<br/>
PERFORMANCE ANALYSIS OF THE TURBULENCE MODELS FOR A TURBULENT FLOW IN A TRIANGULAR ROD BUNDLE
W. K. In,T. H. Chun,H. K. Myong 한국전산유체공학회 2005 한국전산유체공학회지 Vol.10 No.1
A computational fluid dynamics(CFD) analysis has been made for fully developed turbulent flow in a triangular bare rod bundle with a pitch to diameter ratio (P/D) of 1.123. The nonlinear turbulence models predicted the turbulence-driven secondary flow in the triangular subchannel. The nonlinear quadratic k- ε models by Speziale[1] and Myong-Kasagi[2] predicted turbulence structure in the rod bundle fairly well. The nonlinear quadratic and cubic k- ε models by Shih et al.[3] and Craft et al.[4] showed somewhat weaker anisotropic turbulence. The differential Reynolds stress model by Launder et al.[5] appeared to overpredict the turbulence anisotropy in the rod bundle.
엇갈린 V-형 리브가 부착된 냉각유로에서의 열유동 수치해석
명현국(H.K. Myong),김광용(K.Y. Kim) 한국전산유체공학회 2008 한국전산유체공학회 학술대회논문집 Vol.2008 No.-
The present study numerically simulates the flow and heat transfer characteristics of rib-induced secondary flow in a cooling channel with staggered V-shaped ribs, extruded on both walls. The rib pitch-to-height ratio (p / h) varies from 2.8 to 10 with the rib-height-to-hydraulic diameter ration (h/Dh) of 0.07 and the Reynolds number of 50,000. Shear stress transport (SST) turbulence model is used as a turbulence model. Computational results show that complex secondary flow patterns are generated in the duct due to the snaking flow in the streamwise direction for all tested cases. In the range of p/h=5 to 10 the staggered V-shaped rib gives about 3 times higher heat transfer augmentation than the reference smooth channel with high heat transfer on both front side and the area around the leading edge of the ribs, while the former cases give about 2.5 times higher streamwise pressure drop than the latter ones. Consequently, for the thermal performances, based on the equal pumping power condition, the staggered ones give about 2 times higher values than the latter ones with more uniform heat transfer distribution.
PERFORMANCE ANALYSIS OF THE TURBULENCE MODELS FOR A TURBULENT FLOW IN A TRIANGULAR ROD BUNDLE
In W.K,Chun T.H,Myong H.K Korea Society of Computational Fluids Engineering 2005 한국전산유체공학회지 Vol.10 No.1
A computational fluid dynamics(CFD) analysis has been made for fully developed turbulent flow in a triangular bare rod bundle with a pitch to diameter ratio (P/D) of 1.123. The nonlinear turbulence models predicted the turbulence-driven secondary flow in the triangular subchannel. The nonlinear quadratic κ-ε models by Speziale[1] and Myong-Kasagi[2] predicted turbulence structure in the rod bundle fairly well. The nonlinear quadratic and cubic k-ε models by Shih et al.[3] and Craft et al.[4] showed somewhat weaker anisotropic turbulence. The differential Reynolds stress model by Launder et al.[5} appeared to over predict the turbulence anisotropy in the rod bundle.
소형 제트엔진 배기플룸의 열유동장 및 화학성분의 IR 신호 영향성 전산해석
채준혁(J.H. Chae),이지현(J.H. Lee),이지원(J.W. Lee),하남구(N.K. Ha),김동건(D.G. Kim),장현성(H.S. Jang),명노신(R.S. Myong) 한국전산유체공학회 2019 한국전산유체공학회지 Vol.24 No.3
Because of high levels of infrared signature generated by engine exhaust plume, aircraft can be detected by infrared guided missiles equipped with a modern detector. In order to investigate the characteristics of plume IR and reduce the level of its signature, the exhaust plume around an engine nozzle was calculated with a Navier-Stokes-Fourier computational code. The narrow-band model was employed to calculate the spectral characteristics of the IR signature. Computational models were compared with the experimental results of a micro jet engine. By considering an aircraft flying at an altitude of 20,000 ft, the effects of thermal flow field and chemical components on the IR signature was investigated. As expected, the plume IR signature showed the greatest effect at 4~4.5 μm CO₂ and 5~8 μm H₂O, and the temperature affected the IR signature over the whole band. In addition, the molar fraction change in CO₂ and H₂O resulted in higher variation in plume IR signature.
Ahmed Body 주위의 3차원 난류유동 해석 - 난류모델의 평가
명현국,진은주,박희경,Myong, H.K.,Jin, E.,Park, H.K. 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.7
A numerical simulation has been carried out for three-dimensional turbulent flows around an Ahmed body. The Reynolds-averaged Navier-Stokes equation is solved with the SIMPLE method in general curvilinear coordinates system. Several k-.epsilon. turbulence models with two convective difference schemes are evaluated for the performance such as drag coefficient, velocity and pressure fields. The drag coefficient, the velocity and pressure fields are found to be changed considerably with the adopted k-.epsilon. turbulence models as well as the finite difference schemes. The results of simulation prove that the RNG k-.epsilon. model with the QUICK scheme predicts fairly well the tendency of velocity and pressure fields and gives more reliable drag coefficient. It is also demonstrated that the large difference between simulations and experiment in the drag coefficient is due to relatively high predicted values of pressure drag from vertical rear end base.