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임계 노즐을 통하는 기체 유동의 유출계수와 임계 압력비에 관한 연구
김재형(J. H. Kim),우선훈(S. H. Woo),김희동(H. D. Kim),박경암(K. A. Park) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
The air flow through a critical nozzle with a small throat diameter is significantly affected by viscous<br/> effect. In this paper, computational study using the axisymmetric, compressible, Navier-Stokes Equations is<br/> carried out to analy ze flow characteristic through a critical nozzle at low-Reynolds numbers. The nozzle<br/> throat diameters of D=0.28~4.48mm are used in this study. Computational results are compared with the<br/> previous experimented ones. It is found that the present computational results predict the critical pressure ratio<br/> and the discharge coefficient well. As the diameter of a critical nozzle increases, the discharge coefficient and<br/> critical pressure ratio increase. At the nozzle throat, the displacement and momentum thicknesses of the<br/> boundary layer are obtained by an empirical equation.
Numerical Study of Plume Interference on Missile Bodies at Transonic Speeds
이영기(Y. K. Lee),우선훈(S.H. Woo),김희동(H. D. Kim) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
Strongly underexpanded jets may lead to the plume-induced shock and wall boundary layer separation on the<br/> afterbody surface of flight objects, resulting in doing harm to their maneuverability and deteriorating the overall<br/> perfomance. To understand the general physics on this area, numerical studies were conducted for the missile model<br/> with a rectangular base to simulate moderately and highly underexpanded exhaust plumes at transonic speeds. Fully<br/> implicit finite volume scheme was applied to mass averaged Navier-Stokes equations with a two-equation<br/> turbulence model, RNG k- ε. The results showed that the plume-induced boundary layer separation on the missile<br/> afterbody was generated at high plume supply pressures and Mach number of 1.2. The plume-induced shock moved<br/> downstream movement as the free steam Mach number increased.