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Characteristics of Supersonic Jet Impingement on a Flat Plate
홍승규,이광섭,박승오 한국전산유체공학회 2001 한국전산유체공학회 학술대회논문집 Vol.2001 No.-
Viscous solutions of supersonic jet impinging on a flat plate normal to the flow are simulated using three-dimensional Navier-Stokes solver. The jet impinging flow structure exhibits such complex nature as shock shell, plate shock and Mach disk depending on the flow parameters. Among others, the dominant parameters are the ratio of the nozzle exit pressure to the ambient pressure and the distance between the nozzle exit plane and the impinging plane. In the present study, the nozzle contour and the pressure ratio are held fixed, while the jet impinging distance is varied to illuminate the characteristics of the jet plume with the distance.<br/> As the plate is placed close to the nozzle at 3D high, the computed wall pressure at or near the jet center oscillates with large amplitude with respect to the mean value. Here D is the nozzle exit diameter. The amplitude of wall pressure fluctuations subsides as the distance increases, but the maximum pressure level at the plate is achieved when the distance is about 4D high. The frequency of the wall pressure is estimated at 6.0 ㎑, 9.3 ㎑, and 10.0 ㎑ as the impinging distance varies from 3D, 4D, to 6D, respectively.
홍승규,성웅제 한국전산유체공학회 2001 한국전산유체공학회 학술대회논문집 Vol.2001 No.-
For rapid and abrupt control of a missile in supersonic flight, side jet on a missile body is found to be a useful devise as evidenced by recent missile development at several nations. The magnitude of the side jet and the duration of it decide the level of control of such a missile system. In this paper, the aerodynamic characteristics of the side jet devise itself are examined in terms of key parameters such as the side jet nozzle contour, the chamber pressure and temperature. Specifically attention is focused on the effect of the chamber shape between the straight nozzle and the bended nozzle by 90 degrees. The flow properties as well as the thrust level are compared between the two shapes. Particular attention is paid at the way the nozzle is bended at the joint. Effects of the length and the divergence angle of the nozzle on the thrust magnitude are also quantified among the three different side jet nozzles.
Application of Characteristic Boundary Conditions
홍승규,이광섭 한국전산유체공학회 1996 한국전산유체공학회 학술대회논문집 Vol.1996 No.-
Characteristic boundary conditions are discussed in conjunction with a flux-difference splitting formulation as modified from Roe's linearization. Details of how one can implement the characteristic boundary conditions which are compatible with the discrete formulation at interior points are given for different types of boundaries including subsonic outflow and adiabatic wall. The latter conditions are demonstrated through computation of supersonic ogive-cylinder flow at high angle of attack and the computed wall pressure distribution is compared with experiment.