• Title/Summary/Keyword: Oblique Shock Wave

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Computational Study of the Passive Control of the Oblique-Shock-Interaction Flows (경사충격파 간섭유동의 피동제어에 관한 수치해석적 연구)

  • Chang, Sung-Ha;Lee, Yeol;Lee, Yong-Hee
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2006.11a
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    • pp.327-330
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    • 2006
  • Numerical study on the passive control of the oblique shock wave/turbulent boundary-layer interaction control utilizing slotted plates over a cavity has been carried out. Numerical results have been compared with the experimental observations, such as pitot/wall surface pressures and Schlieren flow visualizations, obtained for the same boundary conditions. It was found that the present numerical results shows a good agreement with experimental data. Further, the effect of different slot configurations including various number, location and angle of slots on the characteristics of the interactions are also tested, focusing on the variation of the piot pressure and the boundary-layer characteristics downstream of the interaction and the recirculating mass flux through cavity.

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Computational Study of the Passive Control of the Oblique-Shock-Interaction Flows (경사충격파 간섭유동의 피동제어에 관한 수치해석적 연구)

  • Chang, Sung-Ha;Lee, Yeol
    • Journal of the Korean Society of Propulsion Engineers
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    • v.11 no.2
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    • pp.18-25
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    • 2007
  • Computational study on the passive control of the oblique shock-wave/turbulent boundary-layer interaction utilizing slotted plates over a cavity has been carried out. The numerical boundary layer profile upstream of the interaction follows the compressible turbulent boundary-layer theory reasonably well, and the other results also show good agreements with the experimental observations, such as the wall surface pressures and Schlieren flow visualizations. Further, the effects of various slot configuration including number, location and angle of the slots on the characteristics of the interactions, such as the variation of the total pressures, the boundary-layer characteristics downstream of the interaction and the recirculating mass flux through the slots, are also tested and compared.

Numerical Study on the Suppression of Shock Induced Separation on a Strongly Heated Wall (강하게 가열된 벽면 위에서 충격파에 의한 경계층 박리의 제거에 관한 수치 연구)

  • LEE Doug-Bong;SHIN Joon-Cheol
    • Journal of computational fluids engineering
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    • v.2 no.2
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    • pp.59-72
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    • 1997
  • A numerical model is constructed to simulate the interactions of oblique shock wave / turbulent boundary layer on a strongly heated wall. The heated wall temperature is two times higher than the adiabatic wall temperature and the shock wave is strong enough to induce boundary layer separation. The numerical diffusion in the finite volume method is reduced by the use of a higher order convection scheme(UMIST scheme) which is a TVD version of QUICK scheme. The turbulence model is Chen-Kim two time scale model. The comparison of the wall pressure distribution with the experimental data ensures the validity of this numerical model. The effect of strong wall heating enlarges the separation region upstream and downstream. In order to eliminate the separation, wall suction is applied at the shock foot position. The bleeding slot width is about same as the upstream boundary layer thickness and suction mass flow is 10% of the flow rate in the upstream boundary layer. The final configuration of the shock reflection pattern and the wall pressure distribution approach to the non-viscous value when wall suction is applied.

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Morphological Transformation of Shock Waves Behind a Flat Plate

  • Chang, Se-Nyong;Lee, Soogab;Chang, Keun-Shik
    • Journal of Mechanical Science and Technology
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    • v.15 no.5
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    • pp.665-670
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    • 2001
  • The interaction of a travelling shock with the shear layer of a flat plate is studied computationally. The Euler and Navier-Stokes equations are solved numerically on quadrilateral unstructured adaptive grids. The flat plate is installed horizontally on the central axis of a shock tube. The shear layer is first created by two shock waves at different speeds splitted by a flat plate. A series of small vortices is developed as a consequence in the shear layer. The shock wave reflected at the end wall impinges the shear layer. The complicated shock dynamics in the evolution to the pseudo-steady state is represented with the morphological transformation of a planar shock into an oblique shock.

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Measured Effect of Shock Wave on the Stability Limits of Supersonic Hydrogen-Air Flames (충격파가 초음속 수소-공기 화염의 안정한계에 미치는 영향)

  • Hwanil Huh
    • Journal of the Korean Society of Propulsion Engineers
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    • v.3 no.1
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    • pp.86-94
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    • 1999
  • Measured shock wave effects were investigated by changing shock strength and position with particular emphasis on the stability limits of hydrogen-air jet flames. For this purpose, a supersonic nonpremixed, jet-like flame was stabilized along the axis of a Mach 2.5 wind tunnel, and wedges were mounted on the sidewall in order to interact oblique shock waves with the flame. This experiment was the first reacting flow experiment interacting with shock waves. Schilieren visualization pictures, wall static pressures, and flame stability limits were measured and compared to corresponding flames without shock-flame interaction. Substantial improvements in the flame stability limits were achieved by properly interacting the shock waves with the flameholding recirculation zone. The reason for the significant improvement in flame stability limits is believed to be the adverse pressure gradient caused by the shock, which can elongate the recirculation zone.

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Flow Analysis of POSRV Subsystem of Standard Korean Nuclear Reactor (한국 표준형 원전의 POSRV 하부 배관 유동해석)

  • Kwon, Soon-Bum;Kim, In-Goo;Ahn, Hyung-Joon;Lee, Dong-Eum;Baek, Seung-Cheol;Lee, Byeong-Eun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.10
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    • pp.1464-1471
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    • 2003
  • In order to investigate the flows with shock wave in branch, 108$^{\circ}$ elbow and T-junction of the IRWST system of standard Korean nuclear reactor, detail time dependent behaviors of unsteady flow with shock wave, vortex and so on are obtained by numerical method using compressible three-dimensional Navier-Stokes equations. At first, the complex flow including the incident and reflected shock waves, vortex and expansion waves which are generated at the corner of T-junction is calculated by the commercial code of FLUENT6 and is compared with the experimental result to obtain the validation of numerical method. Then the flow fields in above mentioned units are analyzed by numerical method of [mite volume method. In numerical analysis, the distributions of flow properties with the moving of shock wave and the forces acting on the wall of each unit which can be used to calculate the size of supporting structure in future are calculated specially. It is found that the initial shock wave of normal type is re-established its type from an oblique one having the same strength of the initial shock wave at the 4 times hydraulic diameters of downstream from the branch point of each unit. Finally, it is turned out that the maximum force acting on the pipe wall becomes in order of the T-junction, 108$^{\circ}$ elbow and branch in magnitude, respectively.

The Interaction Between Modules Caused by Thermal Choking in a Supersonic Duct (덕트내 초음속 유동에서 열폐색에 의한 모듈 간의 간섭)

  • Kim, Jang-Woo;Koo, Kyung-Wan;Han, Chang-Suk
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.2 s.257
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    • pp.109-115
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    • 2007
  • Airframe-integrated Scramjet engines of NASA Langley type consist of a compressor, a combustion chamber and a nozzle. When some disturbances occur in one module of the engine, its influences are propagated to other modules. In this study, it is investigated numerically how shock waves were caused by thermal choking in one module propagate upstream and how they influence adjacent modules. The calculations are carried out in 2-dimensional supersonic viscous flow model using explicit TVD scheme in generalized coordinates. The adverse pressure gradient caused by heat addition brings about separation of the wall boundary layers and formation of the oblique shock wave that proceed to upstream. This moving shock wave formed one module blocks the flow coming into the adjacent modules, which makes the modules unstarted.

A Numerical Study on Flow Characteristics of Second Throat Exhaust Diffuser with Shock Cone Shape (램 구조물 형상에 따른 이차목 디퓨저의 유동 특성에 관한 수치적 연구)

  • Yu, Seongha;Jo, Seonghwi;Kim, Hongjip;Ko, Youngsung;Na, Jaejeong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.346-351
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    • 2017
  • A numerical study has been conducted to investigate flow characteristics of STED with ram structure shape. By increasing the attack angle of shock cone, vacuum pressure is increased because of oblique shock at ram structure and separation point moved to the downstream of the second throat. By increasing blockage ratio, expansion wave angle is increased at ram structure while vacuum pressure is constant.

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On the Use of Standing Oblique Detonation Waves in a Shcramjet Combustor

  • Fusina, Giovanni;Sislian, Jean P.;Schwientek, Alexander O.;Parent, Bernard
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.03a
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    • pp.671-686
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    • 2004
  • The shock-induced combustion ramjet (shcramjet) is a hypersonic airbreathing propulsion concept which over-comes the drawbacks of the long, massive combustors present in the scramjet by using a standing oblique detonation wave (a coupled shock-combustion front) as a means of nearly instantaneous heat addition. A novel shcramjet combustor design that makes use of wedge-shaped flameholders to avoid detonation wave-wall interactions is proposed and analyzed with computational fluid dynamics (CFD) simulations in this study. The laminar, two-dimensional Navier-Stokes equations coupled with a non-equilibrium hydrogen-air combustion model based on chemical kinetics are used to represent the physical system. The equations are solved with the WARP (window-allocatable resolver for propulsion) CFD code (see: Parent, B. and Sislian, J. P., “The Use of Domain Decomposition in Accelerating the Convergence of Quasihyperbolic Systems”, J. of Comp. Physics, Vol. 179, No. 1,2002, pages 140-169). The solver was validated with experimental results found in the literature. A series of steady-state numerical simulations was conducted using WARP and it was deter-mined by means of thrust potential calculations that this combustor design is a viable one for shcramjet propulsion: assuming a shcramjet flight Mach number of twelve at an altitude of 36,000 m, the geometrical dimensions used for the combustor give rise to an operational range for combustor inlet Mach numbers between six and eight. Different shcramjet flight Mach numbers would require different combustor dimensions and hence a variable geometry system in or-der to be viable.

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An Experimental Study of Shock Wave Effects on the Model Scramjet Combustor (모델 스크램제트 연소기에서 충격파 영향에 대한 실험적 연구)

  • 허환일
    • Journal of the Korean Society of Propulsion Engineers
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    • v.3 no.1
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    • pp.65-71
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    • 1999
  • An experimental study was carried out in order to investigate the effect of shock waves on the supersonic hydrogen-air jet flames stabilized in the Mach 2.5 model scramjet combustor. This experiment was the first reacting flow experiment interacting with shock waves. Two identical $10^{\cire}$ wedges were mounted on the diverging sidewalls of the combustor in order to produce oblique shock waves that interacted with the flame. Schlieren visualization pictures, wall static pressures, and combustion efficiency at two different air stagnation temperatures were measured and compared to corresponding flames without shock wave-flame interaction. It was observed that shock waves significantly altered the shape of supersonic jet flames, but had different effects on combustion efficiency depending on air temperatures. At the higher air stagnation temperature and higher fuel flow rates, combustion of efficiency showed a better result.

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