• Title/Summary/Keyword: hypersonic flow

Search Result 131, Processing Time 0.029 seconds

CALCULATION OF SHOCK STAND-OFF DISTANCE FOR A SPHERE IN NONEQUILIBRIUM HYPERSONIC FLOW (비평형 극음속 유동에서 구에 대한 충격파 이탈거리 계산)

  • Furudate, M. Ahn
    • Journal of computational fluids engineering
    • /
    • v.17 no.4
    • /
    • pp.69-74
    • /
    • 2012
  • Hypersonic flowfields over a sphere is calculated by using a nonequilibrium flow solver. The flow solver features a two-temperature model and finite rate chemical reaction models to describe nonequilibrium thermochemical processes. For the purpose of validation, the calculated shock stand-off distance is compared with the experimental data which is measured in a ballistic range facility. The present nonequilibrium calculation well reproduced the experimental shock stand-off distance in the cases where the experimental flowfields are expected to be nearly equilibrium, as well as in the cases to be nonequilibrium flowfields in the velocity range 4000 to 5500 m/s.

Optimal Design of Two-Dimensional Hypersonic Intake Geometry (2차원 극초음속 흡입구 형상 최적 설계)

  • Kim, Chae-Hyoung;Jeung, In-Seuck
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.18 no.6
    • /
    • pp.1-10
    • /
    • 2014
  • The optimal method to intuitively and systematical design hypersonic intakes is reported. In Mach 7 flow condition, the hypersonic intake model designed by theoretical approach is corrected by CFD(Computational Fluid Dynamics) analysis based on viscous flow condition, leading to the optimum hypersonic intake model. For performance comparison with CFD analysis, the double ramp intake is superior to the single ramp intake. Furthermore, in the off-design condition, the performance of the designed hypersonic intake is little degraded.

DSMC Calculation of the Hypersonic Free Stream and the Side Jet Flow Using Unstructured Meshes (비정렬 격자 직접모사법을 이용한 희박 유동과 측면 제트의 상호 작용에 관한 연구)

  • Kim M. G.;Kwon O. J.;Ahn C. S.
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2004.03a
    • /
    • pp.126-131
    • /
    • 2004
  • The interaction between the hypersonic free stream and the side jet flow at high altitudes is investigated by direct simulation Monte Carlo(DSMC) method. Since there is a great difference in density between the free stream and the side jet flow, the weighting factor technique which could control the number of simulation particles, is applied to calculate these two flows simultaneously. Chemical reactions are not considered in the calculation. For validation, the corner flow passing between a pair of plates that are perpendicularly attached is solved. The side jet flow is then injected into this comer flow and solution is found for the merged flow. Results are compared with the experiments. For a more realistic rocket model, the flow past a blunted cone cylinder shape is solved. The leeward or windward jet injection is merged with this flow. The effect on the rocket surface is observed at various flow angles. The lambda effect and the wake structure are found like low attitudes. High interaction between the free stream and the side jet flow is observed when the side jet is injected in the windward direction.

  • PDF

Nonlinear Flow-Induced Vibration Analysis of Typical Section in Supersonic and Hypersonic Flows with Angle-of-Attack Effect (받음각 효과를 고려한 발사체 날개단면의 초음속극초음속 비선형 유체유발진동해석)

  • Kim, Dong-Hyun;Kim, Yu-Sung;Yoon, Myung-Hoon
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.10 no.4
    • /
    • pp.12-19
    • /
    • 2007
  • In this study, nonlinear flow-induced vibration(flutter) analyses of a 2-DOF launch vehicle airfoil have been conducted in supersonic and hypersonic flow regimes. Advanced aeroelastic analysis system based on computational fluid dynamics and computational structural dynamics is successfully developed and applied to the present analyses. Nonlinear unsteady aerodynamic analyses considering strong shock wave motions are conducted using inviscid Euler equations. Aeroelastic governing equations for the 2-DOF airfoil system is solved by the coupled integration method with interactive CFD and CSD computation procedures. Typical wedge type airfoil shapes with initial angle-of-attacks are considered to investigate the nonlinear flutter characteristics in supersonic(15). Also, the comparison of detailed aeroelastic responses are practically presented as numerical results.

Computational Study of Hypersonic Real Gas Flows Over Cylinder Using Energy Relaxation Method (에너지 완화법을 이용한 실린더 주위의 극초음속 실제기체 유동에 관한 수치해석적 연구)

  • Nagdewe, Suryakant;Kim, H.D.
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2008.03b
    • /
    • pp.216-217
    • /
    • 2008
  • In recent years, scientific community has found renewed interest in hypersonic flight research. These hypersonic vehicles undergo severe aero-thermal environment during their flight regimes. During reentry and hypersonic flight of these vehicles through atmosphere real gas effects come into play. The analysis of such hypersonic flows is critical for proper aero-thermal design of these vehicles. The numerical simulation of hypersonic real gas flows is a very challenging task. The present work emphasizes numerical simulation of hypersonic flows with thermal non-equilibrium. Hyperbolic system of equations with stiff relaxation method are identified in recent literature as a novel method of predicting long time behaviour of systems such as gas at high temperature. In present work, Energy Relaxation Method (ERM) has been considered to simulate the real gas flows. Navier-Stokes equations A numerical scheme Advection Upstream Splitting Method (AUSM) has been selected. Navier-Stokes solver along with relaxation method has been used for the simulation of real flow over a circular cylinder. Pressure distribution and heat flux over the surface of cylinder has been compared with experiment results of Hannemann. Present heat flux results over the cylinder compared well with experiment. Thus, real gas effects in hypersonic flows can be modeled through energy relaxation method.

  • PDF

Computational Study on the Heat Transfer Prediction Hypersonic Flows (극초음속 유동의 열전달 예측에 관한 수치해석적 연구)

  • Nagdewe, Suryakant;Kim, H.D.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2007.11a
    • /
    • pp.27-30
    • /
    • 2007
  • In recent years, scientific community has found renewed interest in hypersonic flight research. These hypersonic vehicles undergo severe aero-thermal environments during their flight regimes. One of the most important topics of research in hypersonic aerodynamics is to find a reasonable way of calculating either the surface temperature or the heat flux to surface when its temperature is held fixed. This requires modeling of physical and chemical processes. Hyperbolic system of equations with stiff relaxation method are being identified in recent literature as a novel method of predicting long time behavior of systems such as gas at high temperatures. In present work, Energy Relaxation Method (ERM) has been considered to simulate the real gas flow over a 2-D cylinder. Present heat flux results over the cylinder compared well with the experiment. Thus, real gas effects in hypersonic flows can be modeled through energy relaxation method.

  • PDF

Drag Reduction Effect by Counter-flow Jet on Conventional Rocket Configuration in Supersonic/Hypersonic Flow

  • Kim, Yongchan;Kim, Duk-Min;Roh, Tae-Seong;Lee, Hyoung Jin
    • Journal of Aerospace System Engineering
    • /
    • v.14 no.4
    • /
    • pp.18-24
    • /
    • 2020
  • The counter-flow jet from a supersonic/hypersonic vehicle causes a structural change in the shock wave generated around the aircraft, which can lead to reduced drag and heat loads. Since the idea is to mount a counter-flow jet device for drag reduction in the aircraft, it is necessary to understand the effect of such a device on the entire aircraft. In this study, the effect of drag reduction due to counter-flow jet on a conventional rocket configuration was analyzed through CFD analysis. The results showed that the drag reduction effect was the largest in the blunt region and that the counter-flow jet also affected the downstream of the aircraft. The analysis indicated that the drag reduction effect by the counter-flow jet was about 10 to 25 % when targeting the entire rocket-shaped area, while the effect was as high as 50% when targeting only blunt objects.

Hypersonic Aero-Heating Ground-Test Simulation Technique

  • Li, Ruiqu;Yao, Dapeng;Sha, Xinguo;Gong, Jian
    • International Journal of Aerospace System Engineering
    • /
    • v.2 no.2
    • /
    • pp.50-53
    • /
    • 2015
  • It would encounter some complicated flow fields, such as transition, separation, reattachment and disturbances, in the hypersonic flight. Thus, it is difficult to theoretically analyze the hypersonic aerothermodynamics effects, so that the ground-test simulation is thought of as one of the most important methods to improve the understanding level of the hypersonic aerothermodynamics. However, the aero-heating tests could not simulate all aerodynamics and geometry parameters in the real flight due to the differences between the experimental environments supplied by the ground facilities and the flight, so that the feasible technique for the ground-test simulation of the hypersonic aerothermodynamics effects is required to be advanced. The key parameters that are especially required to simulate for aero-heating tests are analyzed and one detailed approach is suggested to perform the experimental investigation on the hypersonic aero-heating effects in the ground facilities in this paper, and the tests are performed in the FD-20 gun tunnel of CAAA (China Academy of Aerospace Aerodynamics) to give out the data which could be used to confirm the equation from the theoretical analysis.

Analytical Solution for Hypersonic Flow on Blunt Bodies (뭉뚝한 물체 주변에 형성된 극초음속유동해석)

  • Baik Doo Sung
    • Journal of computational fluids engineering
    • /
    • v.8 no.4
    • /
    • pp.1-5
    • /
    • 2003
  • A Thin-layer Wavier-Stokes equations are applied for the hypersonic flow over blunt bodies with applications to laminar as well as turbulent flows. The equations are expressed in the forms of flux-vector splitting and explicit algorithm. The upwind schemes of Steger-Warming and Van Leer are investigated to predict accurately the heating loads along the surface of the body. A mixed scheme has been presented for the differencing the convective terms and the mixed scheme is found to be less dissipative producing accurate solutions.