• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.156.2-156
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• 2001

Hypersonic civil airplanes are recently heated up again in USA and Japan, but there are several difficulties when we obtain its optimal trajectories. In this paper, we formulated the trajectory optimization problem as an optimal control problem and solved it by the direct shooting method with the Genetic Algorithm, GA. The result shows it is effective to use this method for the trajectory optimization of the hypersonic flight.

• Journal of computational fluids engineering
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• v.10 no.3 s.30
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• pp.1-8
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• 2005

In this study, unsteady aerodynamic analyses of a wedge-type airfoil based on nonlinear piston theory and Euler equations have been performed in supersonic and hypersonic flows. The third-order nonlinear piston theory (NPT) to calculate unsteady lift and moment coefficients is derived and applied in the time-domain. Also, unsteady flow quantities are obtained from the two-dimensional time-dependent Euler equations. For the CFD based unsteady aerodynamic analyses, an arbitrary Lagrangean-Eulerian (ALE) formulation for the Euler equations is used to calculate flow fluxes in the computational flow field with moving boundaries. Numerical comparisons for unsteady lift and moment coefficients are presented between NPT and Euler approaches. The results show very good agreements in the high supersonic and hypersonic flows. It means that the present NPT can be efficiently used to predict unsteady aerodynamic forces ol wedge type airfoils with dynamic motions in the high supersonic and hypersonic flow regimes.

• Journal of computational fluids engineering
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• v.5 no.2
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• pp.47-54
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• 2000

A robust Navier-Stokes code has been developed to efficiently predict hypersonic flows in chemical nonequilibrium. The HLLE+ flux discretization scheme is used to improve accuracy and robustness of hypersonic flow analysis. An efficient LU approximate factorization method is also used to solve the flow equations and species continuity equations in fully coupled fashion to implicitly treat stiff source terms of chemical reactions. The HLLE+ scheme shows lower grid dependency for the wall heating rates than other schemes. The developed code has been used to compute chemical nonequilibrium air flow through expanding hypersonic nozzle and past two and three dimensional blunt-nosed bodies. The results are in good agreement with existing numerical and experimental results.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.6
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• pp.81-90
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• 2015

In order to know the characteristics of the hypersonic air-breahting engine, high altitude and Mach number ground test is necessary. Therefore, high pressure and high temperature condition should be simulated to do ground test of the hypersonic air-breathing engine. In this paper, the hypersonic air-breathing engine ground test facility of the Korea Aerospace Research Institute was introduced and the composition and characteristics were described.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.1-10
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• 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.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.3
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• pp.193-200
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• 2010

Through experimental investigations utilizing hypersonic shock tunnel-coaxial thermocouples as well as blow down hypersonic wind tunnel-temperature sensitive paints, the heat flux and the temperature over a protuberance were measured and analyzed. The experimental data were subsequently compared to heat flux data that was obtained by using blow down hypersonic wind tunnel and heat flux gauges. According to the comparison, both sets of data illustrated correlation with one another. The measured heat flux was large when the height of the protuberance was large. Experimental results show that heat flux measurements taken at higher locations were greater than those taken at lower locations. For high protuberances, a severe jump in the heat flux was observed, ranging in values within 0.6-0.7 of the height of the protuberances. However, when the protuberance was sufficiently short, a rise in the heat flux was rarely observed as the protuberance was totally submerged under the separation region.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.4
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• pp.328-336
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• 2008

The shock tunnel as a hypersonic ground test facility was designed, constructed and its performance test was conducted to reproduce the high speed flow which the hypersonic propulsion system is encountered. The design points were understood and the conceptual design was completed using the quasi one dimensional operation analysis code. After that, the specific performance and compartment design were completed using CFD simulation as the part analysis. The facility was then constructed according to those design results and the performance test was conducted for various operation conditions. In this paper, we suggested the compartment design method using CFD analysis, construction process and various performance test results in detail.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.503-505
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• 2008

The purpose of the current study is to examine the aerodynamic characteristics of two hypersonic vehicles in near space. One is derived from waverider shape, and the other from liftbody. The objective of this study are threefold. The first is to creat an computational database for hypersonic vehicle configurations. The second is to examine the effects of individual vehicle components on hypersonic configurations and to determine the differences in aerodynamic characteristics that result from integrating all vehicle components. The third objective is to evaluate the controllability of each of the fully integrated vehicles and the effectiveness of the control surface design. These objectives were accomplished using DSMC solutions and aerodynamic code developed in Northwestern Polytechnical University. The results are analyzed also in three sections. First, the results of the waverider shape and liftbody shape without integrated vehicle components are presented. Second, the results of adding aircraft components to the waverider shape and liftbody shape are presented. Finally, the aerodynamic characteristics of the fully integrated waverider-derived configuration and liftbody-derived configuration are examined and compared with those of the pure waverider shape and liftbody shape. Comparation between fully integrated waverider-derived configuration and liftbody-derived configuration are also presented in this paper.

• Advances in aircraft and spacecraft science
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• v.10 no.1
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• pp.1-18
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• 2023

This paper investigates the integrated control of an air-breathing hypersonic vehicle considering the safety of propulsion system under acceleration. First, the vehicle/engine coupling model that contains a control-oriented vehicle model and a quasi-one-dimensional dual-mode scramjet model is established. Next, the coupling process of the integrated control system is introduced in detail. Based on the coupling model, the integrated control framework is studied and an integrated control system including acceleration command generator, vehicle attitude control loop and engine multivariable control loop is discussed. Then, the effectiveness and superiority of the integrated control system are verified through the comparison of normal case and limiting case of an air-breathing hypersonic scramjet coupling model. Finally, the main results show that under normal acceleration case and limiting acceleration case, the integrated control system can track the altitude and speed of the vehicle extremely well and adjust the angle deflection of elevator to offset the thrust moment to maintain the attitude stability of the vehicle, while assigning the two-stage fuel equivalent ratio to meet the thrust performance and safety margin of the engine. Meanwhile, the high-acceleration requirement of the air-breathing hypersonic vehicle makes the propulsion system operating closer to the extreme dangerous conditions. The above contents demonstrate that considering the propulsion system safety will make integrated control system more real and meaningful.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.2
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• pp.285-293
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• 2024

This paper describes the interception using fine fragments and particles to hypersonic vehicles which have a vulnerability in thermal and pressure during glide-phase flight. This interception concept is based on the fast relative velocity and the flight vulnerability of hypersonic vehicles. For the density calculation of fragmentation and particle in interception, error analysis of end-phase was performed including radar, intercept missile and target maneuvering errors. In relation to the vulnerability and error analysis, the penetration characteristics of fine fragments in high temperature were analyzed. Presented the interception in glide-phase could be applied to the concept of horizontal multi-layer defense to hypersonic vehicles.