• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.151-155
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• 2005

Three-dimensional structures of unsteady detonation wave propagating through a square-shaped tube is studied using computational method and parallel processing. Inviscid fluid dynamics equations coupled with variable-${\gamma}$ formulation and simplified one-step Arrhenius chemical reaction model were analysed by a MUSCL-type TVD scheme and four stage Runge-Kutta time integration. Results in three dimension show the two unsteady detonation wave propagating mode, the Rectangular and diagonal mode of detonation wave instabilities. Two different modes of instability showed the same cell length but different cell width and the geometric similarities in smoked-foil record.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.15-19
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• 2005

Three-dimensional structures of unsteady detonation wave propagating through a square-shaped tube is studied using computational method and parallel processing. Inviscid fluid dynamics equations coupled with variable-${\gamma}$ formulation and simplified one-step Arrhenius chemical reaction model were analysed by a MUSCL-type TVD scheme and four stage Runge-Kutta time integration. Results in three dimension show the two unsteady detonation wave propagating mode, the Rectangular and diagonal mode of detonation wave instabilities. Two different modes of instability showed the same cell length but different cell width and the geometric similarities in smoked-foil record.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.278-281
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• 2012

Numerical studies were performed to investigate the three-dimensional front structure and dynamics features of detonation wave propagating in a circular tube such as Pulse Detonation Engine (PDE). By carrying out a series of parametric study using one step irreversible Arrhenius kinetics model, mechanisms of the three-dimensional front structure were investigated for two-, three-, four and six-cell mode detonations. A comparison with two-dimensional results, the effects of slapping transverse waves in radial direction were confirmed. In the all muti-cell modes, the detonation front structures and smoked-records on the wall are formed by the propagation of transverse waves along the wall in clockwise and counter-clockwise while the slapping move in radial direction. And the strength of reflected waves on the curved wall is changed by the multi-dimensional confinement effect.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.1-14
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• 2006

Present study examines the numerical issues of cell structure simulation for various regimes of detonation phenomena ranging from weakly unstable to highly unstable detonations. Inviscid fluid dynamics equations with $variable-{\gamma} $ formulation and one-step Arrhenius reaction model are solved by a MUSCL-type TVD scheme and 4th order accurate Runge-Kutta time integration scheme. A series of numerical studies are carried out for the different regimes of the detonation phenomena to investigate the computational requirements for the simulation of the detonation wave cell structure by varying the reaction constants and grid resolutions. The computational results are investigated by comparing the solution of steady ZND structure to draw out the minimum grid resolutions and the size of the computational domain for the capturing cell structures of the different regimes of the detonation phenomena.

• 한국가시화정보학회:학술대회논문집
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• 2004.04a
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• pp.29-36
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• 2004

A numerical study is carried out on the detonation wave propagation through a T-shaped flame tube, which represents a crucial part of the combustion wave ignition (CWI) system aimed for simultaneous ignition of multiple combustion chambers by delivering detonation waves. The formulation includes the Euler equations and an induction-parameter model. The reaction rate is treated based on a chemical kinetics database obtained from a detailed chemistry mechanism. A second-order implicit time integration and a third-order TVD algorithm are Implemented to solve the theoretical model numerically. A total of more than two-million grid points are used to provide direct insight into the dynamics of the detonation wave. Several important phenomena including detonation wave propagation, degeneration, and re-initiation are carefully examined. Information obtained can be effectively used to facilitate the design and optimization of the flame tubes of CWI systems.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.597-601
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• 2008

Three-dimensional structures of detonation wave propagating in circular tube were investigated. Inviscid fluid dynamics equations coupled with a conservation equation of reaction progress variable were analyzed by a MUSCL-type TVD scheme and four stage Runge-Kutta time integration. Variable-$\gamma$ formulation was used to account for the variable properties between unburned and burned states and the chemical reaction was modeled by using a simplified one-step irreversible kinetics model. The computational code was parallelized based on domain decomposition technique using MPI-II message passing library. The computations were carried out using a home made Windows based PC cluster having 160 AMD AthloxXP and Athlon64 processor. The computational domain consisted of through a roundshaped tube with wall conditions. As an initial condition, analytical ZND solution was distributed over the computational domain with disturbances. The disturbances has circumferential large gradient. The unsteady computational results in three-dimension show the detailed mechanisms of multi-cell mode of detonation wave instabilities resulting diamond shape in smoked-foil record.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.367-370
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• 2006

This paper deals with the modeling and simulation of the internal flowfield in a valveless airbreathing pulse detonation engine (PDE) currently under experimental development at the U.S. Naval Postgraduate School. The system involves no valves in the airflow path, and the isolation between the inlet and combustor is achieved through the gasdynamics in an isolator. The analysis accommodates the full conservation equations in axisymmetric coordinates, and takes into account variable properties for ethylene/oxygen/air system. Chemical reaction schemes with a single progress variable are implemented to minimize the computational burden. Detailed flow evolution during a full cycle is explored and propulsive performance is calculated. Effect of initiator mass injection rate is examined and results indicate that the mass injection rate should be carefully selected to avoid the formation of recirculation zones in the initial cold flowfield. Flow evolution results demonstrate a successful detonation transmission from the initiator to the combustor. However, strong pressure disturbance may propagate upstream to the inlet nozzle, suggesting the current configuration could be further refined to provide more efficient isolation between the inlet and combustor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.221-224
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• 2003

A numerical study is carried out for the detonation wave propagation through a T-branch. The T-branch is a crucial part of the combustion wave igniter, a novel concept of rocket ignition system aimed for the simultaneous ignition of multiple combustion chambers by delivering detonation waves. Euler equation and induction parameter equation are used as governing equations with a reaction term modeled from the chemical kinetics database obtained from a detailed chemistry mechanism. Second-order accurate implicit time integration and third-order space accurate TVD algorithm were used for solution of the coupled equations. Over two-million grid points enabled the capture of the dynamics of the detonation wave propagation including the degeneration and re-initiation phenomena, and some of the design factors were be obtained for the CWI flame tubes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.4
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• pp.383-391
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• 2009

The detonation wave characteristics of JP-7 and oxygen mixture is investigated by one-step induction parameter model (IPM) obtained from a detailed chemistry mechanism. A general procedure of obtaining reliable one-step kinetics IPM for hydrocarbon mixture from the fully detailed chemistry is described in this study. The IPM is obtained by the reconstruction of the induction time database obtained from a detailed kinetics library. The IPM was confirmed by the comparison of the induction time calculations with that from detailed kinetics. The IPM is later implemented to a fluid dynamics code and applied for the numerical simulation of detonation wave propagation. The numerical results show the detailed characteristics of the detonation wave propagation in JP-7 and oxygen mixture at affordable computing time, which is not be possible by the direct application of the detailed chemical kinetics mechanism of hydrocarbon fuel combustion.

• Journal of Korean Society of Steel Construction
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• v.28 no.4
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• pp.271-280
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• 2016

The need to accurate quantification of blast pressure loading in the near field is important because the focus of security design of critical infrastructure, buildings and bridges is for near-field detonations. Incident and reflected pressures for near-field detonations are very difficult to be measured by commercially available pressure transducers due to the high pressure and temperature, which requires a verified and validated computational fluid dynamics code to reasonably predict the near-field pressures and impulses. This paper presents numerical studies to verify and validate a CFD code for calculations of incident and reflected overpressures and impulses. The near field is emphasized and recommendations for mesh sizes to optimally simulate the near-field detonation are provided.