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Numerical simulation of the auto-ignition and DDT by AMR

Tang X., Dziemińska E., Hayashi A. K., Tsuboi N., Asahara M.

Archivum Combustionis

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2017

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Vol. 37 nr 2

79--92

EN

In our previous work, combustion flows in a smooth tube are simulated with fixed computational meshes to investigate the auto-ignition and the subsequent deflagration to detonation transition (DDT). In this paper, we use another approach, which is adaptive mesh refinement (AMR) technology, to reproduce above detailed DDT as a pilot study of the further study of three-dimensional (3D) DDT with high resolutions and detailed chemical reaction mechanism. The auto-ignition and DDT are successfully captured by AMR system with a much smaller cost. The results are similar to the previous ones. In this paper especially the formation of precursor shock is discussed in details to present how the piston effect works and why the present initial condition can allow a rapid DDT. It is shown that due to the choice of initial conditions, the flame acceleration process in this work is carried out in a very short time because that the reflected shocks with an adequate strength successfully generate a region with high pressure and another region on the flame tip with a fresh gas of a high density. Subsequently, the pressure accumulation benefits the temperature distribution in the form of shock heating, especially in the boundary layer. An auto ignition triggers the DDT in the heated mixture in front of the flame.

2

Two-dimensional analysis of hydrogen/oxygen cylindrical detonation using AUSMDV scheme

Asahara M., Tsuboi N., Hayashi A. K., Yamada E.

Archivum Combustionis

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2011

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Vol. 31 nr 3

177-186

EN

Many researchers have simulated detonation using a Harten-Yee upwind TVD scheme. Such scheme has a strong numerical diffusivity around calculating a discontinuity surface as shock wave. However, the numerical result of discontinuity surface using the Harten-Yee upwind TVD scheme is diffusive. To avoid this diffusivity, an AUSMDV scheme is used instead of the Harten-Yee upwind TVD scheme. As the results, we obtained a sharp cellular structure of cylindrical detonation in the maximum pressure histories like open-shutter photograph and smoked-foil record which are obtained experimentally. However, the irregular cells were observed because grid resolution was not enough for cylindrical detonation. In the future work, the grid density must be kept constant for each direction of shock propagation.

3

Transition to detonation after a 'Volume Explosion' Oppenheim's experiment validation with a numerical calculation

Dzieminska E., Fukuda M., Hayashi A. K., Tsuboi N.

Archivum Combustionis

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2011

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Vol. 31 nr 3

187-195

EN

Over many years of research Oppenheim's group performed a lot of experimental work concerning detonation. According to his notes the birth of detonation starts as a smooth-surfaced and spheric ally propagating flame which front wrinkles and accelerates. In a short time it produces compression waves that coalesce into a precursor shock which travels with some distance from the flame. Its structure eventually changes to a turbulent flame, while the surface creates so called 'tulip-shape' form. This phenomenon is associated with pressure waves' generation, which becomes slightly more intense in time as the flame becomes highly turbulent. They merge and form shock fronts. This leads to an 'explosion in the explosion' (appearing in the region of the accelerating flame) [1,2], which would be the last stage of the detonation wave birth, just before deflagration-to-detonation transition (DDT). In the first stages of propagation the reflections of the explosion from the back wall help the flame acceleration but later they have no significant meaning.

4

AKO's some scientific thoughts and related work at AGU

Hayashi A. K.

Archivum Combustionis

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2011

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Vol. 31 nr 3

139-157

EN

Professor Antoni K. Oppenheim's memory is presented through his notes, book, and papers together with jet ignition and fundamental study of pulse detonation engine at Aoyama Gakuin University (AGU). These works at AGU are strongly related with the work done by Prof. Oppenheim. Paper presented at A.K. Oppenheim Memorial Seminar, August 2-3,2009 Warsaw University of Technology

5

Three-dimensional structure of cornstarch-oxygen two-phase detonation in a circular tube

Tsuboi N., Hayashi A. K., Matsumoto Y.

Archivum Combustionis

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2001

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Vol. 21 nr 2

101-116

EN

Numerical simulations were performed with a parallel computer to solve for the behaviour of the three-dimensional gas-solid two-phase detonation. The numerical method is a second-order modified Harten-Yee TVD upwind scheme and time integration uses a first order Euler integration. A two-step chemical reaction model represents the reaction of constarch-particles and oxygen. The numerical results show that a periodic two-headed detonation appears with a three-dimensional propagation mechaism before and after a triple point collisions. A comparison between the numerical and experimental results reveals that detonation velocity of numerical results agrees well with that of experimental results.

6

Ignition properties of cornstarch dust-air mixture

Matsuda T., Sato T., Benkiewicz K., Hayashi A.K.

Archivum Combustionis

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2001

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Vol. 21 nr 2

83-91

EN

Study of gas-solid two-phase mixtures has been performed recently in many different ways. One of the ultimate purposes of this study is to prevent dust explosion accidents. The present study focuses on experimentally measuring ignition delay times to provide data for numerical analyses. Experiments are performed using a vertical shock tube to ignite the reactive dust layer on the bottom of the tube by a high temperature and high pressure condiction behind a reflected shock wave. Cornstarch dusts are selected as reactive dust particles. Ignitions of the dust particles are detected and ignition delay times are also measured. These values agree well with the published data to the Arrhenius plots as far as the similar experimental system is concerned.

7

Chemically non-equilibrium analysis on flame quenching phenomena by mist water for various hydrocarbon flames

Yamazaki Y., Hayashi A. K., Tuzuki M.

Archivum Combustionis

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2001

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Vol. 21 nr 2

143-152

EN

Quenching of various hydrocarbon flames using water mist, halon, and CO2 are studied applying non-equilibrium chemical reaction and flame code PREMIX from CHEMKIN package. It is found that the smaller size of water mist is the more effective among considered mists for the flame quenching and the evaporation of water mist is the main cause for the flame quenching.