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Toshisuke Hirano

Bio: Toshisuke Hirano is an academic researcher from University of Tokyo. The author has contributed to research in topics: Premixed flame & Combustion. The author has an hindex of 25, co-authored 91 publications receiving 1736 citations. Previous affiliations of Toshisuke Hirano include Ibaraki University & Chiba Institute of Science.


Papers
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Journal ArticleDOI
TL;DR: In this paper, heat transfer and gas phase chemical kinetic aspects of the flame spread process are addressed separately for the spread of flames in oxidizing flows that oppose or concur with the direction of propagation.
Abstract: Recent advances in the experimental study of the mechanisms controlling the spread of flames over the surface of combustible solids are summarized in this work. The heat transfer and gas phase chemical kinetic aspects of the flame spread process are addressed separately for the spread of flames in oxidizing flows that oppose or concur with the direction of propagation. The realization that, in most practical situations, the spread of fire in opposed gas flows occurs at near extinction or non-propagating conditions is particularly significant. Under these circumstances, gas phase chemical kinetics plays a critical role and it must be considered if realistic descriptions of the flame spread process are attempted. In the concurrent mode of flame spread, heat transfer from the flame to the unburnt fuel appears to be the primary controlling mechanism. Although gas phase chemcial kinetics is unimportant in the flame spreading process, it is important in the establishment and extension of the diffusion ...

266 citations

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TL;DR: In this paper, a model of hydrogen-air deflagration on the base of advanced lumped parameter theory and comparison with experiments in closed and vented large scale vessels have been carried out.
Abstract: Modeling of hydrogen-air deflagrations on the base of advanced lumped parameter theory and comparison with experiments in closed and vented large scale vessels have been carried out. Burning velocity and overall thermokinetic index for hydrogen-air mixtures with hydrogen concentrations of 20.0–41.7% by volume and at elevated temperature 373.15 K were determined. The slight decrease of overall thermokinetic index with equivalence ratio in enriched by hydrogen mixtures has been revealed, that is inverse to observed for hydrocarbon-air systems. It has been determined that flame stretch during vented deflagration constitutes about 1.5–2.2 for investigated conditions. The Le Chatelier-Brown principle analog, revealed previously for vented hydrocarbon-air deflagrations, has been verified for hydrogen-air systems. It has been shown that suggested correlation for the deflagration-outflow-interaction number, χ/μ, in dependence on vessel scale and Bradley number is right for both hydrocarbon- and hydrogen-air mixtures. It has been concluded that gained data on vented hydrogen-air deflagrations obey the same general physical regularities that were revealed previously for hydrocarbon-air systems.

82 citations

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TL;DR: In this article, the combustion zone propagating through an iron particle cloud and the combustion behavior of individual iron panicles have been examined by using high-speed photomicrographs.
Abstract: The combustion zone propagating through an iron particle cloud and the combustion behavior of individual iron panicles have been examined by using high-speed photomicrographs. Propagation of the combustion zone of 4˜5 mm in width was observed as the movement of a luminous zone which consists of burning iron particles. In the region just behind the leading edge, burning particles of various diameters are examined. As the distance from the leading edge becomes larger, smaller particles are fading away, and then only large particles are observed to remain luminous in the region where the distance is larger than 2 mm. Each iron particle bums at the combustion zone without gas phase flame. The burn-out time (the duration of light emission) is proportional to the diameter of iron particle when the particle diameter is not so large. It agrees well with the result of a simple analysis. As the particle diameter becomes larger, the burn-out time becomes much larger than that predicted by the simple analysis.

75 citations

Journal ArticleDOI
TL;DR: In this paper, a set of 34 experiments on vented hydrocarbon-air and hydrogen-air deflagrations in unobstructed enclosures of volume up to 4000m 3 was processed with use of the advanced lumped parameter approach.
Abstract: A set of 34 experiments on vented hydrocarbon–air and hydrogen–air deflagrations in unobstructed enclosures of volume up to 4000 m 3 was processed with use of the advanced lumped parameter approach. Reasonable compliance between calculated pressure–time curves and experimental pressure traces is demonstrated for different explosion conditions, including high, moderate, low and extremely low reduced overpressures in enclosures of different shape ( L max : L min up to 6:1) with different type and position of the ignition source relative to the vent, for near-stoichiometric air mixtures of acetone, methane, natural gas and propane, as well as for lean and stoichiometric hydrogen–air mixtures. New data were obtained on flame stretch for vented deflagrations. The fundamental Le Chatelier–Brown principle analog for vented deflagrations has been considered in detail and its universality has been confirmed. The importance of this principle for explosion safety engineering has been emphasized and proved by examples. A correlation for prediction of the deflagration–outflow interaction number, χ / μ , on enclosure scale, Bradley number and vent release pressure is suggested for unobstructed enclosures and a wide range of explosion conditions. Fractal theory has been employed to verify the universality of the dependence revealed of the deflagration–outflow interaction number on enclosure scale. In spite of differences between the thermodynamic and kinetic parameters of hydrocarbon–air and hydrogen–air systems, they both obey the same general regularities for vented deflagrations, including the Le Chatelier–Brown principle analog and the correlation for deflagration–outflow interaction number.

63 citations

Journal ArticleDOI
TL;DR: In this article, the number density profile of particles across a flame propagating through an iron particle cloud has been examined experimentally, where the iron particles were suspended in air and ignited by an electric spark.

60 citations


Cited by
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Journal ArticleDOI
01 Jan 2002
TL;DR: A broad survey of combustion research can be found in this article, where a number of closed loop feedback concepts are used to improve the combustion process as demonstrated by applications to automotive engines.
Abstract: Combustion dynamics constitutes one of the most challenging areas in combustion research. Many facets of this subject have been investigated over the past few decades for their fundamental and practical implications. Substantial progress has been accomplished in understanding analysis, modeling, and simulation. Detailed laboratory experiments and numerical computations have provided a wealth of information on elementary dynamical processes such as the response of flames to variable strain, vortex rollup, coupling between flames and acoustic modulations, and perturbed flame collisions with boundaries. Much recent work has concerned the mechanisms driving instabilities in premixed combustion and the coupling between pressure waves and combustion with application to the problem of instability in modern low NO x heavyduty gas turbine combustors. Progress in numerical modeling has allowed simulations of dynamical flames interacting with pressure waves. On this basis, it has been possible to devise predictive methods for instabilities. Important efforts have also been directed at the development of the related subject of combustion control. Research has focused on methods, sensors, actuators, control algorithms, and systems integration. In recent years, scaling from laboratory experiments to practical devices has been achieved with some successebut limitations have also been revealed. Active control of combustion has also evolved in various directions. A number of experiments on laboratory-scale combustors have shown that the amplitude of combustion instabilities could be reduced by applying control principles. Full-scale terrestrial application to gas turbine systems have allowed an increase of the stability margin of these machines. Feedback principles are also being explored to control the point of operation of combustors and engines. Operating point control has special importance in the gas turbine field since it can be used to avoid operation in unstable regions near the lean blowoff limits. More generally, closed loop feedback concepts are useful if one wishes to improve the combustion process as demonstrated by applications to automotive engines. Many future developments of combustion will use such concepts for tuning, optimization, and emissions reduction. This article proposes a broad survey of these fast-moving areas of research.

726 citations

Journal ArticleDOI
TL;DR: Several models have been suggested utilizing this approach and the first laboratory and industrial applications of them have shown encouraging results as mentioned in this paper, and these successful applications motivate a thorough discussion and further development of the approach.

517 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the progress that has been made to the understanding of chemical and physical processes, which occur during combustion of solid fuels, is presented, and the effects of bubble formation on the transport of volatiles during thermal degradation of non-charring fuels, described through a one-step global reaction, have been modeled.

434 citations

Journal ArticleDOI
TL;DR: In this article, the authors present the state-of-the-art of dust explosion state of the art, and present the ways available to prevent dust explosion, and on cushioning the impact of a dust explosion by venting when the accident does take place.

406 citations