Investigation of the Explosion Control Problems in a Mixtures of Reactive Gases/Air Suspension under Inert Particle Action

Abstract

[[abstract]]本計畫為台俄國際合作計畫,探討惰性粒子對反應性氣體/空氣混合物之爆炸控制的問題,在三年的合作研究中共獲得以下的具體成果:本計畫首先提出一估算氣體中分散有惰性微粒子的一維爆轟波傳播與爆轟網格尺吋(detonation cell size)之方法。此方法並實際估算一當量濃度的氫-氧混合物與鎢、三氧化二鋁、二氧化矽等三種惰性微粒子注入對抑制爆轟波傳播的影響,並用管徑與爆轟網格尺吋之比值來估算非均相爆轟波的極限,抑制爆轟波傳播所需的最少粒子質量與粒子雲的大小也計算出來。結果顯示抑制最有效的是選擇高比熱、低熔點與高熔解熱之粒子,在所考慮的粒子當中,三氧化二鋁最適合抑制爆轟波的傳播。本計畫其次提出一估算氣體中分散有惰性微粒子的一維爆轟波在剛性容器壁反射傳播之方法。此方法並實際估算一當量濃度的氫-氧混合物與三氧化二鋁惰性微粒子注入對抑制爆轟波傳播的影響,結果顯示惰性粒子可有效抑制反射的爆轟波,降低爆轟波對設備的影響。本計畫亦探討在當量濃度、富燃料、貧燃料等不同燃料與氧化劑混合物之惰性微粒子爆轟波抑制的效率,結果發現,在環己烷-氧氣混合物與不同質量的三氧化二鋁微粒子,爆轟波抑制的效率在貧燃料的混合物中最佳。本計畫最後提出一估算爆轟極限以及不同濃度惰性微粒子混合物的穩態爆轟波存在之範圍之方法。此方法並實際估算甲烷-氧氣混合物與二氧化矽惰性微粒子的爆轟極限,結果與現有實驗數據比較相符,證明本研究所提方法之可行性。最後與俄方共同研究非穩態爆轟波與惰性微粒子在爆轟波內與後方之結構,透過不同模式之爆轟波傳播分析與計算爆轟波的臨界參數,可分析爆轟波的抑制機制與所需條件。3本報告為三年計畫的期末報告。初步的成果已有投稿與刊登於俄文與英文版的期刊Combustion, Explosion and Shock Waves一篇,Journal of Engineering Physics andThermophysics三篇,另完成一本俄文專書「Physical and Mathematical Modeling ofDetonation Suppression by Clouds of Small Particles」,此專書之英文版亦在修訂中,預定明年初會出版。另在研討會會中亦共同發表論文兩篇,成果豐碩,完成本計畫[[abstract]]An algorithm for calculation parameters of a steady detonation wave in mixtures of a gaswith chemically inert microparticles and estimation the detonation cell size in suchmixtures is proposed. As intermediate step of the algorithm an approximate model ofchemical equilibrium in heterogeneous mixtures of a combustible gas with chemicallyinert solid or liquid particles has been suggested. The calculated detonation parametersand cell size in methane-, cyclohexane-and hydrogen-oxygen mixtures with W, Al2O3,and SiO2 particles are used to analyze the method of suppression of multifront gasdetonation by injecting chemically inert particles ahead of the leading wave front. Theratio between the channel diameter and detonation cell size is used to estimate the limit ofheterogeneous detonation in the mixtures considered. The minimal total mass of theparticles and characteristic size of the cloud, which are necessary for detonationsuppression, have been calculated. Results of calculations correspond to the availableexperimental data. It is shown, that such suppression is more effective, if the particleshave high heat capacity, low melting point and high heat of melting. Among the particlesunder consideration the particles of Al2O3 are the best for detonation wave suppression.An algorithm for calculation reflection of a steady one-dimensional detonation wavefrom a rigid wall in mixtures of a gas with chemically inert micro-particles is proposed.Parameters of reflected wave in stoichiometric cyclohexane–oxygen mixtures with Al2O3particles are calculated. It is shown, that particles can essentially reduce pressure andtemperature behind the reflected wave and therefore prevent crucial destruction ofequipment, caused by detonation.The efficiency of detonation wave suppression by chemically inert microparticles instoichiometric, fuel-lean and fuel-rich mixtures is investigated. As an example,cyclohexane-oxygen mixture with different mass fractions of Al2O3 microparticles anddifferent relations between fuel and oxidizer are considered. It is shown, that detonationwave suppression by particles injection is more effective for fuel lean compositions.5An algorithm for calculation the detonability limits and the existence regionof a steadydetonation wave in the gas-chemically inert microparticles mixture with different massfraction of condensed phase is proposed. The limits of detonation wave inmethane-oxygen gaseous mixture with SiO2 microparticles are calculated. Results ofcalculations correspond to the available experimental data.In collaboration with Russian participants of the Project the unsteady interaction ofgaseous detonation wave with cloud of particles and evolution of the wave structureinside and behind of it is calculated numerically. Different modes of detonation wavepropagation have been analyzed and critical parameters of the cloud, which are necessaryfor successful quenching of detonation, are calculated.The main results, obtained in the frames of the Project, were published (both in Englishand in Russian) in articles [1-4], monograph [5], Proceedings of InternationalConferences [6, 7] and were presented in National First University of Science andTechnology, Taiwan, Institute of Theoretical and AppliedMechanics Siberian Branch ofRussian Academy of Sciences and Novosibirsk State University of Architecture and CivilEngineering, Novosibirsk, Russia. This report summarized the important results from thejoint research work.[[note]]NSC97-2923-E327-001-MY

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