【作者】 林志勇；

【导师】 周进；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2008， 博士

【摘要】 本文从化学反应动力学分析出发,通过理论分析、数值计算及实验手段,系统深入地研究了高静温预混超声速气流中爆震的直接起爆与发展过程及初温对其的影响。采用敏感性分析方法,结合三种反应器所得的实验数据,对几种常用的氢氧详细反应模型进行验证,发现Connaire与Balakrishnam反应模型能在较大的工况范围内得到较合理的结果。建立了基于敏感性分析和准稳态假设的复杂反应模型简化方法,得到了一组适用于氢氧爆震自适应化学数值模拟的反应模型。基于爆震简化理论和ZND模型对爆震参数和结构的分析表明:当来流混合物初温升高时,CJ爆震波传播马赫数与压升比明显下降;由于波后温度略升而压升明显下降,因此来流初温对爆震结构的影响关系复杂。通过分析爆震结构中诱导区长度和放热区组分消耗对反应的敏感性,采用元素跟踪法研究了诱导区与反应区中的关键组分,得到了爆震发展过程中的关键反应和重要组分。采用自适应化学数值方法分别模拟了二维等直管道中爆震的发展过程和斜爆震的起爆及发展过程。研究表明:在等直管道内的爆震发展过程中,横波在爆震三波点的演化和发展过程中起重要作用;来流静温升高导致横波和三波点的强度下降,爆震波面发展趋于一维平面波结构,并使得自持爆震发展过程中更容易发生熄灭。在斜爆震的起爆及发展过程中,来流静温升高导致起爆点前移,三波点附近的爆震波角度变化趋于平缓。研制了连续式高焓预混超声速加热器,通过对其混合过程的数值模拟和着火延迟分析及实验研究,验证了该加热器既保证了混合均匀又解决了预着火问题。采用高速纹影技术研究了斜激波诱导燃烧与爆震发展的动态过程,分析了斜激波角度、混合物当量比及其他因素对其的影响与作用机制。结果表明高静温预混气流中爆震波的平均传播速度比CJ爆震速度低。起爆过程中,燃烧与流动的相互作用使得斜激波角度略增,导致波后温度和压力略有上升;当波后的气流处于起爆临界状态并出现较大扰动时,由于激波与燃烧的正反馈作用将发生迅速起爆。发展过程中,由于脱体爆震波本身的不稳定性及其与边界层的耦合振荡作用,导致爆震波角度与起爆三波点位置发生振荡;当可燃混合物的活性增大时,出现爆震波三波点向上游突跃的现象。对于低活性的来流混合物,即使强度较大的斜激波也较难起爆或维持爆震状态;随着来流活性的增加,爆震发展过程中出现了起爆-熄灭-再起爆的现象;随来流活性的进一步提高,脱体爆震波能持续发展。更多还原

【Abstract】 Starting from an analysis of chemical reaction mechanism and by means of theoretical analysis, numerical simulation and experimental studies, this dissertation systematically and thoroughly studies the direct initiation and development of detonation in high temperature premixed supersonic flow as well as the effect of initial temperature on detonation.By adopting the sensitivity analytical method, several popular hydrogen/oxygen detailed reaction models are verified by reference to the experimental data obtained from three kinds of reactor. It is found that relatively reasonable results can be obtained from the Connaire and Balakrishnam reaction models under a wider range of experimental conditions. Methods for simplifying complex reaction models are put forward on the basis of sensitivity analysis and quasi-steady state assumptions, and a set of reaction models suitable for the numerical simulation of hydrogen/oxygen detonation by using the adaptive chemical method are established.On the basis of detonation theory and analysis of the parameters and structure of detonation according to ZND model, it can be found that when the initial temperature of the mixture rises, the velocity of CJ detonation wave and pressure rise ratio will drop drastically. Since the temperature after the wave rises only slightly while the pressure rise ratio drops greatly, it can be seen that the influence of initial temperature of the mixture on the structure of detonation is a complex one. By analyzing the sensitivity of induction segment length in detonation structure and species consumption in heat release segment to reactions, and by studying the crucial species in induction segment and heat-released segment through element-tracking method, the key reactions and important species in detonation development are identified.The detonation development and the oblique detonation initiation and development in planar constant area duct are respectively simulated by using adaptive chemical numerical method. The research demonstrates that in detonation developmental in planar constant area duct, the traverse wave plays an important role in the evolution and development of detonation three wave point. The elevation of the mixture temperature will reduce the strength of traverse wave and three wave point, cause the structure of detonation to change into a 1D planar one, and make it more likely for detonation failure to occur in the development of self-sustained detonation. In the initiation and developmental process of oblique detonation, the elevated temperature of mixture will cause the onset location to move forward, and the change of detonation wave angle near the three wave point tends to become mild.A continuous high-enthalpy premixed supersonic combustor is designed. Through numerical simulation of its combination process and combustion delay analysis and experiment, it is proved that this combustor can not only ensure an effective combination process but also solve the pre-ignition problem. By adopting the high speed schlieren technique, the dynamic processes of the shock-induced combustion and detonation development are studied, and the influence of shock angle, mixture stoichiometric ratio and other factors on these processes as well as the underlying mechanism are analyzed. The result shows that the average propagation speed of detonation wave in high-temperature premixed flow is lower than that of CJ detonation. During the initiation, the interaction between combustion and flow slightly increases the shock angle, causing the temperature and pressure after the wave to rise slightly. When the flow after the wave is on the verge of detonation onset and large disturbance occurs, detonation will take place rapidly because of the interaction of shock and combustion. During the development, because of the instability of detached detonation itself and its coupled oscillation with the boundary, the detonation angle and the position of initiation location three wave point will oscillate; when the reaction mixture activity of combustible mixture increases, the three wave point of detonation will move abruptly upward. For the mixture of low mixture mobility, it is even hard for oblique detonation with relative large force to initiate the detonation and keep the status; with the increase of mixture mobility, the phenomenon of onset followed by detonation failure and then followed by onset again will occur in the detonation developmental process; and with the further increase of mixture mobility, the detached detonation will be able to keep developing.更多还原