共查询到18条相似文献,搜索用时 203 毫秒
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本文实验观测到一种微型燃气轮机的DLN燃烧室工作在预混模式时存在低频燃烧振荡现象,其振荡频率为1~2 Hz。采用数值模拟方法探讨了该低频振荡的形成原因。燃烧室流场的数值模拟结果再现了该低频振荡现象,结果表明,产生该低频振荡的原因为进入燃烧室之前的腔体内存在周期性回流,诱发了该低频振荡。通过修改结构,可有效消除该低频振荡,这进一步印证了该低频振荡产生的原因。本文实验观测到的低频燃烧振荡现象在以往文献中未见报道,本文工作对于理解燃烧振荡的成因及DLN燃烧室的设计有重要意义。 相似文献
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燃气轮机的燃烧噪声是反映燃烧室燃烧稳定性的主要参数.本文对国内某座煤基IGCC示范电站的40 MW级燃气轮机在诸多运行条件下的燃烧噪声进行了现场测试,分析了气液双燃料喷嘴在燃烧轻柴油、燃烧合成气以及油气切换过程中燃烧室的燃烧噪声,另外分析了合成气掺烧驰放气与合成气加湿对燃烧稳定性的影响.结果表明:合成气燃烧室在油气切换过程中燃烧噪声会增加,但距离振荡燃烧的阈值仍有很大的裕度;烧合成气时随着燃气轮机功率增加燃烧噪声降低;合成气加湿时随着蒸汽流量增加污染物NOx排放显著降低,并且燃烧噪声也有降低的趋势. 相似文献
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对Solar低排放预混燃烧系统的燃烧稳定性进行了数值研究.应用非定常N-S方程、雷诺应力紊流模型及涡团耗散燃烧模型,数值模拟了该类型燃烧器在不同的燃料空气供给条件下的气流流动特性和压力振荡特性,并给出了不稳定发生时压力和速度振荡的幅值和频率.根据供给条件的不同,燃烧可以是稳定的或是不稳定的,取决于燃料到火焰前沿的迟滞时间.采用CFD方法,可精确地获得燃料到火焰前沿的迟滞时间,证实了所采用的模型能够精确预测不稳定燃烧的出现及振荡特性.通过调整燃料与空气的供给条件,可使振荡激励或阻尼. 相似文献
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亥姆霍兹共振器抑制振荡燃烧理论分析 总被引:2,自引:0,他引:2
燃烧室是燃气轮机的核心部件之一,其中的燃烧过程的关键技术之一是如何避免和抑制振荡燃烧现象.本文简要阐述了发生振荡燃烧的机理以及亥姆霍兹共振器抑制振荡燃烧的声学分析,并且通过线性分析与CFD计算相结合的研究方法对燃烧系统的燃烧稳定性进行计算;同时分析了共振器共振频率和安装位置对燃烧稳定性的影响,得出在不同因素影响下,系统的稳定性和模态.这些分析有助于我们在设计和运行燃烧系统时,实现燃烧系统的安全、高效和清洁运行. 相似文献
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振荡燃烧过程的计算和诊断 总被引:1,自引:0,他引:1
振荡燃烧现象是在发展洁净,高效和安全动力推进系统经常会遇到的问题.本文综述了作者近些年在针对油雾振荡燃烧方面的研究工作.通过把CFD和稳定性分析结合起来,发展了预测和诊断振荡燃烧的非稳定性及其振荡频率的新方法.运用这一方法,求解系统稳态方程和线性扰动方程可得到流场的动态信息和其稳定模态,将为深入认识振荡燃烧机理和开发控制方法提供指导. 相似文献
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M. F. Ivanov A. D. Kiverin 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(1):110-116
Numerical simulations are used to study the effect of the chemical composition of the combustible mixture on the development
of the hydrodynamic instability of the flame front, its acceleration, and the possibility of transition to the detonation
regime. The combustion of hydrogen-containing mixtures in confined spaces (channels) was considered. Calculations were performed
within the framework of a two-dimensional hydrodynamic model for the combustion of premixed mixtures with account of viscosity,
heat conduction, multicomponent diffusion, and chemical kinetics. It was demonstrated that the presence of an inert component
and the deviation of the mixture composition from stoichiometry caused not only a quantitative but also a qualitative change
in the character of burning of gaseous combustible mixtures. 相似文献
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Jae-Yeon Lee Eugene Lubarsky Ben T. Zinn 《Proceedings of the Combustion Institute》2005,30(2):1757-1764
This paper describes an experimental investigation of the feasibility of using “slow” active control approaches, which “instantaneously” change liquid fuel spray properties, to suppress combustion instabilities. The objective of this control approach was to break up the feedback between the combustion process heat release and combustor pressure oscillations that drive the instability by changing the characteristics of the combustion process (e.g., the characteristic combustion time). To demonstrate the feasibility of such control, this study used a proprietary fuel injector (NanomiserTM), which can vary its fuel spray properties, to investigate the dependence of acoustics–combustion process coupling, i.e., the driving of combustion instabilities, upon the fuel spray properties. This study showed that by changing the spray characteristics it is possible to significantly damp combustion instabilities. Furthermore, using combustion zone chemiluminescence distributions, which were obtained by Abel’s deconvolution synchronized with measured acoustic data, it has been shown that the instabilities were mostly driven midway between the combustor centerline and wall, a short distance downstream from the flame holder, where the mean axial flow velocity is approximately zero in the vortex near the flame holder. The results of this study strongly suggest that a “slow” active control system that employs controllable fuel injectors could be effectively used to prevent the onset of detrimental combustion instabilities. 相似文献
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N.N. Smirnov V.F. Nikitin J. Khadem Sh. Alyari-Shourekhdeli 《Proceedings of the Combustion Institute》2007,31(2):2195-2204
Investigations of detonation onset in pulverized fuel–air mixtures were carried out. Combustion and detonation processes in sprays differ greatly from that in homogeneous mixtures, because not only chemical reactions, but physical processes of combustible mixture formation take place within the combustion zone (droplets atomization and evaporation). The polydispersed character of mixture and non-uniformity of droplet spatial distribution strongly affects spray combustion and detonation onset. The present paper contains the results of theoretical and experimental investigations of detonation onset peculiarities in polydispersed non-uniform hydrocarbon–air mixtures. 相似文献
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We analyze the experimental time series of internal pressure in a four cylinder spark ignition engine. In our experiment, performed for different spark advance angles, apart from the usual cyclic changes of engine pressure we observed additional oscillations. These oscillations are with longer time scales ranging from one to several hundred engine cycles depending on engine working conditions. Based on the pressure time dependence we have calculated the heat released per combustion cycle. Using the time series of heat release to calculate the correlation coarse-grained entropy we estimated the noise level for internal combustion process. Our results show that for a larger spark advance angle the system is more deterministic. 相似文献
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Jeong-Yeol Choi Edward J.-R. Shin In-Seuck Jeung 《Proceedings of the Combustion Institute》2009,32(2):2387-2396
The instability of oblique shock wave (OSW) induced combustion is examined for a wedge with a flow turning angle greater than the maximum attach angle of the oblique detonation wave (ODW), where archival results rarely exist for this case in previous literatures. Numerical simulations were carried out for wedges of different length scales to account for the ratio of the chemical and fluid dynamic time scales. The results reveal three different regimes of combustion. (1) No ignition or decoupled combustion was observed if a fluid dynamic time is shorter than a chemical time behind an OSW. (2) Oscillatory combustion was observed behind an OSW if a fluid dynamic time is longer than a chemical time behind an OSW and the fluid dynamic time is shorter than the chemical time behind a normal shock wave (NSW) at the same Mach number. (3) Detached bow shock-induced combustion (or detached overdriven detonation wave) was observed if a fluid dynamic time is longer than a chemical time behind a NSW. Since no ignition or decoupled combustion occurs as a very slow reaction and the detached wave occurs as an infinitely fast reaction, the finite rate chemistry is considered to be the key for the oscillating combustion induced by an OSW over a wedge of a finite length with a flow turning angle greater than the maximum attach angle for an ODW. Since this case has not been previously reported, grid independency was tested intensively to account for the interaction between the shock and reaction waves and to determine the critical time scale where the oscillating combustion can be observed. 相似文献
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At first this paper simply introduces the ignition mechanism and combustion characteristics of Huadian oil shale. Combustion behaviour was found to be homogeneous at the beginning of combustion, shifting to heterogeneous combustion in the high-temperature stage; combustible matter was noted to be volatile in the low-temperature stage, but in the high-temperature stage combustible matter included fixed carbon and residual volatile. On the basis of the combustion characteristics of Huadian oil shale, homogeneous and heterogeneous combustion processes of Huadian oil shale are modelled. In the mathematical models, conductive, convective and radiative heat transfer between particles and the surrounding atmosphere, pyrolytic heat and also the heat value of the volatiles are all included in the energy equations; inference of volatile release to particle density is also considered in the models. Thermogravimetric experimental data are used to validate the described models. 相似文献