共查询到19条相似文献,搜索用时 234 毫秒
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分析热声耦合领域和内燃机爆震的研究现状,给出根据KIVA燃烧模型推导出的三维波动方程,将之与KIVA相耦合,对一台内燃机爆震燃烧时的声波进行计算.结果显示,燃烧室内声学波动频率很高,且爆震时其幅值可达数个兆帕.对比实测爆震气缸压力高频信号可知,该波动方程可正确计算爆震时燃烧室内声波.对比高速摄影实验结果.声场计算结果和气体获得声功的分布图可知,声场的振荡比火焰传播更快、更复杂;内燃机燃烧的热声振荡没有特定部位稳定声功的输出或输入.最后,总结了常规热声机和内燃机热声耦合性质的异同. 相似文献
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印染污泥与木屑混燃特性及动力学 总被引:3,自引:0,他引:3
采用综合热重分析法,在不同升温速率及印染污泥与木屑不同比例混合条件下,对印染污泥、木屑及其混合物的燃烧特性进行了研究.结果表明,印染污泥的热重曲线存在4个明显的失重峰,分别与水分的析出、两个挥发分的析出以及固定碳的燃烧阶段相对应.混合试样燃烧过程中,污泥和木屑基本保持各自的挥发分析出特性,其燃烧曲线位于污泥和木屑燃烧曲线之间,且混合试样微熵热重曲线的变化趋势与组成比例较大的成分DTG曲线变化趋势较为接近.污泥与木屑混合后其综合燃烧特性指数SN有所增大,说明挥发分含量越高对应的燃烧特性越好;采用积分法(Coats-Redfern方程)计算得到各阶段燃烧反应的机理方程及相应的活化能参数,分析表明单一印染污泥燃烧的活化能较低,活化能的大小与试样的燃烧阶段是相对应的. 相似文献
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煤质常规分析指标与燃烧特性参数的综合运用有利于指导电厂的优化运行。对81个煤样进行了热重分析实验并获得燃烧特性参数,利用人工神经网络建立基于煤质分析数据的燃烧特性参数预测模型,并通过相关性分析、遗传算法和多次预测取平均的方法对模型进行优化。结果表明:优化建立的着火稳燃特性指数(R_w)预测模型的拟合度(R~2)为0.957,10个预测样品的平均绝对误差(MAE)为0.15;燃尽特性指数(R_j)预测模型的R~2为0.938,MAE为1.17。在生产现场利用常规分析快速预测煤粉的燃烧特性。 相似文献
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高温空气燃烧技术具有高效节能和低NOx排放等多重优越性,是一种新型燃烧技术。为了深入研究高温空气燃烧机理和低氮氧化物排放特性,将湍流N—S方程与扩散燃烧模型和热力型NO生成模型相结合,研究了低氧浓度条件下,燃烧参数,如燃气供应量,过量空气系数,进口空气预热温度以及进口空气氧含量对燃烧的影响,为发展高温空气燃烧技术提供了理论依据。 相似文献
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采用混沌和分形理论对实测锅炉炉膛火焰信号进行了定性分析和定量计算,通过相空间重构得到了稳定燃烧和不稳定燃烧两种工况下燃烧火焰时间序列的相平面图和关联维。分析计算结果表明:在稳定燃烧状态下,火焰信号的二维相平面图比较宽,关联维在6.5855~6.8415之间;在非稳定燃烧状态下,火焰信号的二维相平面图比较窄,关联维在5.8843~6.0907之间。两种工况下,火焰时间序列的相平面图和关联维有明显的差异,稳定燃烧时的关联维总比不稳定燃烧时的关联维大得多,因此,采用关联维作为火焰燃烧状态识别的特征参数。文中所提出的燃烧诊断方法为发展新型光学式火焰检测器提供了一种行之有效的解决方案。 相似文献
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A general flamelet transformation useful for distinguishing between premixed and non-premixed modes of combustion 总被引:1,自引:0,他引:1
The flame index was originally proposed by Yamashita et al. as a method of locally distinguishing between premixed and non-premixed combustion. Although this index has been applied both passively in the analysis of direct numerical simulation data, and actively using single step combustion models, certain limitations restrict its use in more detailed combustion models. In this work a general flamelet transformation that holds in the limits of both premixed and non-premixed combustion is developed. This transformation makes use of two statistically independent variables: a mixture fraction and a reaction progress parameter. The transformation is used to produce a model for distinguishing between premixed and non-premixed combustion regimes. The new model locally examines the term budget of the general flamelet transformation. The magnitudes of each of the terms in the budget are calculated and compared to the chemical source term. Determining whether a flame burns in a premixed or a non-premixed regime then amounts to determining which sets of these terms most significantly contribute to balancing the source term. The model is tested in a numerical simulation of a laminar triple flame, and is compared to a recent manifestation of the flame index approach. Additionally, the model is applied in a presumed probability density function (PDF) large eddy simulation (LES) of a lean premixed swirl burner. The model is used to locally select whether tabulated premixed or tabulated non-premixed chemistry should be referenced in the LES. Results from the LES are compared to experiments. 相似文献
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为了满足NT6135ZR柴油机动力性及经济性要求,移植奥地利AVL公司快速燃烧技术,改进设计了NT6135ZR柴油机燃烧系统.重点介绍了NT6135ZR柴油机燃烧室的结构特点、设计思路及试验结果. 相似文献
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基于径向基函数神经网络的内燃机气缸压力识别 总被引:10,自引:2,他引:8
提出了一种新的利用内燃机缸盖振动信号识别气缸压力的径向基函数(radial basis function,RBF)神经网络方法。首先,给出了该方法的实现原理与步骤,并根据内燃机的工作特性,对径向基函数神经网络的参数进行了有效的设置,建立了完整的内燃机缸盖振动信号与气缸压力之间的非线性映射关系;然后,对试验数据进行了处理。结果表明,这种方法不仅在压力波形而且在特征点的数值上都具有较高的识别精度并有较强的鲁棒性。最后,对有关问题进行了讨论。 相似文献
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Herein, we report two different modes of combustion synthesis to prepare Ag/Co3O4 for glycerol electro-oxidation reaction. The synthesis technique allows us to deposit and disperse cobalt on the surface of silver and understand the effect of silver-cobalt interactions on the electrocatalytic performance. The bimetallic AgCo catalyst was synthesized via conventional solution combustion (AgCo-SCS); in addition, a novel second wave solution combustion synthesis (AgCo-SWC) was also used to synthesize a sample with a higher degree of surface alloying between the elements. XRD results of AgCo-SWC show peak shifts in 2θ to indicate the formation of a solid solution alloy that could improve the structural and electronic characteristic of the material. In AgCo-SCS, smaller Ag particles are found to be more on the surface, while in AgCo-SWC, Ag particles were largely covered with cobalt particles. The electro-oxidation results indicate that AgCo-SWC has improved electrochemical properties in terms of higher oxidation current and lower onset potential, which makes it an ideal candidate for glycerol oxidation reaction. 相似文献
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稻壳燃烧特性与动力学模型的研究 总被引:1,自引:0,他引:1
采用热重分析仪,在空气气氛下对稻壳的燃烧热失重状况进行了研究,并分析了四种升温速率(5,10,20,50℃/min)对燃烧特性指数的影响。利用Coats-Redfern模型,Freeman—Caroll模型和Flynn—Wall-Ozawa模型分别计算了稻壳燃烧的活化能及频率因子。实验表明:随着升温速率的升高,燃烧性能得到良好改善,但反应起始温度和终止温度由于受热滞后性影响,向高温区偏移使着火温度升高。模型计算结果表明:稻壳燃烧的表观活化能较低,升温速率对活化能的影响并不明显,Coats—Redfern模型、Freeman-Caroll模型可用于估算,Flynn—Wall—Ozawa模型可作为重要数据参考。 相似文献
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The results of three-dimensional Direct Numerical Simulation (DNS) of Moderate, Intense Low-oxygen Dilution (MILD) and conventional premixed turbulent combustion conducted using a skeletal mechanism including the effects of non-unity Lewis numbers and temperature dependent transport properties are analysed to investigate combustion characteristics using scalar gradient information. The DNS data is also used to synthesise laser induced fluorescence (LIF) signals of OH, CH2O, and CHO. These signals are analysed to verify if they can be used to study turbulent MILD combustion and it has been observed that at least two (OH and CH2O) LIF signals are required since the OH increase across the reaction zone is smaller in MILD combustion compared to premixed combustion. The scalar gradient PDFs conditioned on the reaction rate obtained from the DNS data and synthesised LIF signals suggests a strong gradient in the direction normal to the MILD reaction zone with moderate reaction rate implying flamelet combustion. However, the PDF of the normal gradient is as broad as for the tangential gradient when the reaction rate is high. This suggests a non-flamelet behaviour, which is due to interaction of reaction zones. The analysis of the conditional PDFs for the premixed case confirms the expected behaviour of scalar gradient in flamelet combustion. It has been shown that the LIF signals synthesised using 2D slices of DNS data also provide very similar insights. These results demonstrate that the so-called flameless combustion is not an idealised homogeneous reactive mixture but has common features of conventional combustion while containing distinctive characteristics. 相似文献