共查询到18条相似文献,搜索用时 328 毫秒
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本文运用电容层析成像(ECT)方法,以非侵入的方式,对多孔介质燃烧中的火焰分布进行可视化测量.针对高孔隙率泡沫陶瓷(8PPI)的孔隙结构特点,提出了一种"十字架形"几何结构模型,用丁泡沫型多孔介质内甲烷-空气预混燃烧的二维数值模拟.ECT成像结果与数值模拟结果吻合,显示了两个不同学科信息的融合性和互验性. 相似文献
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本文通过自行研制的多孔介质燃烧实验系统,研究了液体燃料在热多孔介质中的燃烧可行性及其燃烧特性.燃烧系统包括燃烧室、供气系统、供油系统和测量系统等,该系统分别以气体和液体作为燃料,先通过多孔介质内的预混合燃烧对多孔介质固相进行预热,然后喷入液体燃料,实现燃烧,实验证实了液体燃料在热多孔介质内汽化及自维持燃烧的可行性,并讨论了空气量和喷油量等对燃烧室温度的影响. 相似文献
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温度分布在线实时测量对于燃烧过程优化和污染物控制具有重要意义, 针对以往非接触三维温度分布重建过程的耗时性问题和忽略壁面辐射的不足, 本文提出了一种新的离散重建模型, 用于三维吸收、 发射和散射性高温燃烧介质以及壁面温度的快速联合非接触测量. 该模型以四个CCD(Charge Coupled Device) 为测量传感器, 通过构建辐射逆问题求解方程, 从CCD输出的辐射投影图像重建温度分布. 介质中不同投影方向内的辐射传递过程通过离散传递法来描述, 介质的散射和壁面反射则通过离散坐标法来近似. 离散后计算局部辐射强度的病态方程通过最小二乘余量法来求解, 论文对其计算速度进行了优化. 通过非对称温度分布测量算例分析了该模型的有效性, 讨论了测量噪音、 介质和壁面辐射特性对重建精度的影响, 并与其他方法对比分析了模型的重建速度. 计算结果表明本文提出的离散模型可以有效地用于大型高温燃烧介质和壁面温度分布的联合非接触测量. 即使在有噪声的情况下, 该模型也能获得准确的测量结果, 与其他计算方法相比, 采用改进的最小二乘余量法, 能有效地提高温度分布的重建计算速度. 相似文献
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多孔介质燃烧室内湍流气液两相流的数值研究 总被引:1,自引:0,他引:1
以多孔介质发动机为背景,用数值模拟方法考察气缸内加入多孔介质蓄热体后对燃烧室内湍流流场及混合气形成的影响.建立了多孔介质随机结构的简化模型,把多孔介质视为随机分布的大量固相单元的集合.在多孔介质区域引入了Antohe和Lage提出的双方程κ-ε湍流模型.为研究喷雾液滴与多孔介质的高温壁面碰撞,引入新的喷雾模型.在模型中考虑了液滴的破碎、碰撞和合并,并且描述了喷雾和多孔介质壁面之间的相互作用.针对燃油喷雾在不同结构多孔介质内流场进行了数值计算.计算表明,喷雾与多孔介质相互作用对燃烧室内燃油液滴的蒸发、混合气的形成过程和均匀化具有重要的影响. 相似文献
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Three-phase flow pattern recognition in horizontal pipelines using electrical capacitance tomography
A. E. Corlett 《显形杂志》1999,2(1):31-36
An experimental study was performed to evaluate the suitability of using an electrical capacitance tomography (ECT) system to visualise three component mixtures of crude oil, water and gas. The performance of the ECT system was examined over a range of three-phase flow conditions and regimes. The flow visualisations from the tomography system were compared with the images filmed using a CCD camera aligned with a Perspex pipe section. Results indicated that ECT was most successful in flow pattern identification for low water fraction flows. However, slug and stratified regimes could be identified for high water fraction flows. A critical factor in the quality and reliability of the generated image was the image reconstruction scheme used. 相似文献
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Potential measurement can be applied to electrical capacitance tomography (ECT) systems. However, the relationship between potential and the capacitance is not well understood. This paper reveals that a potential is dependent on the capacitance ratio for a given excitation voltage, independent of capacitance themselves. The conditions for using this method are discussed. Finally, image reconstruction based on the Generic Algorithm for Electrical Capacitance Tomography (GA-ECT) is implemented satisfactorily for square and circular sensors respectively. 相似文献
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Lihui Peng Henk Merkus Brian Scarlett 《Particle & Particle Systems Characterization》2000,17(3):96-104
Image reconstruction of electrical capacitance tomography (ECT) is a typical inverse problem owing to non‐linearity and ill‐posedness. At the same time, progress towards the solution of this kind of problem has been made at good speed as a branch of mathematics in the past three decades. In this paper, most of the regularization tools developed for the inverse problem are applied to the reconstruction of various simulated images by ECT. The results show promise for ECT image reconstruction by regularization methods. The non‐linearity of the sensitivity matrix seems to be the major problem. 相似文献
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The measurement circuit of electrical capacitance tomography (ECT) system mainly includes CMOS switches, C/V conversion circuit and Data processing circuit. In order to improve the image reconstruction quality, conversion circuit is very necessary to the small capacitance measurement circuit. A charge/discharge measurement circuit is one of the most suitable for the C/V conversion circuit in ECT. The stray capacitance between the measurement electrodes and earth can be large and have an effect on the capacitance measurement. This paper analyzes this effect, taking into account the ON-resistance of the COMS switch, the unit gain frequency of op-amp, and gain error in the measurement circuit. Finally, it is shown that if the range of stray capacitance is 150 ± 60 pF, overall error would be estimated. Comparing the effects of the circuit parameters, this charge/discharge-based capacitance is effectively stray-immune. It is a more efficient analysis to C/V circuit in ECT and offers a great benefit to information processing. 相似文献
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多旋风分离器及返料系统是保证循环流化床锅炉高效燃烧的关键设备,是循环流化床大型化研究的关键部件之一。本文采用电容层析成像技术结合压力测量,对多旋风分离器返料系统内部气固两相流场进行实验研究。通过六旋风分离器冷态循环流化床电容层析成像浓度分布和压力测量,揭示循环流化床多分离返料系统颗粒流动分配特性,为循环流化床锅炉大型化,特别是超临界锅炉多旋风分离器的优化布置提供科学依据,基础实验数据库和技术手段,研究内容将电容层析成像技术的应用扩展到工程设计中,对实际工程起到理论指导的作用。 相似文献