物理环境因素对新型聚合物石英压电传感器检测频率信号影响的数值模拟研究

发布时间：2018-03-21 21:43

本文选题：数值模拟　切入点：石英压电传感器　出处：《北京交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：中国白酒的种类繁多,风格各异。其微量香味物质的成分含量及相互之间的配比关系,是决定白酒香味风格的关键因素。由于微量香味物质的复杂性和相似性,准确的识别不同香味风格的中国白酒非常困难。聚合物石英压电传感器电子鼻是近年来基于石英压电微天平(QCM)原理研发的一种中国白酒检测设备,其结构主要包括两大系统:以8个聚合物石英压电传感器组成阵列为核心的气体信息采集系统和基于特定模式识别算法的模式识别系统。由于各个涂层吸附性之间的差异,当传感器阵列与中国白酒挥发气体接触时,各个传感器因吸附程度不同导致对应检测频率信号的差异性输出,并且各个检测频率信号的值均呈现"先减小,再稳定"的变化趋势。模式识别系统对各个检测频率信号稳定阶段的值进行分析、描述、判断、识别,即可实现电子鼻对中国白酒的检测与识别。为了保证聚合物石英压电传感器电子鼻稳定的、可靠的识别中国白酒,以前电子鼻优化设计方案更多关注其识别系统的改进。但由于电子鼻检测方式特殊,并适合在各类场合下使用,某些物理环境因素(如磁场、气动力)对其内部各个聚合物石英压电传感器检测频率信号的影响不可避免。针对物理环境因素对传感器检测频率信号的影响,以前的研究没有给予充分的考虑和评估。因此,在本文中,我们以数值模拟为主要研究手段,分别分析了磁场和气动力对聚合物石英压电传感器检测频率值的影响,具体研究内容如下:1)研究了均匀、稳定的静磁场对聚合物石英压电传感器检测频率信号的影响。基于节约计算成本、减少计算时间的原则,通过ANSYS/Multiphysics程序化语言设计,给出了一个包含电磁分析和压电预应力模态分析的单向间接耦合分析过程,预测了均匀稳定静磁场下,聚合物石英压电传感器上的电磁力分布特征、应力分布特征和检测频率信号变化。2)为了研究气动力对聚合物石英压电传感器的影响,首先通过基于有限体积法的CFD模拟,尽大限度的还原了中国白酒挥发气体在真实检测场景中的流动。然后,从时间和概率密度分布的角度,展示了气动力作用在聚合物石英压电传感器轴线方向(如图2-2)的合力(Fy)。最后,为了保证电子鼻稳定检测中国白酒,通过对比了 Fy的方差与传感器检测频率信号值在稳定阶段的方差,估计气动力对聚合物石英压电传感器对传感器检测频率信号值的影响。本文给出的模拟方法和得到的结论可为我们未来优化设计聚合物石英压电传感器电子鼻,提供理论依据及技术指导。
[Abstract]:There are many kinds of liquor in China and its style is different. The content of trace aroma substances and their proportion are the key factors to determine the flavor style of liquor, because of the complexity and similarity of trace aroma substances. It is very difficult to accurately identify Chinese liquor with different flavor styles. Polymer quartz piezoelectric sensor electronic nose is a kind of Chinese liquor detection equipment developed in recent years based on the principle of quartz piezoelectric microbalance (QCM). The structure consists of two main systems: a gas information acquisition system based on an array of eight polymer quartz piezoelectric sensors and a pattern recognition system based on a specific pattern recognition algorithm. When the sensor array is in contact with the volatile gas of Chinese liquor, the difference of the corresponding detection frequency signal is caused by the different adsorption degree of each sensor, and the value of each detection frequency signal is reduced first. The pattern recognition system analyzes, describes, judges and recognizes the values of each stable phase of the detected frequency signal. It can realize the detection and recognition of Chinese liquor by electronic nose. In order to ensure the stability and reliability of electronic nose of polymer quartz piezoelectric sensor, In the past, more attention was paid to the improvement of electronic nose identification system. However, due to the special detection method of electronic nose and suitable for use in various situations, some physical environmental factors (such as magnetic field, magnetic field, etc.). The influence of aerodynamic force on the detection frequency signal of each polymer quartz piezoelectric sensor is inevitable. The previous research has not given sufficient consideration and evaluation to the influence of the physical environment on the frequency signal of the sensor. In this paper, we analyze the influence of magnetic field and aerodynamic force on the detection frequency of polymer quartz piezoelectric sensor by numerical simulation. The influence of stable static magnetic field on the frequency signal of polymer quartz piezoelectric sensor. Based on the principle of saving calculation cost and reducing calculation time, the method is designed by ANSYS/Multiphysics programming language. A unidirectional and indirect coupling analysis process including electromagnetic analysis and piezoelectric prestressing mode analysis is presented, and the electromagnetic force distribution characteristics of polymer quartz piezoelectric sensor under uniform and stable static magnetic field are predicted. In order to study the effect of aerodynamic force on polymer quartz piezoelectric sensor, the CFD simulation based on finite volume method is carried out. The flow of volatile gas in Chinese liquor is reduced to the maximum extent in the real detection scene. Then, from the angle of time and probability density distribution, The resultant force of aerodynamic force in the axis of polymer quartz piezoelectric sensor (Fig. 2-2) is demonstrated. Finally, in order to ensure the stability of the electronic nose for the detection of Chinese liquor, By comparing the variance of Fy with the variance of the frequency signal of the sensor at the stable stage, The influence of aerodynamic force on the detection frequency signal of polymer quartz piezoelectric sensor is estimated. The simulation method and the conclusion obtained in this paper can be used to optimize the design of polymer quartz piezoelectric sensor electronic nose in the future. To provide theoretical basis and technical guidance.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

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