基于声学法的混合气体温度、浓度和速度分布同时测量方法研究

发布时间：2019-03-23 19:24

【摘要】：混合气体的温度、浓度和速度分布的同时测量对于确保系统安全、高效运行,减少污染物排放具有重要意义。由于混合气体系统中温度、浓度和速度对测量信息的耦合影响,实时、准确地获取系统物理状态参数非常具有挑战性。声学法因具有非侵入传感、全场监测、在线测量等优点被认为是具有广阔发展前景的可视化测量方法。基于声波弛豫衰减,本文提出了将气体的弛豫衰减作为新的声学参数,联合声速和经典衰减,对混合气体的温度、浓度和速度分布进行同时重建。不同于一种传感器只测量一种物理参数的测量方法,本文提出的方法可以利用声学传感器对复杂热物理场中多参数同时测量。主要工作如下：(1)声学基本理论研究对实现混合气体温度、浓度和速度分布的同时测量具有重要意义。本文研究了声波的产生及传播机理,比较了声传播三种计算模型,确定了以射线模型作为本文的基本计算模型。给出了声波经典衰减的计算方法；讨论了多原子气体中的分子碰撞能量转移模型,明确了弛豫过程中的能量转移模式；总结了弛豫衰减系数的计算过程；并提出了高温环境中的弛豫衰减系数的计算模式。(2)建立声学参数与混合气体温度、浓度和速度的耦合模型是实现复杂热物理场内多参数同时测量的关键。本文揭示了混合气体的温度、浓度以及速度与声学测量参数的耦合关系,建立了混合气体温度、浓度和速度信息的同时重建模型。提出了基于声速和声衰减的测量,对混合气体的温度、浓度和速度分布进行同时重建的方法,并通过数值仿真验证了方法的可行性和有效性。(3)提出了一个广义Tikhonov正则化算法求解声学反问题。通过建立新的目标泛函将声学反问题转化为一个最优化问题的求解。该目标泛函采用M估计缓解测量粗差的影响,同时引入了全变差正则和被测对象的低秩约束；提出了一个集成了分裂Bregman算法优势的迭代格式有效求解该目标泛函。数值仿真结果表明,该算法是可行的,能够确保稳定的数值解,并能够有效改善重建质量,为实现复杂热物理场多参数的高精度同时重建奠定了基础。(4)采用数值仿真途径,对炉膛烟气中的温度分布,气体混合过程的温度与浓度分布,以及大气表层的气体流动及温度分布进行了仿真重建,验证了本文提出的复杂热物理场多参数同时重建方法的可行性。(5)搭建了可以联合测量声速和声衰减的实验系统。测量了声波在不同混合气体中的传播参数,对声学参数与气体温度、浓度耦合关系模型进行了修正,验证了均场下的温度、浓度同时重建方法的有效性。本文的研究工作是对声学测量思路的扩展,将原有的侧重于测量单一热物理参数的测量方法推广到多种参数(包括温度、浓度与速度等)的同时测量,为复杂热物理场参数的测量提供了一种新的有效方法。
[Abstract]:The simultaneous measurement of the temperature, concentration and velocity distribution of the mixture gas is of great significance to ensure the safe and efficient operation of the system and to reduce the emission of pollutants. Because of the coupling effect of temperature, concentration and velocity on the measurement information in the mixed gas system, it is very challenging to obtain the physical state parameters of the system in real time and accurately. Because of the advantages of non-invasive sensing, full-field monitoring and on-line measurement, acoustic method is considered to be a visual measurement method with broad development prospects. Based on acoustic relaxation attenuation, the gas relaxation attenuation is proposed as a new acoustic parameter, which combines sound velocity and classical attenuation to reconstruct the temperature, concentration and velocity distribution of the mixture gas at the same time. Different from one kind of measurement method that only one physical parameter is measured by a sensor, the method proposed in this paper can simultaneously measure the multi-parameter in complex thermal physical field by using acoustic sensor. The main work is as follows: (1) it is very important to measure the temperature, concentration and velocity distribution of the mixture gas simultaneously by studying the basic theory of acoustics. In this paper, the generation and propagation mechanism of sound wave are studied, three kinds of calculation models of sound propagation are compared, and the ray model is selected as the basic calculation model of this paper. The calculation method of classical attenuation of acoustic wave is given, the energy transfer model of molecular collision in polyatomic gas is discussed, the energy transfer mode in relaxation process is defined, and the calculation process of relaxation attenuation coefficient is summarized. The calculation model of relaxation attenuation coefficient in high temperature environment is put forward. (2) the coupling model of acoustic parameters and temperature, concentration and velocity of gas mixture is the key to realize simultaneous measurement of multi-parameters in complex thermal physical field. In this paper, the coupling relations between the temperature, concentration and velocity of the mixture gas and the acoustic measurement parameters are revealed, and the simultaneous reconstruction model of the temperature, concentration and velocity information of the mixture gas is established. Based on the measurement of sound velocity and sound attenuation, the temperature, concentration and velocity distributions of mixed gases are reconstructed simultaneously. The feasibility and effectiveness of the method are verified by numerical simulation. (3) A generalized Tikhonov regularization algorithm is proposed to solve the inverse acoustic problem. The inverse acoustic problem is transformed into an optimization problem by establishing a new objective functional. The objective functional uses M estimation to mitigate the influence of gross error, and introduces the regularization of total variation and the low rank constraint of the tested object, and proposes an iterative scheme which integrates the advantages of the split Bregman algorithm to solve the objective functional effectively. The numerical simulation results show that the proposed algorithm is feasible and can ensure stable numerical solution and improve the reconstruction quality effectively. It lays a foundation for the high precision simultaneous reconstruction of complex thermal physical field. (4) the temperature distribution in furnace flue gas and the temperature and concentration distribution in gas mixing process are simulated by numerical simulation. The simulation reconstruction of gas flow and temperature distribution in the surface of atmosphere is carried out to verify the feasibility of the multi-parameter simultaneous reconstruction method of complex thermal physical field. (5) an experimental system for joint measurement of sound velocity and sound attenuation is built. The propagation parameters of acoustic wave in different gas mixtures have been measured. The coupling model of acoustic parameters with gas temperature and concentration has been modified to verify the effectiveness of the method for simultaneous reconstruction of temperature and concentration in the mean field. The research work of this paper is to extend the idea of acoustic measurement, and extend the original measurement method, which focuses on the measurement of single thermophysical parameters, to the simultaneous measurement of various parameters (including temperature, concentration and velocity, etc.). A new and effective method is provided for the measurement of complex thermal physical field parameters.
【学位授予单位】：华北电力大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TK31

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