传热对脉动燃烧稳定性影响的研究

发布时间：2017-12-28 18:05

本文关键词：传热对脉动燃烧稳定性影响的研究　出处：《天津科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：微燃烧器是微型动力系统的核心部件,但现有微燃烧器都是基于连续燃烧的方式工作,在微尺度效应的作用下,燃烧器内易出现工作不稳定、燃烧不完全、燃烧效率和热效率低、污染物排放浓度高等问题。脉动燃烧具有燃烧效率高、燃烧强度大、热效率高、污染物排放低等优点,或可克服现有微燃烧技术难题。课题组提出了一种微脉动燃烧技术的概念,并通过实验验证微脉动燃烧的可行性。基于此本文对微小管径的Rijke型脉动燃烧器在不同的换热条件下运行稳定性进行了实验研究,通过对不同工况下运行频率、稳定性、信噪比以及传热特性的分析,得到了如下研究结果：1. Rijke型脉动燃烧器中产生脉动燃烧需要满足以下几个条件：燃烧位置位于管子下半部的某个区域,管内需要达到一定的气体流速,燃烧放热必须达到一定强度。2.脉动燃烧器运行过程中存在频率跳变现象,并且尾管外的换热增强会丰富燃烧器内的频率含量。按照频率特性,其运行工况可分为四个区域：低频区、高频区、高次谐波区和湍动区,石英管脉动燃烧器在湍动区易出现熄火的现象,而不锈钢管脉动燃烧器没有出现类似的现象。3.绘制了不同管径不同烧嘴高度不同换热条件下的脉动燃烧运行稳定性图。发现管径越小,燃烧位置越低,燃烧器内能够产生脉动的气体流量范围越大,运行也越稳定。随着Rijke管外换热的增强,燃烧器内起振所需的最小丙烷流量增加,频率跳变时的丙烷流量增加,脉动停止时的丙烷最大流量也有所增加,燃烧器的稳定性更好。4.对信噪比的研究发现,信噪比并不是随着丙烷流量(功率)的增大而简单的增大,而是随着丙烷流量的增大先增大后减小,在中间某个丙烷流量下达到最大值,出现了热源功率“饱和”现象。并且随着Rijke管外换热的增强,烧嘴位置的升高,信噪比是逐渐降低的。5.在燃烧器的换热效率研究方面,换热效率与脉动频率、振动强度是成正比的,空气流量和丙烷流量的增大,会减弱频率和振动强度减小对热效率的负面影响。
[Abstract]:Micro combustor is the core component of micro power system, but the existing micro burner are continuous combustion based on the way, in the micro scale effect, burner prone to instability, incomplete combustion, combustion efficiency and thermal efficiency, low pollutant emission concentration is high. Pulsating combustion has the advantages of high combustion efficiency, high burning intensity, high thermal efficiency and low emission of pollutants, and can overcome the existing micro combustion technology problems. A concept of micro pulsating combustion technology is proposed by the project team, and the feasibility of micro pulsating combustion is verified by experiments. In this paper, the Rijke type pulsating combustor for small diameter operation stability in heat exchanger under different conditions has been studied based on the analysis, through the frequency, stability, noise and heat transfer characteristics of different conditions, the results were shown as follows: pulse combustion need to meet the following conditions to produce 1. Rijke type pulse combustor a regional position is located in the lower part of the combustion tube, pipe to gas flow rate of combustion must reach a certain strength. The frequency hopping phenomenon exists during the operation of 2. pulsating burners, and the increase of heat transfer outside the tail tube will enrich the frequency content in the burner. According to the frequency characteristics, the operation conditions can be divided into four parts: low frequency area, high frequency region, high harmonic area and turbulent area. The quartz tube pulsating combustor is prone to extinguish in turbulent area, while the stainless steel tube pulsating burner has no similar phenomenon. 3. the stability diagram of pulsating combustion in different heat transfer conditions of different nozzle height and different burner height was drawn. It is found that the smaller the diameter of the tube and the lower the combustion position, the larger the flow range of the pulsating gas in the burner, the more stable the operation is. With the increase of heat transfer outside the Rijke tube, the minimum propane discharge required in the burner increases, the propane flow rate increases during the frequency jump, and the maximum propane flow rate increases when the pulsation stops, and the stability of the burner is better. 4., the study of SNR shows that SNR does not increase simply with the increase of propane flow rate (power), but increases with the increase of propane flow, and then reaches the maximum value at a propane flow in the middle, which results in the phenomenon of "saturation" of heat source power. The signal to noise ratio is gradually reduced with the increase of the heat transfer outside the Rijke tube and the increase of the burner position. 5., in terms of the research of the heat transfer efficiency of the burner, the heat transfer efficiency is directly proportional to the pulsating frequency and the vibration intensity. The increase of air flow rate and propane flow will weaken the negative effect of frequency and vibration intensity on the thermal efficiency.
【学位授予单位】：天津科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK16

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