配风方式对部分预混燃烧系统燃烧振荡的影响

Influence of air distribution on combustion oscillation of partially premixed system

部分预混燃烧系统是燃气热水器的常用燃烧系统,研究这种燃烧系统中配风方式和燃烧工况的关系十分重要。通过搭建实验台,研究了一个具有三次风的部分预混燃烧系统在不同过量空气系数下的燃烧振荡区域。发现该系统存在一个介于两正常工作区域之间的燃烧振荡区域,该区域的界限随着配风方式的变化发生偏移,减小一次风量时其正常工作范围扩大。通过分析,认为其燃烧振荡范围与一次过量空气系数值有直接关系,该范围具有一个上限,对应一次过量空气系数为0.80～0.95;具有一个下限,一次过量空气系数为0.40～0.50,此范围内发生燃烧振荡的概率较大。

Partially premixed combustion systems were widely used for the household hot water supply system. The purpose of this study is to investigate the combustion oscillation in a new gas storage water heater, which utilizes primary, secondary and tertiary air supply. The effect of each air stage is investigated by observing flow changes. The pressure fluctuation in combustion chamber is one of the characters of combustion oscillation that are visible most easily. Hence, the pressure was observed to determine the oscillation. Experimental result shows that the pressure fluctuation is larger than 400 Pa during the oscillation. The total air excess ratio and primary air excess ratio are the most important parameters affecting the combustion oscillation. In the experiment, seven zones appeared at different operation parameters. The oscillation occurred between two normal combustion zones as the primary air excess ratio increased from 0.4 to 0.8. With the CH4 concentration measured directly, the range of primary air excess ratio could be determined. It shows that combustion oscillation will occur when the primary air excess ratio is from 0.44 to 0.93, consistent with those measured directly. The investigation shows that the occurrence of combustion oscillation is influenced by the primary air excess ratio directly.