火焰燃烧区域空气声速与温度关系的实验研究

为使声学方法能对火焰温度进行精确测量,实验研究了火焰燃烧区域中空气声速与温度的关系。首先对非火焰气体环境中的声速与温度进行测量,然后在此基础上对不同燃料燃烧的火焰区域进行声速测量实验,并结合热电偶测得火焰温度,进而得到火焰中空气声速与温度的关系。结果表明:在固定距离下,与室温空气环境相比,高温烟气环境会使声波的传播时间减小,火焰环境会使声波的传播时间变长;在非火焰区域,空气声速与温度的关系符合理想气体中声速与温度的关系;在火焰燃烧区域,空气声速与温度关系偏离理想气体的声速与温度方程,与按照理想气体计算的声速结果相比,实际声速测量值偏小;对于同种燃料的火焰,随着火焰温度升高会出现空气中的声速减小的现象。

Research on the relationship between temperature and sound velocity of air in the flame burning zone

In order to accurately measure flame temperature by acoustic method, the relationship between sound velocity and temperature of air in flame burning region is studied experimentally. Firstly, the relationship between sound velocity and temperature of air in the non-flame burning environment is measured, and then on this basis, the experiments of the sound velocity of air in the flame burning region of different fuel combustion are carried out, and the relationship between sound velocity and temperature of air in the flame is obtained by measuring the flame temperature with thermocouple. The results show that at a fixed distance, the acoustic wave travel time is reduced in the high-temperature smoke environment than in the room-temperature air environment, but the flame environment makes the travel time longer. It means that in the non-flame region, the relationship between sound velocity and temperature of air is consistent with that of ideal gas. In the flame burning region, the relationship between sound velocity and temperature of air deviates from the equation of sound velocity and temperature of ideal gas, and the measured value of actual sound velocity of air is smaller than that calculated for ideal gas. For the same fuel flame, the sound velocity of air decreases with the increase of flame temperature.