旋流燃烧器出口气固两相流场的光学波动法测量研究

Experimental measurement of gas-solid two-phase flow of a swirl burner by optical wave method

为了精确测量旋流燃烧器出口的固相质量分数和颗粒细度,介绍了光学波动法测量固相质量分数的基本原理,并在气固两相流实验台上采用基于光学波动法的激光探针测量固相质量分数,对不同的一、二次配风条件下的回流区大小、扩散特性以及质量分数分布变化进行了测量研究.试验结果表明:在燃烧器出口流场中,固相质量分数最高点和气相速度的最高点均处于二次风口附近,在离燃烧器出口0～200mm范围内,气相速度衰减迅速,而固相质量分数的衰减缓慢;各次风对固相质量分数分布的作用各不相同:一次风大小的改变对中心回流区内固相质量分数影响微弱,主要影响周边区域;增强内二次风对增强回流区内的固相质量分数的差异最为明显;增加外二次风限制了颗粒对外扩散,固相质量分数的分布在周向上更加均匀.

In order to measure the particle concentration and diameter distribution precisely, the principles of particle concentration measurement by the optical wave method were firstly introduced, and then the method was employed to investigate the particle concentration out of a swirl burner on a gas-solid test rig. The scale of recirculation zone, particle diffusion characteristics and particle concentrations in the flows at different cross-sections under various primary air and secondary air ratios were measured. The test results show that the zones of high solid-phase mass fraction are overlapped by those of high gas velocity, and all these zones are located close to exit of secondary air. Within 0-200 mm to the outlet of swirl burner, the attenuation of gas velocity is fast while the solid-phase mass fraction has little change. The influences of each air on particle distributions are different. Primary air has little influence on the concentration in the recirculation zone, but affects the peripheral region greatly. The enhancing of the inner secondary air will increase the concentration differences in the recirculation zone. The enhancing of the outer secondary air would limit particles external diffusion, resulting in the concentration distribution well-distributed at circumferential direction.