Instantaneous and simultaneous PIV and OH-PLIF measurement for lean premixed swirl flame

To better study the flame flowfield and structure in lean and premixed swirling flames,a premixed swirling burner with strong confined combustor was designed,and the experimental instantaneous and simultaneous system of PIV (particle image velocimetry) and OH-PLIF (planar laser-induced fluorescence) was built. With this system,the measurement research was carried out in swirling flame under typical operating condition,meanwhile time-averaged and instantaneous simultaneous flame velocity flowfield and OH distribution structures in multiple sections were obtained. Results showed that multiple flame reaction zones existed in the bottom corners of combustor under condition of unsteady combustion at low equivalence ratio,accompanied by flash back in corner vortices. Due to shear effect of swirling flow,lots of wrinkles appeared along the edge of OH distribution structure,and many isolated OH blocks were observed. The root of swirling flame lied at inner side of shear layer of the jet flow. As equivalence ratio increased,the swirling flame velocity flowfied and OH distribution structures were similar to low equivalence ratio. But the combustion was more stable,and the flame height increased somehow. It was found that the typical two vortices were split into multiple vortices sometime. There were phenomena with vortex moving and breaking down.