Research On Swirling Combustion Characteristic Based On Simultaneous Reconstruction Of Three-dimensional Velocity And Temperature Field

The latest research direction of combustion flow field visualization and combustion diagnosis has been extended to the development of non-contact,multi-parameter new measurement method for qualitative analysis and multi-dimensional visualization.Velocity and temperature are important parameters to reflect the characteristics of combustion flow field and affect the combustion dynamics and combustion mechanism,which has become the key to characterizing and diagnosing the combustion process.Combined with the particle image velocimetry method and deflection tomography temperature measurement method,the three-dimensional velocity and temperature field of combustion were reconstructed,and the swirl combustion characteristics were studied on this basis.The non-premixed burner was designed to generate swirling flame,and an experimental system was constructed for simultaneous measurement of velocity and temperature to acquire tracer particle images and Moiré fringe images.Three-dimensional particle recognition technology and cross-correlation algorithm were used to reconstruct three-dimensional combustion velocity field.Fringe displacement analysis technique and deflection angle correction iterative tomography algorithm were used to reconstruct three-dimensional temperature field.The influence of different swirl number and swirl vanes position on the characteristics of swirl flame morphology,velocity distribution and temperature distribution was investigated.The swirling combustion characteristics were simulated by CFD and compared with the experimental results.The results show that as the swirl vanes move away from the outlet of the air tube or the swirl number decreases,the high-temperature zone of the swirl combustion becomes higher and narrower,and the high-speed zone of the swirl combustion becomes smaller.The acceleration ability of the swirl vanes to air and the acceleration effect of the combustion process are weakened.The velocity and temperature in the central zone of swirl combustion are low.With the increase of the radial distance from the swirl center,the velocity and temperature both increase first and then decrease.The high-speed zone and high-temperature zone have similar closed or semi-closed ring structure on sections with different heights from the nozzle.In the central longitudinal section,the V-shaped high-speed zone and the inverted U-shaped high-temperature zone show the swirling structure of the combustion flow field.The high-speed zone and the high-temperature zone partially overlap.The high-speed zone is much larger than the high-temperature zone and is located in the periphery of the high-temperature zone.The results of this study will help to study the combustion reaction mechanism and swirl combustion model,and guide the design and optimization of swirl burners.