DIFFUSION COMBUSTION OF THE ROUND HYDROGEN JET EFFLUX FROM CURVED CHANNEL WITH THE DEAN’S VORTICES

Read more Results of the experimental studies of the round hydrogen jet efflux from curved micronozzle with Dean's vortices are presented in this work. Existence of the «bottleneck flame region» is revealed, as well as in situations of the hydrogen microjet combustion efflux from linear round and plane micronozzles. It is shown that interaction of the Kelvin – Helmholtz ring vortices with Dean’s vortices leads to distortion of the «bottleneck flame region» and curvature of front of the gas density gradient between laminar combustion of hydrogen in «bottleneck flame region» and its turbulent combustion. It is found that with growth of the microjet efflux velocity it is possible to observe already and distortion of a turbulent flame region in presence of the «bottleneck flame region». It is shown that position of this distortion is placed in region of the velocity maximum in mean velocity profile at the nozzle exit and obviously this distortion is connected with influence of the Dean’s and ring vortices. Further growth of the microjet efflux velocity leads to «bottleneck flame region» disappearance and flame detachment from the nozzle exit, but distortion of the region of a turbulent flame remains. Disappearance of the «bottleneck flame region» and a flame separation from the nozzle exit indicate transition of subsonic diffusion combustion of a hydrogen microjet with Dean's vortices to supersonic diffusion combustion and possible emergence of supersonic cells.

Keywords:
round hydrogen microjet with Dean’s vortices, diffusion combustion, «bottleneck flame region», interaction of the Dean’s vortices with Kelvin – Helmholtz ring vortices, flame deformation, subsonic and supersonic combustion. 
УДК 544.452.42

DIFFUSION COMBUSTION OF THE ROUND HYDROGEN JET EFFLUX FROM CURVED CHANNEL WITH THE DEAN’S VORTICES