Flashback is a key operability issue for low NOx premixed combustion of hydrogen enriched fuels. Previous work has systematically investigated the impact of fuel composition on flashback propensity and noted the coupling of flashback with burner tip temperature. It led to models for critical velocity gradient as an indicator of flashback propensity as a function of parameters studied, such as fuel composition, burner tip temperature and laminar flame speed, etc. The present work further analyzes existing data and develops an empirical physical model for flashback propensity as a function of dimensionless groups. A comprehensive parameter screening is conducted and the potential variables determining flashback behavior are catalogued into five types: operational parameters, unburnt conditions, ambient conditions, rig properties and others. The objective of the analysis is to predict the critical operational parameters with given unburnt conditions which are generally known to the hardware designer. Other factors, such as ambient conditions and rig properties might also affect the prediction performance. To account for such factors, a dimensional analysis is conducted based on Buckingham Pi theorem. The critical Damköhler number is selected as the indicator of flashback propensity and a model is developed suggesting the significance of preferential diffusion (Le), heat loss (TuT0), thermal coupling effect (TtipTu) and flame Péclet number (Pef) as follows:


Finally, preliminary results for pressure effects are presented.

This content is only available via PDF.
You do not currently have access to this content.