CORRELATING FLASHBACK TENDENCIES FOR PREMIXED INJECTION OF HYDROGEN AND METHANE MIXTURES AT ELEVATED TEMPERATURE AND PRESSURE

摘要

Flashback is a critical operability issue for lean premixed fuel injection strategies. This is particularly true for hydrogen and high hydrogen content fuels. As a result, efficient analytical tools to help predict the occurrence of flashback would be of great value to the hardware designer. In the present work, a RANS based CFD strategy is used in conjunction with analytical expressions for determining flashback likelihood. The approach uses local flow properties combined with 1 D models to establish a flashback propensity factor that can be used to screen designs. Peclet number based models are also considered. The methods are applied to one micromixer configuration for a variety flow rates, pressures, equivalence ratios, and temperatures. The micromixing injector is a small premixing cup with multiple fuel injection sites in close proximity to air inlets to produce rapid mixing between fuel and air, with an axial core flow that is intended to prevent ingress of flame into the injector. The results illustrate the effectiveness of the approach for screening for flashback for the premixer studied over the range of conditions studied. The analysis suggests that, for the current test hardware, the critical ingress pathway is via boundary layer propagation. Further, the approach successfully provides a qualitative indication of whether ingress can be expected for a given condition.