Investigation of Pressure Effects on Combustion Characteristics of Hydrogen Annular Micro-Mixing Nozzles

Abstract In pursuit of achieving near-zero emissions and preventing flashback, micro-mixing combustion technology has been developed and implemented in hydrogen gas turbines. This investigation proposed an annular micro-mixing nozzles comprising seven annular nozzles arranged in a regular hexagonal pattern. Experimental investigations based on OH* Chemiluminescence with OH-PLIF synchronous measurement technique were performed. Results indicate that with increasing pressure, the flames become smaller and shorter, and the interaction between flames weakens compared to atmospheric pressure. At higher pressures, the flames predominantly rely on the bluff bodies of the annular nozzles for stability. This leads to a more concentrated flame reaction zone, increased local heat release, and an exponential increment in NO emissions. However, the experiments reveal that at combustion pressures equal to or below 0.2 MPa., NO emissions under the test conditions remain below 10ppm (@15%O2).