Flame burning speeds and combustion characteristics of undiluted and nitrogen-diluted hydrogen–nitrous oxide mixtures

In the present study, some explosive properties of undiluted and nitrogen-diluted H2–N2O mixtures were characterized. Laminar burning speeds and the explosion-induced pressure rises were determined experimentally for a range of mixture equivalence ratios (ϕ=0.15−1.0)(ϕ=0.15−1.0), dilutions (0−55%N2), and initial pressures (20−80kPa). The measured burning speeds were used to validate laminar burning speed computations using a detailed chemical kinetic mechanism. The computations were then used to estimate burning speeds at high initial pressure and low dilution conditions that could not be measured experimentally. The results demonstrate that hydrogen–nitrous oxide mixtures exhibit laminar burning speeds as large as 350 cm/s and pressure rise coefficients (Kg) as large as 35 MPa m/s. Also, flames in lean mixtures are shown to be highly unstable which can lead to flame acceleration and possible deflagration-to-detonation transition.

► Flammable hydrogen-nitrous oxide mixtures generated by radioactive waste.
► Accidental ignition can lead to failure of pipelines, storage structures.
► Spark ignition tests of undiluted and nitrogen diluted H2-N2O mixtures.
► Determined laminar flame burning speeds, explosion pressures.
► Experimental measurements used to validate flame speed computations.