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Abstract
Computational fluid dynamics (CFD) modeling was conducted on flow inside of three different sonic probes used for sampling gases from a combustion reactor. The effects of inlet temperature and pressure were analyzed to quantify thermal quenching rates resulting from expansion cooling. Gas-phase nitrogen was used to simulate flows occurring in jet-stirred reactors, which commonly utilize >97% (vol.) N2. The process was modeled as adiabatic (i.e. wall heat transfer is neglected because of the probe material (quartz) and short residence time) and boundary conditions were: (1) Pinlet = 1, 10, and 25 atm; (2) Poutlet = 0.08 atm; (3) Tinlet = 500, 750, 1000 K; (4) Toutlet = 300 K. The major outcomes are computed temperature and pressure gradients in space and time and over the length of the sonic probe (0.85 m), which provided comprehensive understanding of sonic probe flow.