CFD simulations of hydrogen deflagration in slow and fast combustion regime

Robert Cherbański , Eugeniusz Molga

Abstract

This paper presents CFD modelling of hydrogen-air deflagrations. The proposed mathematical models are validated with the experiments provided to SARNET2 (Severe Accident Research NETwork of Excellence 2) project [A. Bentaib, A. Bleyer, N. Chaumeix, B. Schramm, P. Kostka, M. Movahed, H.S. Kang and M. Povilaitis, Final results of the SARNET Hydrogen deflagration Benchmark Effect of turbulence on flame acceleration. (2012), pp. 1–15; A. Bentaib, A. Bleyer, N. Meynet, N. Chaumeix, B. Schramm, M. Höhne, P. Kostka, M. Movahed, S. Worapittayaporn, T. Brähler, H. Seok-Kang, M. Povilaitis, I. Kljenak and P. Sathiah, SARNET hydrogen deflagration benchmarks: Main outcomes and conclusions. Ann. Nucl. Energy 74 (2014), pp. 143–152. doi:10.1016/j.anucene.2014.07.012]. The goal of SARNET2 project was to investigate the effect of blockage ratio on flame propagation and pressure evolution during deflagration of a lean mixture of hydrogen and air. Three blockage ratios were tested: BR = 0, 0.33 and 0.63. The experiments were carried out in the ENACCEF facility. The proposed mathematical models test the effect of turbulence models and radiative heat losses on flame front position and absolute pressure in the testing facility. A good agreement between the calculated and experimental results for the three BRs is found for the SST k-ω model alone and in combination with the γ transition model when radiative heat losses are accounted for in the modelling. In addition, an unstable tulip flame is evidenced in our CFD simulations what corroborates previous reports on premixed combustion in a closed tube.