화학공학소재연구정보센터
International Journal of Hydrogen Energy, Vol.42, No.16, 11902-11910, 2017
Mechanism of self-ignition of pressurized hydrogen flowing into the channel through rupturing diaphragm
The paper considers numerically the mechanism of hydrogen self-ignition occurring when hydrogen flows into the channel through gradually rupturing diaphragm. The analysis focuses on the near-critical self-ignition regimes arising at initial hydrogen pressure similar to 60 atm that is marginal for self-ignition occurrence for selected channel geometry. Numerical simulation reproduces two types of ignition kernels observed experimentally. Both types of kernels arise on the contact surface between the released hydrogen and air heated behind the outrunning shock wave. In the initial stage the self-ignition kernels arise on the side contact surface interacting with channel walls and compression waves reflected from the walls. However, because of oxygen deficit these ignition kernels are extinguished. In the subsequent stage the self-ignition kernel arises in the region where the side contact surface penetrates into the boundary layer heated behind the shock wave. The further evolution of the ignition kernel is provided by the vortical structures evolving at the side contact surface and defining the mixing of hydrogen with air as well as the sustained supply of the mixture into the ignition kernel. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.