Laser Rayleigh measurement of mixing processes and control of hydrogen combustion using quenching meshes

Two issues concerning hydrogen combustion under a severe accident scenario are addressed: (1) a laser Rayleigh scattering technique to investigate hydrogen mixing processes; and (2) the installation of metallic meshes between compartments to control and isolate hydrogen combustion within a single compartment. The Rayleigh scattering techniques are tested to determine hydrogen/air mixing processes locally and temporally as a non-intrusive probing method. To simulate mixing processes, helium is injected into a chamber filled with n-butane. Results show that helium concentration can be successfully monitored with sufficiently fast responses. Isolation and control of hydrogen burning is simulated by installing metallic meshes between compartments. Hydrogen is injected into one compartment and subsequently transported to the second compartment. Two sets of experiments are conducted with and without installing metallic meshes between the compartments. With the mixture ignited near the second compartment outlet, hydrogen combustion can be successfully contained within the second compartment with meshes, while flame propagates to the first compartment when meshes are not installed. These results demonstrate that hydrogen combustion can be controlled and isolated by installing meshes locally such that unwanted rapid pressure rise in a containment can be prevented. It also suggests the applicability of meshes for equipment survivability and protection from flame propagation by enclosing equipments with properly designed meshes.