Investigation of the structure of a diffusion hydrogen plume in a supersonic high-enthalpy air jet

The results of investigation of the plume structure in the case of diffusion combustion of hydrogen in a cocurrent supersonic high-enthalpy off-design air jet are presented. Based on the registration of radiation within the wavelength range of 260–350 nm across and along the flame, a three-dimensional tomographic reconstruction of the plume was obtained, which confirmed the interrelation between the gas-dynamic structure and combustion intensity. A possibility of existence of combustion regimes with periodically repeated cycles of complete extinction and subsequent ignition of hydrogen in accordance with the barrel-shaped structure of the off-design jet is established experimentally. The existence of local peripheral regions of combustion is noted, which can indicate the presence of vortex structures. In the three-dimensional representation (obtained under the assumption of axial symmetry of radiation), these vortex structures have the form of annular zones. In a real flow, helical structures are possibly formed at the plume periphery.