Calculation of the process of blast wave diffraction in a cylindrical channel

We performed a numerical investigation of the process of transition of a spherical leading front into a plane one in a cylindrical channel. The processes of the collision of reflected shock waves, formation of a nonstationary grating-like structure of flow, and of the overtaking interaction of shock waves are investigated. We found that in the presence of hot gas layers on the walls of the channel a plane head front is not formed.Notation r,z radial and axial coordinates - t time - p pressure - T temperature - u,v radial and axial velocity components - a distance between the planes - b half-distance between the planes - d channel diameter (in experimental data) - R₀ inital radius of the shock wave front - p^*(r, z),u^*(r, z),v^*(r, z),T^*(r, z) distributions of pressure, radial, and axial velocity, and temperature at the initial time moment - L length of the zone of formation of a plane front - T₁,T₂ temperature of gas in the lower and upper thermal layers - h₁,h₂ thicknesses of the lower and upper thermal layersDepartment of Theoretical Problems of the Russian Academy of Sciences, Moscow Physicotechnical Institute, Moscow. Translated from Inzhernerno-Fizicheskii Zhurnal, Vol. 68, No. 4, pp. 583–588, July–August, 1995.