Structure of the flow of gas escaping from a gap in a pipeline

A study is made of the two-dimensional steady flow of gas escaping from a circular gap formed when the ends of pipes move apart along their common symmetry axis. A study is made of the rearrangement of the flow from the shockless flow in the neighborhood of the symmetry axis to the shocked flow. A numerical investigation gave the value H_* of the width of the gap at which the transition takes place from a shockless flow structure to one with a shock. A study is made of the influence on H_* of the pressure ratio ?_a (?_a = P_a/P₀, where P_a is the pressure in the ambient space and p₀ is the stagnation pressure) and the specific—heat ratio. Godunov's scheme 1] was used for the numerical realization.