Real gas effects on the normal shock behavior near curved walls

The influence of dense gases on the curvature and the strength of a normal shock near curved walls is discussed. In classical gasdynamics there is a postshock expansion and the shock is curved upstream if the wall is convex. The transonic small disturbance theory for the problem has been derived, including the fundamental gasdynamic derivative Γ and the second nonlinearity parameter Λ. Special attention is drawn on flows where Γ becomes either zero or negative. According to the similarity laws, change of the sign of Γ changes the sign of the velocity disturbances φ_x and φ_y and of the wall curvature. Thus an expansion shock is followed by a compression if Γ<0 and the wall is concave. Again the shock is curved upstream. A variation of the second nonlinearity parameter Λ influences the strength of the shock, its curvature, and of the postshock expansion. Considering a Γ>0 flow at a convex wall, the postshock expansion and the shock curvature are weakened if Λ>0. Comparing the real gas flow with the perfect gas flow (e.g., Γ=1.2 and Λ=0), both the expansion behind the shock and the shock curvature increase if Λ becomes negative.