Features of the Density Field of Dissociating Hypersonic Flows
The influence of dissociative chemical reactions on the flow fields encountered during flight into and out of the atmospheres of the inner planets is discussed. Blunt-body flow, and therefore the flow after a curved shock wave, is particularly relevant, and density is the variable that is most strongly affected, while it is at the same time the easiest to obtain field measurements of. The direction of the density gradient at the curved shock is determined analytically by obtaining a local solution of the Euler equation. The density gradient has two contributions: one from the shock curvature and one from the dissociation rate. Its direction undergoes a sudden change by 180 at a particular point on the shock, indicating a saddle point in the density field. The location of the saddle point is a sensitive indicator of the dissociation rate and directly provides an approximate measure of the reaction rate parameter. Experimental results are used to illustrate the theoretical findings. uey wordsX hyperveloity flowD dissoitive nonequiliriumD luntEody flowD urved shok wg (IWWIAX UTuHS