An investigation of wind tunnel wall effects at high Mach numbers

This paper presents the results of an investigation of wind tunnel wall interference in a two-dimensional wind tunnel at high Mach numbers. The results are presented in the form of curves of lift coefficient versus the ratio of model chord to tunnel height, as functions of Mach number and angle of attack. The investigation was carried out by the authors at the Guggenheim Aeronautical Laboratory of the California Institute of Technology during the school year 1944-45.

Tests were carried out on the NACA low drag airfoil section 65,1-012 at Mach numbers from .60 to .80, and angles of attack of from 1 to 3 degrees. Models were 1", 2", 4" and 6" chord, giving values of the chord to tunnel height ration of .1 to .6. Schlieren photographs were made of shock waves where they occurred.

Effects of injection nozzle configuration on secondary injection into supersonic flow

Gaseous nitrogen and argon were injected into a primary stream of air moving at Mach 2.56. The gases were injected at secondary to primary total pressure ratios from 3.2 to 28.6 through four different nozzles. Two nozzles, one sonic and one supersonic (M = 3.26), injected normal to the primary stream; and two sonic nozzles injected at 45° angles to the primary flow, one injecting upstream and the other downstream. Data consisted of static pressure measurements on the wall near the injector, total pressure profiles in the wake of the injectant plume, and concentration measurements downstream of the flow. Scale parameters were calculated based upon an analytical model of the flow field and their validity verified by experimental results. These scale heights were used to compare normalized wall side forces for the different nozzles and to compare the mixing of the two streams.