A Factor Affecting Transonic Leading-edge Flow Separation

A change in flow pattern that was observed as the free-stream Mach number was increased in the vicinity of 0.8 was described in NACA Technical Note 1211 by Lindsey, Daley, and Humphreys. The flow on the upper surface behind the leading edge of an airfoil at an angle of attack changed abruptly from detached flow with an extensive region of separation to attached supersonic flow terminated by a shock wave. In the present paper, the consequences of shock-wave - boundary layer interaction are proposed as a factor that may be important in determining the conditions under which the change in flow pattern occurs. Some experimental evidence in support of the importance of this factor is presented

Investigation with an Interferometer of the Turbulent Mixing of a Free Supersonic Jet

The free turbulent mixing of a supersonic jet of Mach number 1.6 has been experimentally investigated. An interferometer, of which a description is given, was used for the investigation. Density and velocity distributions through the mixing zone have been obtained. It was found that there was similarity in distribution at the cross sections investigated and that, in the subsonic portion of the mixing zone, the velocity distribution fitted the theoretical distribution for incompressible flow. It was found that the rates of spread of the mixing zone both into the jet and into the ambient air were less than those of subsonic jets

NACA Technical Notes

From Summary: "Interferometric measurements were made of the density profiles of an unsteady turbulent boundary layer on the flat wall of a shock tube. The investigation included both subsonic and supersonic flow (Mach numbers of 0.50 and 1.77) with no pressure gradient and with heat transfer to a cold wall. Velocity profiles and average skin-friction coefficients were calculated. Effects on the velocity profile of surface roughness and flow lengths are examined.

NACA Technical Notes

Report presenting a change in flow pattern that was observed as the free-stream Mach number was increased in the vicinity of 0.8. The paper presents an investigation of the consequences of shock-wave-boundary-layer interaction, which are proposed as a factor that may be important in determining the conditions under which the change in flow pattern occurs

NACA Technical Notes

From Summary: "Interferograms were taken of the flow around a sphere at Mach numbers of 1.30 and 1.62. The results of the evaluation of these interferograms are shown as plots of contours of constant density ratio in the flow field around the sphere and as the distribution of flow variables along the axis of symmetry between the shock wave and the sphere. In appendixes the theory of the analysis is reviewed, sources of error are discussed, and the detailed procedure used in the evaluation of interferograms is described.