Visualization of Low-Density Flows by Means of Oxygen Absorption of Ultraviolet Radiation

Abstract

The high absorption of ultraviolet radiation (1,400 A.-l,500 A.) by ox3^gen has been employed to obtain photographs of several flow configurations. A vacuum spectrograph-monochromatorcamera with a 1,470 A. radiation source was adapted for installation in the low-density wind tunnel of the University of California at Berkeley. The photographs taken were of shock waves formed by flow over a sphere, a cone-cylinder, wedges, and a cylinder with axis aligned parallel to the direction of the flow. All photographs were taken at a free-stream Mach Number of ^ 3 . 9 , with a uniform jet area approximately two in. in diameter at the nozzle exit plane, and a tunnel test chamber static pressure of ^114// Hg. An analytical method of determining stream density in axially symmetric flow from the absorption of radiation as indicated by the photographs is presented. Limitations of the method are discussed.