A Three Dimensional Density Field Measurement of Transonic Flow From a Square Nozzle Using Holographic Interferometry

Abstract

The three dimensional static density field was measured for transonic flow from a square nozzle using holographic interferometry. These measurements are presented in order to show the efficiency of this method for obtaining accurate experimental data of transonic flows. The accuracy of the measurement was estimated by operating the nozzle at a pressure ratio of 1.89 where the flow should expand to the ambient pressure with no afterexpansion effects. The standard deviation in the static density was approximately 1 percent over the isentropic (potential core) part of the flow. Data are also presented for a pressure ratio of 2.14 where afterexpansion effects are important. The method described represents a significant technical improvement in practical interferometry.