SIMULTANEOUS STREAK AND FRAME INTERFEROMETRY FOR USE IN SHORT DURATION HYPERVELOCITY FACILITIES,
Abstract
A unique instrumentation system for simultaneous investigation of free stream and flows around a model in an expansion tube is described. A Mach-Zehnder interferometer with the proper combination of masks, filters, a dichroic mirror and a rotating mirror, are used. Streak interferograms of 400 microsec duration and framing records of microsec duration are obtained. A streak interferogram in green monochromatic light gives a continuous history of the free stream flow, while single frame interferograms in blue monochromatic light record the flow field about the model. The streak interferogram, in addition to monitoring quality of free stream flow, can be used in conjunction with pressure, wave-velocity measurements and perfect gas theory to determine free stream conditions, notably static temperature, as necessary for the study of the flow around the model. An interferogram yields the local optical refractivity, which is a variable of state. For many applications, including the anticipated free stream conditions, this variable is simply proportional to density. The local refractivity measured from the frame interferograms of flow around models can immediately be compared with theoretical predictions, even though the flow be reacting. The exact time of each interferogram frame is selected and indexed directly on the streak photograph. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1964
- Accession Number
- AD0460155
Entities
People
- D. D. Shear
- J. H. Spurk
Organizations
- Ballistic Research Laboratory