Investigation of Diffusers for Gas Dynamic Laser Nozzles
Abstract
Schlieren photographs were used to analyze the flow characteristics of diffusers for a Mach 6.0 double nozzle assembly. This assembly of two nozzles, comprised of one (1) full center and two (2) half side channels, was more conducive to greater boundary layer growth than a nozzle assembly with more nozzle throats. Schlieren photographs of the air flow were in line with the laser beam's orientation to the nozzles of a Gas Dynamic Laser. Dry air at 85 F total temperature, and 120 psia total pressure was expanded with a nozzle area ratio of 66.0. Different diffuser configurations were tried to determine the diffuser throat area required to start the cavity. It was determined that the cavity would start when the ratio of diffuser throat area to channel cross- sectional area was near 0.6, which is in agreement with other studies, considering the presence of wakes in the flow. Boundary layer growth is accelerated at these high Mach numbers, limiting the distance between the nozzles and diffuser; excellent optical charity flow was obtained emerging from the nozzles and close to the channel center using a multi-element diffuser, but, deteriorates rapidly further downstream.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1973
- Accession Number
- AD0774391
Entities
People
- David G. Clawson
Organizations
- Air Force Institute of Technology