Accession Number : ADB024631

Title :   Experiments on The Wakes of Multiple Nozzle Cusps.

Descriptive Note : Final rept.,


Personal Author(s) : Demetriades,Anthony

Report Date : NOV 1977

Pagination or Media Count : 56

Abstract : The objective of this work is to provide basic gas-dynamical information on the wakes of nozzle cusps such as employed in gas-dynamic-laser nozzle arrays. A three-nozzle array was designed, built and installed in the Aeronutronic supersonic Wind Tunnel. Test runs were made to check the overall performance of the nozzle-diffuser system at Mach 4, nozzle exit Reynolds number of 100,000 and nozzle wall temperatures down to 60% of stagnation, in continuous airflow. Diagnostics consisted of spark-schlieren photography, pitot and static pressure probes, total-temperature probes and hot film anemometers. It was found that continous unchoked flow could be obtained with a simple diffuser, and that the flow was two-dimensional even without resorting to sidewall junction tailoring. Good qualitative and fair to good quantitative agreement was found with earlier wake predictions published under the present contract. The virtual wake orgin was found to lie near the nozzle throat and the near wake nonequilibrium region occupied a length equal to two nozzle exit heights beyond the trailing edge. Without cooling the wake was laminar, with long wavelength fluctuations which merit further study. With nozzle cooling transition to turbulence in the wake advanced upstream in agreement with earlier predictions of wake stability. (Author)

Descriptors :   *Wake, *Nozzle gas flow, *Gas dynamic lasers, Turbulent flow, Boundary layer transition, Laminar flow, Boundary layer, Supersonic nozzles, Configurations, Mathematical prediction, Wind tunnel tests

Subject Categories : Lasers and Masers
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE