Accession Number:

ADA222918

Title:

An Optical Study of the Flow Start-Up Process in Four Convergent-Divergent Nozzles

Descriptive Note:

Corporate Author:

FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E V FREIBURG (GERMANY F R) ERNST-MACH-INST

Personal Author(s):

Report Date:

1990-03-01

Pagination or Media Count:

91.0

Abstract:

Large blast simulators LBS are specialized shock tunnels for generating decaying blast waves such as are associated with nuclear explosions. Blast simulators employ convergent-divergent nozzles at the driver exit to retard the outflow of the high-pressure driver gas and generate long flow durations. The LBS nozzle design in this study differs from the nozzle design used in previous studies in that it has the flow-initiating diaphragm mounted in the throat of the nozzle itself. When the diaphragm is ruptured, a shock forms and travels downstream into the divergent section, while a rarefaction fan travels upstream into the convergent section. No previous experimental research is known for this problem. Therefore, a shock tube test was proposed in which the diaphragm separating the high-pressure driver from the low-pressure driven section was mounted in the throat of a convergent-divergent nozzle which formed the transition from the driver to the driven section of the shock tube. The objectives of this investigation were 1 to obtain optical records of the shock formation in the convergent-divergent nozzle immediately after rupturing the diaphragm 2 to determine the influence of the cone angle and length of a divergent nozzle on the pressure signature in the expansion region behind the nozzle and 3 to facilitate comparisons with one-, and two-dimensional hydrocode computations. The test set-up and the results of this experimental study are presented and the most significant findings are discussed. West Germany.

Subject Categories:

  • Test Facilities, Equipment and Methods
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE