An Optical Study of the Flow Start-Up Process in Four Convergent-Divergent Nozzles
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1990
- Accession Number
- ADA222918
Entities
People
- Heinz Reichenbach
- Klaus O. Opalka