The Flow Starting Process in Constant Area Supersonic Diffusers in a Ludwieg Tube.
Abstract
A Ludwieg tube with a diaphragm located either upstream or downstream of the test section was used to investigate starting times of flow. For a downstream diaphragm location the starting times were found to be dependent on the diffuser length, but independent of the initial pressure ratio across nozzle and diffuser, as long as this ratio was low enough to allow supersonic flow to be established. For the upstream diaphragm location, the starting times were much shorter than those for downstream diaphragm location. In this second situation, the starting times, however, increased with the pressure ratio across the entire nozzle-diffuser section. For both upstream and downstream diaphragm locations the starting times for supersonic flow at the nozzle exit were longer for the longer diffusers. The lowest overall pressure ratio needed for the flow to start was about 1.2 times the value of the optimum operating pressure recovery ratio for steady flow. The latter ratio was found in previous experiments in a smaller continuous wind tunnel with a geometrically similar nozzle and diffuser. The required diffuser length for starting at the optimum pressure ratio corresponds to the expected recovery length of the diffuser as derived from the earlier work with steady flow.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1976
- Accession Number
- ADA033317
Entities
People
- Nesim Abuaf
- Peter E. Merkli
Organizations
- Yale University