Accession Number:

ADA129406

Title:

Unsteady Transonic Flow in a Two-Dimensional Diffuser: Interpretation of Experimental Results.

Descriptive Note:

Scientific rept. 1 Apr 81-31 Mar 82,

Corporate Author:

MCDONNELL DOUGLAS RESEARCH LABS ST LOUIS MO

Personal Author(s):

Report Date:

1982-03-31

Pagination or Media Count:

76.0

Abstract:

Experimental data obtained over a four-year period on transonic, oscillatory diffuser flows were examined and compared with the predictions of simple, one-dimensional theories. Acoustic theory, accounting for upstream- and downstream-propagating acoustic waves, correctly describes pressure perturbations in attached flows, provided the wave reflection process at the shock is properly modeled. Unsteady boundary layers strongly influence pressure perturbations in separated flows and velocity perturbations in both attached and separated flows, with the result that acoustic theory fails in these cases. The boundary layers display slow, transverse, downstream-moving waves termed interface waves that strongly influence the core flow velocity and pressure perturbations through displacement effects. The Eulerian velocity perturbations associated with this wave motion are large within the boundary layer. A one-dimensional model was constructed, incorporating both acoustic waves and the interface waves their effect is most evident in the phase-angle distributions and in the predicted natural frequencies.

Subject Categories:

  • Fluid Mechanics
  • Air Breathing Engines (Unconventional)

Distribution Statement:

APPROVED FOR PUBLIC RELEASE