Unsteady Transonic Flow in a Two-Dimensional Diffuser: Interpretation of Experimental Results.
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 31, 1982
- Accession Number
- ADA129406
Entities
People
- Miklos Sajben
- Thomas J. Bogar