Unsteady Transonic Flows in a Two-Dimensional Diffuser.
Abstract
Extensive measurements of shock position and pressure distributions (wall static, core flow static, and core flow total) were made, complemented by spark schlieren and high-speed schlieren photographic information. Measurements were made at shock Mach numbers up to 1.35, with and without excitation. The excitation amplitudes were low, with frequencies from 0 to 330 Hz. Unexcited flows displayed two dominant natural frequencies for attached flows (shock Mach numbers below 1.27) and one dominant peak for separated flows (shock Mach numbers above 1.28). The dominant frequencies depend strongly on shock strength. Diffuser response to excitation appears to follow patterns expected on the basis of low-amplitude (acoustic) wave propagation concepts, provided that the stream-wise variation of the flow speed is considered and realistic boundary conditions are applied at the ends of the channel. The study strongly suggests that the effective acoustic impedance associated with the shock/boundary-layer interaction zone is an important determinant of diffuser response to small-amplitude external perturbations.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1980
- Accession Number
- ADA088231
Entities
People
- Joseph C. Kroutil
- Miklos Sajben
- Thomas J. Bogar