Boundary Layer Stability Measurements over a Flat Plate at Mach 3.
Abstract
Amplification of natural disturbances in a flat plate laminar boundary layer at edge Mach number 3 have been measured in a supersonic wind tunnel with and without turbulent sidewall boundary layers. Detailed flowfield measurements were made to define the self-similar region and the point where the velocity profile first departs from the Blasius theory. The first instability mode was detected with a minimum critical momentum Reynolds number of 190 and a maximum amplified frequency of 0.000225. Amplification rates for this mode agree with the available theoretical predictions, and its low-frequency, low-R region is not as distorted by monotonic amplification as previously thought. A second, very prominent and extensive instability was found which extends to much higher frequencies beyond F = 0.00035 and which dominates the pretransitional flow. The neutral branch location of this mode associates it with the second instability mode found in hypersonic flow and serves to clarify and present a stability diagram rational over the M = 0-8 range. The overall amplitude gain before the first departure is still confined to low frequencies with the first mode contributing little net gain, the combined first-second modes contributing a gain of about 3, while an additional factor of 5-10 is provided by a mechanism active near the leading edge and apparently consistent with Mack's forcing-stability approach. Keywords: Boundary layer transition, Laminar boundary layer, Computer programs.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1985
- Accession Number
- ADA166188
Entities
People
- Anthony Demetriades
Organizations
- Montana State University