Supersonic Flow Past Oscillating Airfoils Including Nonlinear Thickness Effects
Abstract
A solution to second order in thickness is derived for harmonically oscillating two-dimensional airfoils in supersonic flow. For slow oscillations of an arbitrary profile, the result is found as a series including the third power of frequency. For arbitrary frequencies, the method of solution for any specific profile is indicated, and the explicit solution derived for a single wedge. Nonlinear thickness effects are found generally to reduce the torsional damping, and so enlarge the range of Mach numbers within which torsional instability is possible. This destabilizing effect varies only slightly with frequency in the range involved in dynamic stability analysis, but may reverse to a stabilizing effect at high flutter frequencies. Comparison with a previous solution exact in thickness suggests that nonlinear effects of higher than second order are practically negligible. The analysis utilizes a smoothing technique which replaces the actual problem by one involving no kinked streamlines. This strategem eliminates all consideration of shock waves from the analysis, yet yields the correct solution for problems which actually contain shock waves.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1953
- Accession Number
- ADA381440
Entities
People
- Milton D. Van Dyke
Organizations
- National Aeronautics and Space Administration