VIBRATION OF CAVITATING ELASTIC WING IN A PERIODICALLY PERTURBED FLOW: EXCITATION OF SUBHARMONICS

• Published in: Journal of fluids and structures Vol. 14; no. 5; pp. 735 - 751
• Main Authors: AMROMIN, E., KOVINSKAYA, S.
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 01.07.2000; Elsevier
• Subjects: Applied fluid mechanics; Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Hydrodynamics, hydraulics, hydrostatics; Physics; Wing; Periodic flow; Strouhal number; Elastic structure; Vibration amplitude; Two dimensional flow; Low frequency; Beam(mechanics); Vibrations; Subharmonic; Numerical analysis; Frequency band; Hydroelasticity; High frequency
• ISSN: 0889-9746; 1095-8622
• DOI: 10.1006/jfls.2000.0291

The vibration of an elastic wing with an attached cavity in periodically perturbed flows is analyzed. Because the cavity thickness and length L also are perturbed, an excitation with a fixed frequency ω leads to a parametric vibration of the wing, and the amplitudes and spectra of its vibration have nonlinear dependencies on the amplitude of the perturbation. Numerical analysis was carried out for a two-dimensional flow of ideal fluid. Wing vibration was described by means of the beam equation. As a result, two frequency bands of a significant vibration increase were found. A high-frequency band is associated mainly with an elastic resonance of the wing, and a cavity can add a certain damping. A low-frequency band is associated with cavity-volume oscillations. The governing parameter for the low-frequency vibration is the cavity length-based Strouhal number StC=ωL/U, where U is the free-stream speed. The most significant vibration in the low-frequency band corresponds to approximately constant values of ShCand has the most extensive subharmonics.