FLOW NOISE TRANSMITTED THROUGH DOMES OR ACOUSTICALLY MODIFIED BY NON-RIGID BOUNDARIES
Abstract
Flow-induced noise generated by pressure fluctuations in a turbulent boundary layer is studied here theoretically with regard to its acoustic transmission through a dome to a transducer element or array. Particular attention is given to a unilayer dome in the form of a finite slab, described as a fluid but serving as a prototype for a realizable solid slab. A similar dome with a thin outer cover having nonvanishing impedance is also considered. Likewise, attention is given to acoustic modification of the flow noise on a flush element due to mobility of the surrounding baffle. To demonstrate clearly what properties of the boundary layer pressure fluctuations are essential, high- and low-wavenumber ranges are distinguished in the wavenumber spectrum of pressure at given frequency, the former range corresponding to possible generation by a convected eddy field. By various approximations and simplification of boundary conditions, the contributions of these respective ranges to the frequency spectrum of average pressure on a dome-shielded element are related to their respective contributions in the reference case of an element flush-mounted in a rigid plate.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1966
- Accession Number
- AD0488867
Entities
People
- David M. Chase
Organizations
- Control Data Corporation