The Nonlinear Interaction of Two-Crossed Focussed Ultrasonic Beams in the Presence of Turbulence
Abstract
This paper examines the scattering of a nonlinearly generated sum frequency acoustic wave component from a region of turbulence defined by the overlap volume of two mutually perpendicular crossed focused ultrasonic beams. The scattered sum frequency pressure amplitude is measured at different radial scan positions across the jet flow stream providing conclusions that explain some qualitative results governing the sum frequency scattering mechanism. Information about the instantaneous velocity components of the turbulent field in the sound-sound interaction volume is measured with an electronic spectrum analyzer. Average spectral shapes of the spectrum near the sum frequency represent information about the probability distribution function of the turbulent velocities. Acoustic measurements are correlated with velocity measurements of circular jets. These correlations demonstrate that the focused crossed beam apparatus is an effective diagnostic tool for the experimental study of turbulent fluid fields in water. The results of the nonlinear crossed beam experiments indicate the apparatus can be utilized as a diagnostic tool to measure some parameters of turbulent velocity. The measured pressure of the radiated sum frequency correlates with turbulent velocities in the interaction region. Measurements of the Doppler shift and sum-frequency broadening are used to determine mean velocity and turbulent rms velocities respectively. Keywords: Sound waves, Scattering, Turbulence.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 10, 1988
- Accession Number
- ADA200405
Entities
People
- Stephen C. Rife
Organizations
- United States Naval Academy