Nonlinear acoustic streaming in straight and tapered tubes
Open Access
- Author:
- Tuttle, Brian Craig
- Graduate Program:
- Acoustics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- March 16, 2012
- Committee Members:
- Victor Ward Sparrow, Dissertation Advisor/Co-Advisor
Anthony A Atchley, Committee Member
Robert Mitchel Keolian, Committee Member
Philip John Morris, Committee Member - Keywords:
- nonlinear acoustics
acoustic streaming
thermoacoustics
computational fluid dynamics - Abstract:
- In thermoacoustic and Stirling devices such as the pulse-tube refrigerator, efficiency is diminished by the formation of a second-order mean velocity known as Rayleigh streaming. This flow emerges from the interaction of the working gas with the wall of the tube in a thin boundary layer. Recent studies have suggested that streaming velocity can be decreased in a tube by tapering it slightly. This research investigates that claim through the development of a numerical model of Rayleigh streaming in variously tapered tubes. It is found that the numerical simulation of streaming in a straight tube compares well with theory, and the application of different thermal boundary conditions at the tube wall shows that for pressurized helium, inner streaming vortices which appear near an adiabatic tube wall do not develop near an isothermal wall. An order analysis indicates that the temperature dependence of viscosity and thermal conductivity contributes appreciably to an accurate numerical model of streaming. Comparison of Rayleigh streaming in tapered tubes shows the effects of taper angle on the circulation and velocity of the mean flow.