Linear stability analysis of circular jets: integer, fractional, and multiple mode excitation

The linear stability analysis of Huang [1995] has been adapted to ignore the effects of swirl, and to allow calculation of the eigenvalues and eigenfunctions for integer, fractional, and multiple modes of excitation. The investigation was intended to be exploratory; to gain the best possible insights into the flow characteristics from analysis of the linearized Euler equations. All of the azimuthal modes investigated (one-half, one, three-halves, and two) were found to lead to the continuous, helical, vortical structure evolution in the streamwise direction of the jet. The analysis for fractional modes of excitation predicted aphysical behavior near the jet center that has been attributed to a unresolved questions in the mathematical analysis of the problem. Multiple mode excitation at the axisymmetric mode and one or more azimuthal modes were found to result in un-even, periodic, vortex-ring growth in the shear layer. An argument was presented for the axisymmetric mode (m=O) resulting in the highest levels of entrainment for all integer, fractional, and multiple modes of excitation. Finally the importance of the azimuthal component of vorticity in the entrainment process was identified.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Mechanical Engineering

Department dc:contributor.department

Mechanical Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1995

Author dc:creator

• Leimkuhler, Matthew Pancoast

• flow characteristics

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-06082009-170937

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/42902