Active Control of Jet Flowfields
Abstract
Passive and active control of jet shear layer development were investigated as mechanisms for modifying the global characteristics of jet flowfields. Slanted and stepped indeterminate origin (I.O.) nozzles were used as passive, geometry-based control devices which modified the flow origins. Active control techniques were also investigated, in which periodic acoustic excitation signals were injected into the I.O. nozzle shear layers. Flow visualization techniques based on a pulsed copper-vapor laser were used in a phase-conditioned image acquisition mode to assemble optically averaged sets of images acquired at known times throughout the repetition cycle of the basic flow oscillation period. Hot wire data were used to verify the effect of the control techniques on the mean and fluctuating flow properties. The flow visualization images were digitally enhanced and processed to show locations of prominent vorticity concentrations. Three-dimensional vortex interaction patterns were assembled in a format suitable for movie mode on a graphic display workstation, showing the evolution of three-dimensional vortex systems in time. Keywords: Fluid mechanics; Shear layers; Jet flows; Passive control; Active control; Image processing; Control of turbulence; Asymmetric nozzles; Slanted nozzles.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 29, 1987
- Accession Number
- ADA186736
Entities
People
- Richard W. Wlezien
- Valdis Kibens