Experimental Investigation of a Spanwise Forced Mixing Layer
Abstract
The control of mixing by manipulation of instability modes leading to the formation of vortical structures has a direct impact on the performance of propulsion systems. In the plane mixing layer, mixing is accomplished by two- dimensional entrainment associated with spanwise vortices, and three-dimensional motion induced by packets of streamwise counter-rotating vortex pairs. Our research goal is to advance the state of understanding of the basic fluid mechanics of the mixing layer to aid in the implementation of real-time closed loop control schemes. To this end, the evolution of spanwise and streamwise instabilities has been investigated by independent forcing in the streamwise and spanwise directions. The flow is forced by means of a mosaic of individually controlled surface heaters, which allows for flexible programming of complex spatial/temporal forms of excitation. The downstream evolution of the spanwise instability and its dependence on the configuration are studied using Schlieren visualization and velocity measurements taken with a rake of hot wire probes. Pulsed 2-D and 3-D forcing is also used to study the temporal evolution of the flow. Mixing layer, Surface heaters, Streamwise vortices, Spanwise vortices, Mixing transition.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 28, 1988
- Accession Number
- ADA204557
Entities
People
- A. Glezer
- I. J. Wygnanski
- T. F. Balsa
Organizations
- University of Arizona