Turbulent Flow Control
Final technical rept. 1 Nov 90-28 Feb 95
STANFORD UNIV CA DEPT OF MECHANICAL ENGINEERING
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The primary purpose of this project was to explore actuators, sensors, and control strategies for active control of turbulent jets and boundary layers. Potential applications of this work are to boundary layer control in aircraft and propulsion systems, which should be enabled by concurrent developments in MEMS fabrication technology. The present experiments were performed in a low-speed water flow, where the turbulence is large scale and slow, allowing easy measurement of flow properties and use of actuators and sensors that could be fabricated individually. A zero net mass flow actuator was developed and used in conjunction with wall stress sensors to demonstrate control of laminar flows containing steady and unsteady streamwise vorticies similar to those found in the near-wall region of turbulent boundary layers. Various closed loop control schemes, including an adaptive inverse neural net control, were explored. An early phase of the project was devoted to extension of work on control of round jets by acoustic excitation. It was shown that the jet direction and mixing can be strongly influenced by acoustic and fluidic actuation.
- Fluid Mechanics