Accession Number:

ADA250700

Title:

Adaptive and Nonadaptive Feedback Control of Global Instabilities with Application to a Heated 2-D Jet

Descriptive Note:

Final technical rept. 15 Jun 1989-31 Dec 1991

Corporate Author:

CALIFORNIA UNIV LOS ANGELES SCHOOL OF ENGINEERING AND APPLIED SCIENCE

Personal Author(s):

Report Date:

1992-04-01

Pagination or Media Count:

63.0

Abstract:

Close to the onset of self-excited fluid oscillations the generic complex Ginzburg-Landau is proposed as the lowest order model for the plant. Its linear part which provides the stability boundaries is derived from first principles for both doubly-infinite and semi-infinite flow domains. Concentrating on a single global mode, the model is further simplified to the Stuart-Landau equation. For this latter model a methodology is developed for the design of single-input single-output controllers. The so designed controllers have been implemented on a self-excited, heated two-dimensional jet with one hot wire as sensor and an acoustic speaker as actuator, and are shown to be effective within their limitations in suppressing or enhancing limit-cycle oscillations. Finally, the effect of of a controller designed to suppress the most unstable global mode on other modes is investigated experimentally in the wake of a cylinder at low Reynolds number, where an encouraging semi- quantitative correspondence to the Ginzburg-Landau model is found.

Subject Categories:

  • Fluidics and Fluerics
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE