Experimental Application of an Active Control Loop on Backward-Facing Step Flow.

AIAA Journal ◽  
2005 ◽  
Vol 43 (6) ◽  
pp. 1176-1186 ◽  
Author(s):  
F. Marrot ◽  
P. Gajan ◽  
S. Pauzin ◽  
F. Simon
Keyword(s):  
Active Control ◽  
Control Loop ◽  
Backward Facing Step ◽  
Step Flow ◽  
Experimental Application

Active Control of a Backward Facing Step Flow With Plasma Actuators

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Juan D'Adamo ◽  
Roberto Sosa ◽  
Guillermo Artana
Keyword(s):  
Shear Layer ◽  
Active Control ◽  
Flow Behavior ◽  
Plasma Actuators ◽  
Backward Facing Step ◽  
Step Flow ◽  
Separated Shear Layer ◽  
Image Velocimetry ◽  
Layer Flow ◽  
Electrohydrodynamic Actuator

Active control over a backward facing step flow is studied experimentally by means of plasma based devices. The Reynolds number based on the step height h is 1520. An electrohydrodynamic actuator (EHD), dielectric barrier discharge (DBD) type, is flush mounted to the step wall. The DBD configuration adds momentum locally, normal to the separated shear layer, thus producing strong modifications downstream. The actuation is periodic and its frequency and amplitude are scrutinized to characterize the flow behavior under forcing. Measures of velocity fields for these flows are obtained from particle image velocimetry (PIV). As reported by previous works, the reattachment length shows an important reduction for an optimum forcing frequency. This value closely matches the shear layer flow natural frequency. On the other hand, the flow is less sensitive to the forcing amplitude though the analysis allows us to optimize the actuation in order to save power consumption.

Active control of a backward-facing step flow

2000 ◽  
Author(s):  
Franck Marrot ◽  
Franck Simon ◽  
Pierre Gajan ◽  
Simone Pauzin
Keyword(s):  
Active Control ◽  
Backward Facing Step ◽  
Step Flow

Stochastic dynamics and model reduction of amplifier flows: the backward facing step flow

2013 ◽  
Vol 719 ◽  
pp. 406-430 ◽  
Author(s):  
G. Dergham ◽  
D. Sipp ◽  
J.-Ch. Robinet
Keyword(s):  
Stochastic Dynamics ◽  
Empirical Orthogonal Functions ◽  
Backward Facing Step ◽  
Orthogonal Functions ◽  
Step Flow ◽  
Flow Response ◽  
Entire Flow ◽  
Random Flow ◽  
Value Decomposition ◽  
And Diffusion

AbstractMethods for investigating and approximating the linear dynamics of amplifier flows are examined in this paper. The procedures are derived for incompressible flow over a two-dimensional backward-facing step. First, the singular value decomposition of the resolvent is performed over a frequency range in order to identify the optimal and suboptimal harmonic forcing and responses of the flow. These forcing/responses are shown to be organized into two categories: the first accounting for the Orr and Kelvin–Helmholtz instabilities in the shear layer and the second for the advection and diffusion of perturbations in the free stream. Next, we investigate the dynamics of the flow when excited by a white in space and time noise. We compute the predominant patterns of the random flow which optimally account for the sustained variance, the empirical orthogonal functions (EOFs), as well as the predominant forcing structures which optimally contribute to the sustained variance, the stochastic optimals (SOs). The leading EOFs and SOs are expressed as a linear combination of the suboptimal forcing and responses of the flow and are related to particular instability mechanisms and/or frequency intervals. Finally, we use the leading EOFs, SOs and balanced modes (obtained from balanced truncation) to build low-order models of the flow dynamics. These models are shown to accurately recover the time propagator and resolvent of the original dynamical system. In other words, such models capture the entire flow response from any forcing and may be used in the design of efficient closed-loop controllers for amplifier flows.

Sign in / Sign up

Export Citation Format

Share Document