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Flow Control Objectives

Actively pulsing a jet can favorably influence many aspects of a flowfield such as the spread and mixing of the jet into its surroundings. It is hypothesized these parameters will be maximized with the formation of strong, well spaced vortex rings at the jet exit. Periodic, low duty cycle pulses appear to be the most effective way to accomplish this but challenges exist in forming well-defined pulses due to non-linear distortion in the actuation system revealed by the coherence plots of the hotwire transducer. The objectives of this research program are to develop the hardware and control algorithms for pulse formation at the jet exit thereby enabling fundamental experiments in jets-in-crossflow.

schematicpulse

Dynamic Phase Compensation for Modulated-Demodulated Control of Jets in Crossflow

Modulated-demodulated control is an effective method for asymptotic disturbance rejection and reference tracking of periodic signals, however, conventional static phase compensation often limits the loop gain in order to avoid sensitivity function peaking in a neighborhood of the frequencies targeted for rejection or tracking. We have recently introduced dynamic phase compensation for modulated-demodulated control which improves disturbance rejection characteristics by inverting the plant phase in a neighborhood of the control frequency. Dynamic phase compensation is implemented at baseband which enables the use of low-bandwidth compensators to invert high frequency dynamics.

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Identification and Compensation of Intermodulation Distortion

At higher forcing amplitudes the jet velocity exhibits significant nonlinear coupling between harmonics of the periodic reference (magnitude shown far right). The coupling can create instability if the controller design is based on a model identified at a lower RMS reference amplitude (diagonal coupling at immediate right indicates a linear response). We have quantified the coupling for different RMS forcing conditions and synthesized controllers that maintain stability over a wider range of experimental jet forcing conditions.

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Relevant Publications:

Hendrickson, C. and M'Closkey, R.T., "Compensation of Nonlinear Harmonic Coupling for Pulsed-Jet-Velocity Shaping", AIAA J., 51(11): 1-15, Nov. 2013

34. Hendrickson, C. and M'Closkey, R.T., "Identification and Control of Nonlinear Harmonic Coupling for Pulsed Jet Injection", Proc. 51st IEEE Conf. Decision Control, Maui, 502-507, Dec. 2012

Hendrickson, C. and M'Closkey, R.T., "Phase Compensation Strategies for Modulated-Demodulated Control With Application to Pulsed Jet Injection", J. Dyn. Sys., Meas., and Control, Trans. ASME, Vol 124, pp. 1-9, Jan. 2012

Hendrickson, C., and M'Closkey, R.T., "Dynamic Phase Compensation in Modulated-Demodulated Control for Pulsed Jet Injection", Proc. 2011 American Control Conf., San Francisco, pp. 3053-3058, June 2011

Davitian, J., Hendrickson, C., Getsinger, D., M’Closkey, R.T. and Karagozian, A.R., "Strategic Control of Transverse Jet Shear Layer Instabilities", AIAA J., Vol. 48, No. 9, pp. 2145 - 2156, Sept. 2010

Davitian, J., Hendrickson, C., Getsinger, D., M’Closkey, R. T., and Karagozian, A. R., "Controlled Excitation of Transverse Jet Shear Layer Instabilities", Western States Section/The Combustion Institute Spring Meeting (Paper 08S-24), 1-26, Mar. 2008

Davitian, J., Hendrickson, C., M’Closkey, R. T., and Karagozian, A. R, "Strategic Control of Transverse Jet Flows", 46th AIAA Aerospace Sciences Meeting (Paper AIAA-2008-0741), Jan. 2008

Shapiro, S.R., King, J.M., M'Closkey, R.T., and Karagozian, A.R., "Optimization of Controlled Jets in Crossflow", AIAA J., Vol. 44, No. 6, pp. 1292 - 1298, 2006

Lau, K., Goodwin, G.C., and M'Closkey, R.T., "Properties of Modulated and Demodulated Systems with Implications to Feedback Limitations", Automatica, 41:2123 - 2129, October 2005

Karagozian, A. R., Megerian, S., Alves, L., George, M., Kelly, R. E., and M’Closkey, R. T., "Control of Vorticity Generation in an Acoustically Excited Jet in Crossflow", 43rd AIAA Aerospace Sciences Meeting and Exhibit (AIAA Paper 2005-0303), Jan. 2005

Lau, K., Goodwin, G.C., and M'Closkey, R.T., "Fundamental Performance Limitations of Modulated and Demodulated Control Systems", Proc. 2004 American Control Conf., Boston, pp. 2069-2074

M'Closkey, R.T., King, J.M., Cortelezzi, L., and Karagozian, A.R., "Active Control of Jets in Crossflow", in Manipulation and Control of Jets in Crossflow, CISM Courses and Lectures No. 439, Springer-Verlag, A.R. Karagozian, L. Cortelezzi, and A. Soldati (Eds.), pp. 247 - 256, 2003

Cortelezzi, L., M'Closkey, R.T., and Karagozian, A.R., "A Framework to Design Controllers for Engineering Applications of Transverse Jets", in Manipulation and Control of Jets in Crossflow, CISM Courses and Lectures No. 439, Springer-Verlag, A.R. Karagozian, L. Cortelezzi, and A. Soldati (Eds.), pp. 237 - 245, 2003

M'Closkey, R.T., King, J.M., Cortelezzi, L., and Karagozian, A.R., "The Actively Controlled Jet in Crossflow", J. Fluid Mech., Vol. 452, pp. 325 - 335, Feb. 2002

Cortelezzi, L., King, J., Lobbia, R., M'Closkey, R.T., and Karagozian, A.R., "Actively Controlled Transverse Gas Injection", Proc. 39th IEEE Conf. Decision Control, Sydney, Australia, 1736-1741, 2000