title: Nonlinear standing waves in a resonator with feedback control.
abstract: An experimental study is presented to demonstrate that nonlinear effect on standing waves in a resonator can be reduced by a feedback loop responding to the second harmonic. The resonator was a cylindrical tube sealed at one end and driven by a horn driver unit at another end. The feedback control loop consisted of a pressure sensor, a frequency filter, a phase shifter, and an actuator. The results show that the waveform distortions can be eliminated and large amplitude sinusoidal pressure oscillations are obtained. A simple model is proposed for a qualitative discussion on the control mechanism, which shows that the feedback loop alters the imaginary part of the complex mode frequency so as to suppress (or enhance) the second harmonic.
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, Singapore. mxhuang@ntu.edu.sg
authors.forename: X Y
authors.initials: XY
authors.lastname: Huang
authors.forename: N T
authors.initials: NT
authors.lastname: Nguyen
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Jiao
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D004867:Equipment Design; D005246:Feedback; D008962:Models, Theoretical; D009038:Motion; D017711:Nonlinear Dynamics; D009991:Oscillometry / Q000295:instrumentation; D011312:Pressure; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation; D014160:Transducers, Pressure; D014732:Vibration