Nonlinear acoustic response of stand-off tubes used in acoustic pressure measurements—Part II: Analysis

2015 ◽  
Vol 138 (3) ◽  
pp. 1801-1801
Author(s):  
John M. Quinlan ◽  
David Scarborough ◽  
Anthony Rehl ◽  
Ben Zinn
Keyword(s):  
Acoustic Pressure ◽  
Pressure Measurements ◽  
Acoustic Response ◽  
Nonlinear Acoustic

scholarly journals Swirl–nozzle interaction experiment: quasi-steady model-based analysis

2021 ◽  
Vol 62 (8) ◽  
Author(s):  
Lionel Hirschberg ◽  
Friedrich Bake ◽  
Karsten Knobloch ◽  
Angelo Rudolphi ◽  
Sebastian Kruck ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Acoustic Pressure ◽  
Quantitative Information ◽  
Acoustic Response ◽  
Flow Measurements ◽  
Flow Rate Change ◽  
Interaction Experiment ◽  
Swirl Stabilized Combustion

AbstractMeasurements of sound due to swirl–nozzle interaction are presented. In the experiment a swirl structure was generated by means of unsteady tangential injection into a steady swirl-free flow upstream from a choked convergent–divergent nozzle. Ingestion of swirl by the choked nozzle caused a mass-flow rate change, which resulted in a downstream-measured acoustic response. The downstream acoustic pressure was found to remain negative as long as the swirl is maintained and reflections from the open downstream pipe termination do not interfere. The amplitude of this initial acoustic response was found to be proportional to the square of the tangential mass-flow rate used to generate swirl. When the tangential injection valve was closed, the mass-flow rate through the nozzle increased, resulting in an increase of the downstream acoustic pressure. This increase in signal was compared to the prediction of an empirical quasi-steady model, constructed from steady-state flow measurements. As the opening time of the valve was varied, the signal due to swirl evacuation showed an initial overshoot with respect to quasi-steady behavior, after which it gradually decayed to quasi-steady behavior for tangential injection times long compared to the convection time in the pipe upstream of the nozzle. This demonstrates that the acoustic signal can be used to obtain quantitative information concerning the time dependence of the swirl in the system. This could be useful for understanding the dynamics of flow in engines with swirl-stabilized combustion. Graphic abstract

The stable nonlinear acoustic response of free-floating lipid-coated microbubbles

2014 ◽  
Vol 135 (4) ◽  
pp. 2310-2311
Author(s):  
Ying Luan ◽  
Guillaume Renaud ◽  
Tom Kokhuis ◽  
Antonius van der Steen ◽  
Nico de Jong
Keyword(s):  
Acoustic Response ◽  
Nonlinear Acoustic
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