Fluid dynamics of a flow excited resonance, part I: Experiment
Abstract
This is the first of two companion papers concerned with the physics and detailed fluid dynamics of a flow excited resonance. The phenomenon has been examined by using a rather different approach from others to date, in which usually stability theory has been applied to small wavelike disturbances in an unstable shear layer with an equivalent source to describe the radiation of sound providing the feedback. The physics of the flow acoustic interaction is explained in terms of the detailed momentum and energy exchanges occurring in the fluid itself. Gross properties of the flow and resonance are described in terms of the parameters necessary to determine the behaviour of the selfoscillatory system. In this first paper a full experimental investigation of a flow excited Helmholtz resonator is described, in which the detailed fluid dynamical and acoustic data necessary to develop a mathematical model for the flow was obtained, and a new theory of the interaction process is presented in the companion paper (Part II). The investigation described involved the use of a twocomponent LaserDoppler Velocimeter (L.D.V.) and probe microphones to specify completely the velocity and pressure fields and a flow visualization to give qualitative information of the vortex shedding process. The overall aim of the work described in the two papers was to increase fundamental understanding of flow/acoustic interactions.
 Publication:

Journal of Sound Vibration
 Pub Date:
 September 1981
 DOI:
 10.1016/S0022460X(81)801563
 Bibcode:
 1981JSV....78...15N
 Keywords:

 Acoustic Excitation;
 Flow Measurement;
 Flow Velocity;
 Fluid Dynamics;
 Helmholtz Resonators;
 Pressure Distribution;
 Energy Transfer;
 Flow Visualization;
 Laser Doppler Velocimeters;
 Mathematical Models;
 Momentum Transfer;
 Pressure Oscillations;
 Reynolds Stress;
 Shear Layers;
 Shear Stress;
 Sound Pressure;
 Static Pressure;
 Velocity Distribution;
 Fluid Mechanics and Heat Transfer