Acoustic resonance in heat exchanger tube banks

Fluid mechanics of acoustic resonance in heat exchanger tube bundles continues. Data and theory, development of models for the acoustics of tube bundles, and construction of a wind tunnel and tube array model were previously reviewed. In the present phase of the problem, both the wind tunnel model and the analytical model were exercised. Using the wind tunnel, the ability of coherent sound to shift the natural frequency of vortex shedding was demonstrated. Sound at the vortex shedding frequency can also increase the magnitude of the shed vortex and increases the spanwise coherence. Acoustic resonance due to vortex and shedding from tube arrays was observed. The acoustic mode of the resonance was measured, and it is found to agree well with analytical predictions. Work on development of a nonlinear dynamic model for vortex shedding has been initiated. This model features coupled nonlinear oscillators that will simulate the sound-induced entrainment phenomena.