Fluid-Resonant Oscillations in a Cavity Flow Including a Parallel-Plate Stack with Temperature Gradient

An intense tone can be radiated because of the coupling between vortex shedding in the shear layer and acoustic resonance (fluid-resonant oscillations) in a cavity flow. Here, we propose controlling the intense fluid-resonant oscillations in the flow around a rectangular cavity using a parallel-plate stack with a temperature gradient. The effects of the installation of the stack and the temperature gradient applied to the stack on the fluid-acoustic interactions in the cavity flow were clarified using direct aeroacoustic simulations. The results indicated that intense fluid-resonant oscillations were maintained with the stack position close to the bottom of the cavity. Positive and negative temperature gradients were applied to the stack, where the increase in the stack temperature in the direction from the cavity opening towards the cavity bottom corresponded to a positive temperature gradient. An increase and decrease in the sound pressure level at the fundamental frequency were observed with positive and negative temperature gradients in the stack, respectively. Fluid-resonant oscillations were suppressed by a large negative temperature gradient, where the number of vortices in the shear layer also changed. The predicted energy flow indicates that thermoacoustic energy exchange between the acoustic intensity and heat flow occurs through the stack. These results show that fluid-resonant oscillations with aerodynamic sound radiation can be controlled utilising heat and cold energy.