Acoustic streaming in closed thermoacoustic devices

Area of Science:

• Acoustics
• Fluid Dynamics
• Thermodynamics

Background:

• Acoustic streaming is a phenomenon driven by acoustic waves in fluids.
• Thermoacoustic devices utilize sound waves to generate heat transfer or vice versa.
• Understanding acoustic streaming is crucial for optimizing thermoacoustic device performance.

Purpose of the Study:

• To derive analytical expressions for acoustic streaming in steady-state thermoacoustic devices.
• To provide a method for evaluating acoustic streaming in different geometries and device components.
• To establish relationships between acoustic parameters and fluid behavior in temperature gradients.

Main Methods:

• Derivation of acoustic streaming equations for a non-looped thermoacoustic device.
• Development of analytical expressions for second-order velocity, pressure gradient, and mass flux.
• Consideration of parallel plate and cylindrical tube geometries with varying boundary separations.
• Analysis under conditions of zero second-order time-averaged mass flux and a mean temperature gradient.

Main Results:

• Analytical expressions for time-independent second-order velocity and pressure gradient were obtained.
• The time-averaged mass flux was determined for the specified conditions.
• The derivation is applicable to a fluid confined between solid boundaries with a temperature gradient.
• The results are valid for both parallel plate and cylindrical tube geometries.

Conclusions:

• The derived expressions enable the evaluation of acoustic streaming in thermoacoustic stacks, regenerators, pulse tubes, and resonators.
• This work provides a foundational understanding for analyzing acoustic streaming in closed tubes with temperature gradients.
• The method requires knowledge of acoustic pressure, its longitudinal derivative, and mean temperature variation.