PIV wave propagation investigation of non-linear losses through 90 degree bends in a thermoacoustic engine's feedback loop

Thermoacoustic engine technology has recently been applied to renewable energy to convert heat energy into acoustic energy for the purpose of electricity generation. One of the vital components of the engine is its feedback loop which is sensitive to geometrical changes that can cause system losses. We previously postulated that a critical Acoustic Dean Number exist above which the Acoustic Power Transmission Loss increases drastically for a wave propagating though a bend. This paper investigates the wave propagation through the bend using Particle Image Velocimetry(PIV). This technique has not been used in this field of investigation and allows the flow visualization as well as the planar velocity field measurement of the system. The PIV results confirmed earlier pressure measurements that a critical Dean number does exist, and describes visualizations of the flows causing the losses.