Experimental and Analytical Investigation on a Liquid Balance Ring for Automatic Washing Machines

A high-speed camera and a Particle Image Velocimetry (PIV) technique are used on a transparent liquid balancing device typical of modern washing machines. Experimental results indicate that the baffles placed inside the ring cavity interact with the fluid for it to develop modes of vibration of circumferential and axial type, thus rendering a complex swirl flow inside the annular cavity comprised of two inertial waves. One of such waves travels backwards relative to the rigid body motion. As as a result, a damping effect is induced and a phase lag with respect to the exciting unbalance occurs. An analytical dynamic model of the unbalanced response is derived and correlated with fluid flow visualization experiments and vibration measurements.