Mechanism of liquid jetting by driving jet tube for reciprocating motion

The reciprocating motion of a jet tube along its axial direction enables on-demand jetting, which is a novel method. However, related research is limited, and the jetting mechanism has not been thoroughly explained. In this study, a piezoelectric ceramic is used to drive a jet tube in a reciprocating motion to achieve on-demand jetting. Based on experimental and simulation results, the jetting process is described and analyzed, the jetting mechanism is revealed and the effects of various factors on the jetting process are discussed. The results show that the inertial force caused by abrupt changes in tube velocity is the main driving force for jetting, and the velocity changes at both ends of the tube motion stroke dominate the jetting process. During a down-then-up reciprocating motion of the tube, the inertial force pushes the liquid inside the tube downwards to form a jet and then pulls the liquid upward, causing the tail of the jet to break, achieving on-demand jetting. Changes in liquid level height and tube motion amplitude affect the jetting process by influencing the magnitude of the inertial force, while the tube motion period impacts the process by influencing the time interval of the pushing and pulling caused by inertial force, as well as the superposition of pressure waves. When the reciprocating motion of the jet tube follows an up-then-down pattern, the kinetic energy gained by the liquid during the pushing process is smaller, making this pattern less favorable for jetting.