Improving and Predicting Fluid Atomization via Hysteresis-Free Thickness Vibration of Lithium Niobate

Acoustically driven atomization from the broad perspective of materials choice, vibration mode, and fluid characteristics is considered to identify a simple method for improving both the understanding of the atomization phenomena and the overall efficiency of atomization. Whether by the definition of a “figure of merit” (a function of the transducer quality factor and electromechanical coupling coefficient), its output vibration displacement at a given input power, or the fluid flow rate during atomization, it is found that the combination of single-crystal 127.86° Y-rotated lithium niobate and thickness-mode vibration produces an order of magnitude greater atomization flow rate and efficiency in comparison to all known atomizers, including classic lead zirconate-based devices and newer, Rayleigh wave or Rayleigh/Lamb spurious-mode-based devices alike. By using this improved approach, for the first time, fluids with viscosities up to 48 cP are reported to be atomized, and an atomization Reynolds number Re_A is defined which can be used to both predict the atomization flow rate for Re_A ≳ 40 and the inability to atomize a given fluid at a particular vibration amplitude when Re_A ≲ 40.