Study on perturbation transfer in a liquid droplet generator based on piezoelectric excitation

• The perturbation transfer model in liquid droplet generator is developed by utilizing lumped-parameter method; • A visual liquid droplet generator is constructed for the validation of the perturbation transfer model; • Utilizing the working fluid's resonance in the spray cavity enhances the laminar jet's initial perturbation; • Increasing nozzles form 1 to 16 raises resonance frequency 450 Hz to 1100 Hz while reducing pressure amplitude 1252 Pa to 591 Pa; • The presence of bubbles reduces resonance frequency by 44.4%-55.5% and the pressure amplitude by 72.9–80.0%. In a liquid droplet radiator, the droplet generator critically governs system cooling efficiency. This study developed a multi-nozzle liquid droplet generator and investigated perturbation transfer within its cavity. The effects of voltage amplitude, excitation waveform, nozzle number, and bubble volume on working fluid pressure pulse were measured. Experimental results evaluated a lumped-parameter resonance frequency predictive model. The results show that: pressure pulse amplitude increases with excitation voltage amplitude. With 1 and 8 nozzles, square wave excitation enhances pressure amplitudes at resonant frequency by 44.8 % and 37.7 % compared to sine wave excitation, while triangular wave excitation reduces them by 9.8 % and 15.9 %. With 16 nozzles in 900 Hz-1250 Hz range, square wave excitation exhibits markedly distinct amplitude trends. Compared to the condition without bubbles, bubbles reduce resonance frequency by 44.4 % to 55.5 % and pressure amplitude by 72.9 % to 80.0 %, demonstrating strict bubble elimination is required during jet ejection.