Abstract
Bubble dynamics including the growth and collapse process of explosive micro thermal single and dual bubbles are investigated experimentally and are compared with simulation results in details. For the characteristic of high speed and micro scale in micro explosive bubbles growth process, there are non-intrusive flow visualization techniques are demonstrated and developed in the study. The high speed photography and micro PIV coupling with the phase averaged techniques are applied for the sequential bubble growth/collapse process and induced flow fields respectively. For the interesting of micro flow visualization techniques, the micro PTV with embedded color time code is developed and successfully applied in the flow field visualization of H-type rapid micro mixer. The single heater with size in 30x30um2, 30x60um2, and 20x60um2 is applied 4us heat pulse with heat fluxes of 1.2, 1.4, and 1.6 GW/m2 separately for undergone the nucleate boiling. Dual bubbles are generated on two microheaters of heating areas of 30umx60um each with supplied heat flux of 1.61 to 2.14 GW/m2 and the heaters are separated by different distances ranging from 25 to 125um. Excellent agreements on the bubble shape variations and the induced flowfields from measurements and computations are achieved in details and the strong bubble-bubble interactions are illustrated in terms of bubble appearance, flowfields and pressure fields as the heaters are getting closer. Droplet ejected by dual bubbles in an animated inkjet system is demonstrated with droplet quality of no satellites.