Peng-Sheng Wei
National Sun Yat-Sen University, Taiwan (ROC)
Title: Incapability of laser drilling affected by interfacial transport processes across the induced keyhole
Biography
Biography: Peng-Sheng Wei
Abstract
This study theoretically identifies the factors affecting the keyhole collapse during drilling with a high power density laser beam. Laser drilling is widely used in various manufacturing technologies. This work studies quasi-steady one-dimensional compressible flow behavior of the two-phase vapor-liquid dispersion in a vertical keyhole of varying cross-section, paying particular attention to the transition between the annular and slug flows. The results find that the effects of transport processes across the induced keyhole wall affected by surface tension, friction force, and liquid entrainments on incapability of drilling. The predicted results agree with physical intuition and exact closed-form solutions in the absence of friction and energy absorption. Controlling the factors to enhance efficiency and quality of drilling is therefore provided in this work.