- 作者: Wei-Ming LU, Hong-Zhang WU, Nai-Yu CHUANG, and Yu-Li LIN
- 中文摘要: To examine the effects of the impeller blade size on gas dispersion within gas-liquid agitated vessels, trailing vortexes behind impeller blades were investigated thoughtfully using both a computational simulation and an experimental method. The loci and conformation of the vortices were determined, and the sizes of bubbles dispersed by impellers with different blade sizes are measured and compared at the central axis, tail and circumference of the vortices under different operational conditions. Comparing the calculated deformation rate, shear stress and dispersed bubble size for different blade size impellers, it was found that with the same rotational speed (almost equivalent to the same power input per unit blade area), a large-blade impeller, drawing the most power, could induce a fully developed vortex structure and greater vortex strength, which resulted in better gas dispersion. However, with the same power consumption per unit liquid volume, a small-blade impeller always produced the greatest vortex strength but failed to disperse bubbles of the smallest size due to mergence of the vortex pair while the standardblade impeller produced the most effective gas dispersion in this situation. It was found that no matter the impeller type, more than 60% of the sparged gas was dispersed at the vortex tail, which indicates that gas dispersion mainly takes place at the tail of the vortex when the cavity structure is that of a vortex cavity or clinging cavity.
- 英文摘要: --
- 中文關鍵字: blade size, gas dispersion, vortex structure, bubble size distribution, stirred vessel
- 英文關鍵字: --