Delft University of Technology, Multiphase Systems (3ME-P&E), 2628 CA Delft, The Netherlands.
Phys Rev Lett. 2018 Nov 9;121(19):194501. doi: 10.1103/PhysRevLett.121.194501.
Using ultrasound imaging velocimetry, we are able to present unique insight in transitional particle-laden flows. Together with a Moody diagram of time-averaged properties, we demonstrate that the laminar-turbulent transition behavior at high volume fractions is distinct from the single-phase case and cases with low volume fractions. For low volume fractions, a sharp transition is found with the presence of turbulent puffs, similar to the single-phase case. Seemingly, particles in this regime trigger subcritical transition. For high volume fractions a smooth transition is discovered without turbulent puffs in the transition regime. For this regime, particles cause a supercritical transition.
利用超声成像测速技术，我们能够对过渡性含颗粒流提供独特的见解。结合时均特性的穆迪图，我们证明了在高体积分数下的层流-湍流转变行为与单相情况和低体积分数情况明显不同。对于低体积分数，发现存在湍流脉冲时会发生急剧转变，类似于单相情况。显然，在该区域中的颗粒会引发亚临界转变。对于高体积分数，在转变区域中发现没有湍流脉冲的平滑转变。对于该区域，颗粒会引发超临界转变。
