Guest Speaker: Prof. Zhong Shan
Department of Mechanical, Aerospace and Civil Engineering
The University of Manchester, UK
Prof. Zhong obtained her BEng and MEng degree from Tsinghua University and her PhD degree from Cambridge University. She joined The University of Manchester as a faculty member in 1997 after having completed a three-year postdoctoral project at Oxford University. She is now Professor of Experimental Fluid Mechanics at the Department of Mechanical, Aerospace and Civil Engineering, and a fellow of Royal Aeronautical Society.
Shan's research work spans flow regimes from Stokes flow to supersonic flow. Her main research area in the past twenty years is flow control with a focus on maximising the control effectiveness of flow control devices for engineering applications and understanding the flow physics involved. She has led research investigations on both passive and active flow control techniques, including leading edge tubercles, micro-scale surface patterns, synthetic jets and sweeping jets. The targeted engineering applications include mitigation of flow separation on aircraft wings, reduction of secondary flow losses in turbomachines, control of afterbody vortical flows behind high-speed trains and enhancement of fluid mixing in process engineering.
Abstract
Convergent-divergent (C-D) riblets (or herringbone riblets) are a new type of surface patterns which begins to receive research attention in the recent years. They consist of sections of left-tilted and right-tilted micro grooves which are joined together side by side (see figure). Such micro patterns have been found on shark skins and on the secondary flight feathers of birds. Due to the directional orientation of these micro grooves, C-D riblets are capable of generating weak large-scale secondary flow motion in the near-wall region resulting in a significant modification of boundary layer characteristics in the spanwise direction.
In this seminar, the finding from a series of experimental studies undertaken at Manchester demonstrating the effectiveness of this type of bio-inspired riblets in reducing the pressure losses in linear cascades and attenuating shockwave-induced flow separation will be presented. The results from both computational and experimental studies on flat-plate boundary layers and channel flows aiming to understand the impact of these riblets on boundary layer development and turbulent structures will also be shown.
