Bio-inspired patterned surface for submicron particle deposition in a fully developed turbulent duct
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Bio-inspired patterned surface for submicron particle deposition in a fully developed turbulent duct
1. Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China 2. Department of Mechanical Engineering, The University of Hong Kong, Pok Fu Lam, Hong Kong, China
Abstract
Keywords
Arrays of surface ribs have been reported to significantly enhance particle collection efficiency in particle removal devices. However, the surface ribs also cause a higher pressure drop. Therefore, the overall performance needs to take into consideration the above factors. In this study, different forms of surface ribs inspired by nature were designed and parametric studies were performed to enhance deposition efficiency. Our parametric studies comprised three different aspects: geometry of the patterned surface, pitch-to-height ratio, and particle size. The flow field around patterned surfaces was simulated in a two-dimensional channel flow by using the Reynolds stress model, corrected by turbulence velocity fluctuation in the wall-normal direction. The particle trajectory was solved by using Lagrangian particle tracking. When the overall efficiency ratio was considered, a semi-circular pattern had the best overall efficiency with 1137 times increase when compared to the case without patterns. Although the open-circular pattern has the minimum particle deposition enhancement, the overall efficiency of the open-circular pattern has 862 times increase compared to the case without patterns. Surface ribs (semi-circular, triangular and rectangular) can achieve a higher particle deposition velocity, but a higher flow resistance is generated compared with applying the open-circular surface ribs. The deposition location was then investigated for different surface ribs at different pitch-to-height ratios (p/e). This study shows that the semi-circular surface pattern should be recommended to enhance the overall performance of particle removal devices, especially for submicron particles.
bio-inspired,
Introduction
The number concentration of particulate matters (PM) significantly affects indoor air quality. The demands to deposit PM, especially in the range of 0.1 to 1 μm are intense; however, the restraints come from the low efficiency of submicron particle deposition in many air cleaners and energy-inefficiency with the aerodynamics of air cleaners currently used. The removal of submicron PMs is difficult due to their tiny size. This is the most challenging size range to be filtered because neither interception, inertial impaction, nor the Brownian diffusion mechanism dominates. A higher collection efficiency of submicron particles can be achieved by electric filters which are composed of permanently charged E-mail: [email protected]
surface rib array, particle deposition, submicron particles, fully developed turbulent flow
Article History Received: 30 November 2019 Revised: 10 June 2020 Accepted: 18 June 2020 © Tsinghua University Press and Springer-Verlag GmbH G
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