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Effects of Morphological Integrity of Secondary Feather on Their Drag Reduction in Pigeons

Journal of Bionic Engineering 2022年第5期19卷 1422-1438页

作者： Qian Li Huan Shen Qingfei Han Aihong Ji Zhendong Dai Stanislav N.Gorb Institute of Bio-Inspired Structure and Surface Engineering College of Mechanical and Electrical EngineeringNanjing University of Aeronautics and Astronautics29 Yudao StreetNanjing 210016China Department of Functional Morphology and Biomechanics Kiel UniversityAm Botanischen Garten 924118 KielGermany

Flight feathers of birds interact with the air flow during *** the observed low drag and high lift values at wind speeds from 9.0 to 19.8 m/s can be achieved due to the feather aerodynamics remains *** the present paper,we tested and compared morphological changes,drag reduction and flow visualization results of intact,damaged,and artificial feathers at different wind speeds in a wind *** the analysis of the drag force and resultant force angle,we proved that the integrity of feathers,whose barbs are usually closely interconnected,played an important role in the drag,which potentially triggers excellent drag reduction *** wind tunnel tests indicated that intact secondary feathers had a surprisingly high maximum drag reduction property at v?=?9 m/s compared with the feathers,where the integrity of barbs was *** hook cascades facilitated elasticity under pressure and suitable permeability in an intact feather,when the hooks were *** was indicated that the suitable permeability of intact feathers would prevent flow separation and reduce drag force at low wind speed;at high wind speed,elasticity under pressure and suitable permeability in an intact feather would facilitate strong squeezing effect,helping feathers withstand larger aerodynamic forces to which they might be subjected during *** was revealed that the intact secondary feather is a compromise between strong lift generation and drag reduction,which has a great significance for the bird’s flight.

关键词： Morphological integrity Secondary feather Drag reduction Wind tunnel smoke visualization Bioinspiration

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Experimental research on nonlinear characteristics of natural convection in a 3-D shallow cavity

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Science China(Technological Sciences) 2011年第12期54卷 3304-3310页

作者： ZHAN NaiYan GAO Qing BAI Li YANG Mo College of Automotive Engineering Jilin University Changchun 130022 China Scool of Municipal and Environmental Engineering Jilin Institute of Architectural and Civil Engineering Changchun 130021 China College of Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China

Experiments were conducted to study the temperature field,flow field,3-D characteristics and self-sustained oscillation of the natural air convection in a 3-D shallow cavity which was heated from underneath. The experiments were conducted by the methods of laser holographic interferometry photography and smoke visualization. To ensure the temperature of both plates to be constant and the accuracy of laser interferometer,the instrument was calibrated and error has was analyzed. The results showed that the flow field was stable at lower Rayleigh numbers. When the Rayleigh number increased,the flow field became instable and the isotherms distorted. The rolls merged at Ra=12500 and formed along both axes when Ra was over 18500. The air rose from the middle and descended in the circumference while the flow field and heat transfer converted to 3-D characteristic from 2-D characteristic. When the Rayleigh number increased,the flow field became more instable. The rolls became irregular and time dependent when Ra≥Rac(=30500) ,which is nonlinear. When lateral walls were heated or cooled,the rolls merged along the long axis and two rolls formed along the short axis. Three rolls formed occasionally in the process.

关键词： interferometric tomography smoke visualization critical Rayleigh number 3-D characteristic oscillation and chaos

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smoke Hazard Assessment Model Based on Fire Dynamics Simulator and FED Model

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Journal of Computer and Communications 2020年第9期8卷 81-93页

作者： Nianfeng Li Shang Zhou Zhiguo Xiao Yifei Zhao School of Computer Science and Technology Changchun University of Science and Technology Changchun China

smoke is the main cause of fire death. In order to minimize the potential danger of smoke hazard, a rational VR based fire training simulator should fully consider all aspects of smoke hazard. In the simulator, the visualization of data based on FDS (Fire Dynamics Simulator) and FED fire dynamic data and volume rendering is further optimized, which can be effectively and quickly applied to virtual fire protection. In addition, a comprehensive smoke hazard assessment model based on FED and FED is established to assess the IHD value of different paths, which represents the safety of different paths, and can be used for evacuation or rescue in virtual training. Taking the case of campus fire drill as an experiment, the research shows the accuracy and effectiveness of smoke assessment based on FDS and FED model. The road force with the highest safety can be selected through the comprehensive model. So the assessment model is proved to be valuable.

关键词： smoke Hazard smoke visualization Integrated smoke Assessment Model FDS FED

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