| Transit time difference and equal or non-equal transit time theory for airfoils with lift |
| |
| 作者姓名： | Chenyuan BAI Ziniu WU |
| |
| 作者单位： | Ministry of Education Key Laboratory of Fluid Mechanics,Beihang University,Beijing 100083,China;Department of Engineering Mechanics,Tsinghua University,Beijing 100084,China |
| |
| 基金项目： | the National Science and Technology Major Project of China (No. 2017-II-003-0015)；;the National Natural Science Foundation of China (No. 11721202)； |
| |
| 摘 要： | The transit time difference of fluid particles moving along the upper and lower surfaces of a lift-producing airfoil is studied here both theoretically and numerically. We show that, under thin airfoil assumption and for potential flow, the transit time difference is equal to the circulation divided by the square of the inflow velocity and the lift coefficient is equal to half of the number of chords travelled by the airfoil during the transit time difference. An analysis of transit time differe...
|
| 收稿时间： | 5 February 2021 |
Transit time difference and equal or non-equal transit time theory for airfoils with lift |
| |
| Chenyuan BAI,Ziniu WU.Transit time difference and equal or non-equal transit time theory for airfoils with lift[J].Chinese Journal of Aeronautics,2022,35(2):8-11. |
| |
| Authors: | Chenyuan BAI Ziniu WU |
| |
| Institution: | 1. Ministry of Education Key Laboratory of Fluid Mechanics, Beihang University, Beijing 100083, China;2. Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China |
| |
| Abstract: | The transit time difference of fluid particles moving along the upper and lower surfaces of a lift-producing airfoil is studied here both theoretically and numerically.We show that,under thin airfoil assumption and for potential flow,the transit time difference is equal to the circulation divided by the square of the inflow velocity and the lift coefficient is equal to half of the number of chords travelled by the airfoil during the transit time difference.An analysis of transit time differ-ence for very thick airfoil (c.f.very large angle of attack) suggests the transit time may change sign beyond thin airfoil assumption,a conclusion supported by an example of flow with an attached vor-tex.Thus,fluid particles may transit the upper surface with less,equal and more time than those transiting the lower surface for lift producing airfoils,depending on the configuration of flow struc-ture and geometry. |
| |
| Keywords: | Airfoil Equal transit time theory Lift Non-equal transit time theory Transit time |
| 本文献已被 万方数据 ScienceDirect 等数据库收录！ |
