A parametric study of devices to control the three-dimensional juncture flow

• Main Authors: Huang, Chi-Wen, 黃琦雯
• Other Authors: Chen, Jiahn-Horng
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/a9t589

碩士 === 國立臺灣海洋大學 === 系統工程暨造船學系 === 107 === Junction flow occurs when a flow encounters a three -dimensional appendage-body junction. It is a complicated physical phenomenon. The boundary layer becomes thicker as the inflow passes the obstacle. The flow separates upstream of the body due to an adverse pressure gradient. Then the vortex system wrapping around the configuration is formed, which is named horseshoe vortex. Many engineering applications associated with appendage-body junction will cause some undesirable effects, such as scouring hole around a pier or acoustic noise of far-field wake. In this thesis, we used the Reynolds-averaged Navier-Stokes (RANS) equations, and the Spalart-Allmaras turbulence model for studying the phenomenon. The model of the wing/flat-plate was employed in order to investigate the turbulent junction flow, and the Reynolds number is 5*10^5 based on the chord length. Basically, the main flow features are captured in the simulation. We can observe the leading-edge horseshoe vortex and the non-uniformity of the far-field wake. Some simple configurations on the wing, like strake and fairing, is a way to control the flow separation. The shape of the strake/fairing were studied parametrically by using the CAD software. We conducted the simulation by changing three relevant parameters of the strake/fairing, including the non-dimensional length, non-dimensional height and steepness. At last, we found that with a proper strake, the leading-edge horseshoe vortex could be suppressed, and the non-uniformity of the wake was improved. However, the wake distortion was not eliminated completely by adding the fairing. This design of fairing might not solve the engineering problems on juncture flow efficiently.