紊流模式應用於彈底噴流效應之數值研究

• Main Author: 鄭澄國
• Other Authors: 戴昌賢
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/14728441607442667528

碩士 === 中正理工學院 === 兵器系統工程研究所 === 88 === The aim of present study is to simulate the transonic flow field and aerodynamic coefficients of a 20mm projectile with and without base bleed. A computer code based on the control volume method was developed to solve the Reynolds-averaged Navier-Stokes equations. Three different turbulent model(κ-ε, κ-ω, R-κ-ε) were employed in the present study. The parameters including the Mach number, ranged from 0.91 to 1.20, and the angle of attack, ranged from 0o to 6o, were tested. In spite of the previous used two-dimensional grid system, a three-dimensional and multi-block grid system is constructed. Based on the flow field characteristic, the grid adaptive technique is used in the region close to the projectile to reduce the time consumption and storage capacity during calculation. The present results show that the transonic flow structure of a 20mm projectile is strongly related to the turbulence model used in the simulation. For the present test cases at various Mach number and the angle of attack, the growth of boundary layer, expansion wave and base flow, and even the aerodynamic coefficient are found to be affected by the adopted turbulence model. Generally, the shock-induced separation can be obviously observed when theκ-ωturbulence model is used, especially for cases at large angle of attack. It is also found that in the cases of projectile with base bleed, the base drag can effectively be reduced in the tested range of Mach number.