有限長円柱の空気力学的特性に関する研究
その2風洞実験
1988 年 1988 巻 36 号 p. 27-43
詳細
1988 年 1988 巻 36 号 p. 27-43
The effects of free stream turbulence on the aerodynamic forces acting on a circular cylinder of finite length have been studied experimentally in the subcritical and critical Reynolds-number ranges. The aspect ratio of the cylinder was varied from unity to 4. Measurements were made of the time-averaged and fluctuating pressures on the cylinder surface, position of the flow separation point and vortex shedding frequency in grid-generated turbulent flows.
The results indicated that the aerodynamic properties of a cylinder were only minutely affected by the free-stream turbulence in the subcritical flow.The critical Reynolds-number at which the mean drag coefficient obtains a predetermined value was found to be expressed as a function of the Taylor number Tx defined in terms of the longitudinal integral scale of the free-stream turbulence. The mean drag coefficient and the position of the flow separation point were fairly well-correlated with the parameter Re3.34 Tx, Re being the Reynolds number, which indicates that this parameter may control some aspects of the flow around the circular cylinder. Furthermore, on the basis of the experimental results, it was found that some aerodynamic coefficients were closely correlated among themselves; some empirical formulas were presented.
