tailieunhanh - UNSTEADY AERODYNAMICS, AEROACOUSTICS AND AEROELASTICITY OF TURBOMACHINES Episode 3

Tham khảo tài liệu 'unsteady aerodynamics, aeroacoustics and aeroelasticity of turbomachines episode 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 96 bodies resembling road vehicles. These bodies are characterized by different after-body scant angles from zero to 40 degrees. Earlier on Bearman 1971a and Bearman 1971b performed important experiments on fat plates and circular disks in turbulent and laminar fl w and calculated the admittance for the drag force or side force in the present nomenclature of these bodies. The systems were placed in a wind tunnel in a position normal to the incoming fbw. These plates were a particular case of bluff bodies for which ft w separation plays a major role. Bearman s paper discusses a number of fundamental issues such as the general behavior of the admittance in turbulent ft w and the theory used to correlate the wind tunnel data Vickery 1965 . Vickery s experimental and theoretical work led to a semi-empirical relationship for the admittance of fat plates in normal turbulent ft w. This correlation is sometimes used to predict the admittance in wind engineering applications. Howell and Everitt 1983 considered a high speed train with two degrees-of-freedom pitch and yaw in order to identify the risk of a train overturning in high cross winds and the effects associated to track-side structures and passengers. Larose et al. 1999 have performed wind tunnel experiments to derive the frequency response of very large ships at sea. This study was aimed at providing controls to large vessels at port. Data for aerospace systems could not be found in the technical literature perhaps because wing controls are considered in terms of effectiveness rather than admittance. We will use a development based on an indicial approach which in spite of some underlying simplifications is fast and powerful. This paper will discuss the properties of the admittance functions and their practical meaning. The theory originates from a mathematical treatment of the results determined by Drischler and Diederich 1957 who considered sharp-edged traveling gusts past two-dimensional wings in a wide range of