AIR LOADS ON A RIGID PLATE OSCILLATING NORMAL TO A FIXED SURFACE

This paper deals with a theoretical and experimental investigation on a rigid, rectangular plate oscillating in the proximity of a fixed surface. The plate is suspended by springs. The airloads generated by the oscillating motion of the plate are determined. Due to the fact that the plate is rigid, the system is modelled as a 1-DOF system. The influence of the surrounding air is detected by changes in the plate’s natural frequency and damping. For the behaviour of the air in the gap between the plate and the fixed surface an analytical solution is presented. This solution includes the effects of inertia, viscosity, compressibility and thermal conductivity. It is shown that the main parameters governing the motion of the air in the gap are the shear wave number, the reduced frequency, the narrowness of the gap and the aspect ratio of the plate. With these parameters the validity of several simplifications can easily be demonstrated and solutions, given in the literature, can be put in perspective. Special experiments were carried out with an oscillating solar panel in order to verify the analytical model. The analytical results and the experimental results show fair agreement. The solutions shows that for low shear wave numbers the effects of viscosity cannot be discarded. 7 1997 Academic Press Limited

[1]  P. N. Whitton,et al.  The damping of structural vibration by thin gas films , 1980 .

[2]  Michael F. Modest,et al.  Squeeze Film Flow Between Arbitrary Two-Dimensional Surfaces Subject to Normal Oscillations , 1978 .

[3]  The Flow Between Two Parallel Circular Disks, One of Which is Subject to a Normal Sinusoidal Oscillation , 1969 .

[4]  E. C. Kuhn,et al.  Fluid Inertia Effect on the Film Pressure between Axially Oscillating Parallel Circular Plates , 1964 .

[5]  J. V. Beck,et al.  Experiment and Analysis of a Flat Disk Squeeze-Film Bearing Including Effects of Supported Mass Motion , 1969 .

[6]  B. Drachman,et al.  The steady streaming generated by a vibrating plate parallel to a fixed plate , 1982 .

[7]  E. E. Ungar,et al.  On panel vibration damping due to structural joints , 1966 .

[8]  T. T. Yeh,et al.  The effect of fluid viscosity on coupled tube/fluid vibrations , 1978 .

[9]  T. Önsay.  Effects of Layer Thickness on the Vibration Response of a Plate-Fluid Layer System , 1993 .

[10]  B. J. Roylance,et al.  Analysis of an oscillatory oil squeeze film including effects of fluid inertia , 1989 .

[11]  H. J.,et al.  Hydrodynamics , 1924, Nature.

[12]  R. J. Pinnington,et al.  Practical industrial method of increasing structural damping in machinery, II: Squeeze-film damping with liquids , 1987 .

[13]  W. Kahlert.  Der Einfluß der Trägheitskräfte bei der hydrodynamischen Schmiermitteltheorie , 1948 .

[14]  C. D. Mote,et al.  Pressure and flow in fluid films constrained between translating and vibrating flexible surfaces , 1991 .

[15]  Jagdish Prakash,et al.  Squeeze Films between Two Rough Rectangular Plates , 1978 .

[16]  G. Maidanik.  Energy Dissipation Associated with Gas‐Pumping in Structural Joints , 1966 .

[17]  U. S. Rao,et al.  The steady streaming generated by a vibrating plate parallel to a fixed plate in a dusty fluid , 1987 .

[18]  H. H. Richardson,et al.  A Study of Fluid Squeeze-Film Damping , 1966 .