Oscillating reed valves - An experimental study

The results of experiments on the threshold behavior and large-amplitude os cillation of "outward-swinging door" vibrating flap valves in an air enviro nment are reported and compared with the predictions of a simple nonlinear theory that parametrizes aerodynamic effects by means of a simple damping c oefficient together with a contraction coefficient for the flow. The agreem ent is acceptably good for the threshold blowing pressure for valve oscilla tion, the large-signal vibration amplitude, the pressure jump in the transi tion from threshold to large-signal behavior, and the variation in vibratio n frequency, all as functions of reservoir volume. The calculated pressure waveform in the reservoir has the observed phase and magnitude but fails to reproduce finer details. It is concluded that the simple theory provides a n adequate account of the behavior of such valves. There are just two param eters in the theory, describing jet contraction and aerodynamic damping, re spectively. Since these may depend significantly upon the detailed geometry , valves with different shapes may behave in quantitatively different ways. (C) 2000 Acoustical Society of America. [S0001-4966(00)04107-2].