Excitation of Vibration of a Water-Column by a Fluttering Valve (3rd Report)

Abstract

The paper deals with the possibility of generating sustained water-hammer by a fluttering valve which statically increases its opening with the increase of the pressure in the up-stream and which is usually expected to make a system rather stable, contrarily to the valve in the author's previous papers which decreases its opening with the increase of pressure in the up-stream. When the frequency of pressure variation in the up-stream is slightly higher than the natural frequency of the valve, the phase of the motion of the valve treated here is almost reversed relatively to the phase of pressure variation, and the amplitude of the valve is considerably large. This means that the valve can act as a negative resistance for pressure waves having frequencies slightly higher than its natural frequency, if only the damping of the valve motion is sufficiently small.