Flow‐Induced Vibrations

Flow-induced vibration in nuclear reactors: A review

Review of sound induced by vortex shedding from cylinders

On acoustical resonance in tube arrays part I: Experiments

Identification of nonlinear dynamic coefficients in plain journal bearings

In this investigation experimental studies on the acoustic resonance are undertaken. In the first place the effect of the pitch of tubes on Strouhal number or the nondimensional acoustic resonance frequency is studied in a wind tunnel test using many model banks. According to the result the Strouhal number increases with a decreasing pitch of tubes. In the second place a two-dimensional model basin test is undertaken and putting together the theory on the single tube in a flow previously reported and the observation result on the model basin test, a self-iduced vibration theory for the acoustic resonance is proposed.

The Acoustic Resonance in a Tube Bank

While oil whip phenomena can rationally be explained by Y. Hori's theory, it does not quantitatively give a good agreement for the stability of a rotor because of the assumption ; "the bearing is infinitely long". In the present paper, the oil film force on journal is derived under the short bearing approximation, and the stability chart of an elastic rotor supported by journal bearings is given by means of the Routh-Hurwitz's criterion from the equation of motion of the rotor under the action of oil film force. Experimental results by using journal bearings with L/D ratios ranging from 0.07 to 2 are comparea with calculated values from this chart. It is concluded that the chart is extensively applicable to most of practical rotating machinery with journal bearings.

Stability Criterion of an Elastic Rotor in Journal Bearings

The Mechanism of the Excitation Acting on a Circular Cylinder Supported by a Spring in a Fluid Flow

In this report experimental results on the vibration of a cylinder caused by shedding vortices are presented. The experiments were undertaken at larger Reynolds number than in author's previous report. There are two experiments in this study, one being on an elastically supported cylinder and the other on a crank-excited cylinder. In the former, the exciting force coefficient is determined from a decrement and an amplitude of the cylinder. In the latter, the exciting force coefficient is found by an integration of pressures on the cylinder surface. These two results coincide with each other ; the exciting force suddenly decreases at nearly the critical Reynolds number. Moreover, at sub-critical Reynolds number a self-exciting force is induced just as in authors' previous report, but at super-critical Reynolds number the exciting force decreases with an increasing cylinder amplitude and at too large an amplitude the force is changed to a damping force.

Masaya Funakawa

Papers

The Acoustic Resonance in a Tube Bank

Stability Criterion of an Elastic Rotor in Journal Bearings

The Mechanism of the Excitation Acting on a Circular Cylinder Supported by a Spring in a Fluid Flow

Vibration of a Cylinder Caused by Wake Force