Most of the underlaps of four-way valves measured were not even. The unevenness of these underlaps has large effect on the characteristics of a valve-controlled cylinder. An unevenness of the underlaps of a valve, i = (Δ₁/Δ)-1, is introduced, where Δ₁ is the underlap on the supply side and Δ the mean value of the underlaps.
Considering the unevenness (1) of a valve, the frequency response of a valve-controlledc ylinder with viscous friction, Coulomb friction and mass load is under theoretical analysis where the flow versus pressure characteristic curves are approximated as polynomials of degree 3 of the pressure.
The tendency of theoretical results agreed well with that of experimental results. For i = -0.6, as y_ο (amplitude of spool displacement y_i ) becomes large, the gain of piston velocity (v) versus y_i at low frequency, | V (jω)/Y(jω)|_ω∼οdecreases and the resonance frequency increases. For i = 0.6, as y_ο becomes large, the peak gain increases but both |V (jω)/Y(jω)_ω∼ο and the resonance freequency chyange liettle.

View full abstract

The velocity distributions of laminar axisymmetric oscillatory flows in the inlet region of a long circular tube in case the flowrate changes to sinuous status are measured with laser Doppler velocimeter, and the unsteady incompressible NaviesStokes equations expressed in terms of voracity and stream functions are also analied numerically as to the internal oscillatory flow.
The numerical results, as compared with the experimental results, proved in close agreement with each other as regards velocity profile. It was furthermore shown that the behavior of its variation is much characterized by Strauhal Numbers defined by mean flowrate, frequency and tube diameter.

View full abstract