\section{Facility Static and Dynamic Control}\label{Calibr} The facility calibration is the transfer function between the oscillating gauge pressure $P_C(t)$ in the chamber (described in ~\autoref{Sub31}) and the liquid flow rate $q(t)$ in the distributing channel, i.e. the test section. Due to practical difficulties in measuring $q(t)$ within the thin channel, and being the flow laminar, this transfer function was derived analytically and validated numerically as reported in ~\autoref{Sub32} and ~\autoref{Sub33}. \subsection{Pressure Chamber Response}\label{Sub31} Fig.\ref{fig:2a} shows three example of pressure signals $P_C(t)$, measured in the pneumatic chamber. On each of these signals it is fitted, in red, an harmonic pulsating pressure: …show more content…
The user controls the pulsation frequency $f_p$, through the motor speed $\omega_m$, and the mean pressure $p_M$, through the pressure regulator in the inlet line. The pressure amplitude $p_A$, on the other hand, depends on the facility line-cavity behavior. As shown in Fig.\ref{fig:2b}, the relative pressure amplitude $\hat{p}_A=p_A/p_M$ decreases when increasing mean pressure and the pulsation frequency, though asymptotically approaching a constant