Coefficient of Discharge of Unsteady-State Spool Valve (Ist Report)

When the opening of the spool valve was given a small oscilation under constant pressure drop, the coefficient of discharge became larger as compared with steady state. This tendency was promoted by increase of pressure drop across the metering orifice, frequency or amplitude, and was prevented by increase of Reynolds number or mean opening. The writer presumed that this tendency might be due to acceleration of fluid in valve chamber.