Equipment for piezometric measurement of the static and velocity pressure heads of a liquid

Conclusions

• 1. An apparatus has been developed for studying the dynamics of the flow of true liquids, aggressive and non-aggressive, with various densities and viscosities. After studying the flow of a two-phase medium (“hydro-mixture”) past a body, the apparatus can be used to study the dynamics of the flow of slurry.

• 2. The optimum parameters of the apparatus are as follow: diameter of internal duct of piezohydrodynamic tube, 0.5 mm if its length is 50 mm or more; length of feed tubes of 6×4 mm diameter, 16 m or more; for shorter feed tubes, some kind of local resistance must be incorporated in the line. If the ratio of the diameter of the internal duct to the external diameter is 1:12, the shape coefficient is practically equal to 1. For other ratios, a correction coefficient k must be made to the pressure head readings. For the above parameters and with air flow rates of about 1–2 bubbles per second, a uniform yield of bubbles is obtained from the piezohydrodynamic tube, and the possibility of ingress of liquid into the piezotube is eliminated, thus preventing its duct from being blocked by solid particles.

• 3. The effect of the angle of taper depends on the velocity of the current. Measurements to within 1% are obtained for currents flowing at 30 cm/sec with ±2° angle of taper, and for currents flowing at 1 m/sec with ±15° angle of taper.

• 4. The piezometric method and apparatus enables us to select a manometer sealing liquid with the desired density, and to place the measuring device (manometer) above the object of measurement, at some distance if desired, and also eliminates the necessity of correcting the manometer readings for differences in the graduations of the measuring device at the point of measurement, which can cause large errors.

• 5. The characteristics given above can be used for the construction of apparatus for studying the flow dynamics of true liquids and suspensions.