Abstract
Acceleration of inviscous flow through a straight pipe varies in proportion to the axial pressure gradient. Two pressure taps spaced a small distance apart along the flow direction are made on a pipe. The pressure difference between these taps, which is a finite difference approximation for the axial pressure gradient, is picked up by a manometer of high sensitivity. The output of the manometer is proportional to the acceleration of the flow through the pipe. A trial device was built which utilized two condenser microphones for picking up the pressure difference. The new mehtod has been verified by experiments with this device.
A new flowmeter is proposed for measuring pulsating flow. The new flowmeter consists of a conventional differential pressure flowmeter and a device based on the method described above. The device is employed for estimating the acceleration term in the output of the differential pressure flowmeter under pulsating conditions. The estimated acceleration term being subtracted, the acceleration error in the measurement of pulsating flow can be eliminated. An experimental apparatus which employed a venturi meter as a differential pressure flowmeter was built on a trial basis. Several measurements for air flow have been performed with this apparatus. The results indicate that the proposed flowmeter is capable of measuring directly the instantaneous rate of pulsating flow.
