Measuring flow in a pipe

DETAILED DESCRIPTION We claim: 1.
A full bore, multi-hase fluid flowmeter having no internal obstructions comprising; a first section of pipe with a first diameter; a second section of pipe with a second diameter less than said first diameter; a third section of pipe intermediate and connecting said first and second pipe sections and having a smoothly and gradually changing diameter from said first diameter to said second diameter; a first pressure sensor positioned in the neighborhood of the start of the change of diameter of said third section of pipe from said first diameter to said second diameter; a second pressure sensor in said first section of pipe spaced in one direction from said first pressure sensor; a third pressure sensor spaced in the other direction from said first pressure sensor; whereby, the density of the fluid flowing through the pipe obtained from a first differential pressure measurement made between said first and second pressure sensors is combined with the flow rate of the fluid flowing through the pipe sections obtained from said density value and a second differential pressure measurement made between said first and third pressure sensors to obtain a multi-phase fluid flow determination compensated for phase slippage and friction pressure losses.
2.
A flow meter according to claim 1, further comprising a non-obstructive homogenizer connected to the end of said first section of pipe not connected to said third section of pipe, said non-obstructive homogenizer consisting of a pipe section which has an abrupt change in cross-section for creating turbulence.
3.
A method of measuring the flow rate of a two-phase fluid comprising a lighter and a heavier phase, using a gradiomanometer and a venturi meter in series in a pipe, comprising the steps of: a.
measuring a first differential pressure in the gradiomanometer; b.
measuring a second differential pressure in the venturi; c.
calculating an estimated vaue of the mean flow density on the basis of the first differential pressure measurement; d