Acoustic flow measurement device including a plurality of chordal planes each having a plurality of axial velocity measurements using transducer pairs
A self-checking ultrasonic flow meter for measuring fluid flow in a conduit which includes a plurality of transducers engaged with the conduit. The flow meter includes a signal processor in electrical communication with the transducers which produces a measurement of flow rate and an associated estimate of uncertainty due to changes that have affected the accuracy of the measured flow rate. The transducers form multiple transducer pairs positioned to form acoustic transmission paths that are co-located in two or more chordal measurement planes. A plurality of axial velocity measurements are made in each chordal plane. A method for measuring fluid flow in a conduit with an ultrasonic flow meter.
1. An ultrasonic flow meter for measuring fluid flow in a conduit having a conduit axis comprising:
multiple transducer pairs positioned to form acoustic transmission paths that are co-located in one or more chordal measurement planes, in each chordal measurement plane the multiple transducer pairs located in the chordal measurement plane are positioned to form acoustic transmission paths that traverse at least once from one side of the plane to another side of the plane, each traverse is either direct from one transducer to another or via one or more reflection points and whereby a plurality of axial velocity measurements are made in each chordal plane with a minimum of three traverses in each chordal plane, each chordal plane is in parallel with the conduit axis.
2. The ultrasonic flow meter of claim 1 having three direct paths per chordal plane wherein a first pair of paths are used in the computation of an axial velocity measurement in the chordal plane, and a second axial velocity measurement in the chordal plane is made using one of the first pair of paths and a third path such that a second pair of paths is defined as one of the first pair of paths and the third path or another one of the first pair of paths and the third path.
3. The ultrasonic flow meter of claim 1 having three direct paths per chordal plane wherein two axial velocity measurements are made in each plane according to equations:
v
axialAB
=
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v
B
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v
A
Z
A
X
B
X
A
Z
B
)
(
1
-
Z
A
X
B
X
A
Z
B
)
v
axialBC
=
(
v
C
-
v
B
Z
B
X
C
X
B
Z
C
)
(
1
-
Z
B
X
C
X
B
Z
C
)
.
4. The ultrasonic flow meter of claim 1 , whereby a multi-directional transducer is used such that two or more paths have a beginning or end that is a shared transducer.
5. The ultrasonic flow meter of claim 1 , whereby a reflection point is common to two or more paths.
6. The ultrasonic flow meter of claim 1 , whereby a transducer also serves as a reflection point for another path.
7. An ultrasonic flow meter for measuring fluid flow in a conduit having a conduit axis comprising:
multiple transducer pairs positioned to form acoustic transmission paths that are co-located in one or more chordal measurement planes in each chordal measurement plane the multiple transducer pairs located in the chordal measurement plane are positioned to form acoustic transmission paths that traverse at least once from one side and whereby a plurality of axial velocity measurements is made in each chordal plane with a minimum of three traverses in each chordal plane, each chordal plane is in parallel with the conduit axis.
8. The ultrasonic flow meter of claim 7 having three paths per chordal plane and transmission is on a direct path between individual transducers.
9. The ultrasonic flow meter of claim 7 having two paths per chordal plane, each path being a reflected path with two traverses of the chordal plane and one reflection in each of the two paths.
10. The ultrasonic flow meter of claim 7 having three paths per chordal plane and transmission on two paths is direct between transducers, and one path is a reflected path with two traverses of the chordal plane and one reflection point.
11. The ultrasonic meter of claim 7 wherein there are no shared nodes and there are only 6 or 7 nodes.
12. The ultrasonic meter of claim 7 wherein one node is shared by two paths and the total number of nodes can be reduced from six to five.
13. The ultrasonic meter of claim 7 wherein one node is shared by three paths and the total number of nodes can be reduced from six to four.
14. The ultrasonic meter of claim 7 wherein two nodes are each shared by two paths and the total number of nodes can be reduced from six to four or from seven to five.
15. The ultrasonic meter of claim 7 wherein three nodes are each shared by two paths and the total number of nodes can be reduced from seven to four.
16. The ultrasonic meter of claim 7 wherein two nodes are each shared by two paths and a third node is shared by three paths and the total number of nodes can be reduced from seven to three.
17. The ultrasonic flowmeter of claim 7 wherein the paths in each chordal plane overlap.
18. A method for measuring fluid flow in a conduit with an ultrasonic flow meter comprising the steps of:
forming with multiple transducer pairs positioned with respect to the conduit acoustic transmission paths that are co-located in one or more chordal measurement planes, in each chordal measurement plane the multiple transducer pairs located in the chordal measurement plane are positioned to form acoustic transmission paths that traverse at least once from one side of the plane to another side of the plane, whereby two axial velocity measurements are made in each plane with a minimum of three traverses in each chordal plane, each chordal plane is in parallel with the conduit axis; and
determining the fluid flow in the conduit from signals received by the transducers from the paths.
19. An ultrasonic flow meter for measuring fluid flow in a conduit having a conduit axis comprising:
multiple transducer pairs positioned to form acoustic transmission paths that are co-located in one or more chordal measurement planes, in each chordal measurement plane the multiple transducer pairs located in the chordal measurement plane are positioned to form acoustic transmission paths that traverse at least once from one side of the plane to another side of the plane, each traverse is either direct from one transducer to another or via one or more reflection points and whereby a plurality of axial velocity measurements are made in each chordal plane, and wherein there are three direct paths per chordal plane wherein two axial velocity measurements are made in each plane according to equations:
v
axialAB
=
(
v
B
-
v
A
Z
A
X
B
X
A
Z
B
)
(
1
-
Z
A
X
B
X
A
Z
B
)
v
axialBC
=
(
v
C
-
v
B
Z
B
X
C
X
B
Z
C
)
(
1
-
Z
B
X
C
X
B
Z
C
)
.
20. An ultrasonic flow meter for measuring fluid flow in a conduit having a conduit axis comprising:
multiple transducer pairs positioned to form acoustic transmission paths that are co-located in one or more chordal measurement planes, in each chordal measurement plane the multiple transducer pairs located in the chordal measurement plane are positioned to form acoustic transmission paths that traverse at least once from one side of the plane to another side of the plane and which overlap, each traverse is either direct from one transducer to another or via one or more reflection points and whereby a plurality of axial velocity measurements are made in each chordal plane with a minimum of three traverses in each chordal plane.
21. An ultrasonic flow meter for measuring fluid flow in a conduit having a conduit axis comprising:
multiple transducer pairs positioned to form acoustic transmission paths that are co-located in one or more chordal measurement planes, in each chordal measurement plane the multiple transducer pairs located in the chordal measurement plane are positioned to form acoustic transmission paths that traverse at least once from one side of the plane to another side of the plane, each traverse is either direct from one transducer to another or via one or more reflection points and whereby a plurality of axial velocity measurements are made in each chordal plane with a minimum of three traverses in each chordal plane; and
a signal processor determining the fluid flow from the acoustic transmission paths where transverse velocity of the fluid flow has been eliminated.