Patent Number: 
Section: claims

1. A method for measuring flow rate within a volume comprising:transmitting, by a transmission device, a first signal through fluid contained within the volume, wherein the volume is bounded, at least in part, by an interior surface of an outer structure and an object at least partially located within the outer structure, wherein the transmission device is located at a first location on the outer structure;measuring a first time of flight of the first signal from the first location to a second location on the outer structure;propagating a second signal through the fluid from the second location to a third location on the outer structure;measuring a second time of flight of the second signal; anddetermining the flow rate of the fluid within the volume based, at least in part, on both the first time of flight and the second time of flight. 2. The method of claim 1, wherein the first signal travels through the fluid along a substantially linear path that passes between the object and the interior surface of the outer structure before arriving at the second location. 3. The method of claim 2, wherein the second signal travels through the fluid along a substantially linear path that passes between the object and the interior surface of the outer structure before arriving at the third location, and wherein the method further comprises:transmitting one or more additional signals through the fluid along a substantially linear path; andaggregating a plurality of the linear paths as a combined signal path that passes around the object. 4. The method of claim 3, wherein the combined signal path passes completely around the object. 5. The method of claim 2, wherein the object comprises a cylindrically shaped surface, and wherein the volume comprises an annular region formed between the cylindrically shaped surface of the object and the interior surface of the outer structure. 6. The method of claim 1, wherein determining the flow rate of the fluid within the volume comprises taking an average of the first time of flight and the second time of flight. 7. The method of claim 1, wherein determining the flow rate of the fluid within the volume comprises taking a weighted average of the first time of flight and the second time of flight to account for structural interference to the flow of the fluid within the volume. 8. The method of claim 1, further comprising comparing the first time of flight with the second time of flight to identify irregularities in flow rate of the fluid through the volume. 9. The method of claim 8, further comprising identifying a cold slug of the fluid within the volume based, at least in part, the comparison of the first time of flight with the second time of flight. 10. The method of claim 1, further comprising determining a temperature of the fluid based, at least in part, on an average of the first time of flight and the second time of flight. 11. An apparatus for measuring flow rate within a volume, comprising:means for transmitting a first signal through fluid contained within the volume, wherein the volume is bounded, at least in part, by an interior surface of an outer structure and by an object at least partially located with the outer structure, wherein the means for transmitting is located at a first location on the outer structure;means for measuring a first time of flight of the first signal from the first location to a second location on the outer structure;means for propagating a second signal through the fluid from the second location to a third location on the outer structure, wherein a second time of flight is measured for the second signal; andmeans for determining the flow rate of the fluid within the volume based, at least in part, on both the first time of flight and the second time of flight. 12. The apparatus of claim 11, wherein the means for propagating is located at the second location on the outer structure. 13. The apparatus of claim 12, wherein the means for propagating comprises a means for transmitting the second signal through the fluid. 14. The apparatus of claim 13, wherein the means for propagating further comprises means for receiving the first signal, and wherein the means for transmitting the second signal and the means for receiving the first signal are co-located at the second location on the outer structure. 15. The apparatus of claim 14, wherein the second signal is transmitted to the third location in response to the first signal being received by the means for receiving. 16. The apparatus of claim 12, wherein the means for propagating comprises means for reflecting the first signal to propagate the second signal. 17. The apparatus of claim 11, wherein the outer structure is associated with an overall length through which the fluid flows, and wherein the first location, the second location, and the third location are associated with different longitudinal positions along the overall length of the outer structure, and wherein both the first signal and the second signal travel along a signal path formed at a non-perpendicular angle with respect to the flow of the fluid through the volume. 18. The apparatus of claim 11, wherein the first signal and the second signal travel along at least a portion of a signal path formed between the first location and the third location, and wherein the means for transmitting and the means for propagating are positioned on the outer structure so that the signal path avoids the object. 19. A system for measuring flow rate within a volume, comprising:a first transmission device configured to transmit a first signal through fluid contained within the volume, wherein the volume is bounded, at least in part, by an interior surface of an outer structure and by an object at least partially contained within the outer structure, and wherein the first transmission device is located at a first location on an exterior surface of the outer structure so as to transmit the first signal while avoiding the object;a processing device configured to measure a first time of flight of the first signal from the first location to a second location on the exterior surface of the outer structure; anda second transmission device located at the second location and configured to transmit a second signal through the fluid from the second location to a third location on the exterior surface of the outer structure while avoiding the object, wherein the processing device is further configured to measure a second time of flight for the second signal, and wherein the flow rate of the fluid within the volume is determined based, at least in part, on both the first time of flight and the second time of flight. 20. The system of claim 19, further comprising a receiving device co-located with the second transmission device at the second location, wherein the first transmission device and the receiving device are associated with different longitudinal positions along the overall length of the outer structure, and wherein the second transmission device is configured to transmit the second signal in response to the receiving device having received the first signal.