Mass flow meter including a flexible plate

1. A mass flow meter, comprising:

a tubular housing extending along a longitudinal axis and configured to receive a flow of fluid therethrough;

a flexible plate having a length positioned along the longitudinal axis and at least partially coupled to an interior wall of the tubular housing at opposed longitudinal ends of the flexible plate such that the flexible plate can vibrate in torsion;

an actuator positioned on a surface of the tubular housing, the actuator configured to apply an oscillating torque to the flexible plate sufficient to vibrate the flexible plate in torsion; and

at least two sensors each configured to measure a plurality of oscillations of the flexible plate as a function of time at different locations arising from the applied torque.

2. The mass flow meter of claim 1 , further comprising a computing device in electrical communication with the at least two sensors and configured to determine a mass flow of fluid passing through the tubular housing based upon a phase shift between the oscillations of the flexible plate measured by the at least two sensors.

3. The mass flow meter of claim 1 , wherein a length of the tubular housing extends between a housing inlet and a housing outlet and is substantially straight therebetween.

4. The mass flow meter of claim 1 , wherein the flexible plate is configured to deform elastically when vibrating.

5. The mass flow meter of claim 1 , wherein a width of the flexible plate is approximately equal to an inner diameter of the tubular housing.

6. The mass flow meter of claim 1 , wherein the flexible plate includes at least one vane extending radially outward from a hollow shaft.

7. The mass flow meter of claim 6 , wherein the flexible plate includes four vanes.

8. The mass flow meter of claim 6 , wherein the actuator is configured to apply the oscillating torque to the hollow shaft of the flexible plate.

9. The mass flow meter of claim 1 , wherein the actuator is configured to apply the oscillating torque at about a longitudinal center of the flexible plate.

10. The mass flow meter of claim 1 , wherein the at least two sensors are configured for measurement of the oscillations at approximately symmetric locations on each side a longitudinal center of the flexible plate.

11. A method for measuring mass flow through a tubular housing, comprising:

driving, by an actuator, a flexible plate within a tubular housing to vibrate in a torsional mode at a selected frequency, wherein the actuator is positioned on a surface of the tubular housing, and wherein the flexible plate includes opposed longitudinal ends that are attached to an inner wall of the tubular housing;

receiving a flow of fluid within the tubular housing;

measuring a plurality of oscillations of the vibrating flexible plate as a function of time at two different positions of the flexible plate; and

determining a mass flow of the fluid within the tubular housing based upon a phase shift between the oscillations measured at the two different positions.

12. The method of claim 11 , wherein driving the flexible plate comprises applying a torque at about a longitudinal center of the flexible plate.

13. The method of claim 11 , wherein the selected frequency is a resonance frequency of the flexible plate.

14. The method of claim 11 , wherein the oscillations are measured at approximately symmetric locations on each side a longitudinal center of the flexible plate.

15. The method of claim 11 , wherein the flexible plate deforms elastically in vibration.

16. The method of claim 11 , wherein the flexible plate includes at least one vane extending radially outward from a hollow shaft and the flexible plate is driven to vibrate in a torsional mode by applying an oscillating torque to the hollow shaft.

17. The method of claim 16 , wherein the flexible plate includes four vanes.