Bi-directional oscillating jet flowmeter

1. A bi-directional flowmeter comprising a first fluidic oscillator device arranged to measure the flow of fluid in a first direction and a second fluidic oscillator device arranged to measure the flow of fluid in a second direction opposite to the first direction, in which the two oscillators devices are connected together in series between an inlet port and an outlet port of the flowmeter between which the fluid to be measured can flow, and in which the first and second oscillator devices are connected back to back such that the inlet side for one is connected to the inlet side for the other.

2. The bi-directional flowmeter of claim 1 in which the two oscillator devices are provided within a single body.

3. The bi-directional flowmeter of claim 1 in which the two oscillator devices define an asymmetrical structure in which fluidic oscillator devices in forward and reverse directions are capable of being used for metering but with a different overall metering performance for forward and reverse flows.

4. The bi-directional flowmeter of claim 1 in which the oscillator first encountered by the flow of fluid on passing through the flow meters acts as a flow conditioner to the fluid flow prior to its entering the other oscillator.

5. The bi-directional flowmeter of claim 1 in which each oscillator device includes a measurement means adapted to provide an output signal indicative of the rate of oscillation of fluid flowing through the oscillator at least when operating in its “normal” direction, i.e, fluid flowing from its inlet to its outlet.

6. The bi-directional flowmeter of claim 5 in which the measurement means comprises an inductive sensor, an ultrasonic sensor or a pressure sensor.

7. The bi-directional flowmeter according to claim 5 in which each oscillator device provides an output signal which has an amplitude and/or frequency and/or stability of the frequency of oscillation that falls within a different range when operating in its normal direction (flow from inlet to outlet) than in the reverse direction.

8. The bi-directional flowmeter of claim 5 in which each device produces an output signal having a stability of frequency of oscillation representing the flow rate which lies within a first range of frequencies, amplitudes or stability of frequency for the normal operation for non-zero flow rates and which lies within a second range of frequencies, amplitudes or stability of frequency of oscillation for the reverse operation, the two ranges not overlapping such that the signals from both devices can be compared and the flow direction to be unambiguously determined.

9. The bi-directional flowmeter of claim 8 in which the devices are arranged such that there is no oscillation for a device operating in the reverse mode.

10. The bi-directional flowmeter of claim 1 in which the two devices are configured such that any reflection of fluid along the joining axis is such that the pressure drop across the whole device is no greater than that across a single fluidic oscillator.

11. The bi-directional flowmeter of claim 1 in which each fluidic oscillator device comprises a reducer section which creates a jet of fluid feeding into a diffuser section which has first and second diffuser walls and first and second feedback channels respectively associated with the first and second walls which enable some of the jet flow to be fed back to the exit of the reducer section.

12. The bi-directional flowmeter of claim 1 in which the first and second oscillator devices are identical and comprise of a plurality of flow passages that are symmetrically reflected about an axis whereby the performance of the oscillators is the same in both the forward and reverse directions.