A sensing apparatus for monitoring fluid flow in a fluid pipe

Abstract

A sensing apparatus for monitoring fluid flow velocity in a fluid pipe, the sensing apparatus comprising at least one flow velocity sensor element configured to generate characteristic acoustic events at a rate indicative of the fluid flow velocity and a sensing fibre provided within the fluid pipe, the sensing fibre configured to detect said characteristic acoustic events.

Description

[0001] A SENSING APPARATUS FOR MONITORING FLUID FLOW IN A FLUID PIPE

[0002] Technical Field of the Invention

[0003] The present invention relates to monitoring of fluid pipes. In particular, the invention relates to monitoring of the properties of fluid with a fluid pipe using a sensing fibre. The present invention further relates to an apparatus and a method for monitoring fluid flow and / or pressure in a fluid pipe as well as a network comprising one or more pipes monitored using the apparatus or the method of the present invention.

[0004] Background to the Invention

[0005] Many modern services rely upon a network of pipes to carry or distribute fluids. Examples include fresh water, waste water and sewage, and fuels such as oil or gas. It is common to monitor the operation of the network and the condition of pipes. In this manner, blockages, leaks or other issues can be identified and scheduled for repair.

[0006] Fibre sensing is a technique that uses the changes in the properties of a fibre, or sensing fibre, to make measurements of the fibre’s environment, such as pressure, temperature, strain, and vibrations (acoustics). As fibres can be made relatively cheaply, they can be run over long distances and then used to make measurements at different points along their length. This makes them very useful for data collection activities where power or access is limited, such as along buried pipes or in remote areas. This can assist in the monitoring of pipe networks such as fresh water, waste water and sewage, and fuels such as oil or gas. It is common to monitor the operation of the network and the condition of pipes. In this manner, blockages, leaks or other issues can be identified and scheduled for repair.

[0007] In order to make measurements, light pulses are coupled into a sensing fibre. The external environment and conditions of the sensing fibre affect backscattered light pulses generated as the light pulses travel through the sensing fibre. These backscattered pulses can then be detected and used to make a measurement of a property of interest at different points along the sensing fibre. There are a number of different techniques that can be employed such as distributed acoustic sensing (DAS) (or distributed vibration sensing (DVS)), distributed strain sensing (DSS) and distributed temperature sensing (DTS). This technique is also further described in WO2019 / 166809A1.

[0008] A current limitation of widespread monitoring systems is the cost of deployment of highly distributed sensors. This can involve significant capital and labour costs. Additionally, it can be difficult to arrange an adequate power supply for a sensor to operate. At present these are very dispersed and infrequently located, meaning the full realisation of the benefits of highly distributed sensors cannot be achieved.

[0009] Another limitation is that backhaul of data on a real time basis is problematic, finite battery capacity means that sensor data is often only transmitted once per day (typically via radio, where power consumption is high), or if land lines are used this can be at very high operations (circuit rental) cost.

[0010] It is therefore an object of embodiments of the present invention to at least partially address the above issues.

[0011] Summary of the Invention

[0012] According to an aspect of the present invention, there is provided a sensing apparatus for monitoring a fluid pipe, the apparatus comprising: at least one sensing fibre provided within the pipe; a light emitter for introducing light pulses with particular characteristics into the fibre; a light detector module configured to detect backscattering of the light pulses from the sensing fibre in multiple different sensing modes and output a detector output signal in response thereto; at least one flow velocity sensor element configured to generate characteristic acoustic events at a rate indicative of fluid flow velocity; and a fluid flow processing unit configured to process the detector output signal to extract a component of the detector output signal derived from said characteristic acoustic events from the detector output signal so as to monitor flow velocity. Providing a sensing apparatus as defined above allows provision of a flow velocity sensor at a low cost and with information provided on a highly granular time basis (ideally in real-time and 24 / 7 / 365). This allows detailed real time monitoring with a network and allow for accurate predictive analysis. This may allow for instance provision of real time data on actual pipe network operation and immediate identification and / or localisation of events which may disturb normal operation, as well as providing highly granular data on pipeline hydraulic performance which can be used to create long term ‘whole network’ models, on a diurnal up to annual basis, for predictive and alerting purposes, as well as an increased ability to control equipment such as pumps and valves within a network. Furthermore, such a sensor requires no local power source.

[0013] In the context of the present application, the term ‘fluid’ in relation to a fluid pipe or conduit may refer to any material, liquid or gaseous, including fuels such as oil or gas or associated distillates, additionally in industrial uses which may include mining and similar, the invention may more specifically refer to a primarily water-based fluid, such as potable water, pre-treatment water, wastewater or water-based slurries.

[0014] Similarly, in the context of the present application, the term ‘pipe’ or ‘conduit’ may refer to any fluid conduit used to convey a fluid (gas, liquid or a mixture including a slurry) between two points, spaced apart at or below local ground level. In particular, the ‘pipe’ or ‘conduit’ may traverse at a relatively regular displacement from local ground level, without requiring the ‘pipe’ or ‘conduit’ to be horizontal. Thus, the terms “pipe” and “fluid pipe” may be used interchangeably.

[0015] The sensing fibre may be provided at least partially inside the pipe. This enables the sensing fibre to conveniently travel between sensing locations and a base module without needing to separately lay or otherwise install the sensing fibre.

[0016] In one form, the at least one flow velocity sensor element may be provided in the form of at least one rotor located in the fluid flow for rotation according to the fluid flow.

[0017] In another form, the at least one flow velocity sensor element may be provided in the form of at least one rotor associated with the fluid flow for rotation according to the fluid flow. In this form, the at least one rotor may be located in a bypass configuration relative to the fluid flow within the fluid pipe in which a portion of the fluid flow is diverted outside the fluid pipe, through a housing within which the at least one rotor is located, causing rotation of the at least one rotor, before the fluid re-enters the fluid pipe.

[0018] In some embodiments, more than one flow velocity sensor element may be provided in a fluid pipe. In some such embodiments, a single sensing fibre may be provided for each flow velocity sensor element. In other embodiments, a single sensing fibre element may be provided for multiple flow velocity sensor elements.

[0019] The at least one flow velocity sensor element may comprise a rotor. The rotor may be a rotor of any type configured to rotate under fluid flow in the fluid pipe.

[0020] The rotor may be mounted for rotation about an axis which is parallel to the direction of fluid flow in the fluid pipe or transverse to the direction of fluid flow in the fluid pipe. If the rotor may be mounted for rotation about an axis which is transverse to the direction of fluid flow the rotation axis may be substantially horizontal or substantially vertical.

[0021] A transverse rotation axis may be preferred as this may allow a larger surface area of rotor, especially where the rotor is installed through an access opening in a pipe. Such access openings are often located on an upper side of a pipe favouring a vertical transverse axis. In concert with lower flow velocities, for instance in water pipes, this may be advantageous as the diameter of a rotor / blade assembly may be limited to the diameter of an access opening in the pipe (where such may be in the range 100mm to 200mm), but the length or the rotor / blade assembly may be up to the internal diameter of the fluid pipe itself.

[0022] The rotor (regardless of the rotor type used) may have any number of rotor elements or blades.

[0023] The rotor may be formed from any suitable material including but not limited to metals such as stainless steel or polymers. Use of such commonly available materials can ensure the cost of the rotor is minimised. The rotor material or rotor blade thickness can be selected so that the rotor has a relatively low mass. This can assist start of rotation in a low flow velocity environment. The rotor blade length may be selected to be relatively long. This can assist start of rotation in a low flow velocity environment.

[0024] The rotor may be a Savonius type rotor. A Savonius type rotor may be mounted for rotation about an axis which is transverse (horizontal) to the direction of fluid flow in the fluid pipe but preferably is mounted for rotation about an axis which is transverse (vertical) to the direction of fluid flow in the fluid pipe. A Savonius type rotor may be a ‘push’ rotor in which the rotational velocity of the rotor is directly linked to fluid flow velocity.

[0025] A Savonius type rotor may not need in-field calibration since rotational velocity of such a rotor may match fluid flow velocity (in situations in which the rotor was not under any load).

[0026] A Savonius type rotor may offer benefits since a push rotor may operate at a lower start-up velocity compared with a lift rotor. Such a rotor may be used for instance in water pipes where flow velocities may be quite low (often in the range 0.2-lm / s).

[0027] The rotor may be a propellor or Darrieus type rotor. A Darrieus type rotor may be mounted for rotation about an axis which is which is parallel to the direction of fluid flow in the fluid pipe or mounted for rotation about an axis which is transverse (vertical) to the direction of fluid flow in the fluid pipe. A Darrieus type rotor may preferably be a ‘lift’ rotor in which the rotational velocity may be a multiple of the fluid flow velocity, based on a combination of blade dimensions / parameters and fluid density.

[0028] A Darrieus type rotor may potentially require calibration or temperature compensation (even where the rotor was not under any load) - temperature compensation may be achieved by monitoring using DTS from a remote analyser. In another form, the rotor may be or comprise an Archimedes screw rotor or an articulated Archimedes screw rotor with at least two Archimedes screw portions articulated relative to one another.

[0029] In embodiments where the fluid flow velocity sensor element comprises a rotor, the fluid flow velocity sensor element may additionally comprise a static component, wherein interaction between the at least one rotor and the static component generates the characteristic acoustic event. As mentioned above, the characteristic acoustic event may be detected by the sensing fibre.

[0030] The interaction between the rotor and the static component may occur at a particular rotor orientation. The interaction between the rotor and the static component may generate the characteristic acoustic event only when the rotor is rotating. For example, the interaction may only occur once the at least one rotor is rotating at a substantially steady state in the fluid flow and not for example, at startup.

[0031] The static component may be or may project from a mount upon which the rotor is provided. In suitable embodiments, the static component may be a tube through which the at least one sensing fibre and / or sensing cable may enter or exit the fluid pipe.

[0032] The interaction between the rotor and the static component may be direct or may be indirect.

[0033] In embodiments where there is direct interaction between the rotor and the static component, the interaction may be a physical interaction with a contact member. In such embodiments one or more contact members may be provided on the rotor and / or on the static component. In such embodiments, the interaction may be contact between a contact element mounted on the rotor and the static component or a contact element mounted on the static component, when the rotor is in motion. Similarly, the interaction may be contact between a contact element mounted on the static component and a rotor blade or element. In each above case, such physical contact when the rotor is in motion, may generate a characteristic acoustic event. When the rotor is in motion, the rate at which such characteristic acoustic events are generated is related directly to the rotation rate of the rotor. Where the rotor is driven by fluid flow, the rate of generation of characteristic acoustic events can thereby be directly related to the fluid flow.

[0034] If multiple contact members are mounted on the rotor, the contact members may be evenly spaced around the circumference of the rotor. If multiple contact members are provided on the static component, each contact member may be evenly spaced around the rotation path of the rotor.

[0035] In such embodiments, each contact members may be elongate. In such embodiments, each contact member may be solid or may be wholly or partially hollow. In such some embodiments, each contact member may comprise a spiral or helical form. In particular, such contact members may comprise helical or spiral springs. In this context, hollow or helical form contact members may beneficially generate acoustic vibrations more efficiently and / or may be beneficially tuned to generate acoustic vibrations at a desired frequency range. Each contact member may be resiliently deformable. This can beneficially allow a contact member to deform on interaction allowing rotor rotation to continue with relatively little resistance from the interaction. This can also reduce wear on the contact member and the rotor or static component as appropriate.

[0036] The contact member may be formed from any suitable material. Suitable materials can comprise metals, such as stainless steel, polymers or the like.

[0037] In embodiments where there is indirect interaction between the rotor and the static component, the interaction may result from a magnetic interaction between cooperating magnetic elements on the rotor and the static component. In such embodiments, the cooperating magnetic elements may be configured to mutually attract or mutually repel as required or desired.

[0038] The magnetic cooperating elements provided on the static component may be provided on a movable contact arm. The movable contact arm may be mounted on a pivot axis. The movable contact arm may be adapted to interact with the static component. The contact arm may be urged towards the static component by a biasing mechanism in the absence of magnetic interaction with the cooperating magnetic element on the rotor and may be urged away from the static component by magnetic interaction with the cooperating magnetic element on the rotor. Alternatively, the contact arm may be urged away from the static component by a biasing mechanism in the absence of magnetic interaction with the cooperating magnetic element on the rotor and may be urged towards the static component pad by magnetic interaction with the cooperating magnetic element on the rotor. In this manner, rotation of the rotor causes the contact arm to be successively urged away from and towards the static component. In each case when urged towards the static component, physical contact can generate the characteristic acoustic event. In some such embodiments, a contact pad may project from the contact arm and / or a contact pad may project from the static component to provide such physical contact. This can beneficially reduce the required range of movement of the contact arm. Additionally or alternatively, the contact pad can help reduce wear on the contact arm or static component or can help tune the acoustic qualities of the characteristic acoustic events.

[0039] In such embodiments, the contact arm may be solid or may be wholly or partially hollow. In such some embodiments, each contact arm may comprise a spiral or helical form. In particular, such contact arms may comprise helical or spiral springs. In this context, hollow contact or helical form arms may beneficially generate acoustic vibrations more efficiently and / or may be beneficially tuned to generate acoustic vibrations at a desired frequency range. Furthermore, hollow or helical form contact arms may be relatively light and thus more easily moved by the magnetic interaction and / or the biasing element.

[0040] The contact arm, and biasing element may comprise a magnetic mechanism.

[0041] The detector output signal may comprise multiple channels, each channel corresponding to a particular location along the sensing fibre. Each channel may be defined by reference to the round-trip time for backscattered pulses from the particular location. Neighbouring channels may be defined by the minimum resolvable time interval between backscattered pulses from neighbouring sensing fibre locations. Accordingly, each flow velocity sensor element location can correspond to a particular channel within the detector output signal. In such embodiments, the fluid flow processing unit may be configured to extract the component of the detector output signal derived from said characteristic acoustic events by reference to a particular channel within the detector output signal. The referenced channel may correspond to the location of a particular flow velocity sensor element along the length of the sensing fibre. Accordingly, if the location of each flow velocity sensor element along the length of the sensing fibre is known the component of the detector output signal derived from said characteristic acoustic events can be extracted by reference to the corresponding channel within the detector output signal. In embodiments with multiple flow velocity sensor elements, there may be multiple referenced channels. In such cases, each channel may correspond to the location of a flow velocity sensor element. The fluid flow processing unit may be configured to identify the characteristic acoustic events within the extracted component of the detector output signal. This may be achieved by filtering the extracted component to an acoustic frequency range corresponding to the characteristic acoustic events.

[0042] The fluid flow processing unit may be configured to calculate a fluid flow velocity from the identified the characteristic acoustic events. This may be achieved by determining the repetition rate of the characteristic acoustic events. This may further involve applying a conversion factor or series of conversion factors to the determined repetition rate to thereby calculate the fluid flow velocity. Accordingly, suitable analysis of the sensing fibre can enable calculation of a flow velocity in the fluid pipe at the sensor location, without requiring a local power source for the flow velocity sensor element.

[0043] The sensing apparatus may further comprise a base module comprising the light emitter and the light detector. The base module may comprise a coupling assembly configured to remotely couple light pulses into the sensing fibre and backscattered light pulses out of the sensing fibre.

[0044] The sensing apparatus may comprise an analyser to analyse the detector output signal. In some embodiments, the analyser may be provided within the base module. In other embodiments, the analyser may be located remotely from the base module. The analyser may interrogate a specific location of the sensing apparatus. The fluid flow processing unit may be integrated into the analyser or may be provided separately to the analyser.

[0045] The at least one sensing fibre may be provided as a part of a sensing cable extending with or within the fluid pipe.

[0046] The sensing arrangement may comprise a tube through which the at least one sensing fibre and / or sensing cable may enter or exit the fluid pipe. Such a tube may be mounted relative to a fluid pipe or pipe fitting, as described below.

[0047] The tube be mounted relative to the fluid pipe and / or pipe fitting via an isolation valve. The isolation valve may be configured to selectively fluidly isolate the tube and / or at least one sensing fibre and / or sensing cable from the fluid pipe. The isolation valve may comprise any type of suitable valve such as a ball valve, gate valve, plug valve, butterfly valve or the like. Thus, the isolation valve can allow easy connection and disconnection of the tube and / or at least one sensing fibre and / or sensing cable from the fluid pipe as needed, such as for maintenance or if it is no longer required.

[0048] The isolation valve may be provided on a section of the tube configured to, and / or intended to, remain outside the fluid pipe. The isolation valve may be provided outside the fluid pipe. This ensures that the isolation valve remains easily accessible.

[0049] The tube may comprise an opening at one end in fluid communication with the fluid pipe. The tube may extend into the fluid pipe to be monitored. The opening may be provided inside the fluid pipe to be monitored. The isolation valve may be provided between the opening and the sensing element. Thus, the tube is conveniently in communication with the fluid inside the fluid pipe.

[0050] The tube may be configured to connect to an access valve provided on the pipe to be monitored. The access valve may be configured to position the tube within the fluid pipe. The access valve may be configured to selectively fluidly isolate the tube from the fluid flow within the pipe. The access valve may comprise any suitable valve, for example as described in relation to the isolation valve.

[0051] The fluid pipe may comprise an access tube extending from the inside of the pipe to the access valve. In such embodiments, the tube may, or may not, comprise an isolation valve.

[0052] In an embodiment, the tube may extend into the fluid pipe transversely. The tube may extend to position the opening at the in-pipe end adjacent to but spaced from the pipe invert, which is the fluid pipe wall opposite to the entry end of the tube. This may assist with locating or positioning the at least one sensing fibre and / or sensing cable substantially parallel to the pipe invert. The at least one sensing fibre and / or sensing cable may abut the pipe invert.

[0053] The tube may function as a mount for the at least one flow velocity sensor element. A separate mount for the at least one flow velocity sensor element may however be provided. The sensing apparatus may be provided relative to a pipe fitting provided on the fluid pipe, through which a sensing cable may enter or exit the fluid pipe. The pipe fitting may be configured to support the sensing fibre and or the tube. The pipe fitting may be configured to be fitted to the pipe. Thus, the pipe fitting provides convenient attachment of the sensing fibre to the fluid pipe.

[0054] The pipe fitting may provide an entry / exit point on the fluid pipe for the sensing fibre. The pipe fitting may provide an entry / exit point on the fluid pipe for the tube of the sensor. The pipe fitting may provide entry / exit points on the fluid pipe for the sensing fibre and the tubes of two sensors, each sensor associated with one of the two sensing locations. Thus, the pipe fitting enables simple and efficient connection to the inside of the pipe. The entry / exit points may be standard access openings on the fluid pipe or may be dedicated openings formed for mounting the sensing fibre and / or the tube of the sensor.

[0055] The pipe fitting may comprise a semi-rigid tubular arrangement configured to be inserted into the fluid pipe. The tubular arrangement may be configured to resist a fluid flow within the pipe. The sensing fibre may be provided inside the tubular arrangement. The tubular arrangement may be configured to control placement of the sensing fibre within the fluid pipe. Thus, the sensing fibre position in the pipe is better controlled.

[0056] In other embodiments, the pipe to be monitored may provide entry / exit points and / or tubular arrangements as described above. The pipe fitting may be configured to mount the sensing fibre and one or more sensing locations (e.g. two sensing locations) to an outside of the pipe to be monitored. Thus, the pipe fitting can be simply and easily mountable to the pipe.

[0057] The fluid pipe in which the sensing arrangement is provided may be a single unbranched length of pipe. In such embodiments, the sensing fibre may run along the pipe from one end to the other. In other such embodiments the sensing cable may run in a loop from one end of the pipe to be monitored to the other end and back again.

[0058] The fluid pipe in which the sensing arrangement is provided may comprise a branched network of pipes or part of a branched network of pipes. In such embodiments the sensing cable may run in a loop from an entry point to the far end of each branch in turn.

[0059] The branched network may be any suitable branched network of fluid pipes. In one example, the branched network is a district metered area of a water supply network.

[0060] In some embodiments, a sensing apparatus may be adapted to monitor multiple pipes under test. In such embodiments, each pipe to be monitored may be a single unbranched length of pipe or each pipe to be monitored may be branched network of pipes or part of a branched network of pipes. In further such embodiments, some pipes to be monitored may be single unbranched lengths of pipe and other pipes to be monitored may be branched networks of pipes or parts of branched networks of pipes.

[0061] In some embodiments, where power is required for one or more components, the power can be provided by a battery or similar, or by provision of a power generator in association with a rotor / sensing element located at least partially within the fluid flow and / or with access to the fluid flow, such as in a bypass configuration.

[0062] According to an aspect of the present invention, there is provided a sensing apparatus for monitoring fluid flow velocity in a fluid pipe, the sensing apparatus comprising: at least one flow velocity sensor element configured to generate characteristic acoustic events at a rate indicative of the fluid flow velocity; and a sensing fibre provided within the fluid pipe, the sensing fibre configured to detect said characteristic acoustic events.

[0063] In a further aspect of the invention, there is provided a fluid flow velocity sensor element for use with a sensing fibre, the fluid flow velocity sensor element comprising at least one rotor and a static component, wherein interaction between the at least one rotor and the static component generates a characteristic acoustic event.

[0064] As mentioned above, the characteristic acoustic event may be detected by the sensing fibre.

[0065] The interaction between the rotor and the static component may occur at a particular rotor orientation. The interaction between the rotor and the static component may generate the characteristic acoustic event only when the rotor is rotating. For example, the interaction may only occur once the at least one rotor is rotating at a substantially steady state in the fluid flow and not for example, at startup.

[0066] As mentioned above, the interaction may be direct, or may be indirect.

[0067] In an aspect of the resent invention there is provided a method for monitoring the condition of a fluid pipe, the method comprising the steps of: providing a sensing fibre within the pipe to be monitored; introducing light pulses generated by a light emitter into the sensing fibre; detecting backscattered light pulse from the sensing fibre with a light detector configured to output a detector output signal corresponding to the detected backscattered light; and extracting the component of the detector output signal derived from said characteristic acoustic events so as to monitor flow velocity.

[0068] The detector output signal may comprise multiple channels, each channel corresponding to a particular location along the sensing fibre. Each channel may be defined by reference to the round-trip time for backscattered pulses from the particular location. Neighbouring channels may be defined by the minimum resolvable time interval between backscattered pulses from neighbouring sensing fibre locations. Accordingly, each flow velocity sensor element location can correspond to a particular channel within the detector output signal. In such embodiments, the component of the detector output signal derived from said characteristic acoustic events can be extracted by reference to a particular channel within the detector output signal. The referenced channel may correspond to the location of a particular flow velocity sensor element along the length of the sensing fibre. In embodiments with multiple flow velocity sensor elements, there may be multiple referenced channels. In such cases, each channel may correspond to eth location of a flow velocity sensor element.

[0069] The method may comprise the step of identifying the characteristic acoustic events within the extracted component of the detector output signal. This may be achieved by filtering the extracted component to an acoustic frequency range corresponding to the characteristic acoustic events.

[0070] The method may comprise the step of calculating a fluid flow velocity from the identified the characteristic acoustic events. This may be achieved by determining the repetition rate of the characteristic acoustic events. This may further involve applying a conversion factor or series of conversion factors to the determined repetition rate to thereby calculate the fluid flow velocity. Accordingly, suitable analysis of the sensing fibre can enable calculation of a flow velocity in the fluid pipe at the sensor location, without requiring a local power source for the flow velocity sensor element.

[0071] In a further aspect of the invention, there is provided a method claim for monitoring fluid flow velocity in a fluid pipe, the method comprising the steps of: positioning at least one flow velocity sensor element configured to generate characteristic acoustic events at a rate indicative of fluid flow velocity, in a fluid flow; and detecting said characteristic acoustic events using a sensing fibre provided within the fluid pipe.

[0072] Detecting said characteristic acoustic events may comprise the steps of introducing light pulses generated by a light emitter into the sensing fibre; detecting backscattered light pulse from the sensing fibre with a light detector configured to output a detector output signal corresponding to the detected backscattered light; and extracting the component of the detector output signal derived from said characteristic acoustic events.

[0073] In another aspect of the present invention, there is provided a fluid distribution system comprising one or more fluid pipes and at least one sensing apparatus according to the present invention provided at one or more points within the fluid distribution system; and a system controller wherein each sensing apparatus is connected to the system controller.

[0074] In this manner, the system controller can monitor fluid flow at multiple points within a fluid distribution system. The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the aspects, methods, examples or embodiments described herein may be applied to any other method, aspect, example, embodiment or feature. Further, the description of any aspect, method, example or feature may form part of or the entirety of an embodiment of the invention as defined by the claims. Any of the examples described herein may be an example which embodies the invention defined by the claims and thus an embodiment of the invention.

[0075] Detailed Description of the Invention

[0076] In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0077] Figure 1A is a schematic side elevation view of a pipe with a rotor therein according to an embodiment.

[0078] Figure IB is a top view of the configuration illustrated in Figure 1A.

[0079] Figure 2A is a schematic side elevation view of a pipe with a rotor therein according to an embodiment.

[0080] Figure 2B is a top view of the configuration illustrated in Figure 2A.

[0081] Figure 3A is a schematic side elevation view of a pipe with a rotor therein according to an embodiment.

[0082] Figure 3B is a top view of the configuration illustrated in Figure 3A.

[0083] Figure 4A is a schematic side elevation view of a pipe with a rotor therein according to an embodiment.

[0084] Figure 4B is a top view of the configuration illustrated in Figure 4A.

[0085] Figure 5A is a schematic side elevation view of a pipe with a rotor with a contact assembly therein according to an embodiment.

[0086] Figure 5B is a top view of the configuration illustrated in Figure 5A.

[0087] Figure 6A is a schematic side elevation view of a pipe with a rotor with a contact assembly therein according to a further embodiment. Figure 6B is a top view of the configuration illustrated in Figure 6A.

[0088] Figure 7A is a schematic side elevation view of a pipe with a rotor with a contact assembly therein according to an embodiment.

[0089] Figure 7B is a detailed view of a mechanism identified by 18 in Figure 7A in a first condition.

[0090] Figure 7C is a detailed view of the mechanism identified in Figure 7B in a second condition.

[0091] Figure 8 is a schematic side elevation view of a pipe with a sensor arrangement as illustrated in any one of Figures 5 to 7 showing a trace of the contacts made.

[0092] Figure 9A is a schematic block diagram of a sensing apparatus for monitoring the condition of a fluid pipe as used in the present invention.

[0093] Figure 9B a schematic block diagram of a processing arrangement, according to the prior art, for the sensing apparatus of figure 9A.

[0094] Figure 10 is a schematic side elevation view of a pipe with a sensor arrangement in a bypass configuration.

[0095] Figure 11 is a detailed view of the sensor arrangement as shown in Figure 13.

[0096] Many examples of sensing arrangements are illustrated in the accompanying Figures.

[0097] Figures 1A to 4B show variations of rotor configurations which may be used in different embodiments. The rotors shown in these Figures are mounted within a fluid pipe 2, relative to a pipe access port 1 which in the illustrated embodiments, includes a flange.

[0098] Figures 1A to 2B show a side view and a top view of a Savonius type rotor 3. A Savonius type rotor may be mounted for rotation about an axis 4a which is transverse (horizontal) to the direction of fluid flow 6 in the fluid pipe 6 as shown in Figure 1A and IB, or mounted for rotation about an axis 4b which is transverse (vertical) to the direction of fluid flow 6 in the fluid pipe 2as shown in Figures 2A and 2B. A Savonius type rotor is considered to be a ‘push’ rotor in which the rotational velocity of the rotor in the direction 5 is directly linked to fluid flow velocity.

[0099] A Savonius type rotor 3 may offer benefits since a push rotor may operate at a lower start-up velocity compared with a lift rotor. Such a push rotor may be used for instance in water pipes where flow velocities may be quite low (often in the range 0.2- Im / s).

[0100] The rotor may be a propellor or Darrieus type rotor such as the examples illustrated in Figures 3 A to 4B . A Darrieus type rotor may be mounted for rotation about an axis 7 which is parallel to the direction of fluid flow 6 in the fluid pipe 2 or mounted for rotation about an axis 9 which is transverse to the direction of fluid flow 6 in the fluid pipe 2. A Darrieus type rotor is considered to be a ‘lift’ rotor in which the rotational velocity in the direction 8 in Figure 3a and 3B and 10 in Figures 4 A and 4B, is a multiple of the fluid flow velocity, based on a combination of blade dimensions / parameters and fluid density.

[0101] The rotor configuration of Figure 3A and 3B is a propeller type rotor and the rotor configuration of Figure 4A and 4B is a H-rotor or H-Darrieus with a number of vertically oriented blades 11 mounted on arms radiating from the axis 9.

[0102] Overall, a vertical axis may be preferred as this may allow a larger surface area of rotor. In concert with lower flow velocities, for instance in water pipes, this may be advantageous as the diameter of a rotor / blade assembly may be limited to the diameter of an opening in the pipe to allow access (where such may be in the range 100mm to 200mm), but the length or the rotor / blade assembly may be up to the internal diameter of the fluid pipe itself.

[0103] A number of alternative configurations of sensing apparatus mounted relative to a fluid pipe access port are illustrated in Figures 5A to 12B.

[0104] In the embodiment shown in Figures 5 A to 6B, the sensing apparatus comprises a sensing fibre 15 extending into a fluid pipe through a pipe access portion, via a fitting top plate 12 mounted to a flange fitting. The sensing fibre 15 is located within a tube 14 which is mounted to the fitting top plate 12 to allow entry / exit of the sensing fibre 15 to / from the fluid pipe 2. The sensing fibre 14 extends through the tube 14 and to the pipe invert and then along a length of the fluid pipe.

[0105] A flow velocity sensor element, a rotor in the form illustrated in Figures 5A to 6B, is mounted within the fluid flow in the fluid pipe. Figures 5a and 5B show a rotor 3 similar to that shown in Figures 2A and 2B, mounted for rotation about a vertical axis 4a.

[0106] The rotor is provided with a number of contact elements 13 to physically contact the tube 14 when the rotor 3 is rotating under flow conditions. This physical contact with the tube 14 generates a characteristic acoustic event as a result of vibration of the contact element 13 and / or rotor 3. This characteristic acoustic event is also experienced by sensing fibre 15 and can be detected as is described in more detail below. As the characteristic acoustic event is generated each time a rotor blade passes the tube 14 the rate of generation of successive characteristic acoustic events is indicative of fluid flow velocity.

[0107] The embodiment shown in Figures 6A and 6B is similar in operating principle to that of the embodiment shown in Figures 5 A and 5B, but is based on the rotor configuration of Figures 4A and 4B, with vertically oriented blades 11 mounted on arms radiating from the vertical axis 9 of rotation.

[0108] As illustrated, the axis 4b, 9 of the rotors in Figures 5A to 6B is mounted using mounting arms 16 mounted to the tube 14.

[0109] In contrast to the rotors of the rotors in Figures 5A to 6B which generate characteristic acoustic events by direct interaction between the rotor 3 and a static component such as tube 14, in an alternative form illustrated in Figures 7A to 7C, the rotation of the rotor may not make direct contact with the tube or the sensing fibre but may instead be indirectly associated with the tube or the sensing fibre, such as via cooperating magnetic elements 17, 18 for example.

[0110] An example of an indirect association is illustrated in Figure 7A where the vertically mounted rotor 3 has multiple blades 11 provided with one or more magnetic elements 17. The tube 14 is provided with a magnetic mechanism 18. As the rotor 3 rotates, each magnetic element 17 passes the magnetic mechanism 18. This results in a magnetic interaction between the magnetic element 17 and the magnetic mechanism 18. This interaction causes the magnetic mechanism 18 to generate a characteristic acoustic event.

[0111] Figures 7Aa and 7B illustrate two possible embodiments of a magnetic mechanism 18. Each embodiment comprises a contact arm 19, which may be a magnetic or ferrite element 19 mounted to the tube 14 which the at least one sensing fibre 15 is mounted.

[0112] In Figures 7B and 7C, the contact arm 19 is mounted on a pivot 22. The contact arm 19 is biased toward (Figure 7B) or away from (Figure 7C) the tube 14 within which the sensing fibre 15 is mounted, by a spring 20 (Figure 7B) or 21 (figure 7C). Interaction with the magnetic element 17 draws the contact arm 19 away from the tube 14 within which the sensing fibre 15 is mounted as the rotor rotates by attraction toward the magnetic element 17 on the rotor 3.

[0113] In Figure 7B, as the magnetic element 17 passes away, the magnetic interaction weakens and the spring 20 pulls the contact arm 19 and back towards the tube 14. The physical contact between contact pad 19a and the tube 14 thereby generates a characteristic acoustic event. In Figure 7C, as the magnetic element 17 passes away, the magnetic interaction weakens and the spring 21 pushes the contact arm 19 back towards the tube 14. The physical contact between contact pad 19a and the tube 14 thereby generates a characteristic acoustic event.

[0114] As in the previous embodiments, the magnetic interaction between magnetic elements 17 and the magnetic mechanism 18 illustrated in Figures 7A to 7C causes a periodic physical contact with the tube 14 within which the sensing fibre 15 is mounted as the rotor 3 rotates.

[0115] Figure 9A is a schematic illustration of a sensing apparatus 100. The sensing monitoring apparatus 100 comprises a base module 110 connected to one end of a sensing fibre 15 provided within a pipe 2. The sensing fibre 15 can be of a pre-set length or may be provided to a length corresponding to that of the pipe 2 to be monitored. If the pipe 2 comprises a branched network, the length of the sensing fibre 15 can be selected to correspond the length of fibre required to loop around all branches of the network to be monitored.

[0116] The base module 110 comprises a light emitter 111 (such as a laser) and a light detector 112 to detect backscattered light and output a detector output signal in response to the detected backscattered light. The base module further comprises a local optical coupling assembly 113 configured to couple the emitter 111 and the detector 112 to the sensing fibre 15.

[0117] The detector output signal comprises multiple channels, each channel corresponding to a particular location along the sensing fibre. Each channel may be defined by reference to the round-trip time for backscattered pulses from the particular location. Neighbouring channels may be defined by the minimum resolvable time interval between backscattered pulses from neighbouring sensing fibre locations. By analysing the detector output signal, indications can be obtained of the condition of the pipe and / or events occurring within or in the vicinity of the pipe.

[0118] The detector 112 typically comprises a photosensor configured to output signals in response to detected backscattered light. Optionally, the detector 112 can also comprise a phase module configured to extract phase information from the photosensor output and thereby generate a detector output signal including phase information. In such cases, each detector output signal channel contains phase information related to the phase of the detected backscattered light from the particular fibre location.

[0119] As illustrated in Figure 9B, the apparatus 100 is connected to a flow processing unit 121, and an analyser 122, in this instance cloud based. One or more users 123 can receive processed data from analyser 122, as required or desired. The skilled person will appreciate that the flow processing unit 121 can be integrated into the analyser 122. The skilled person will also appreciate that the flow processing unit 121 and / or the analyser 122 can each be provided in the base unit 110 or in the cloud.

[0120] As discussed above and illustrated schematically in Figure 8, the periodic physical contact causes a corresponding periodic signal 26 comprising successive characteristic acoustic events. The acoustic signal 26 detectable by the sensing fibre 15. The sensing fibre 15 shown in Figure 8, enters the fluid pipe through entry fitting 23 and exits at exit fitting 24. A base unit 100 (as described above) is provided at the end of the sensing fibre 15 after it exits the pipe 2.

[0121] The flow processing unit 121 is configured to extract the component of the detector output signal derived from said characteristic acoustic events. This can be achieved by reference to the channel corresponding to the rotor 3 location within the detector output signal.

[0122] The location of the rotor 3 (or each rotor 3 if multiple rotors 3 are provided) corresponds to a particular channel within the detector output signal. In such embodiments, the component of the detector output signal derived from said characteristic acoustic events can be extracted by reference to a particular channel within the detector output signal. The referenced channel may correspond to the location of a particular rotor along the length of the sensing fibre.

[0123] Once the component of the detector output signal derived from said characteristic acoustic events is extracted, the flow processing unit 121 can process this extract to identify the characteristic acoustic events. This may be achieved by filtering the extracted component to an acoustic frequency range corresponding to the characteristic acoustic events. Once the characteristic acoustic events are identified the flow processing unit 121 can process the identified signals to calculate a fluid flow velocity by determining the repetition rate of the characteristic acoustic events. This may further involve applying a conversion factor or series of conversion factors to the determined repetition rate to thereby convert a rotor rotation rate to an associated fluid flow velocity. Accordingly, suitable analysis of the sensing fibre can enable calculation of a flow velocity in the fluid pipe at the sensor location, without requiring a local power source for the flow velocity sensor element.

[0124] The embodiment illustrated in Figures 10 and 11 is a bypass configuration. In this embodiment, a containment chamber 75 is provided to allow through flow under dynamic pressure from the upstream 39 and downstream ports 40 within the fluid pipe.

[0125] A rotor, as described above, may then be provided within the containment chamber as shown in Figure 11. The rotor may be of any type previously described or disclosed. A chamber detector apparatus 77 may be provided in association with containment chamber 75 to detect rotor rotation (per previous methods described) and to provide either direct impulse signals to a sensing fibre 15 or tube 14 (per methods previously described), or via electronic means to derive an acoustic or knocking signal (per methods previously described).

[0126] The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

CLAIMS1. A sensing apparatus for monitoring a fluid pipe, the apparatus comprising: at least one sensing fibre provided within the pipe; a light emitter for introducing light pulses with particular characteristics into the fibre; a light detector module configured to detect backscattering of the light pulses from the sensing fibre in multiple different sensing modes and output a detector output signal in response thereto; at least one flow velocity sensor element configured to generate characteristic acoustic events at a rate indicative of fluid flow velocity; and a fluid flow processing unit configured to process the detector output signal to extract a component of the detector output signal derived from said characteristic acoustic events from the detector output signal so as to monitor flow velocity.

2. A sensing apparatus as claimed in claim 1 wherein the at least one flow velocity sensor element is provided as at least one rotor located in the fluid flow for rotation according to the fluid flow.

3. A sensing apparatus as claimed in claim 1 wherein the at least one flow velocity sensor element is provided in the form of at least one rotor located in a bypass configuration associated with the fluid flow for rotation according to the fluid flow.

4. A sensing apparatus as claimed in any one of the preceding claims further comprising a tube through which the at least one sensing fibre enters or exits the fluid pipe.

5. A sensing apparatus as claimed in claim 4 wherein the rotating sensor element or rotor is mounted for rotation about an axis which is parallel to a direction of fluid flow in the fluid pipe or transverse, horizontally or vertically to the direction of fluid flow in the fluid pipe.

6. A sensing apparatus as claimed in claim 4 or claim 5 wherein the rotor is a Savonius type rotor or Darrieus type, with any number of rotor elements or blades.

7. A sensing apparatus as claimed in any one of claims 2 to 6, wherein the fluid flow velocity sensor element additionally comprises a static component, wherein interaction between the at least one rotor and the static component generates the characteristic acoustic event optionally where the static component is a mount or projects from a mount upon which the rotor is provided and / or where the static component is a tube through which the one sensing fibre enters or exits the fluid Pipe8. A sensing apparatus as claimed in claim 7, wherein the interaction is contact between a contact element mounted on the rotor and the static component or a contact element mounted on the static component or wherein the interaction is contact between a contact element mounted on the static component and a rotor blade or element when the rotor is in motion.

9. A sensing apparatus as claimed in claim 8, wherein each contact member is resiliently deformable.

10. A sensing apparatus as claimed in claim 7, wherein the interaction is a magnetic interaction between cooperating magnetic elements on the rotor and the static component.

11. A sensing apparatus as claimed in claim 10, wherein the magnetic cooperating elements provided on the static component are provided on a movable contact arm, the contact arm adapted to be urged towards the static component by a biasing mechanism in the absence of magnetic interaction with the cooperating magnetic element on the rotor and urged away from the static component by magnetic interaction with the cooperating magnetic element on the rotor or the contact arm adapted to be urged away from the static component by a biasing mechanism in the absence of magnetic interaction with the cooperating magnetic element on the rotor and urged towards the static component pad by magnetic interaction with the cooperating magnetic element on the rotor.

12. A sensing apparatus as claimed in any preceding claim, wherein the detector output signal comprises multiple channels, each channel corresponding to a particular location along the sensing fibre.

13. A sensing apparatus as claimed in claim 12, wherein the detector output signal comprises multiple channels, each channel corresponding to a particular location along the sensing fibre and the fluid flow processing unit is configured to extract the component of the detector output signal derived from said characteristic acoustic events by reference to a particular channel within the detector output signal.

14. A sensing apparatus as claimed in claim 13, wherein the fluid flow processing unit is configured to identify the characteristic acoustic events within the extracted component of the detector output signal by filtering the extracted component to an acoustic frequency range corresponding to the characteristic acoustic events15. A sensing apparatus as claimed in claim 14, wherein the fluid flow processing unit is configured to calculate a fluid flow velocity from the identified the characteristic acoustic events by determining the repetition rate of the characteristic acoustic events and applying a conversion factor or series of conversion factors to the determined repetition rate.

16. A sensing apparatus as claimed in any preceding claim, wherein the sensing apparatus comprises an analyser to analyse the detector output signal.

17. A sensing apparatus as claimed in claim 16, wherein the fluid flow processing unit is integrated into the analyser or is provided separately to the analyser.

18. A sensing apparatus for monitoring fluid flow velocity in a fluid pipe, the sensing apparatus comprising: at least one flow velocity sensor element configured to generate characteristic acoustic events at a rate indicative of the fluid flow velocity; and a sensing fibre provided within the fluid pipe, the sensing fibre configured to detect said characteristic acoustic events.

19. A fluid flow velocity sensor element for use with a sensing fibre, the fluid flow velocity sensor element comprising at least one rotor and a static component, wherein interaction between the at least one rotor and the static component generates a characteristic acoustic event.

20. A fluid flow velocity sensor element as claimed in claim 19, wherein the interaction between the rotor and the static component occurs at a particular rotor orientation only when the rotor is rotating.

21. A method for monitoring the condition of a fluid pipe, the method comprising the steps of: providing a sensing fibre within the pipe to be monitored; introducing light pulses generated by a light emitter into the sensing fibre; detecting backscattered light pulse from the sensing fibre with a light detector configured to output a detector output signal corresponding to the detected backscattered light; and extracting the component of the detector output signal derived from said characteristic acoustic events so as to monitor flow velocity.

22. A method as claimed in claim 21, wherein the detector output signal comprises multiple channels, each channel corresponding to a particular location along the sensing fibre and the component of the detector output signal derived from said characteristic acoustic events is extracted by reference to a particular channel within the detector output signal.

23. A sensing apparatus as claimed in claim 22, wherein the characteristic acoustic events within the extracted component of the detector output signal are identified by filtering the extracted component to an acoustic frequency range corresponding to the characteristic acoustic events24. A sensing apparatus as claimed in claim 23, wherein the fluid flow velocity is calculated from the identified characteristic acoustic events by determining the repetition rate of the characteristic acoustic events and applying a conversion factor or series of conversion factors to the determined repetition rate.

25. A method of monitoring fluid flow velocity in a fluid pipe, the method comprising the steps of:positioning at least one flow velocity sensor element configured to generate characteristic acoustic events at a rate indicative of fluid flow velocity, in a fluid flow; and detecting said characteristic acoustic events using a sensing fibre provided within the fluid pipe.

26. A fluid distribution system comprising one or more fluid pipes and at least one sensing apparatus according to any one of claims 1 to 18 or operable according to the method of any one of claims 21 to 25 or incorporating a fluid flow velocity sensor element according to claim 19 or claim 20, wherein the at least one sensing element is provided at one or more points within the fluid distribution system; and a system controller wherein each sensing apparatus is connected to the system controller.

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