A flow measurement device

Abstract

A device 200 for measuring flow of liquid or gas in a pipe comprises: a controller; a sensor assembly 220 comprising at least one pair of sensors 225a, 225b mounted onto each end 250a, 250b of the sen

Description

The present disclosure relates to a device for measuring the flow of a liquid or gas within a pipe, configured to provide accurate flow measurement in conduits of unknown condition and hydraulics. BACKGROUND It is widely known that flow measurement is a vital requirement of many fluid and gas handling systems. In oil and water industries, accurate flow measurement is required to meet operational, process control, and financial objectives. In the water industry accurate flow measurement is essential to managing abstraction and supply of an increasingly scarce resource and minimising leakage. It is also widely known that accurate flow measurement in conduits of unknown condition and hydraulics is notoriously difficult. It has been estimated that the uncertainty around trunk water mains metering is as high as 15%. Traditionally, large diameter (for example >200mm) trunk mains have been metered using full bore mechanical or electromagnetic meters. Whilst the latter are accurate, they are susceptible to errors caused by unknown and variable hydraulics. Replacement is both disruptive and expensive and, in some cases, impractical. Verification of accuracy (currently to an Environmental Agency standard of ±5%) is usually carried out using external clamp-on meters. These are known to be unsatisfactory and cannot be certified to a transferable UKAS standard. As such, an accurate, easily fitted and replaced device for flow measurement is desirable. SUMMARY According to a first aspect of the disclosure, there is provided a device for measuring flow of contents of a pipe, wherein the contents of the pipe is a liquid or a gas, the device comprising: a controller; a sensor assembly comprising at least one pair of sensors mounted onto each end of the sensor assembly, the sensor assembly configured to be inserted into the pipe; and a housing configured to house the controller, wherein the housing is coupled to the sensor assembly; wherein the sensor assembly is configured to move from a first configuration to a second configuration when the device is inserted into the pipe; wherein the device is configured to: output, using the sensor assembly, a plurality of ultrasonic beams; detect, using the sensor assembly, the plurality of ultrasonic beams; receive, by the controller, a signal from the sensor assembly, the signal indicating a time elapsed between the ultrasonic beam being output and detected; measure, using the sensor assembly, a temperature of the contents of the pipe; calculate, by the controller, a diameter and an area of the pipe, based on the signal; and calculate, by the controller, an orientation error and a hydraulic disturbance within the pipe based on the signal; calculate, based on the signal, the diameter of the pipe, the area of the pipe, the orientation error, and the hydraulic disturbance within the pipe, the flow of the contents of the pipe. Optionally, wherein the first configuration comprises the sensor assembly being positioned in line with the housing; and wherein the second configuration comprises the sensor assembly being positioned perpendicular to the housing. Optionally, wherein the sensor assembly further comprises: an axially rotating head coupled to each end of the assembly, on which the at least one pair of sensors is mounted. Optionally, wherein, when in the second configuration, the sensor assembly is rotatable by 180 degrees; wherein the controller is configured to control the sensor assembly to obtain a plurality of signals at rotational positions of the sensor assembly to generate a plurality of independent measurements of the diameter of the pipe diameter. Optionally, wherein the controller is configured to: determine a first position within the pipe at which a signal-to-noise ratio is minimised; and control the sensor assembly to rotate to the first position. Optionally, wherein the plurality of ultrasonic beams are output at different angles to achieve a plurality of beam paths; wherein each beam path is configured to provide information related to the pipe and the flow within the pipe. Optionally, wherein the plurality of beam paths includes at least one of: two vertical beam paths; at least one triangle beam path; at least one V beam path; at least one square beam path; and at least one hexagonal beam path. Optionally, wherein the plurality of beam paths includes two vertical beam paths, one V beam path, and two triangular beam paths. Optionally, wherein the plurality of beam paths further includes two square beam paths and two hexagonal beam paths. Optionally, wherein the two vertical beam paths are orthogonal to the pipe; wherein one vertical beam path is emitted from each end of the sensor assembly; wherein the two vertical beam paths are used to measure an internal diameter and area of the pipe. Optionally, wherein the vertical beam paths and triangle path are used to calculate a metered volume and ovality of the pipe. Optionally, wherein the sensor assembly is further configured to rotate around a vertical axis in line with the housing by 180 degrees. Optionally, further configured to rotate the sensor assembly by 180 degrees and output and receive a second plurality of ultrasonic beams to provide a second set of measurements; wherein the measurements include diameter, area, volume and ovality of the pipe. Optionally, wherein the device is configured to provide an alignment function of the sensor assembly using a first triangle beam path and a second triangle beam path; wherein the first and second triangle beam paths are configured to provide first and second time-of-flight measurement, respectively, the first and second time-of-flight measurements indicating a time elapsed for the beam to leave a sensor on one end of the sensor assembly, bounce off an internal surface of the pipe a number of times such that the beam path is triangle-shaped, and be detected by a sensor on the other end of the sensor assembly; wherein a comparison between the first and second time-of-flight measurements is used to determine an angle of orientation of the sensor assembly relative to the pipe. Optionally, wherein the alignment function comprises: if the comparison indicates a difference between the first and second time-of-flight measurements, it is determined that the sensor assembly is not aligned with the pipe; and adjusting the sensor assembly, based on the comparison, such that it is aligned with the pipe. Optionally, wherein a positive difference between the first and second time-of-flight measurements indicates a first direction of misalignment; and wherein a negative difference between the first and second time-of-flight measurements indicates a second direction of misalignment, different from the first direction of misalignment. Optionally, wherein the at least one pair of sensors are piezoelectric transducers. Optionally, wherein the sensor assembly further comprises at least one temperature sensor configured such that it is in thermal contact with the contents of the pipe. Optionally, wherein the combination of the temperature obtained by the at least one temperature sensor and the signal obtained by the sensor assembly are used to calculate a flow velocity and volume for the contents of the pipe; wherein the flow velocity and volume are traceable to the SI units of time and distance. According to a second aspect of the disclosure, there is provided a method for measuring flow of liquid or gas within a pipe using a device comprising a controller, a sensor assembly comprising at least one pair of sensors mounted onto each end of the sensor assembly, the sensor assembly configured to be inserted into the pipe, and a housing configured to house the controller, the housing coupled to the sensor assembly, the method comprising: moving the sensor assembly from a first configuration to a second configuration when the device is inserted into the pipe; outputting, using the sensor assembly, a plurality of ultrasonic beams; detecting, using the sensor assembly, the plurality of ultrasonic beams; receiving, by the controller, a signal from the at least one pair of sensors, the signal indicating a time elapsed between the ultrasonic beam being output and detected; and calculating, by the controller, the flow within the pipe based on the time elapsed. According to a third aspect of the disclosure, there is provided a system comprising: a plurality of devices according to claim 1, wherein the plurality of devices are installed at a predefined distance apart from one another throughout a pipe; a controller; wherein each device of the plurality of devices is configured to independently collect data, wherein the data includes calculated values of a diameter and area of the pipe, and a flow of contents of the pipe according to the method of claim 15; wherein the controller is configured to: process data from each of the plurality of devices to obtain a set of geographically matched measurements corresponding to the geographically separated plurality of devices; determine, based on the set of geographically matched measurements, differential errors in the data obtained by each of the plurality of devices; identify, based on the differential errors, trends in bulk flow and consequential differential errors for a position of each device of the plurality of devices. BRIEF DESCRIPTION OF THE DRAWINGS The disclosure is described in further detail below by way of example and with reference to the accompanying drawings, in which: Figure 1 is a diagram illustrating a device according to the current disclosure; Figure 2 is a set of diagrams showing retracted and deployed views of a device according to the current disclosure; Figure 3 is a set of diagrams illustrating an insertion mechanism of a device according to the current disclosure; Figure 4 is a diagram showing a variety of ultrasonic beam paths according to the current disclosure; Figure 5 is a diagram showing a variety of ultrasonic beam paths according to the current disclosure; Figure 6 is a diagram showing an automatic alignment function according to the current disclosure; Figure 7 is a flowchart showing a method of operating a device according to the current disclosure; and Figure 8 is a diagram showing a device according to an example of the current disclosure; Figure 9 is a diagram illustrating a device according to the current disclosure. DETAILED DESCRIPTION The current disclosure relates to an ultrasonic insertion flow measuring device for fluids and gases in conduits (for example, pipes) which incorporates several features that enable it to achieve uncertainty levels better than the current industry standard. The device consists of an ultrasonic probe that is installed in contact with the fluid or gas in the conduit through one or more under-pressure tapping points. As a result, it can be retrofitted in small spaces, using existing fittings where available, does not require the flow to be stopped or the provision of a large chamber. Configuration of set-up parameters and outputs further allows the device to be configured to work with a variety of existing communication networks and, where required, in conjunction with existing metering devices, thus reducing inaccuracy further. Figure 1 is a diagram showing a simplistic view of a device 100 according to the current disclosure. The device 100 comprises a controller 110, a sensor assembly 120, and a housing 130. The housing 130 is configured to house the controller 110 and is coupled to the sensor assembly 120. The device 100 may be at least partly inserted into a pipe during normal operation. For example, the sensor assembly 120 and part of the housing 130 may be inserted into the pipe. This is described in more detail with reference to Figure 3. The controller 110 (or processor) is configured to receive signals from the sensor assembly 120. The controller 110 may be configured to calculate qualities related to the pipe (for example, area, diameter, ovality, and the like) as well as qualities related to the liquid or gas inside the pipe (for example, hydraulic swirl, velocity, and the like) using the received signals. The controller 110 may further be configured to communicate with external devices (such as servers, computers, and the like), transmitting and receiving data. The sensor assembly 120 comprises atleast one pair of sensors 125a, 125b mounted onto each end of the sensor assembly, wherein the sensor assembly is configured to be inserted into the pipe. For example, the sensor assembly may be a beam or rod (or similar) of a particular length comprising two ends, wherein each end comprises at least one sensor mounted thereupon. That is, each pair of sensors comprises a first and a second sensor, wherein the first sensor is mounted on one end of the sensor assembly 120 and the second sensor is mounted on the other end of the sensor assembly 120. The at least one pair of sensors 125a, 125b are configured to output and receive a plurality of ultrasonic beams. For example, each individual sensor is configured to output an ultrasonic beam. The at least one pair of sensors may be configured to output the plurality of ultrasonic beams such that the beams are output at different angles to create different beam paths. The different beam paths may be used for different purposes, as discussed in more detail by reference to Figures 4 and 5. The at least one pair of sensors may optionally be configured to output and receive more than one beam path; thus, the at least one pair of sensors may be configured to output and receive two vertical beam paths and one triangle path using only one pair of sensors. The at least one pair of sensors 125a, 125b are configured to detect the plurality of ultrasonic beams. That is, each sensor is configured to detect when an ultrasonic beam has hit the sensor. For example, an ultrasonic beam may be output by a sensor at such an angle that it is caused to bounce at least once off an opposing surface of the pipe, to be received by the same or a different sensor. The receiving sensor may then detect the ultrasonic beam and determine a time elapsed from the ultrasonic beam being output to it being received (for example, a time-of-flight, ToF, measurement). The at least one pair of sensors 125a, 125b are configured to output a signal to the controller 110, the signal indicating the time elapsed between the ultrasonic beam being output and detected. The at least one pair of sensors 125a, 125b, may be piezoelectric transducers. The sensor assembly 120 and the housing 130 are coupled such that the sensor assembly 120 is able to rotate or otherwise move relative to the housing 130. That is, the sensor assembly 120 is coupled to the housing 130 such that the sensor assembly 120 is able to move from a first configuration to a second configuration when the device 100 is inserted into the pipe. For example, the device 100 maybe at least partly inserted into the pipe such that the sensor assembly is fully inserted into the pipe. At this point, the sensor assembly may move from a first configuration to a second configuration. For example, the sensor assembly may be configured to move from a folded configuration to an unfolded configuration. Figure 2 is a set of diagrams showing a more detailed view of a device according to the present disclosure. The device 200 may be the same, or similar to, the device 100 described by reference to Figure 1. Figure 2 (a) shows a retracted view of the device 200, wherein the sensor assembly 220 is in a first configuration. Figure 2 (b) shows a deployed view of the device 200, wherein the sensor assembly 220 is in a second configuration. In the shown example, the sensor assembly 220 is coupled with the housing 230 by a rotatable hinge. In the retracted view, the sensor assembly 220 is disposed such that a first part of the sensor assembly 220 is housed within an open-faced recess of the housing 230 while a second part of the sensor assembly 220 extends through and past the housing 230, such that the sensor assembly 220 is in line with the housing 230. The sensor assembly 220 may be configured such that at least one pair of sensors 225a, 225b are mounted onto each end of the sensor assembly 220. As shown, at least one sensor may be mounted onto each end of the sensor assembly. The spatial separation and geometry of the sensor layout permits the measurement of flow directly traceable to the SI specified units of temperature and time. As can be seen in Figure 2 (b), the sensors of the sensor assembly 220 may be mounted on heads 250a, 250b (or feet) that are rotatably connected to arms of the sensor assembly 220. The heads 250a, 250b maybe axially rotatable such that when the sensor assembly 220 is inserted into the pipe, the sensor assembly can sit flush with the inside of the pipe. This is described in more detail with reference to Figure 3. The heads 250a, 250b may be mechanically axially rotatable via the application of a force (for example, the application of force by the wall of the pipe as the sensor assembly 220 is moved into the second position) or the heads 250a, 250b may be electronically controlled by the controller (that is, they may be powered and controlled to move by the controller). The heads 250a, 250b may be axially rotatable up to 6 degrees in either direction. This is described in more detail in Figure 8. A controller (for example, controller 110 as described by reference to Figure 1) is housed within the housing. The controller may be housed above the sensor assembly 220. The rotatable hinge allows the sensor assembly 220 to be moved from the first configuration into the second configuration. In the second configuration, the sensor assembly 220 is disposed such that it is perpendicular to the housing 230. It should be noted that it is not necessary that the sensor assembly 220 be completely perpendicular to the housing 230. Although the device of Figure 2 is shown with a rotatable hinge, any suitable connection may be used that allows the sensor assembly 220 to move from the first configuration, in which the sensor assembly 220 is in line with the housing 230 (a vertical position), to the second configuration in which the sensor assembly is perpendicular to the housing 230. Additionally, when in the second configuration, the sensor assembly 220 may be rotatable by 180 degrees, wherein the controller is configured to control the sensor assembly 220 to obtain a plurality of signals at different positions of rotation between the first configuration and the second configuration to generate a plurality of independent measurements of the diameter of the pipe. The sensor assembly 220 may rotate around a vertical axis; for example, the vertical axis may be an axis in line with the housing 230. For example, the sensor assembly 220 may be in the second configuration and perform a first set of measurements (as described by Figures 1, 2 (a) and 2 (b)) by emitting and receiving ultrasonic beams before rotating 180 degrees and performing a second set of measurements. The axis of rotation may be offset from a central point of the sensor assembly 220 such that the second set of measurements measures a different part of the pipe than the first set of measurements. Thus, the sensor assembly 220 maybe rotated in situ through 180 degrees, allowing the generation of four independent measurements of the pipe diameter and thereby allowing for variations in diameter within the measurement area to be measured and corrected for. This minimises error in the calculation of cross sectional area and swept volume by the controller. Rotation in this plane also allows the optimal position of the device to be selected by minimising the signal-to-noise ratio. Further, wherein the controller may be configured to determine a first position within the pipe at which a signal-to-noise ratio is minimised and control the sensor assembly 220 to rotate to the first position. The first position may be determined by carrying out a plurality of calibration measurements using the sensor assembly 220 to determine a signal-to-noise ratio at various rotational positions of the sensor assembly 220; from this, an optimal position where the signal-to-noise ratio is minimised may be obtained. Figure 3 illustrates a process of inserting the device (for example, the device 100 or 200 described by reference to Figures 1 and 2) into a pipe or conduit. In step (a), a valve is attached to an opening in the pipe. In this step, the device is in a retracted position, wherein the sensor assembly 220 is in the first configuration. In step (b), the device is inserted into the pipe through the valve. In this step, the device remains in the retracted position, wherein the sensor assembly 220 is in the first configuration. In step (c), the sensor assembly 220 moves from the first configuration to the second configuration. In this step, the sensor assembly 220 may perform an alignment function to ensure that it is correctly aligned with the pipe, as described in more detail with reference to Figure 6. In step (d), the sensor assembly 220 is withdrawn (pulled upwards in the direction that the housing 230 of the device 200 extends) such that it is positioned against a wall of the pipe. The sensor assembly 220 may rotate vertically and / or longitudinally so that it can be positioned flush against the wall of the pipe. As discussed above, the positioning of the sensor assembly 220 may be improved by using (axially) rotatable heads (such as heads 250a and 250b shown in Figure 2). The axially rotatable heads may be freely rotatable such that as the sensor assembly 220 is withdrawn, the heads are able to move to accommodate the wall of the pipe. This enables optimal and stable location of the sensor assembly 220 and the sensor heads themselves against the wall of the pipe, as well as allowing better stability in the case that the wall of the pipe is uneven. Figure 4 is a diagram showing an example of a plurality of ultrasonic beams that may be output by a device according to the current disclosure (for example, any of the devices described by reference to Figures 1 to 3). In this example, the device comprises four pairs of sensors (that is, eight individual sensors wherein four sensors are mounted on each end of the sensor assembly), each configured to output / detectan ultrasonic beam at an angle configured to result in a particular beam path. These beam paths can be seen in a cross-section view of a pipe, as illustrated by Figure 5 (a). Figures 5 (b) and (c) illustrate a sensor assembly within a pipe (represented by the black box), and shows how the beams are output by the sensor assembly and are bounced off the walls of the pipe to be received again by the sensor assembly. The beam paths will now be described in more detail. One pair of sensors is configured to output and detect two vertical beam paths, wherein the vertical beam paths are output at each end of the sensor assembly. The vertical beam paths may be used to measure a diameter of the pipe. For example, based on the dimensions of the sensor assembly and a ToF measurement for each beam to leave the sensor, bounce off the opposing surface of the pipe and be detected by the sensor (which indicates a distance between the sensor and the opposing pipe surface). One pair of sensors is configured to output and detect at least one triangle beam path (although in other examples a larger number of pairs of sensors may be used to output and detect more than one triangle beam path), wherein the triangle path is configured to be output by a first sensor and bounce off an internal wall of the pipe a number of times (to create a triangle-shaped beam path), to be received by a second sensor. One pair of sensors is configured to output and detect at least one “V” (V-shaped) beam path (although in other examples a larger number of pairs of sensors may be used to output and detect more than one V beam path), wherein the V path is configured to be output by a first sensor of the pair and bounce off the wall of the pipe, to be received by a second sensor of the pair. Each pair of sensors may be configured to output both “V” shaped beam paths and vertical beam paths. The triangle beam path and the V path may both be used (individually or in combination) to perform both ToF measurements to provide additional measurements of the diameter of the pipe (in addition to the diameter measurements obtained using two vertical paths), as well as to measure a flow velocity of the contents of the pipe (which may be liquid or gas) to provide an estimate of “hydraulic swirl” or Hydraulic Index, a measure of the swirl of the contents of the pipe at the measured location which can be used to apply error correction to the signal transmitted from the sensors to the controller. The Hydraulic Index may be expressed using equation 1, where T is a triangular beam path and V is a fluid velocity: HI _ v^-v^ xV [1) In more detail, each sensor of a pair is configured to output an ultrasonic beam at an angle to result in a path of a particular shape. For example, the ultrasonic beam may be output at a specific angle (of the sensor head relative to wall of the pipe) to result in a triangle beam path (but the same applies to V paths, square paths, and hexagonal paths), and to receive (detect) the ultrasonic beam output by the other sensor of the pair. That is, two triangle beam paths are being output and detected simultaneously by the sensor pair. This allows a comparison to be made between the triangle beam path output by each of the sensors; difference between ToF measurements can be determined, as well as difference in flow velocity. By measuring the diameter of the pipe with the two vertical beams, and cross checking these measurements with the V and triangle paths, the accuracy and uncertainty of the diameter, pipe area and swept volume are calculated to a greater degree of precision Examples of angles for specific pipe diameters are as follows: Pipe diameter (mm) Angle of Sensor for “V” Path Angle of Sensor for Triangle Path 250 20.7 17.6 300 17.5 14.8 350 15 12.75 400 13.2 11.2 500 10.6 9 750 7.1 6 1000 5.4 4.5 3000 1.8 0.76 Each sensor may be triggered repeatedly (that is, to output / detect an ultrasonic beam) and may transmit data for each trigger event to the controller; this may happen at high frequency. The ToF of each ultrasonic beam, and the difference between this measurement for each of the ultrasonic beams output (of any configuration / shape) may be used to calculate a fluid flow rate using equation 2: Q = A(T_1, T_2, T_3, T_4 ) X 7(At_l, At_(2,), At_3, At_4 w(T_l, T_2, T_3, T_4 )) X (2) Wherein Q is the mass flow rate as a function of pipe area function A, a flow rate function V, and a fluid density function p(T°); wherein Tn is an average measurement of upstream and downstream transit times (a comparison between the ultrasonic beam output by each of a pair of sensors); wherein T° is a dynamically measured fluid temperature; and where V is the fluid velocity; and wherein weighting factor w(T_l, T_2,T_3, T_4) = [wl, w2, w3, w4] and adds a weighting to each At_n measurement. The weighting factor is calculated using extensive data analysis and Computational Fluid Dynamics (CFD) modelling to provide an adaptive response to a live flow profile of the pipe. To do this, models are analysed to provide an optimal weighting factor for different beam paths across a range of flows and hydraulic conditions. The use of equation 2 to calculate the fluid flow rate within the pipe, accounting for hydraulic swirl, provides a significant and substantial improvement in overcoming the uncertainty usually associated with ultrasonic transit time flow measurements. More or fewer ultrasonic beams may be used depending on the size of the pipe being used and the level of accuracy desired. The use of more ultrasonic beams results in a more accurate measurement of the pipe, and larger pipes may require the use of a larger number of ultrasonic beams to provide to increase accuracy. Figure 5 is a diagram showing an example of a plurality of ultrasonic beams that may be output by a device according to the current disclosure (for example, any of the devices described by reference to Figures 1 to 3). In addition to the beam paths described by reference to Figure 4, Figure 5 additionally includes square and hexagonal beam paths. These beam paths can be seen in a cross-section view of a pipe, as illustrated by Figure 5 (a). The device represented in Figure 5 may comprise a larger number of pairs of sensors than the device represented in Figure 4. In this example, the device comprises six pairs of sensors (that is, twelve individual sensors wherein six sensors are mounted on each end of the sensor assembly), each configured to output / detectan ultrasonic beam at an angle configured to result in a particular beam path. Figures 5 (b) and (c) illustrate a sensor assembly within a pipe (represented by the black box), and shows how the beams are output by the sensor assembly and are bounced off the walls of the pipe to be received again by the sensor assembly. One pair of sensors is configured to output and detect at least one square beam path (although in other examples a larger number of pairs of sensors may be used to output and detect more than one square beam path), wherein the square path is configured to be output by a first sensor of the pair and bounce off the wall of the pipe a number of times to create a square-shaped beam path, to be received by a second sensor of the pair. One pair of sensors is configured to output and detect at least one hexagonal beam path (although in other examples a larger number of pairs of sensors may be used to output and detect more than one hexagonal beam path), wherein the hexagonal path is configured to be output by a first sensor of the pair and bounce off the wall of the pipe a number of times to create a hexagon-shaped beam path, to be received by a second sensor of the pair. Similarly to the triangle beam path, the square and hexagonal beam paths may be used to measure a diameter and / or area of the pipe and / or additional characteristics of the pipe and the fluid flow rate of the contents of the pipe. Figure 6 illustrates an alignment function (or process) for a device according to the current disclosure (for example, any of the devices described by reference to Figures 1 to 5). Figure 6 (a) shows an example wherein a sensor assembly of the device is in a state of alignment; Figure 6 (b) shows an example wherein the sensor assembly of the device is in a state of misalignment. The alignment function comprises outputting, using a pair of sensors (a first sensor mounted on one end of the sensor assembly and a second sensor mounted on the other end of the sensor assembly), a pair of triangle beam paths. For example, the first sensor may output a first triangle beam path and the second sensor may output a second triangle beam path. The first and second triangle beam paths may be configured to provide first and second time-of-flight measurements, respectively. The first and second ToF measurements may indicate a time elapsed for the ultrasonic beam output by a first sensor (for example, the sensor 125a or the sensor 225a), bounce off a first surface of the pipe and a second surface of the pipe, and be detected by a second sensor (for example, the sensor 125b, or the sensor 225b). The two ToF measurements may then be compared to determine an angle of orientation of the sensor assembly 220 relative to the pipe. In more detail, the second ToF measurement may be subtracted from the first ToF measurement to find a difference between the two measurements. The difference between the two measurements indicates a level of alignment between the sensor assembly 220 and the pipe; for example, where there is a positive difference between the first and second ToF measurements may indicate a first direction of misalignment; and where there is a negative difference between the first and second ToF measurements indicates a second direction of misalignment, different from the first direction of misalignment. Where there is no difference between the first and second ToF measurements, the sensor assembly 220 is aligned with the pipe. Based on the comparison, the sensor assembly 220 may be adjusted such that it is aligned with the pipe. This may be done iteratively by making an adjustment, performing another ToF measurement and comparison, and determining whether to make a further adjustment based on the updated comparison. The alignment function may be automatic. Figure 7 is a flowchart showing a method of operating a device according to the current disclosure (for example, any of the devices described by reference to Figures 1 to 6). In step S710, the device is configured, via the sensor assembly, to output a plurality of ultrasonic beams. That is, at least one pair of sensors of the sensor assembly are configured to output at least two ultrasonic beams. The controller (or processor) may be configured to control the sensor assembly to output the ultrasonic beams by transmitting a control signal to the sensor assembly, the control signal instructing the sensor assembly to output a specific configuration of ultrasonic beams (for example, the control signal may indicate that the sensor assembly should output two vertical beam paths, two triangle beam paths, and a V beam path). In step S720, the device is configured, via the sensor assembly, to detect the plurality of ultrasonic beams. That is, each sensor of the sensor assembly may be configured to output and / or detect at least one ultrasonic beam. For example, one sensor of the sensor assembly may be configured to output an ultrasonic beam at an angle to achieve a triangle beam path, and may be configured to detect an ultrasonic beam output by another sensor of the sensor assembly. Alternatively, another sensor of the sensor assembly may configured to output an ultrasonic beam at an angle to achieve a vertical (or straight line) beam path and may be configured to detect that same ultrasonic beam after it has bounced off an internal surface of the pipe. In yet another example, a sensor of the sensor assembly may be configured to simply output one or more ultrasonic beams, or to simply detect one or more ultrasonic beams. Optionally, the sensor assembly may be controlled to rotate around a vertical axis by 180 degrees and perform steps S710 and S720 again in a second position. In step S730, the device is configured, via the controller, to receive a signal from the sensor assembly, the signal indicating a time elapsed between the ultrasonic beam being output and being detected (for example, a ToF measurement). The signal may further indicate a flow velocity measurement. In the case that a second set of measurements has been obtained by rotating the sensor assembly by 180 degrees, the signal may comprise the time elapsed the ultrasonic beam being output and being detected for each measurement event. The two ToF measurements maybe averaged. In step S730, the device is configured, via the controller, to calculate the flow within the pipe based on the received signal. For example, the flow may be calculated using equation 2, as discussed above. Figure 8 (a) shows a side view of the sensor assembly of the device 800, showing a sensor head 850a, 850b on each end of the sensor assembly. The device 800 may be the same or similar to the devices described by reference to Figures 1 to 7. Arrows show how the sensor heads 850a, 850b are free to axially rotate such that the sensor assembly may sit flush with the wall of the pipe. Figure 8 (b) shows an end view of a sensor head 850a, 850b of the sensor assembly, with a sensor 825a, 825b at the centre (although the sensor need not necessarily be central). Again, arrows illustrate how the sensor head 850a, 850b is free to axially rotate such that the sensor assembly may sit flush with the wall of the pipe. Figure 9 illustrates an alternative example of a device according to the current disclosure. In this example, the sensor assembly is replaced by a plurality of sensor holders (preferably two), 920a, 920b which are each separately inserted into the pipe or conduit. For example, in the case that four pairs of sensors are used with two sensor holders 920a 920b, there may be four sensors mounted on each of the sensor holders 920a, 920b. For example, the sensor holders may be placed at a predetermined distance from each other in the pipe, depending on an estimated diameter of the pipe. Preferably, the sensor holders may be positioned at a distance of between 25 and lOOcms away from one another. The sensor holders may each be connected to a controller 910 which is external to the pipe or conduit. The sensor holders function almost identically to the sensor assembly described by 5 reference to Figures 1 to 8, but provide an alternative approach which provides less intrusion into the conduit or pipe, as well as providing greater separation of the sensors which leads to reduced measurement uncertainty. The methodology and device described herein are suitable for any single-phase fluid 10 or gas in a circular duct, even in poor hydraulic conditions which would undermine the accuracy of existing flow measurement methods. It can also be noted that if multiphase flow is present, and if the flow regime is bubble flow wherein the bubble size is sufficiently small compared to the acoustic wavelength in the operation and if the void fraction is measured and received pulses are of a sufficient signal 15 strength, then the fluid flow rate may still be measured with good accuracy. Various improvements and modifications can be made to the above without departing from the scope of the disclosure.

Claims

1. A device for measuring flow of contents of a pipe, wherein the contents of the pipe is a liquid or a gas, the device comprising:a controller;a sensor assembly comprising at least one pair of sensors wherein at least one first sensor of the at least one pair of sensors is mounted onto a first axially rotating head coupled to a first end of the sensor assembly and at least one second sensor of the at least one pair of sensors is mounted onto a second axially rotating head coupled to a second end of the sensor assembly, the sensor assembly configured to be inserted into the pipe; anda housing configured to house the controller, wherein the housing is coupled to the sensor assembly;wherein the sensor assembly is configured to move from a first configuration to a second configuration when the device is inserted into the pipe;wherein the device is configured to:output, using the sensor assembly, a plurality of ultrasonic beams;detect, using the sensor assembly, the plurality of ultrasonic beams;receive, by the controller, a signal from the sensor assembly, the signal indicating a time elapsed between the ultrasonic beam being output and detected;measure, using the sensor assembly, a temperature of the contents of the pipe;calculate, by the controller, a diameter and an area of the pipe, based on the signal; andcalculate, by the controller, an orientation error and a hydraulic disturbance within the pipe based on the signal;calculate, based on the signal, the diameter of the pipe, the area of the pipe, the orientation error, the hydraulic disturbance within the pipe, and the flow of the contents of the pipe.

2. The device of claim 1, wherein the first configuration comprises the sensor assembly being positioned in line with the housing; andwherein the second configuration comprises the sensor assembly being positioned perpendicular to the housing.

3. The device of the claim 1, wherein, when in the second configuration, the sensor assembly is rotatable by 180 degrees;wherein the controller is configured to control the sensor assembly to obtain a plurality of signals at rotational positions of the sensor assembly to generate a plurality of independent measurements of the diameter of the pipe diameter.

4. The device of claims 1 and 3, wherein the controller is configured to:determine a first position within the pipe at which a signal-to-noise ratio is minimised; andcontrol the sensor assembly to rotate to the first position.

5. The device of any preceding claim, wherein the plurality of ultrasonic beams are output at different angles to achieve a plurality of beam paths;wherein each beam path is configured to provide information related to the pipe and the flow within the pipe.

6. The device of claim 5, wherein the plurality of beam paths includes at least one of: two vertical beam paths; at least one triangle beam path; at least one V beam path; at least one square beam path; and at least one hexagonal beam path.

7. The device of claim 5, wherein the plurality of beam paths includes two vertical beam paths, one V beam path, and two triangular beam paths.

8. The device of claim 7, wherein the plurality of beam paths further includes two square beam paths and two hexagonal beam paths.

9. The device of claim 6, wherein the two vertical beam paths are orthogonal to the pipe;wherein one vertical beam path is emitted from each end of the sensor assembly;wherein the two vertical beam paths are used to measure an internal diameter and area of the pipe.

10. The device of claim 9, wherein the vertical beam paths and triangle path are used to calculate a metered volume and ovality of the pipe.

11. The device of any preceding claim, wherein the sensor assembly is further configured to rotate around a vertical axis in line with the housing by 180 degrees.

12. The device of claim 11, further configured to rotate the sensor assembly by 180 degrees and output and receive a second plurality of ultrasonic beams to provide a second set of measurements;wherein the measurements include diameter, area, volume and ovality of the pipe.

13. The device of claim 5, wherein the device is configured to provide an alignment function of the sensor assembly using a first triangle beam path and a second triangle beam path;wherein the first and second triangle beam paths are configured to provide first and second time-of-flight measurement, respectively, the first and second time-of-flight measurements indicating a time elapsed for the beam to leave a sensor on one end of the sensor assembly, bounce off an internal surface of the pipe a number of times such that the beam path is triangle-shaped, and be detected by a sensor on the other end of the sensor assembly;wherein a comparison between the first and second time-of-flight measurements is used to determine an angle of orientation of the sensor assembly relative to the pipe.

14. The device of claim 13, wherein the alignment function comprises:if the comparison indicates a difference between the first and second time-of-flight measurements, it is determined that the sensor assembly is not aligned with the pipe; and adjusting the sensor assembly, based on the comparison, such that it is aligned with the pipe.

15. The device of claim 14, wherein a positive difference between the first and second time-of-flight measurements indicates a first direction of misalignment; andwherein a negative difference between the first and second time-of-flight measurements indicates a second direction of misalignment, different from the first direction of misalignment.

16. The device of any preceding claim, wherein the at least one pair of sensors are piezoelectric transducers.

17. The device of any preceding claim, wherein the sensor assembly further comprises at least one temperature sensor configured such that it is in thermal contact with the contents of the pipe.

18. The device of claims 1 and 17, wherein the combination of the temperature obtained by the at least one temperature sensor and the signal obtained by the sensor assembly are used to calculate a flow velocity and volume for the contents of the pipe;wherein the flow velocity and volume are traceable to the SI units of time and distance.

19. A method for measuring flow of liquid or gas within a pipe using a device according to claim 1, comprising a controller, a sensor assembly comprising at least one pair of sensors mounted onto each end of the sensor assembly, the sensor assembly configured to be inserted into the pipe, and a housing configured to house the controller, the housing coupled to the sensor assembly, the method comprising:moving the sensor assembly from a first configuration to a second configuration when the device is inserted into the pipe;outputting, using the sensor assembly, a plurality of ultrasonic beams; detecting, using the sensor assembly, the plurality of ultrasonic beams; receiving, by the controller, a signal from the at least one pair of sensors, the signal indicating a time elapsed between the ultrasonic beam being output and detected; and calculating, by the controller, the flow within the pipe based on the time elapsed.

20. A system comprising:a plurality of devices according to claim 1, wherein the plurality of devices are installed at a predefined distance apart from one another throughout a pipe;a controller;wherein each device of the plurality of devices is configured to independently collect data, wherein the data includes calculated values of a diameter and area of the pipe, and a flow of contents of the pipe according to the method of claim 19;wherein the controller is configured to:process data from each of the plurality of devices to obtain a set of geographically matched measurements corresponding to the geographically separated plurality of devices;determine, based on the set of geographically matched measurements, differential errors in the data obtained by each of the plurality of devices;identify, based on the differential errors, trends in bulk flow and consequential differential errors for a position of each device of the plurality of devices.A

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