Flow regulator and flow measurement system

Abstract

The present invention relates to a flow regulator for regulating fluid flow, comprising a pipe element having a pipe axis and through which fluid can flow in a direction along the pipe axis; and at least one hub body which is rotationally symmetric with respect to a symmetry axis and is fixed in the pipe element such that the symmetry axis coincides with the pipe axis, wherein the hub body fixed in the pipe element has an inflow region which arches outward against the inflow direction. The present invention also relates to a flow measurement system for measuring the fluid flow through the pipe element.

Description

Field of the Invention

[0001] The present invention relates to a flow regulator for regulating fluid flow, including a pipe fitting having a pipe fitting axis, and fluid can flow through the pipe fitting along the direction of the pipe fitting axis. Background Art

[0002] In many technical fields, measurements are made in a flowing fluid (i.e., gas or liquid). For example, the flow rate of a fluid flowing in a pipe or channel can be determined by ultrasonic measurement techniques based on the transit time difference method. For example, the corresponding ultrasonic measurement device and the corresponding method described in DE10 2016 112 295 A1. The volume flow rate of the fluid flowing through the pipe can be determined based on the flow rate and the cross-section of the pipe or channel. Such volume flow measurement devices are often used to determine the delivery and / or consumption of gas or liquid in the form of a meter.

[0003] In such measurements, it is generally desirable that the flow distribution be as uniform as possible to ensure high measurement accuracy. However, in practice, there are often non-uniform or disturbed flow distributions. Nevertheless, in order to ensure the required accuracy, the flow distribution can be sampled by means of multiple measurement paths, which, however, involves a great deal of effort. Another possibility for improving the measurement accuracy includes setting a flow regulator upstream of the measurement point.

[0004] Flow regulators such as those disclosed in, for example, EP 2 607 718 A1 are used to re-regulate a disturbed flow distribution in the direction of the undisturbed flow in front of the measurement point. Known flow regulators can have plates, metal sheets, and inner pipe fittings that are oriented in the direction of the undisturbed flow. In particular, vortices in the flow can be successfully cancelled out by such components. However, the possible flow skew usually cannot be corrected by the components mentioned. In addition, it is difficult to achieve both a high regulation effect and a small pressure loss and a small structural size in practice.

[0005] Therefore, efforts are being made to achieve further improved flow regulation, especially to reduce the pressure loss and the structural size of the flow regulator for this purpose, without unwanted separation or turbulence occurring. Summary of the Invention

[0006] This object is achieved by a flow regulator for regulating fluid flow having the features of claim 1.

[0007] A flow regulator according to the invention comprises a pipe element having a pipe axis and through which fluid can flow in a direction along the pipe axis; and at least one hub which is rotationally symmetric with respect to a symmetry axis and is fixed in the pipe element such that the symmetry axis coincides with the pipe axis, wherein the hub fixed in the pipe element has an inflow region which arches outwards against the onflow direction.

[0008] Accordingly, the shape and arrangement of the hub is similar to that of the hub of a rotor; however, in contrast to such a hub, the hub is not rotatably supported but is fixed to the pipe element.

[0009] It has been found that even with a relatively short axial length, such a hub is able to produce at least a substantially uniform flow distribution and is able to eliminate disturbances regardless of the inflow characteristics. Compared with a plate having a surface normal oriented transversely to the flow direction, the hub of the flow regulator according to the invention is able to effect a radial pulse exchange and can thereby also counteract possible skewing of the flow. Since the inflow region arches outwards (i.e. bulges) against the inflow direction, the flow regulator according to the invention has a small pressure loss even when the inflow region is relatively large. Due to the short minimum length, the flow regulator according to the invention requires only little structural space. In addition, due to the small pressure loss, the energy requirement of the associated pump influencing the flow rate can be kept small. The coaxial orientation of the rotationally symmetric hub in the pipe element prevents the hub itself from generating disturbances.

[0010] A particular advantage of the invention is that the characteristic curve of the flow regulator according to the invention (which represents the mean raw error related to the volume flow rate) is relatively flat due to the hub and, in particular, does not rise steeply at low volume flow rate values as in conventional systems. This enables particularly robust measurements and is particularly advantageous for the calibration performance since complex correction functions do not have to be managed. On the contrary, in the simplest case, calibration can be accomplished by adding an offset value.

[0011] One embodiment of the present invention provides that the hub has an outer diameter measured radially with respect to the pipe axis, which outer diameter reaches at least 40%, preferably at least 50%, more preferably at least 60%, and particularly preferably at least 70% of the inner diameter of the pipe; and / or the cross-section of the inflow region reaches at least 20%, preferably at least 30%, more preferably at least 50%, and particularly preferably at least 60% of the cross-section of the pipe. In this regard, if the outer diameter of the hub and / or the inner diameter of the pipe vary along the pipe axis, the outer diameter of the hub and the inner diameter of the pipe will be determined at the same axial position, for example, at the position where the outer diameter of the hub is at its maximum. The term "cross-section" can be understood as the flow-effective cross-sectional surface or the maximum cross-section along the pipe axis. A bulky hub can, for example, break up an existing, disturbed flow distribution, thereby enabling a uniform flow distribution to be formed in subsequent pipe sections.

[0012] The hub can have a diffuser section, where the cross-section of the hub decreases in the downstream-facing direction along the pipe axis. The diffuser section causes the fluid flowing through the hub to decelerate. The diffuser section preferably extends to the downstream end of the hub. A stable flow field can be formed downstream of the hub.

[0013] According to another embodiment of the present invention, the hub is fixed in the pipe by at least one regional web (such as a plate-shaped web). In this regard, the hub can be integrally formed with the web and / or the pipe. The surface normal of the regional web is preferably oriented transversely to the pipe axis. The regional web not only holds the hub in the desired position but also cancels out vortices, i.e., it achieves a dual function. Despite the additional vortex-reducing components, the axial length of the flow regulator can be kept small.

[0014] It can be arranged that at least one regional web connects the inner wall of the pipe to the radially outer surface of the hub.

[0015] A specific embodiment provides that the hub is fixed in the pipe by a star-shaped arrangement of regional webs. This arrangement ensures secure holding and an additional flow influence that is evenly distributed along the periphery of the hub.

[0016] The inflow region can have a dome-shaped bulge. This ensures a low flow resistance of the hub and avoids eddy currents. For example, the bulge can be spherical. In this regard, the radius of curvature can be adjusted in a specific application manner. Depending on the application, for example, the inflow region can be hemispherical or slightly flat.

[0017] Another embodiment of the present invention provides that: the hub body is annular in cross-section and has a central through-channel. Thereby, a core flow is generated, which helps to form a uniform flow after the hub body. The cross-section of the hub body is preferably circular. The inflow region of the annular hub body may have a toroidal arch at least towards the inflow side. For example, the longitudinal section of the arch of one of the radial halves of the annular hub body may be semi-circular. However, other shapes are also possible.

[0018] The central through-channel may have a diameter that increases in the downstream-facing direction along the pipe axis. Such a through-channel forms a diffuser that causes the fluid flow through the channel to slow down. If, as described above, a diffuser is also formed on the radial outer side of the hub body, the central through-channel can be designed such that the velocity level of the central flow component and the velocity level of the radial outer flow component behind the hub body are approximately equal.

[0019] According to another embodiment of the present invention, a rotationally symmetric additional body is arranged coaxially with the annular hub body in the central through-channel. It has been found that such an additional body further improves the flow regulation. Similar to the hub body, the additional body may have an inflow region that arches outward against the inflow direction to maintain a low flow resistance. This means that the additional body can form another inner hub body.

[0020] The cross-section of the additional body can also be annular, preferably circular. Thereby, another internal through-channel is formed, such that the incoming flow is divided into more partial flows as a whole.

[0021] An internal through-channel can be formed in the annular additional body, and its diameter increases in the downstream-facing direction along the pipe axis. Thereby, another diffuser component that stabilizes the core flow is formed.

[0022] The hub body and the additional body together have a cross-section to which the flow can reach, and this cross-section reaches at least 30%, preferably at least 40%, and particularly preferably at least 50% of the cross-section of the pipe. Thereby, the incoming disturbed flow is decomposed particularly effectively.

[0023] A plurality of correspondingly designed additional bodies arranged coaxially with each other can generally also be arranged with respect to each other.

[0024] The inner diameter of the pipe is preferably at least 10 mm to at most 500 mm, preferably at least 20 mm to at most 200 mm. For such pipe sizes, the advantages of the flow regulator according to the present invention are particularly significant. However, the flow regulator according to the present invention can generally be scaled in a relatively wide size range in a simple manner.

[0025] According to another embodiment of the present invention, the flow regulator has a flow guiding device which is arranged downstream of the hub body (i.e., downstream of its downstream end or behind it in the flow direction), and at least includes a perforated plate, a honeycomb body, a tube bundle and / or a nozzle. By means of the perforated plate, the pulsation balance decomposition of all velocity components in the entire cross-section of the pipe fitting can be achieved. Through this decomposition, the asymmetric axial velocity distribution becomes more uniform. The perforated plate preferably has square perforations. The honeycomb body can include channels separated by thin walls and, for example, has a hexagonal cross-section. The honeycomb body has a screening effect, thus calming the flow. The contraction formed by the nozzle can have a curved or linearly sectional trend in the longitudinal section. The hub body and the flow guiding device can form an adjustment unit.

[0026] The preferred embodiment provides a flow guiding device which includes a perforated plate and a honeycomb body arranged downstream of it. It has been found that by using the combination of the hub body, the perforated plate arranged downstream of it and the honeycomb body arranged downstream of the perforated plate, the flow can be adjusted with almost no separation, so that the axial length of the flow regulator can be limited to an acceptable value.

[0027] The axial length of the flow regulator can reach at most twice the inner diameter of the pipe fitting, preferably 1.5 times the inner diameter of the pipe fitting, and / or the pressure loss coefficient can be at most 8, preferably at most 5.5. Due to the embodiments according to the present invention, a flow regulator which is particularly space-saving and / or causes particularly small pressure loss can be provided. Due to the present invention, the axial length of the flow regulator can even be kept less than the inner diameter of the pipe fitting, and nevertheless, an acceptable flow regulation can still be ensured. Due to the embodiments according to the present invention, the inlet length, i.e., the axial range of the recirculation zone existing between the last component of the flow regulator and the measurement point, can also be kept small.

[0028] The present invention also relates to a flow measurement system for measuring the fluid flow through a pipe fitting. The flow measurement system includes a measuring device and a flow regulator arranged upstream of the measuring device. The measuring device is preferably an ultrasonic measuring device, and the measuring device is used to measure the fluid (especially its flow rate). According to the present invention, the flow regulator is designed as described above in this regard.

[0029] The flow regulation achieved by the flow regulator according to the present invention reduces the interference caused by irregular flow, by vortices, by the irregular distribution of axial velocity components, or by the adverse acoustic signal effects caused by turbulence, so that the determination of the transit time difference of ultrasonic measurement can be used in a very precise manner to determine the fluid velocity.

[0030] Further developments of the present invention can also be seen from the dependent claims, the description and the drawings. Description of the Drawings

[0031] The present invention will be described below by way of example with reference to the accompanying drawings.

[0032] Figure 1 A flow regulator according to a first embodiment of the present invention is shown in a perspective view inclined from the front;

[0033] Figure 2 is a side cross-sectional view of the flow regulator according to Figure 1 ; and

[0034] Figure 3 is a side cross-sectional view of a flow regulator according to a second embodiment of the present invention.

[0035] List of reference numerals:

[0036] 11, 11’. Flow regulators; 13. Pipe fitting; 15. Axis of the pipe fitting; 17, 17’. Hub; 19. Axis of symmetry; 23. Inflow region; 25, 25’. Central through-channel; 27. Additional body; 29. Internal through-channel; 30. Web; 31. Inlet side; 32. Outlet side; 33. Inflow direction; 37. Inflow region of the additional body; 39. Diffusion part of the hub; 41. End provided downstream; 43. Step; 45. Diameter of the central through-channel; 50. Flow guiding device; 55. Hub diameter; 57. Perforated plate; 59. Honeycomb body. Detailed description of the specific embodiments

[0037] Figure 1 and Figure 2 The flow regulator 11 shown in Figure 2 includes a pipe fitting 13 which has at least a substantially straight orientation and accordingly defines a pipe fitting axis 15 (

[0038] ). The pipe fitting 13 can be inserted as an intermediate element, for example, into a flow channel (not shown) such that a fluid (preferably a gas) can flow through the pipe fitting 13 in the direction of the pipe fitting axis 15.

[0039] An annular hub 17 is provided in the pipe fitting 13. The annular hub 17 is rotationally symmetric with respect to an axis of symmetry 19 and has a domed inflow region 23. The hub 17 is positioned such that the axis of symmetry 19 coincides with the pipe fitting axis 15.

[0040] The hub 17 and the additional body 27 are fixed in the pipe fitting 13 by means of star-shaped areal webs 30. The areal webs 30 are oriented such that their surface normals face the pipe fitting axis 15 transversely. The pipe fitting 13, the webs 30, the hub 17 and the additional body 27 are preferably made of plastic. They can be formed by a single injection molding part.

[0041] The pipe fitting 13 has an inlet side 31 and an outlet side 32. During operation of the flow regulator 11, flow occurs from the inlet side 31 in the inflow direction 33 over the hub 17 and the additional body 27. In particular, as can be seen in Figure 2 , the inflow region 23 of the hub 17 facing the inlet side 31 arches outwards against the inflow direction 33. The inflow region 37 of the additional body 27 facing the inlet side 31 also arches outwards against the inflow direction 33. Thereby, a streamline shape of the hub 17 and the additional body 27 is formed.

[0042] The diffuser 39 adjoins the inflow region 23 of the hub 17 in the downstream-facing direction, in which diffuser 39 the cross-section of the hub 17 decreases continuously along the pipe fitting axis 15 as seen from the inflow direction 33. In the illustrated embodiment, a step 43 is formed at the downstream end 41 of the hub 17 and additionally generates a trailing edge effect, i.e., a break in the target flow, which can produce a minimal separation, which is then rotationally symmetric, for example in the case of a very unfavorable inflow. Thus, in the case of a very unfavorable inflow, an unduly long axial separation can also be further reduced and the global flow distribution can be further improved.

[0043] As shown, the diameter of the central through-channel 25 increases continuously in the downstream-facing direction (i.e., along the inflow direction 33) along the pipe fitting axis 15 after the inflow region 23. The diameter of the internal through-channel 29 also increases in the downstream-facing direction at least along the pipe fitting axis 15 in the subsequent part. Thus, in addition to the diffuser 39 of the hub 17, there are also two regions with a diffusing effect, namely the internal through-channel 29 and the part of the central through-channel 25 that is radially arranged outside the additional body 27.

[0044] In the illustrated embodiment, the hub 17 and the additional body 27 together have a cross-section onto which flow can reach, and this cross-section amounts to approximately 45% of the cross-section of the pipe fitting 13. The cross-section onto which flow can reach preferably amounts to at least 30% and at most 95% of the cross-section of the pipe fitting 13.

[0045] As Figure 3The flow regulator 11' shown also has a pipe member 13 including a hub body 17' disposed therein. Similar to the foregoing embodiments, the hub body 17' is annular and has a central through-channel 25'. However, no additional body is provided in the central through-channel 25'. Further, here the minimum diameter 45 of the central through-channel 25' only reaches approximately 14% of the maximum diameter 55 of the hub body 17', that is, the central through-channel 25' is relatively small.

[0046] In addition, according to Figure 3 , a flow guiding device 50 is provided in the flow regulator 11'. The flow guiding device 50 is disposed downstream of the hub body 17' and includes a perforated plate 57 and a honeycomb body 59 positioned downstream of the perforated plate 57. The combination of the hub body 17', the perforated plate 57 and the honeycomb body 59 has proven to be particularly effective in preventing separation.

[0047] In principle, Figure 1 and Figure 2 the hub body 17 including the additional body 27 shown in Figure 3 can also be combined with the perforated plate 57 and the honeycomb body 59 as shown in

[0048] In an embodiment not shown, the flow guiding device is provided with at least one downstream nozzle portion where the pipe member has a constriction. Also in an example of an embodiment not shown, the hub body does not have a central through-channel, and the inflow region has a closed dome-shaped surface.

[0049] The described flow regulators 11, 11' are used to regulate fluid flow, and for this purpose, each flow regulator is inserted into a flow channel (such as a gas pipeline). After the flow regulators 11, 11', a measuring device is provided, for example, an ultrasonic measuring device, by which the fluid throughflow flowing through the flow channel can be measured in a manner known per se.

[0050] Interferences present in the flow (such as those caused by bends or constrictions upstream of the flow regulators 11, 11') are effectively eliminated by the flow regulators 11, 11'. In this regard, the hub bodies 17, 17' decompose the disturbed flow and divide it into a core flow and one or two annular flows. When passing through the hub bodies 17, 17', due to the diffusion effect, part of the flow slows down and stabilizes. The region web 30 simultaneously reduces possible vortices. After the flow regulators 11, 11', mixing occurs, in which axial and radial pulse exchanges take place, and the flow as a whole becomes more uniform. Particularly advantageous in this regard is that with the relatively short flow regulators 11, 11' according to the present invention and a short inlet length, acceptable regulation can already be carried out while accepting a relatively small pressure loss.

Claims

1. A flow regulator (11, 11'), for regulating fluid flow, comprising: a pipe fitting (13) having a pipe fitting axis (15) and through which fluid can flow in a direction along said pipe fitting axis (15); and at least one hub (17, 17') which is rotationally symmetric with respect to a symmetry axis (19) and is fixed in said pipe fitting (13) such that said symmetry axis (19) coincides with said pipe fitting axis (15), wherein the hub (17, 17') fixed in said pipe fitting (13) has an inflow region (23) which arches outwards against the inflow direction (33), and a step (43) is formed at the downstream end of said hub (17, 17'); wherein said hub (17, 17') has a diffuser portion (39), wherein the cross-section of said hub (17, 17') decreases in the downstream-facing direction along said pipe fitting axis (15), and wherein said diffuser portion (39) adjoins said inflow region (23) of said hub (17, 17') in the downstream-facing direction.

2. The flow regulator according to claim 1, characterized in that The hub (17, 17') has an outer diameter (55), the outer diameter (55) being measured radially with respect to said pipe fitting axis (15), and the outer diameter reaching at least 40% of the inner diameter of said pipe fitting (13); and / or wherein, the cross-section of said inflow region (23) reaches at least 20% of the cross-section of said pipe fitting (13).

3. The flow regulator according to claim 2, characterized in that, The outer diameter (55) reaches at least 50% of the inner diameter of said pipe fitting (13).

4. The flow regulator according to claim 2, characterized in that The outer diameter (55) reaches at least 60% of the inner diameter of said pipe fitting (13).

5. The flow regulator according to claim 2, wherein, The outer diameter (55) reaches at least 70% of the inner diameter of said pipe fitting (13).

6. The flow regulator according to claim 2, wherein, The cross-section of said inflow region (23) reaches at least 30% of the cross-section of said pipe fitting (13).

7. The flow regulator according to claim 2, wherein The cross-section of said inflow region (23) reaches at least 50% of the cross-section of said pipe fitting (13).

8. The flow regulator according to claim 2, wherein, The cross-section of said inflow region (23) reaches at least 60% of the cross-section of said pipe fitting (13).

9. The flow regulator according to claim 1, wherein The hub (17, 17') is fixed in said pipe fitting (13) by at least one region web (30).

10. The flow regulator according to claim 9, characterized in that, The hub (17, 17') is fixed in said pipe fitting (13) by a star-shaped arrangement of region webs (30).

11. The flow regulator according to claim 1, wherein, The inflow region (23) has a dome-shaped arch.

12. The flow regulator according to claim 1, wherein, The hub (17, 17') is annular in cross-section and has a central through-channel (25, 25').

13. The flow regulator according to claim 12, wherein The central through-channel (25, 25') has a diameter which increases in the downstream-facing direction along said pipe fitting axis (15).

14. The flow regulator according to claim 12 or 13, characterized in that, A rotationally symmetric additional body (27) is coaxially arranged in said central through-channel (25) with the annular hub (17).

15. The flow regulator according to claim 14, characterized in that, The additional body (27) is also annular in cross-section.

16. The flow regulator according to claim 15, wherein, An internal through-channel (29) is formed in the annular additional body (27), and the diameter of said internal through-channel (29) increases in the downstream-facing direction along said pipe fitting axis (15).

17. The flow regulator according to claim 1, wherein, The flow regulator (11’) has a flow guiding device (50), which is arranged downstream of the hub body (17’) and at least includes a perforated plate (57), a honeycomb body (59), a tube bundle and / or a nozzle.

18. The flow regulator according to claim 17, characterized in that, The flow guiding device (50) includes a perforated plate (57) and a honeycomb body (59) arranged downstream of the perforated plate (57).

19. The flow regulator according to claim 1, characterized in that The axial length of the flow regulator (11, 11’) reaches at most twice the inner diameter of the pipe fitting (13), and / or the pressure loss coefficient of the flow regulator (11, 11’) reaches at most 8.

20. The flow regulator according to claim 19, wherein, The axial length of the flow regulator (11, 11') reaches at most 1 1 / 2 times the inner diameter of the pipe fitting (13).

21. The flow regulator according to claim 19, wherein, The pressure loss coefficient of the flow regulator (11, 11’) reaches at most 5.

5.

22. A flow measurement system for measuring the fluid flow through a pipe fitting, the flow measurement system comprising: Measuring device for measuring the fluid; and a flow regulator arranged upstream of the measuring device, characterized in that the flow regulator (11, 11’) is designed according to any one of claims 1 to 21.

23. The flow measurement system according to claim 22, wherein, The measuring device is an ultrasonic measuring device.

24. The flow measurement system according to claim 22, characterized in that, The measuring device is used to measure the flow rate of the fluid.

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