JP4321862B2 - Cavitation stabilizer - Google Patents

Description

  The present invention relates to a ballast that is mounted on, for example, a submerged nozzle and stabilizes cavitation generated by a liquid jet from the nozzle.

  Currently, jets generated by jetting high-pressure liquid from jet nozzles are used in various technical fields such as processing devices such as cutting, emulsifying devices, and cleaning devices. Among so-called underwater jets that are injected into liquids, there are those that actively use the cavitation crushing effect that was originally supposed to be prevented in order to cause erosion to peripheral equipment (for example, Patent Documents). 1).

  Such a submerged jet generates cavitation due to a very large velocity gradient generated between the jet water and the surrounding water, and a physical phenomenon caused by the cavitation is used for a cleaning device or the like.

Japanese Examined Patent Publication No. 4-43712

  However, in an apparatus using such cavitation of an underwater jet, various piping elements are often attached to realize the layout of the piping and the function of the apparatus in the middle of the supply flow path to the injection nozzle. For example, an elbow pipe for changing the flow direction, a joint for obtaining a step, or a complex combination of these elements may be used. In particular, swivel joints that can freely change the flow path direction over 360 degrees are often used.

  In places where piping elements such as these are arranged and the flow direction is changed, the velocity distribution shape in the piping flow path changes due to the turbulence in the flow, but this change in velocity distribution is When it occurs immediately upstream of the injection nozzle in the supply flow path, it has a great influence on the cavitation itself generated in the submerged jet, and finally the performance of the apparatus also changes due to the change of the cavitation effect.

  In view of the above problems, an object of the present invention is to provide a cavitation stabilizer capable of always generating stable cavitation in an apparatus using a submerged jet flow without being influenced by a piping system.

In order to achieve the above object, a cavitation stabilizer according to the invention described in claim 1 is a cavitation stabilizer attached between a submerged spray nozzle and a pipe tip for supplying high-pressure liquid to the nozzle. The pipe is provided with a bent portion that changes the flow velocity distribution non-uniformly, accepts high-pressure liquid supplied from the pipe tip , and is reduced in diameter at a predetermined throttle ratio with respect to the opening of the pipe. The injection nozzle has a cylindrical straight passage having a cross-sectional area on the inlet side and linearly communicates with an outlet of the cylindrical straight passage, and divides the jet flow from the cylindrical straight passage into a plurality of parallel split flows. A plurality of through-flow passages that are fed into the high-pressure liquid inlet are provided on the outlet side.

  The cavitation stabilizer according to the invention described in claim 2 is the cavitation stabilizer according to claim 1, wherein the flow path lengths of the cylindrical straight passage on the inlet side and each through-passage on the outlet side are each 5 mm or more. It is characterized by being.

  The cavitation stabilizer according to claim 3 is the cavitation stabilizer according to claim 1 or 2, wherein the total flow cross-sectional area of the plurality of through-flow passages is a flow passage of the cylindrical straight passage. It is smaller than the cross-sectional area.

  Furthermore, the cavitation stabilizer according to the invention described in claim 4 is the cavitation stabilizer described in any one of claims 1 to 3, wherein the plurality of through-flow passages on the outlet side constitute the cavitation stabilizer. It consists of a plurality of circular through holes formed on the outlet side of the main body.

  Moreover, the cavitation stabilizer which concerns on invention of Claim 5 is a cavitation stabilizer of any one of Claims 1-3. WHEREIN: The some through-flow path by the said exit side is a cavitation stabilizer. It consists of a lattice space formed by a lattice-like member arranged on the outlet side of the main body to be configured.

  The present invention is mounted between a submerged jet nozzle and a pipe tip for supplying high-pressure liquid to the nozzle, accepts the high-pressure liquid supplied from the pipe tip, and has a predetermined throttle ratio with respect to the opening of the pipe. A cylindrical straight passage having a reduced cross-sectional area with a cylindrical straight passage on the inlet side and linearly communicating with the outlet of the cylindrical straight passage, and the jet from the cylindrical straight passage is divided into a plurality of parallel shunts A cavitation stabilizer provided on the outlet side with a plurality of through-flow passages to be fed to the high-pressure liquid inlet of the injection nozzle, even if a high-pressure fluid whose velocity distribution has changed through the bent portion of the pipe is supplied from the pipe tip, Due to the rectifying effect of the ballast composed of the cylindrical straight passage on the inlet side and a plurality of through-flow passages, the high-pressure fluid is supplied to the injection nozzle in a substantially uniform flow velocity distribution in the radial direction in the flow path. In jets injected in the liquid from the nozzle, good can recover the cavitation force, there is an effect that is always stable cavitation effect without resulting that by upstream piping system.

  According to the present invention, a cavitation stabilizer mounted between a submerged jet nozzle and a pipe tip that supplies high-pressure liquid to the nozzle receives high-pressure liquid supplied from the pipe tip to an inlet side to the opening of the pipe. On the other hand, it has a cylindrical straight passage having a channel cross-sectional area reduced in diameter with a predetermined throttle ratio, and communicates linearly with the outlet of the cylindrical straight passage on the outlet side from the cylindrical straight passage. The jet flow is divided into a plurality of parallel shunts and provided with a plurality of through-flow passages that feed the jet nozzle to the high-pressure liquid inlet.

  Therefore, a high-pressure fluid supplied from the pipe tip generates a flow component (hereinafter referred to as a secondary flow) in a plane perpendicular to the flow axis disturbed by the pipe bend, resulting in a non-uniform flow velocity distribution. Even if the secondary flow component develops and a large vortex flow is formed, it is supplied to the injection nozzle as a high-pressure fluid having a uniform velocity distribution and a uniform flow rate by the rectification effect of the cavitation stabilizer as described below.

  That is, first, by passing through the cylindrical straight passage from the inlet side of the ballast, the fluid is accelerated in the flow direction and the secondary flow component is relatively weakened. Only the main flow from which the vortex flow having a large peripheral speed in the outer peripheral region is eliminated by the cylindrical straight passage having a small diameter is sent to the outlet side. Furthermore, this main stream is sent to a plurality of through-flow passages on the outlet side and divided into parallel shunts, and the cross-sectional area of the flow path gradually decreases and the boundary layer of the outer periphery is blocked. The high-pressure fluid has a substantially uniform flow velocity distribution in the radial direction, and is supplied to the inlet of the injection nozzle as a high-pressure fluid having a constant flow velocity.

  The high-pressure fluid having the so-called top-hat type flow velocity distribution has a sharper velocity gradient with the surrounding fluid at the outlet of the injection nozzle than in the case of a parabolic flow velocity distribution, and can cause severe cavitation. . Therefore, even if there is a bent portion on the piping side, the high-pressure fluid having a uniform flow velocity distribution in the radial direction of the top hat type can be supplied to the injection nozzle by the presence of the ballast of the present invention. Therefore, the cavitation generating force can always be recovered and stable cavitation can be generated in the submerged jet flow from the injection nozzle.

  In order to make the high-pressure fluid have a more uniform flow velocity distribution when it is sent from the cylindrical straight passage on the inlet side to the plurality of through-flow passages on the outlet side, the total channel cross-sectional area of the plurality of through-flow passages is It is desirable to design so that it may become smaller than the channel cross-sectional area of a straight path.

  Further, the longer the straight straight passage on the inlet side and the through-flow passage on the outlet side that constitute the cavitation stabilizer of the present invention, the higher the erosion force due to cavitation, and the better the workability when using the processing apparatus. be able to. Therefore, in the present invention, it is preferable that the channel lengths of the cylindrical straight passage and each through-flow passage be at least 5 mm. More preferably, each is 10 mm or more. When the channel lengths of the cylindrical straight passage and each through-flow passage are shorter than 5 mm, it becomes difficult to recover the cavitation generating force that can sufficiently exert the erosion force.

  In such a cavitation stabilizer, the configuration on the outlet side may be any one as long as a plurality of through-flow passages are formed. For example, by forming a plurality of circular through holes on the outlet side of the main body constituting the cavitation stabilizer, a through-flow passage can be formed, and if a lattice-like member is arranged on the outlet side of the main body, it is formed on the member. The lattice space can be used as a through-flow passage.

  The outlet-side ballast main body portion where the plurality of through-flow passages are provided and the inlet-side ballast main body portion where the cylindrical straight passage is provided may be integrally formed as the same member if possible. What is formed in a separate body may be continuously arranged, and a production method capable of obtaining a cavitation stabilizer more simply and at low cost may be selected as appropriate according to the piping system actually used.

  As one embodiment of the present invention, a cavitation stabilizer provided with a through-flow passage formed by forming a circular through hole on the outlet side of the main body is shown in FIG. FIG. 1A is a side sectional view, and FIG. 1B is a front view seen from the inlet side.

  This cavitation stabilizer 1 is provided with a cylindrical straight passage 3 on the inlet side of a cylindrical main body 2 and seven through-flow passages 4 on the outlet side. In the present embodiment, these through-flow passages 4 are arranged concentrically at a central position and at five equiangular intervals on the outer periphery thereof. The total channel cross-sectional area of all the through-flow passages 4 is set smaller than the channel cross-sectional area of the cylindrical straight passage 3.

  As shown in FIG. 2, the cavitation stabilizer 1 having the above-described configuration was mounted between the tip of the right-angle bent pipe 20 having the elbow portion 21 bent at 90 degrees and the injection nozzle 10. The flow passage cross-sectional area of the inlet-side cylindrical straight through-passage 3 of the cavitation stabilizer 1 is set smaller than the flow passage cross-sectional area of the opening 22 at the tip of the pipe.

  In this piping system, the effect of cavitation generated when water was injected from the injection nozzle 10 through the cavitation stabilizer 1 was evaluated. The results are shown in Table 1 below. This evaluation was performed by measuring the amount of mass defect using the cavitation effect as the erosion (erosion) force against the aluminum plate.

  That is, an aluminum plate (material: A1050) is installed at a certain distance from the injection nozzle 10 so that the plate surface is perpendicular to the jet jet axis, and the injection is continued for 30 minutes while maintaining a constant pressure and a constant water depth. , Causing erosion to the target aluminum plate. The mass of the aluminum plate was measured in advance, and mass measurement was performed again after a predetermined time of injection treatment, and the amount of mass change before and after the treatment was used as a mass defect amount as an index of erosion power.

  In this evaluation test, the cavitation stabilizer 1 includes a cylindrical straight passage 3 having a passage cross-sectional diameter of 9.0 mm and a passage length of 5.0 mm, and each of the seven through-passage passages 4 having a passage cross-sectional diameter of 2.5 mm. It was 5.0 mm. In addition, as the injection treatment conditions at this time, the distance (standoff distance) from the outlet of the injection nozzle 10 to the aluminum plate surface was 75 mm, the nozzle diameter of the injection nozzle 10 was 2.5 mm, and the injection pressure was 4 MPa.

  Along with the above injection process, as a comparison object, when the piping system is only a straight pipe (Comparative Example 1), when only a right angle bending pipe is used (Comparative Example 2), when the cavitation stabilizer 1 is attached to a straight pipe ( Comparative example 3) was carried out under the same processing conditions. The results are shown in Table 1 below.

  As is clear from the results in Table 1, when underwater injection is performed with the right-angle bent pipe of Comparative Example 2, the erosion force seen in the case of only the straight pipe of Comparative Example 1 that is an injection without the influence of the piping system is In contrast, in the present embodiment, when the cavitation stabilizer 1 is attached to a right-angled bending pipe, the erosion force is greatly recovered. This is because the cavitation stabilizer 1 This is because the generation has stabilized. Moreover, even if this cavitation stabilizer 1 is attached to a straight pipe, it has been clarified that the erosion force is not reduced and the cavitation is not adversely affected.

  Except in the case of Comparative Example 2, all of the erosion marks clearly appeared on the aluminum plate, and the central part peculiar to the cavitation erosion of the underwater injection was not eroded, so-called donut-shaped erosion marks.

  Next, evaluation of the cavitation effect in the case where the cylindrical straight passage 3 on the inlet side and the through-flow passage 4 on the outlet side of the ballast attached to the right-angled bending pipe have different flow path lengths by the same evaluation method as described above. went. At this time, as a comparison object, when the one composed only of the portion where the cylindrical straight passage on the inlet side is formed instead of the present cavitation stabilizer 1 (Comparative Examples 11 and 12), seven on the outlet side The same evaluation was carried out for the case where only the portion formed with the through-flow passage was mounted (Comparative Example 13). In any case, the cylindrical straight passage has a common design such that the cross-sectional diameter of the channel is 9 mm, the number of through-flow passages is seven, and the cross-sectional diameter of each flow channel is 2.5 mm. The results are shown in Table 2 below.

  As is clear from the results in Table 2, the longer the cylindrical straight passage 3 and the plurality of through-flow passages 4 are, the higher the erosion force recovery force is. In addition, as shown in Comparative Example 13, erosion force recovery can be seen only with a plurality of through channels, but in this case, it is necessary to set the channel length to be very long, from the viewpoint of piping design. Not practical and not suitable for practical use.

  Further, the same flow path is obtained in the case where the ballast is configured in the reverse arrangement to the case where the cylindrical straight passage 3 is provided on the inlet side and the plurality of through-flow passages 4 are provided on the outlet side in this embodiment (Comparative Example 14). The same evaluation was made for the lengths (10 mm each) and compared. The results are shown in Table 3 below.

  As shown in Table 3, in the configuration of Comparative Example 14, that is, in the case where a plurality of through-flow passages are provided on the inlet side and a cylindrical straight passage is provided on the outlet side, some recovery of erosion force was observed. The cavitation stabilizer is not limited to that of the present embodiment type, and the configuration of the present invention in which a cylindrical straight passage is provided on the inlet side and a plurality of flow-through passages on the outlet side is seen as recovery of erosion power. It was also confirmed that it was optimal for restoring the cavitation effect.

  As shown in the above embodiments, according to the cavitation stabilizer according to the present invention, even in the case of supplying high-pressure liquid via a bent piping system such as a right-angle bent pipe, the underwater jet flow by the injection nozzle is The cavitation effect is recovered satisfactorily, and stable cavitation can always be generated without being affected by the piping system.

It is a schematic block diagram of the cavitation stabilizer by one Example of this invention, (a) is a sectional side view in the state with which the injection nozzle was mounted | worn, (b) is the front view seen from the inlet side. It is a sectional side view which shows the state with which this cavitation stabilizer was mounted | worn between the right angle bending piping and the injection nozzle.

Explanation of symbols

1: Cavitation stabilizer 2: Ballast body 3: Cylindrical straight passage 4: Through-flow passage 10: Injection nozzle 20: Right angle bending pipe 21: Elbow part 22: Opening of pipe tip

Claims (5)

A cavitation stabilizer mounted between a submerged spray nozzle and a pipe tip for supplying high-pressure liquid to the nozzle,
The pipe is provided with a bent portion that changes the flow velocity distribution unevenly,
The pipe receives a high-pressure liquid supplied from the tip of the pipe, and has a cylindrical straight passage having a cross-sectional area with a reduced diameter with respect to the opening of the pipe on the inlet side. The outlet side is provided with a plurality of through-flow passages that communicate linearly with the outlet and divide the jet flow from the cylindrical straight passage into a plurality of parallel shunts and send them to the high-pressure liquid inlet of the injection nozzle. Cavitation stabilizer.   2. The cavitation stabilizer according to claim 1, wherein the flow path lengths of the cylindrical straight passage on the inlet side and the through-flow passages on the outlet side are each 5 mm or more.   3. The cavitation stabilizer according to claim 1, wherein a total cross-sectional area of the plurality of through-flow passages is smaller than a cross-sectional area of the cylindrical straight passage.   The plurality of through-flow passages on the outlet side include a plurality of circular through holes formed on the outlet side of the main body constituting the cavitation stabilizer. Cavitation stabilizer.   The plurality of through-flow passages on the outlet side include a lattice space formed by a lattice-like member arranged on the outlet side of the main body constituting the cavitation stabilizer. The cavitation stabilizer according to item 1.

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