PIPE CONNECTION, NAMELY PIPE ELbow

Description

[0001] The invention relates to a pipe elbow with a flow channel spanned by a jacket body and changing between two circular curvature end cross sections and with an elliptical central cross section of the flow channel having a main axis and a minor axis between the two curvature end cross sections of the flow channel, wherein the central cross section of the flow channel has a central cross-sectional area which essentially corresponds to the mean value of the two curvature end cross-sectional areas of the flow channel, wherein the ratio of the main axis aligned parallel to the curvature axis of the pipe elbow to the minor axis is in the range between 1.1 and 1.5, in particular 1.3.

[0002] US9476531B2 discloses a pipe elbow whose flow channel cross-section changes from a circular cross-sectional area of ​​a first opening via an elliptical central cross-section at the pipe bend to another circular cross-section of a second opening, with the areas of the circular cross-sections equal to the area of ​​the elliptical cross-section. The major axis of the ellipse is approximately four times larger than the minor axis. The disclosed elliptical design of the cross-sectional area can prevent turbulence in the area of ​​the pipe bend and the associated pressure losses.The disadvantage, however, is the fact that, on the one hand, large external dimensions inevitably result at the pipe bend and that the ratio of flow channel circumference to flow channel cross-section is noticeably increased in contrast to a circular design, whereby the contact area between the flowing fluid and the inside of the pipe shell is increased and thus the exact opposite is achieved, namely an increase in the pressure loss due to the enlarged shell surface in the area of ​​the elliptical central cross-section.

[0003] WO2000017562A1 shows pipe connections for particle-laden high-velocity flows. To prevent deposits at the pipe bends of the pipe connections, these also have a flow channel cross-section that changes along the flow direction. One embodiment disclosed in WO2000017562A1 represents a pipe elbow curved around a curvature axis, the flow channel cross-section of which changes from a circular flow channel cross-section, via a first asymmetrically elliptical flow channel cross-section, whose longer ellipse main axis is perpendicular to the radius of curvature, and then forms another circular flow channel cross-section. Due to this, the fluid velocity at the pipe bend is reduced, thereby reducing the collision energy of the particles and thus reducing deposition.Since the flow channel of the pipe elbow is not laterally symmetrical, optimal protection against deposits can only be achieved if the pipe connections are installed in the correct direction.

[0004] US20140202577A1 also discloses a pipe connection with a flow channel spanned by a casing body, which alternates between two circular bend end cross-sections, and with an elliptical central cross-section between the two bend end cross-sections, having a major axis and a minor axis. The central cross-section has a central cross-sectional area that essentially corresponds to the mean of the two bend end cross-sectional areas. The ratio between the major axis and the minor axis is approximately 2. This results, on the one hand, in a large outer dimension in this area and, on the other hand, in a flow channel circumference-to-flow channel cross-section ratio that requires a large contact area between the flowing fluid and the inside of the pipe casing, which in turn leads to an increase in pressure loss.

[0005] The invention is therefore based on the object of proposing a pipe connection which has a minimum resistance coefficient regardless of the installation direction, without noticeably increasing the external dimensions of the pipe connection compared to standard pipe connections.

[0006] The invention achieves the stated object in that, in order to form a circular outer dimension of the jacket body of the central cross-sectional area, the thickness of the jacket body in the extension of the major axis is smaller than the thickness in the extension of the minor axis, wherein the elliptical central cross-section of the flow channel is located exactly halfway along the flow channel spanned by the jacket body, so that the pipe connection sections adjacent to the central cross-section of the flow channel behave like an image and a mirror image, wherein the center point of the central cross-sectional area of ​​the flow channel lies in the center of the circular outer dimension of the jacket body of the central cross-sectional area, and wherein the jacket body of the curved end cross sections has a circular outer dimension.

[0007] The elliptical central cross-section is located exactly halfway along the flow channel spanned by the pipe connection's casing, so that the adjacent pipe connection sections behave like a mirror image. The central cross-sectional area forms an ellipse, and surprisingly, it has been found that particularly low pressure losses occur when the longer main axis of the ellipse is parallel to the pipe bend axis. To promote homogeneous flow velocities across the entire pipe connection, the central cross-sectional area essentially corresponds to the end cross-sectional areas of the bend. "Essential" means that the area can deviate by 5% due to manufacturing defects or the like. To enable pipe sections of different diameters to be connected, the end cross-sectional areas of the bends are not limited to having the same diameter.In this case, the central cross-sectional area is the mean value of the curvature end cross-sectional areas.

[0008] Regardless, the central cross-section has an elliptical central cross-sectional area, whereby it has surprisingly proven particularly advantageous if the ratio of the major axis to the minor axis is in the range between 1.1 and 1.5, especially 1.3. Due to this ratio, the outer dimensions of the pipe connection do not significantly exceed the dimensions of the circular bend end cross-sections, which allows, for example, the use of standardized insulation and the use of existing assembly ducts.

[0009] To enable a transition between the pipe connection according to the invention and the pipes connected to it with as little pressure loss as possible, it is proposed that transition pieces be connected to the end cross-sections of the bends, the circular flow cross-sections of which expand continuously away from the end cross-sectional areas of the bends, with the lateral surfaces that circumferentially delimit the flow channel geometrically merging continuously into one another in the longitudinal direction of the channel in the region of the abutting surfaces of the lateral body and the transition piece. This results in the streamlines of the transition piece and the lateral body forming the lateral surface of the flow channel or the flow tube having the same tangent gradient at their abutment point, thereby preventing separation of the boundary layers.

[0010] To ensure that even pipes with particularly large diameters can be connected to each other in a short distance without pressure loss, it is recommended that end pieces be connected to the transition piece ends. Their circular flow cross-sections expand continuously from the transition piece ends. The lateral surfaces that border the flow channel in the area of ​​the abutting surfaces of the transition piece and end piece merge geometrically into one another in the longitudinal direction of the channel. Particularly simple design conditions result when the flow cross-section expands continuously and strictly monotonically. To make the pipe connection as compact as possible, the increase in flow cross-section in the direction of the pipe axis per unit length can be greater in the end piece than in the transition piece.

[0011] The drawing shows an example of the subject matter of the invention. Fig. 1 a section through an embodiment of the pipe connection according to the invention, Fig. 2 a detailed view of the Fig. 1 , Fig. 3 a section along the lines III-III of the Fig. 1 , Fig. 4 a section along the lines IV-IV of the Fig. 1 and Fig. 5 a section along the lines VV of the Fig. 1 .

[0012] An embodiment of the pipe connection according to the invention, a pipe elbow, has, as shown in Fig.1 shown, has a jacket body 2 which is symmetrical with respect to a central cross-sectional area 1, to which two symmetrical transition pieces 3 are connected at the end section, which in turn geometrically continuously transition into end pieces 4 and thus span a flow channel 5 for a fluid. The central cross-section has, as shown in the Fig. 5 As can be seen, it has an elliptical central cross-sectional area, which results in particularly favorable properties with regard to flow conditions and reduces pressure losses. The elliptical central cross-sectional area 1 is arranged in the flow channel 5 such that the longer main axis 6 of the ellipse is aligned parallel to the axis of curvature 7, which is perpendicular to the plane of the drawing. The casing body 2 has, at its transition to the transition pieces 3, circular curvature end cross-sections 8, the areas of which are essentially the same size as the central cross-sectional area 1. The flow channel cross-section of the transition pieces 3 widens towards the end pieces 4.The continuously expanding flow channels of the connecting pieces 3 are delimited by streamlines corresponding to a circular path section with radius R ue , whereby the streamlines of the flow channel of the connecting pieces 3 geometrically merge continuously into the streamlines of the flow channel of the casing body 2 and therefore have the same tangent gradient at their point of contact. The center of the circle with radius R ue lies in a plane spanned by the end cross-section of the curvature 8. According to the embodiment according to . Fig. 1 End pieces 4 can be connected to the transition pieces 3, the circular flow cross-section 9 of which expands continuously away from the ends of the transition pieces, whereby the streamlines of the flow channel of the end pieces 4 also merge geometrically continuously into the streamlines of the flow channel of the connecting pieces 3. The streamlines of the flow channel of the end pieces 4 correspond to a circular path section with the radius R e , which is smaller than the radius R ue , resulting in a larger increase in flow cross-section in the direction of the pipe axis per unit of length. The center of the circle with the radius R e lies in a plane spanned by the flow cross-section 9. The end pieces preferably form sleeves, are used to hold pipes and are intended to ensure a clean, turbulence-free transition between the pipe and the respective pipe connecting piece, in this case a pipe elbow.

[0013] Application example: Representative examples of a pipe connection according to the invention, here pipe elbows RK1 and RK2, for connecting pipes with a pipe diameter of 20mm are given below, whereby the reference symbols listed here correspond to the reference symbols of the Fig. 1 The invention is not limited to this embodiment, but also encompasses pipe elbows of other pipe diameters, such as 16, 25, and 32 mm. All dimensions mentioned are given in mm or mm 2<. Variante d 0 A 0 d 1 A 1 R e d 2 A 2 R ue a b A 3 R m RK 1 12,348 119,752 10,827 92,067 26 9,7 73,898 445,795 11,1 8,5 74,102 17,02 RK2 12,72 127,076 11,62 106,048 20 11,36 101,355 943,6 13 10 102,1 17,983

Claims

1. Pipe elbow with a flow channel (5) which changes between two circular curvature end cross-sections (8) and is spanned by a jacket body (2), and with an elliptical central cross-section of the flow channel (5) between the two curvature end cross-sections (8) of the flow channel (8), which central cross-section has a main axis (a) and a secondary axis (b), the central cross-section of the flow channel (5) having a central cross-sectional area (1) which essentially corresponds to the mean value of the two curvature end cross-sectional areas of the flow channel (5), the ratio of the main axis (a), which is aligned parallel to the axis of curvature (7) of the pipe elbow, to the secondary axis (b) being in the range between 1.1 and 1.5, in particular 1.3, characterized in that in that, in order to form a circular outer dimension of the jacket body (2) of the central cross-sectional area (1), the thickness of the jacket body in the extension of the main axis (a) is smaller than the thickness in the extension of the secondary axis (b), wherein the elliptical central cross-section of the flow channel (5) is located exactly halfway along the flow channel (5) spanned by the jacket body (2), so that the pipe connection sections adjacent to the central cross-section of the flow channel (5) behave like an image and mirror image, wherein the center of the central cross-sectional area (1) of the flow channel (5) lies in the center of the circular outer dimension of the jacket body (2) of the central cross-sectional area (1), and wherein the jacket body (2) of the curvature end cross-sections (8) has a circular outer dimension2. Pipe elbow according to claim 1, characterized in that the curvature end cross-sections (8) are adjoined by transition pieces (3) whose circular flow cross-section (9) widens continuously away from the curvature end cross-section surfaces, the circumferential surfaces bounding the flow channel (5) merging geometrically continuously into one another in the longitudinal direction of the channel in the region of the joint surfaces of the jacket body (2) and transition piece (3).

3. Pipe elbow according to claim 2, characterized in that the transition piece ends are adjoined by end pieces (4) whose circular flow cross-section (9) widens continuously away from the transition piece ends, the circumferential surfaces bounding the flow channel (5) merging geometrically continuously into one another in the longitudinal direction of the channel in the region of the joint surfaces of the transition piece (3) and end piece (4).

4. Pipe elbow according to claim 2 or 3, characterized in that the flow cross-section (9) expands strictly monotonically and continuously.

5. Pipe elbow according to claim 3 or 4, characterized in that the increase in flow cross-section in the direction of the pipe axis per unit length is greater in the end piece (4) than in the transition piece (3).