Streamlined crescent rib and method of construction thereof

Abstract

The application discloses a streamlined crescent rib and a construction method thereof, and relates to the field of crescent rib structures. The crescent rib has two parts which are symmetrical about a median plane. The crescent rib comprises an upper side, a lower side, an inner side and an outer side. The edge line of the upper side is curve three and curve two. The edge line of the lower side is curve four and curve one. A line intersecting the median plane and the lower side is taken as a polar axis of a plane polar coordinate, and the lower side is taken as a coordinate plane. From the median plane to an end, the projection of curve one, curve two, curve three and curve four on the coordinate plane is as follows: curve three coincides with curve four, the polar angle of curve one, curve two, curve three and curve four gradually increases, and the polar radius gradually decreases; the polar radius of curve two on the polar axis is equal to that of curve one, and the polar radius of curve two is greater than that of curve one on any non-polar axis. The application can reduce turbulent kinetic energy in a flow channel, reduce vortex and pressure pulsation, reduce the peak stress of the crescent rib, and significantly prolong the fatigue life of the structure.

Description

Technical Field

[0001] This invention relates to the field of crescent rib structures, and in particular to a streamlined crescent rib and its construction method. Background Technology

[0002] The water distribution ring pipe is mainly responsible for evenly distributing the water flow to the nozzles of the branch pipe. It is an important water intake component of the impulse turbine. The crescent rib is installed at the junction of the water distribution ring pipe and the branch pipe to guide the water flow so that it enters the runner in a uniform and stable state. Its structural design is a key factor in the efficient and stable operation of the impulse turbine generator set.

[0003] Currently, the crescent-shaped rib structure of the water distribution ring pipe is determined by the shape profiles of the inner and outer edges, such as... Figure 1 As shown, the design method is as follows: 1. Determine the curve of the outer edge, which is an elliptic curve; 2. Determine the inner edge curve, which has no specific shape and is of the type of elliptical curve, parabola, or polyline composed of a straight line and a circular arc; 3. Connect the endpoints of the inner and outer edges of the curve to form a closed geometry. Stretch the curve symmetrically along the plane normal vector direction to a certain thickness to obtain the crescent rib structure. The two inner edge curves are parallel, and the two outer edge curves are also parallel.

[0004] The existing crescent-rib structure is prone to flow separation, resulting in head loss and stress concentration effects. It also has weak structural strength and large overall deformation of the water distribution ring pipe. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems by providing a streamlined crescent rib and its construction method, which can reduce turbulent kinetic energy within the flow channel, decrease eddies and pressure pulsations, reduce peak stress of the crescent rib, and significantly extend the fatigue life of the structure.

[0006] The technical solution adopted in this invention is as follows: A streamlined crescent-shaped rib, the crescent-shaped rib having two symmetrical parts about the mid-plane; the crescent-shaped rib includes an upper side and a lower side in the thickness direction, as well as an inner side and an outer side; the outer edge of the upper side is curve three, and the inner edge is curve two; the outer edge of the lower side is curve four, and the inner edge is curve one; the line intersecting the mid-plane and the lower side is taken as the polar axis of the planar polar coordinates, and the lower side is the coordinate plane of the planar polar coordinates; the projection of curves one, two, three, and four onto the coordinate plane from the mid-plane to the end is as follows: Curve 3 coincides with curve 4, and the polar angles of curves 1, 2, 3, and 4 are gradually increasing, while the polar radii are gradually decreasing. The polar radius of curve 2 is equal to that of curve 1 on the polar axis, and on any non-polar axis, the polar radius of curve 2 is greater than that of curve 1.

[0007] Furthermore, curves one and two have rounded corners, the radius of which gradually decreases from the mid-plane to the end of the crescent rib, and the diameter of the rounded corner at the mid-plane is the distance between curves one and two at the mid-plane.

[0008] Furthermore, the outer surfaces at both ends of the crescent rib are cut with flat surfaces.

[0009] A method for constructing a crescent-shaped rib, comprising the following steps: S1: Determine the profiles of curves 1, 2, 3, and 4; S2: Fill the sides with the curve as the edge and sew the ends to complete the rough construction of the crescent rib; S3: Round off the corners of curves 1 and 2 to complete the construction of the crescent rib.

[0010] Furthermore, in step S1, according to the principles of hydrodynamics, the coordinate points of curve 1, curve 2, curve 3, and curve 4 are obtained through numerical simulation using the Navier-Stokes equations, and curve 1, curve 2, curve 3, and curve 4 are obtained by fitting the coordinate points.

[0011] Further, in step S2, the inner side is filled with curves 1 and 2 as edges, the upper side is filled with curves 2 and 3 as edges, the outer side is filled with curves 3 and 4 as edges, and the lower side is filled with curves 1 and 4 as edges; after each side is filled, the ends are sewn together.

[0012] Furthermore, in step S3, the mid-plane is first rounded, and then rounded from the mid-plane to the end along curve 1 and curve 2, with the radius of the rounded corners gradually decreasing and transitioning smoothly.

[0013] Furthermore, after completing step S3, the outer surfaces of the two ends of the crescent rib are cut into planes according to the transport dimensions.

[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: This invention optimizes the radius of curvature of the ribs by setting specific inner surfaces and specific rounded corners, which can effectively reduce turbulent kinetic energy in the flow channel, reduce eddies and pressure pulsations, reduce peak stress of the crescent ribs, and significantly extend the fatigue life of the structure. Attached Figure Description

[0015] The present invention will be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the existing crescent-shaped rib structure; Figure 2 This is a schematic diagram of the structure of the crude embryo disclosed in this invention; Figure 3 This is a schematic diagram of the structure of the present invention; Figure 4 This is a schematic diagram of the installation of the present invention; Figure 5 for Figure 4 Cross-sectional view along the AA direction; Figure 6 for Figure 4 Cross-sectional view along the middle BB direction; Markings in the diagram: 1-Curve 1; 2-Curve 2; 3-Curve 3; 4-Curve 4; 5-Upper side; 6-Inner side; 7-Outer side; 8-Mid-plane; 9-Rounded corner; 10-Plane; 11-Main pipe; 12-Branch pipe; 13-Crescent rib. Detailed Implementation

[0016] In the description of this specification, it should be noted that if terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," or "outer" appear to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, they are only for the convenience of describing this specification and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this specification.

[0017] Furthermore, the use of terms such as "horizontal" or "vertical" in this specification does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0018] In the description of this specification, it should also be noted that, unless otherwise expressly specified and limited, the terms “set up,” “install,” “connect,” and “link” should be interpreted broadly. For example, a link can be a fixed link, a detachable link, or an integral link; it can be a mechanical link or an electrical link; it can be a direct link or an indirect link through an intermediate medium; it can be a connection within two components.

[0019] Example 1 like Figures 2-6As shown, a streamlined crescent-shaped rib 13 has a crescent shape and two symmetrical parts about the mid-plane 8. The crescent-shaped rib 13 includes an upper side surface 5 and a lower side surface in the thickness direction, as well as an inner side surface 6 and an outer side surface 7. The outer edge of the upper side surface 5 is curve 3, and the inner edge is curve 2. The outer edge of the lower side surface is curve 4, and the inner edge is curve 1. The line intersecting the mid-plane 8 and the lower side surface is taken as the polar axis of the polar coordinate system of plane 10, and the lower side surface is the coordinate plane of the polar coordinate system of plane 10. The projections of curve 1, curve 2, curve 3, and curve 4 onto the coordinate plane from the mid-plane 8 to the end are as follows: Curve 3 coincides with curve 4, and the polar angles of curves 1, 2, 3, and 4 are gradually increasing, while the polar radii are gradually decreasing. The polar radius of curve 2 is equal to that of curve 1 on the polar axis, and on any non-polar axis, the polar radius of curve 2 is greater than that of curve 1.

[0020] It can be determined that, viewed from above, the crescent shape shows that curves 3 and 4 coincide, and curve 2 lies between curves 1 and 3. Along any polar angle, the cross-section is a right trapezoid, with the inner side 6 forming a hypotenuse. When assembling the crescent rib 13 on the water distribution ring pipe, it is assembled with the inner side 6 facing the incoming flow direction, the upper side 5 close to the main pipe 11, and the lower side close to the branch pipe 12. When the water flowing from the main pipe 11 meets the inner side 6 of the crescent rib 13, due to the slope formed by the inner side 6, the water is divided into two parts by the lower side: one part is close to the main pipe 11, and the other part is close to the branch pipe 12. The water close to the main pipe 11 flows down the slope and remains in the main pipe 11, flowing to the next water distribution section. The water close to the branch pipe 12 enters the branch pipe 12.

[0021] It can be seen that during the above process, the incoming water will flow down the slope, which can effectively reduce the turbulent kinetic energy in the flow channel and reduce eddies and pressure pulsations.

[0022] Example 2 Based on Example 1, further feasible implementation methods are proposed.

[0023] In one feasible implementation, there are fillets 9 at curve 1 and curve 2. The radius of the fillet 9 gradually decreases from the mid-plane 8 to the end of the crescent rib 13, and the diameter of the fillet 9 at the mid-plane 8 is the distance between curve 1 and curve 2 at the mid-plane 8. By rounding the crescent rib 13 in this way, the flow effect around the cylinder can be weakened, pressure pulsation can be further reduced, stress concentration can be improved and the peak stress of the crescent rib 13 can be reduced, and the fatigue life of the structure can be significantly extended.

[0024] In one feasible implementation, the outer surfaces 7 at both ends of the crescent rib 13 are cut with planes 10 to facilitate transportation and installation and avoid spatial interference.

[0025] Example 3 like Figures 2-3 As shown, a method for constructing a crescent-shaped rib 13 includes the following steps: S1: Determine the profiles of curves 1, 2, 3, and 4. Based on hydrodynamic principles, obtain the coordinates of curves 1, 2, 3, and 4 through numerical simulation using the Navier-Stokes equations. Fit these coordinates to obtain curves 1, 2, 3, and 4. The coordinates of curves 1, 2, 3, and 4 are in a Cartesian coordinate system. A portion of the coordinates from the mid-plane 8 to one of the end faces are shown below:

[0026] S2: Fill the sides with curves as edges and suture the ends to complete the rough construction of the crescent rib 13; fill the inner side 6 with curve 1 and curve 2 as edges, fill the upper side 5 with curve 2 and curve 3 as edges, fill the outer side 7 with curve 3 and curve 4 as edges, and fill the lower side with curve 1 and curve 4 as edges; after filling each side, suture the ends.

[0027] S3: Round the corners of curve 1 and curve 2 to complete the construction of the crescent rib 13. First, round the corners of the middle surface 8, and then round the corners from the middle surface 8 to the end along curve 1 and curve 2. The radius of the rounded corners 9 on curve 1 and curve 2 gradually decreases from the middle surface 8 to the end and smoothly transitions with the rounded corners 9 at the middle surface.

[0028] Furthermore, after completing step S3, the outer surfaces 7 at both ends of the crescent rib 13 are cut into planes 10 according to the transport dimensions.

[0029] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A streamlined crescent-shaped rib, characterized in that: The crescent rib (13) has a crescent shape and two symmetrical parts about the mid-plane (8). The crescent rib (13) includes an upper side (5) and a lower side in the thickness direction, as well as an inner side (6) and an outer side (7) on the inside. The outer edge of the upper side (5) is curve three (3), and the inner edge is curve two (2). The outer edge of the lower side is curve four (4), and the inner edge is curve one (1). The line intersecting the mid-plane (8) and the lower side is taken as the polar axis of the planar polar coordinates, and the lower side is the coordinate plane of the planar polar coordinates. From the mid-plane (8) to the end, the projections of curve one (1), curve two (2), curve three (3), and curve four (4) on the coordinate plane are as follows: Curve 3 (3) coincides with curve 4 (4), and the polar angles of curve 1 (1), curve 2 (2), curve 3 (3), and curve 4 (4) are gradually increasing, while the polar radius is gradually decreasing; The polar radius of curve 2 (2) is equal to that of curve 1 (1) on the polar axis, and on any non-polar axis, the polar radius of curve 2 (2) is greater than that of curve 1 (1); the cross section generated along any polar angle is in the shape of a right trapezoid, and the inner side (6) forms the hypotenuse; There are rounded corners (9) at curve one (1) and curve two (2). The radius of the rounded corners (9) gradually decreases from the mid-plane (8) to the end of the crescent rib (13), and the diameter of the rounded corners (9) at the mid-plane (8) is the distance between curve one (1) and curve two (2) at the mid-plane (8).

2. The streamlined crescent-shaped rib according to claim 1, characterized in that: The outer surfaces (7) at both ends of the crescent rib (13) are cut with planes (10).

3. A method for constructing a crescent-shaped rib, comprising constructing a streamlined crescent-shaped rib as described in any one of claims 1-2, characterized in that: Includes the following steps: S1: Determine the profiles of curve 1 (1), curve 2 (2), curve 3 (3), and curve 4 (4); S2: Fill the side with the curve as the edge and sew the end to complete the construction of the rough embryo of the crescent rib (13); S3: Round the corners (9) of curve one (1) and curve two (2) to complete the construction of the crescent rib (13).

4. The construction method according to claim 3, characterized in that: In step S1, according to the principle of hydrodynamics, the coordinate points of curve 1 (1), curve 2 (2), curve 3 (3), and curve 4 (4) are obtained by numerical simulation of the NS equation, and curve 1 (1), curve 2 (2), curve 3 (3), and curve 4 (4) are obtained by fitting the coordinate points.

5. The construction method according to claim 3, characterized in that: In step S2, the inner side (6) is filled with curve 1 (1) and curve 2 (2) as the edge lines, the upper side (5) is filled with curve 2 (2) and curve 3 (3) as the edge lines, the outer side (7) is filled with curve 3 (3) and curve 4 (4) as the edge lines, and the lower side is filled with curve 1 (1) and curve 4 (4) as the edge lines; after each side is filled, the ends are sewn together.

6. The construction method according to claim 3, characterized in that: In step S3, the mid-plane (8) is first rounded, and then rounded from the mid-plane (8) to the end along curve 1 (1) and curve 2 (2). The radius of the rounded corner (9) gradually decreases and transitions smoothly.

7. The construction method according to claim 3, characterized in that: After completing step S3, the outer surfaces (7) of the two ends of the crescent rib (13) are cut into planes (10) according to the transport dimensions.

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