WO2020096554A1

WO2020096554A1 - Small dimples with regular shape reducing regional losses on a top surface of a butterfly valve disc

Info

Publication number: WO2020096554A1
Application number: PCT/TR2019/050927
Authority: WO
Inventors: Ahmet Ozan CELIK; Canberk INSEL
Original assignee: Anadolu Universitesi
Priority date: 2018-11-06
Filing date: 2019-11-06
Publication date: 2020-05-14

Abstract

A I body front surface applicable to existing discs for reducing regional load losses on the disc body of butterfly valves and manipulating the flow structures acting on the drag force by conditioning the flow to be formed on the top surface of the valve when the valve is fully open.

Description

SMALL DIMPLES WITH REGULAR SHAPE REDUCING REGIONAL LOSSES ON A

TOP SURFACE OF A BUTTERFLY VALVE DISC

Related Technical Field

The present invention relates to a novel body front surface applicable to existing discs for reducing regional load losses on the disc body of butterfly valves when the valve is fully open .

State of the art

The butterfly valve is a multi-directional type of valve used for opening and closing and also adjusting water flow of water sources. They have achieved extensive usage in a short span of time since they were first designed in 1960s thanks to their properties such as occupying small spaces on the pipeline, excellent sealing, being easily and cost-efficiently adaptable to automation, and providing sealing in both directions. Butterfly valves have a wide application area including heating systems, ventilation and air conditioning systems, water industry and distribution systems, mining industry, ship building and drilling facilities, chemical and petrochemical plants, sugar industry, food and chemical enterprises, oil and gas processes. Butterfly valves are manufactured to have double flanges, and their discs are perpendicular to the flow axis in the closed position. Closing or opening is done by turning the disc at 90°. Valves are provided so as to resist the maximum operating pressure, including impact pressures. Large-diameter butterfly valves are provided with a by-pass system, especially if they are not motorized, since it would be rather difficult to open the valve due to the high pressure on one side, especially with the large pressure values. By means of the by-pass system, water is transferred to the other side of the valve by opening a small diameter sliding valve thus providing a two-way pressure balance on the by-pass line so that the butterfly valve is readily opened.

Butterfly valves consist of a valve body, a disc, a shaft and a sealing member. Discs are usually manufactured by casting and are designed to show minimum resistance to flow and are rounded at their edges. The valve disc moves from fully open to closed state by a 90° angle and the valve seat is designed to be perpendicular to the pipe axis. The top (or side) surfaces of the discs are manufactured generally flat, and in some cases inclined to be streamlined. Regional load losses on the disc body that occur when the valve is fully open are referred as undesirable losses in the state of the art.

Butterfly valve discs available in the state of the art are manufactured generally flat, and in some cases inclined to be streamlined, due to this geometry in the field of application, it is known that this hydrodynamic structure of the disc is not compatible with the basic scientific hydrodynamic principles. The formation of flow separation in the disc and the formation of undesired vortices due to this separation is another problem due to this geometry of the disc. Furthermore, the problems such as high drift coefficient of the disc, high torque of the disc spindle due to high drag force and difficult opening and closing operations of the disc due to these forces, high vibration of the disc and inability to distribute the fluid pressure load of the disc homogeneously are the major current problems of the butterfly valves.

Emergence of excessive pressure differences due to geometry of the disc leads to low safety factor of the disc in terms of strength and to requirement of high forces for opening and closing operation and causes regional load losses occurred when the valve is fully open. In an installment, each member through which the fluid passes cause a portion of the energy of the fluid to be lost. This energy is expressed as the regional load loss coefficient, defined as the ratio of load loss to speed load.

In the state of the art, in the patent application No. US3960177, a butterfly valve disc with generally oval plane surface, arranged in a tilting manner so that the outer periphery forms a perfect circle intersecting with the inner bore of a butterfly valve .

The patent application numbered TR 2016/12807 discloses a valve disc mounted to swivel about an axis of rotation inside a housing and torsionally rigidly connected to a drive shaft pivotably mounted inside the housing. In said invention, geometric studies have been carried out on said valve disc.

The patent application numbered TR 2016/12505 discloses a valve disc with a disc-like valve body, which has a front with two protruding hubs and a back opposite the front. In order to permit improved flow around the valve disk and reduction of eddies on the outflow side, arc-like dimples running along an inside surface of both hubs are arranged on the front of valve body to deflect the flow around hubs.

Although inventions have been made in order to solve some of the problems occurring on butterfly valves in works available in the state of the art, the solutions provided in the state of the art are insufficient to minimize the regional energy losses. These solutions are generally considered to be providing solutions in the manner such that the disc bodies are streamlined. The solutions suggested have disadvantages such as the complete change of existing production patterns (large investment costs), as well as the increase in the weight of the valve itself, although it is predicted to be effective in the art. The energy loss that would occur in the members such as valve causing regional energy loss is known to arise because of the fact that flow lines change direction and are degraded. Therefore, minimizing the loss of terrestrial energy, realizing the design that will cause minimum distortion of the flow lines have led to the subject matter solution. The solution also manipulates the flow structures acting on the drag force by conditioning the flow to be formed on the top surface of the valve .

Brief Description and Objects of the Invention

The present invention relates to a novel body front surface applicable to existing valve discs on the upper portion of disc body of butterfly valves for reducing regional load losses when the valve is fully open.

The inventive valve disc and the top surface of the valve disc are made by regulating complex flow structures which cause losses in the flow (pressure drop) by forming dimples on the top surfaces of the existing bodies. The dimples are able to operate with different efficiency in different lengths and geometric shapes. These dimples can be formed by various methods in existing valve discs. Existing molds can be used with additional parts for the recesses. By using a standard valve disc mold, a more efficient valve disc can be reproduced so that its efficiency is increased, and its weight is reduced by 0.1-0.3%, without any reduction in its strength.

Description of the Figures

Figure 1 illustrates the top view of front surface of the valve disc Figure 2 illustrates the pressure change graph for a 80- diameter length pipe which is an exemplary study showing the pressure difference for the front surface of valve disc that is flat in structure and has recesses .

Description of References in Figures

10. Valve Disc

11. Body Front Surface

111. Dimple 13. Shaft Housing

131. Tie Piece

Description of the Invention

The present invention relates to a novel body front surface (11) applicable to existing valve discs on the disc (10) body of butterfly valves for reducing regional load losses when the butterfly valve is fully open.

The valve disc (10) is in the form of a disc and has dimples (111) formed from cavities of the same and/or different geometrical shapes on the body front surface (11), allowing the flow lines to continue in the flow path without changing direction and minimizing the regional load losses. On the body front surface (11), there are two shaft housings (13) in which the valve disc (10) is connected with the butterfly valve and in which the shaft is positioned when the valve disc (10) rotates around it during its opening and closing. The shaft housings (13) are positioned on the body front surface (10) so as to be close to the outer wall of the body of valve disc (10) and to correspond each other. There is tie piece (131) which the limit shaft housing (13) and support the shaft housing (13) so that the shaft housings (13) bear the shaft which is passed through it and that the shaft remains in the shaft housing (13) and does not move on the valve disc (10) . Said tie piece (131) closes the open base of the shaft housing (13) ensuring that the shaft is positioned in the shaft housing (13) .

Fluids exert a force on the objects they encounter during their flow. When the valve disc (10) is closed, the fluid from the pipe applies pressure to the body front surface (11) . When the valve disc (10) moves from the closed position with an angle of 90°, it goes open and the body front surface (11) is positioned to be in the same plane as the movement direction of the fluid inside the pipe. In this case, the fluid continues to flow by contacting the body front surface (11) of the valve disc (10) . When the butterfly valve is in the open position, it is desired that the movement of the fluid through the pipe around the valve disc (10) is fully symmetrical and does not change the flow.

Due to fluid hitting the valve disc (10) which is open, flow irregularities arise resulting from the fact that fluid contacts with body front surface (11) of the valve disc (10) . This causes the fluid to exert no equal pressure on the body front surface (11) where the fluid hits the valve disc (10) located on the fluid path and causes the flow lines to change their direction and failure. Namely, when the butterfly valve is open, regional load losses are experienced.

In the structure of the inventive valve disc (10) developed, dimples (111) in the form of pit/cavity are formed on entire or on a certain portion of the body front surface following the body front surface (11) . By means of the dimples formed in the shape of pit/cavity inwardly from the body front surface (11) of the valve disc (10), it is ensured that the turbulence area where the fluid contacting the surface of the valve disc (10) is irregular is minimized. The valve disc having dimples (111) in the form of pit/cavity at its body front surface (11), creates a wall effect providing less dragging force in total and less disturbance to the flow because of its effects on both viscous forces and shape dragging.

The surface of the turbulence where the air flow is irregular is thinner on golf balls having dimples on its surface. In this case, since the frictional force acting on the golf ball with dimples on its surface is lower it can reach a greater distance than the ones having smooth surface. Analogously with this example, the structure of the flow on the plane (normally flat) or inclined surface where the dimple geometry is created is modified by the dimple geometry. The time-varying turbulent flow structure that causes losses is controlled by means of this modification and the dimensions of the flow structures that may occur on a larger scale in size are kept close to the dimple sizes. Another effect is the time-varying and elusive flow structure in the boundary layer flow which develops in the same plane becomes regulated under the guidance of the recesses. The effect of the dimples on the flow and the interaction of each effect with each other on the valve disc constitute this regular and controlled flow structure.

As a result of this operation principle, by means of body front surface (11) of the inventive valve disc (10) developed, an exemplary study has been carried out for showing the difference of regional load losses compared to ones occurred on flat structured valve disc body, wherein a valve disc (10) having dimples (111) and a flat structured valve disc (10) are separately used inside a pipe having 80 diameter length. Compared to the body of the valve disc (10) in the flat structure, the body front surface (11) of the valve disc (10) having dimples (111) minimizes the turbulence zone in which the fluid is irregular and ensures that the flow lines continue in the flow path without changing direction, wherein as shown in Figure 2, the valve disc (10) exerts pressure on the body front surface (11) of the fluid coming from the pipe, and when it becomes open moving at an angle of 90° from closed state (horizontal "0") the pressure difference of the body front surface (11) is decreased. The results illustrated in Figure 2 were achieved using the standard butterfly valve disc with DN1800 nominal diameter and the CFD method.

One of the biggest problems that the invention aims to solve is to minimize the regional load losses for the valve disc (10) having dimples (111) on the inventive body front surface (11), wherein the difference between the regional load losses experienced when using the flat structured body and the regional load losses of subject matter of the invention are calculated comparatively. Comparative regional load loss values were calculated by two different methods and the results are shown in table 1 using the flat structured valve disc (10) body and the body front surface (11) of the valve disc (10) having the inventive dimples (111) in an 80-diameter length pipe.

Table 1 . Regional load loss values (calculated by two different methods , n: diameter coefficient for downstream measuring distance) .

The inventive dimples (111) condition large turbulence structures that cause losses and reduce regional energy losses by reducing their size by forming dimples (111) of different geometric shapes according to the fact that the valve disc (10) body is either flat or tilted, or by manipulating the interaction of the flow with the body of the valve disc (10) by being formed as little cavities on newly made valve discs (10) by adding male attachments to the mold.

By means of the dimples (111) formed on the body front surface (11) of the valve disc (10), a mechanism related to the shape resistance and due to the interaction of the flow parallel to the valve disc (10) with the solid surface is realized. The dimples (111) may have the same and/or different geometric shapes, as well as are preferably formed from elliptical or circular cavities. The dimples (111) of the valve disc (10) on its body front surface (11) may be formed on the valve disc (10) in in a manner to have a certain arrangement and, as well as may be disposed irregularly on the valve disc (10) . The diameter, width and depth of the dimples (111) contained by the inventive valve disc (10) vary according to the diameter and type of the valve disc (10) .

The male moldings that will shape the dimples (111) may be incorporated into the mold of valve disc (10) in a manner to form the pattern in order that the invention is made. Thus, the new valve disc to be formed will be lighter than its older state. The depth of the dimples has low values such that it does not affect the structural strength and has structure to transfer loads and stresses by the arch effect.

By means of the inventive valve disc (10) developed and the dimples (111) it comprises, the regional load losses of the butterfly valve are minimized when it is open during flow.

Claims

1. A novel body front surface (11) applicable to existing valve discs on for reducing regional load losses a disc (10) body of butterfly valves when the butterfly valve is fully open, characterized by dimples (111) formed from cavities of the same and/or different geometrical shapes on the body front surface (11), allowing the flow lines to continue in the flow path without changing direction and minimizing the regional load losses by minimizing turbulence zone where fluid contacting surface of the valve disc (10) is irregular .

2. Dimples according to Claim 1, characterized by elliptic or circular cavities/pits.

3. Body front surface (11) according to Claim 1, characterized by two shaft housings (13) in which the valve disc (10) is connected with the butterfly valve and in which the shaft is positioned when the valve disc (10) rotates around it during its opening and closing, and a tie piece (131) which limit the shaft housing (13) and support the shaft housing (13) so that the shaft housings (13) bear the shaft which is passed through it and that the shaft remains in the shaft housing (13) and does not move on the valve disc (10) .