CN101813225B - Low-resistance square pant tee joint - Google Patents

Abstract

The invention discloses a low-resistance rectangular underpants tee, which comprises a main pipe and branch pipes extending symmetrically from the end of the main pipe to both ends. An inner arc surface is arranged along the connecting section of the main pipe and the branch pipe, corresponding to the branch pipes on the inner arc surface. There is an outer arc surface on the top, and it is characterized in that: another inner arc surface is provided at the connecting section between the inner arc surface and the main pipe to form two sections of transitional connection inner arc surfaces; The outer arc surface and the four sides on the main pipe are connected to form a rectangular tee with one inlet channel and two outlet channels. The unique design of the underpants tee eliminates the vortex area generated when the fluid passes through the inner arc of the underpants tee and the vortex area generated by the fluid at the junction of the underpants tee and the straight pipe, thereby reducing the flow of fluid through the underpants Resistance when teeing.

Description

Low Drag Rectangular Short Tee

technical field

The invention relates to a partial component of ventilation and air conditioning, in particular to a low-resistance rectangular underpants tee component.

Background technique

Pants tee is a pipe fitting that changes the flow direction of the fluid and diverts it. In the diversion pipeline, due to the turning of the fluid, there is a centrifugal force from the center of curvature to the outer arc of the pipe, which makes the fluid transition from the straight section of the pipe to the curved pipe section ( Before the end of the turn), the pressure on the outer arc increases and the pressure on the inner arc decreases. Therefore, the flow velocity of the fluid at the outer dome will decrease, while the flow velocity of the fluid at the inner dome will correspondingly increase. Therefore, the diffusion effect appears near the outer arc surface, while the contraction effect appears near the inner arc surface. When the fluid transitions from the curved pipe section to the straight pipe section (after turning), the opposite phenomenon occurs, that is, the diffusion effect occurs near the inner arc surface, and the contraction effect occurs near the outer arc surface. The diffusion effect makes the fluid detach from the wall, and at the same time, the movement of the fluid in the curved pipe section to the outer arc surface due to inertia further aggravates the separation from the inner arc surface.

The fluid flows in the underpants three-way shunt pipe (equivalent to an elbow), and the centrifugal force it receives is proportional to the square of the flow velocity, so the centrifugal force at the high velocity area is greater than that near the wall. This moment makes the water flow generate a secondary circulation (vortex pair) on the cross section of the underpants tee shunt pipe (equivalent to the elbow). That is to form the so-called vortex pair. It is attached to the main flow parallel to the pipeline axis, so that the streamline has a spiral shape. The spiral shape of the water flow is not limited to the shunt pipe itself, but also continues on a certain length of straight pipe section behind the shunt pipe. The local resistance of the pants tee is due to the two phenomena in the above-mentioned water flow structure of the pants tee: (1) the vortex on the inner arc surface of the pants tee. (2) The secondary vortex at the junction of the underpants tee and the straight pipe, as shown in Figure 1. The flow in the vortex zone formed by the separation of the boundary layer and the axial flow have a strong momentum exchange at the interface, which consumes the energy of the mainstream and forms the local resistance loss of the pants tee. Among them, the vortex formed at the inner arc surface plays a major role, which basically determines the resistance of the underpants tee and the deformation of the flow field on a certain straight pipe section behind the underpants tee. Experiments show that the larger the vortex area, the greater the vortex intensity, and the greater the local resistance loss. The secondary flow plays an important role in the redistribution of the axial flow velocity of the pants tee. The redistribution process consumes the energy of the primary flow and increases the local resistance loss of the pants tee. The vortex formed by the inner arc surface together with the secondary flow basically determines the characteristics of the velocity distribution of the pipe after the turn. The energy consumption caused by the flow in the underpants tee is far from limited to the underpants tee itself, but extends to the upstream and downstream of the underpants tee. The impact of the pants tee on the upstream is as far as 1-2 times the pipe diameter, and the downstream is affected by 5 times the pipe diameter.

In the past, people mainly used the common underpants tee in the ventilation and air conditioning system, as shown in Figure 3, and the common underpants tee does not distinguish between confluence and diversion. At the same time, because the radius of the inner arc surface of the ordinary pants tee is too small and the arc surface is small, a vortex area with negative pressure and high flow velocity is generated when the fluid passes through it. This vortex area itself will cause a lot of resistance, and it will also cause a large vortex area to be generated after the fluid passes through the pants tee. And these two vortex regions directly lead to the increase of the resistance when the fluid passes through. In other words, the inner arc surface of the underpants tee is the main part that causes the resistance to increase when the fluid passes through the underpants tee.

In recent years, there have been some streamline turning pipe fittings that reduce resistance at fluid corners, such as the Chinese patent, the patent No. ZL95102932.0 discloses a elbow with guide vanes, and the Chinese patent, the public number is CN101315194 Disclosed is a flue elbow. They all have guide vanes inside, and the vortex at the inner arc surface of the elbow is eliminated by the guide vanes guiding the fluid, so as to reduce the resistance. However, since guide vanes need to be added to the curved pipe, its manufacture and installation are relatively complicated, and the cost will be relatively high.

Contents of the invention

The purpose of this invention is to provide a novel low-resistance rectangular underpants tee. The unique design of this underpants tee simultaneously eliminates the vortex zone that fluid produces when passing through the inner arc surface of the underpants tee; The vortex zone generated at the junction of the pipes, so as to finally reduce the resistance of the fluid passing through the pants tee.

In order to achieve the above object, the object of the present invention is achieved through the following technical scheme, providing a new type of low resistance rectangular pants tee, including a main pipe and branch pipes extending symmetrically to both ends along the main pipe end, along the The connecting section between the main pipe and the two branch pipes is respectively provided with an inner arc surface, and the branch pipe corresponding to the two inner arc surfaces is provided with two outer arc surfaces, and the feature is that another inner arc surface is provided at the connecting section between the inner arc surface and the main pipe, forming Two sections of transitional connection inner arc surface; the two two sections of transition connection inner arc surface are respectively connected with the outer arc surface on the two branch pipes and the four sides on the main pipe, forming an inlet channel and two outlet channels Rectangular Tee.

The two sections of the transitional connecting inner arc surface are the first inner arc surface and the second inner arc surface, and the first inner arc surface is on the side of the main pipe at the lower end of the second inner arc surface; the first inner arc surface The radius and arc length are greater than the radius and arc length of the outer arc surface; the radius and arc length of the outer arc surface are greater than the radius and arc length of the second inner arc surface; and the centers of the first inner arc surface and the second inner arc surface are respectively at Extensions of the inlet and outlet sections.

It can be seen from the above that the present invention first decelerates and slowly changes the direction of the inflow fluid close to the inner arc surface through the first inner arc surface, so that the fluid slowly passes through the first half of the inner arc surface that may generate negative pressure and high-speed vortex area. After the fluid passes through the first half of the inner arc surface, in order to make the fluid turn quickly, the radius and arc length of the second inner arc surface are relatively small. This makes the fluid not form a vortex at the part connected with the underpants tee after passing through the underpants tee. Thereby simultaneously eliminating the vortex at the inner arc surface of the underpants tee and the vortex generated after the fluid passes through the underpants tee, as shown in FIG. 4 . So as to achieve the effect of less resistance.

Compared with the prior art, the present invention eliminates the vortex at the inner arc surface of the elbow without adding guide vanes in the elbow to guide the fluid, so as to achieve the purpose of reducing resistance. Its manufacture and installation are relatively simple, its cost is low, and it is convenient for popularization and application.

Description of drawings

Fig. 1 is a schematic diagram of the internal flow field and the eddy current zone of a common underpants tee;

Fig. 2 is a schematic diagram of the inner flow field and the eddy current region of the new type of low-resistance rectangular underpants tee;

Fig. 3 is the existing rectangular underpants tee schematic diagram;

Fig. 4 is a schematic diagram of a novel low-resistance rectangular underpants tee.

Detailed ways

The specific implementation manners of the present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Figure 4, the novel low-resistance rectangular underpants tee of the present invention includes a main pipe and branch pipes extending symmetrically along the end of the main pipe to both ends, and inner arc surfaces are respectively provided along the connecting section of the main pipe and the two branch pipes. , the branch pipes corresponding to the two inner arc surfaces are provided with two outer arc surfaces 3, wherein: another inner arc surface is set at the connecting section between the inner arc surface and the main pipe to form two sections of transitional connection inner arc surfaces; the two two sections The inner curved surface of the transition connection is respectively connected with the outer curved surface 3 on the two branch pipes and the four sides 4 on the main pipe, forming a rectangular tee with one inlet channel and two outlet channels.

The above-mentioned two transitional connecting inner arc surfaces are the first inner arc surface 1 and the second inner arc surface 2, and the first inner arc surface 1 is on the side of the main pipe at the lower end of the second inner arc surface 2; the first inner arc surface The radius of 1 is greater than the radius of the outer arc surface 3; the radius of the outer arc surface 3 is greater than the radius of the second inner arc surface 2; the arc length of the first inner arc surface 1 is greater than the arc length of the outer arc surface 3; the arc length of the outer arc surface 3 The arc length is greater than the arc length of the second inner arc surface 2; the center of the first inner arc surface 1, the center of the second inner arc surface 2, and the center of the outer arc surface 3 do not overlap each other; the center of the first inner arc surface 1 is at The extension surface of the main pipe entrance section; the center of the second inner arc surface 2 is on the extension surface corresponding to the branch outlet section.

As shown in Figure 2, the present invention first decelerates and slowly changes the direction of the inflow fluid close to the inner arc surface through the first inner arc surface 1, so that the fluid slowly passes through the first half of the high-speed vortex area that may generate negative pressure curved surface. After the fluid passes through the first half of the inner arc surface, in order to make the fluid turn quickly, the radius and arc length of the second inner arc surface 2 are relatively small. This makes the fluid not form a vortex at the part connected with the underpants tee after passing through the underpants tee. Therefore, the vortex at the inner arc surface of the underpants tee and the vortex generated after the fluid passes through the underpants tee are simultaneously eliminated. Thereby reducing the resistance when fluid flows through the pants tee.

Claims (1)

1. lower resistance rectangle pants threeway, comprise that one is responsible for and the arm that extends to the two ends SYMMETRIC BIFURCATION along this person in charge termination, be respectively equipped with intrados along this person in charge and two arm linkage sections, the arm of corresponding two intrados is provided with two outer arced surface (3), it is characterized in that: establish another intrados at described intrados with being responsible for linkage section, constitute two sections transition and connect intrados; Two two sections transition connect intrados respectively with described two arms on outer arced surface (3) and four sides (4) of being responsible for be connected, be formed with an inlet channel and the rectangle threeway of two outlet passages arranged;

It is first intrados (1) and second intrados (2) that two sections transition connect intrados, and first intrados (1) is on the person in charge side of described second intrados (2) lower end; The radius of described first intrados (1) and arc length are greater than the radius and the arc length of outer arced surface (3); The radius of outer arced surface (3) and arc length are greater than the radius and the arc length of second intrados (2); The center of circle non-overlapping copies of the center of circle of the center of circle of first intrados (1), second intrados (2), outer arced surface (3); And the center of circle of first intrados (1) and second intrados (2) is respectively on the elongated surfaces of inlet section and outlet section.

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