CN111594369A - A Francis turbine with double inlet volute suitable for cooling tower - Google Patents

Abstract

The invention discloses a mixed-flow water turbine with a double-inlet volute suitable for a cooling tower, wherein a seat ring is sleeved at an annular opening at the inner side of the double-inlet volute, a circle of movable guide vanes are arranged in the seat ring, a rotating wheel is sleeved at the inner ring of the seat ring, and a water drainage cone is sleeved at the inner ring of the rotating wheel; a tail water pipe is arranged at the bottom of the rotating wheel; the blades of the rotating wheel are of non-uniform thickness twisted structures, and the front surfaces and the back surfaces of the blades are smoothly connected through curved surfaces with different curvatures from top to bottom. According to the mixed-flow water turbine with the double-inlet volute, which is suitable for the cooling tower, the two water inlets are respectively communicated with the water inlet pipe of the cooling tower, so that bidirectional water inflow is realized, the uniformity of water flow in the volute in the circumferential direction is improved, the velocity component of the water flow in the circumferential direction is enhanced, the water flow circulation quantity of incoming flow is further effectively increased, the water flow condition entering the water distributor is improved, the hydraulic loss of the water distributor is reduced, and the mixed-flow water turbine has the advantages of good hydraulic performance, high operation efficiency and the like.

Description

A Francis turbine with double inlet volute suitable for cooling tower

technical field

The invention relates to a Francis water turbine with a double inlet volute suitable for a cooling tower, and belongs to the technical field of water turbines.

Background technique

In recent years, in addition to supporting power generation with generators, hydro turbines are also increasingly used in cooling towers. Instead of the motor, the cooling tower turbine is driven by the residual energy of the circulating cooling water to drive the fan to run, which has the advantages of low consumption, environmental protection and energy saving. Francis turbine is the most widely used type of turbine at present. Its main components include a water diversion chamber, a seat ring, a water guiding mechanism, a runner and a draft tube, which can be applied to low specific speed conditions.

Francis turbines are also used in the market as cooling tower turbines. The volute, as the water diversion component of the turbine, from a hydraulic point of view, its function is to make the water flow form a circulation, so as to ensure that the water flow can enter the seat ring and the movable guide vane with a small angle of attack, and reduce the hydraulic loss of the water guiding mechanism.

In a water turbine in the prior art, all the sections of the volute volute structure section are set to be elliptical, so as to effectively increase the diameter of the runner, so as to increase the output of the unit. However, it only changes the cross-sectional shape of the volute, and does not optimize the water inlet conditions.

The existing volutes are all designed with a one-way water inlet, and the section of the volute structure section is gradually reduced to form a necessary circulation before the water guiding mechanism. When the water flow passes through the inlet section of the volute to the nose section, the change of the tangential velocity of the water flow is greatly affected by the size of the section, and the axisymmetric potential flow cannot be formed ideally.

Therefore, how to overcome the shortcomings of the existing technology has become one of the key problems to be solved urgently in the field of Francis turbine technology.

SUMMARY OF THE INVENTION

Objective: In order to overcome the deficiencies in the prior art, the present invention provides a Francis turbine with a double inlet volute suitable for a cooling tower.

Technical scheme: in order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

A Francis turbine with a double-inlet volute suitable for a cooling tower includes a double-inlet volute, a seat ring is sleeved at the inner annular opening of the double-inlet volute, and a circular movable guide is arranged in the seat ring. The inner ring of the seat ring is sleeved with a runner, and the inner ring of the runner is sleeved with a drain cone; the bottom of the runner is provided with a draft tube.

As a preferred solution, the double-inlet volute includes: a snail-shaped structure segment, two nose-end straight pipe segments are respectively provided in the circumferential direction of the snail-shaped structure segment, and the inlet section of the snail-shaped structure section is an elliptical section; the two The straight pipe section at the nose end is centrally symmetrical with respect to the snail-shaped structure section.

As a preferred solution, the ratio of the length of the major semi-axis to the minor semi-axis of the elliptical section is 1.05-1.5:1.

As a preferred solution, the runner adopts a Francis runner.

As a preferred solution, the blades of the runner adopt an unequal thickness twisted structure, and the front and back surfaces of the blades are smoothly connected by curved surfaces with different curvatures from top to bottom.

As a preferred solution, the number of the blades is 14-19.

As a preferred solution, the centers of the double-inlet volute, the seat ring, the runner, and the draft tube are on the same vertical axis.

As a preferred solution, the draft water pipe adopts a straight conical structure.

As a preferred solution, the cross-sectional airfoil curves of the front and back surfaces of the blade from top to bottom are set as follows:

At a distance of 100mm from the lower edge of the drain cone in the transverse axis, the cross-sectional airfoil curve formula of the curved surface of the blade front is as follows:

y=0.0018x ² -1.44395x+390.86743

The cross-sectional airfoil curve formula of the curved surface on the opposite side of the blade is as follows:

y=0.00187x ² -1.50257x+399.45313

At a distance of 150mm from the lower edge of the drain cone in the transverse axis, the cross-sectional airfoil curve formula of the curved surface of the front of the blade is as follows:

y=3.922×10 ^-6 x ³ -0.0021x ² -0.09877x+213.81885

The cross-sectional airfoil curve formula of the curved surface on the opposite side of the blade is as follows:

y=3.22687×10 ^-6 x ³ -0.00137x ² -0.36516x+243.22

At a distance of 200mm from the lower edge of the drain cone in the transverse axis, the cross-sectional airfoil curve formula of the curved surface of the front of the blade is as follows:

y=2.2885×10 ^-6 x ³ -2.64996×10 ^-4 x ² -0.70085x+261.97

The cross-sectional airfoil curve formula of the curved surface on the opposite side of the blade is as follows:

y=3.5575×10 ^-6 x ³ -0.00185x ² -0.087x+182.41278

The cross-sectional airfoil curve formula of the curved surface of the blade front at a distance of 250mm from the lower edge of the drain cone in the transverse direction is as follows:

y= ^7.71574 × ^{10-7x3 +} 0.00168x2-1.48645x+360.08014

The cross-sectional airfoil curve formula of the curved surface on the opposite side of the blade is as follows:

y ⁼ 6.81816x10-6x3-0.00653x2 ^{+ 2.15092x} -174.62416.

Beneficial effects: The present invention provides a Francis turbine with a double inlet volute that is suitable for a cooling tower. The water turbine of the present invention uses a double inlet volute, and the two water inlets are respectively connected to the cooling tower water inlet pipe to realize bidirectional inlet. Water, improves the uniformity of the water flow in the circumferential direction in the volute, enhances the velocity component of the water flow in the circumferential direction, thereby effectively increasing the water flow circulation of the incoming flow, improving the water flow conditions entering the water guiding mechanism, and reducing the water guiding mechanism. It has the advantages of good hydraulic performance and high operating efficiency.

Description of drawings

FIG. 1 is a schematic structural diagram of a Francis turbine with a double inlet volute that is suitable for a cooling tower proposed by the present invention.

FIG. 2 is a schematic structural diagram of the double inlet volute proposed by the present invention.

FIG. 3 is a schematic cross-sectional view of a Francis turbine with a double inlet volute that is suitable for a cooling tower proposed by the present invention.

FIG. 4 is a schematic front view of the blade proposed by the present invention.

FIG. 5 is a schematic top view of the blade proposed by the present invention.

6 is a schematic diagram of the airfoil curve at different transverse axial distances from the lower edge of the drain cone on the blade proposed by the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, a Francis turbine with a double inlet volute suitable for a cooling tower includes a double inlet volute 1, a seat ring 2, a movable guide vane 3, a runner 4, The draft tube 5, the inner annular opening of the double inlet volute 1 is sleeved with a seat ring 2, a circle of movable guide vanes 3 are arranged in the seat ring 2, and a runner 4 is sleeved at the inner ring of the seat ring 2, and the runner 4. The inner ring is sleeved with a drain cone 6; the bottom of the runner 4 is provided with a draft tube 5.

As shown in FIG. 2 , the double-inlet volute 1 includes: a snail-shaped structure section 101 , two nose-end straight pipe sections 102 are respectively arranged in the circumferential direction of the snail-shaped structure section 101 , and the inlet section of the snail-shaped structure section 101 is an ellipse The ratio of the length of the major semi-axis to the minor semi-axis of the elliptical section is 1.05 to 1.5:1. The two straight pipe sections 102 at the nose end are respectively used to communicate with the water inlet pipes of the cooling tower.

As shown in FIG. 3 , the runner 4 adopts a Francis runner, the blades 401 of the runner 4 adopt an unequal thickness twisted structure, and the number of blades is 14-19. As shown in Figure 4-5, the front and back surfaces of the blade are smoothly connected by curved surfaces with different curvatures from top to bottom. The section airfoil curves of the front and back surfaces of the blade from top to bottom are set as follows:

As shown in Figure 6, at a distance of 100 mm from the lower edge of the drain cone in the transverse axis, the values of the point coordinates on the airfoil curves of the front and back sections of the blade are shown in Table 1.

Table 1

The two fitted curves are expressed as:

Front of blade: y=0.0018x ² -1.44395x+390.86743

The reverse side of the blade: y=0.00187x ² -1.50257x+399.45313

See Table 2 for the coordinates of the points on the airfoil curves of the front and back sections of the blade at a distance of 150 mm from the lower edge of the drain cone in the transverse direction.

Table 2

The two fitted curves are expressed as:

Front of blade: y=3.922×10 ^-6 x ³ -0.0021x ² -0.09877x+213.81885

Back of blade: y=3.22687×10 ^-6 x ³ -0.00137x ² -0.36516x+243.22

Table 3 shows the coordinates of the points on the airfoil curves of the front and back sections of the blade at a distance of 200 mm from the lower edge of the drain cone in the transverse axis.

table 3

The two fitted curves are expressed as:

Front of blade: y=2.2885×10 ^-6 x ³ -2.64996×10 ^-4 x ² -0.70085x+261.97

The reverse side of the blade: y=3.5575×10 ^-6 x ³ -0.00185x ² -0.087x+182.41278

See Table 4 for the coordinates of the points on the airfoil curves of the front and back sections of the blade at a distance of 250 mm from the lower edge of the drain cone in the transverse axis.

Table 4

The two fitted curves are expressed as:

Blade front: y=7.71574×10 ^-7 x ³ +0.00168x ² -1.48645x+360.08014

Back of blade: y=6.81816×10 ^-6 x ³ -0.00653x ² +2.15092x-174.62416

The centers of the double-inlet volute, the seat ring, the runner and the draft water pipe are on the same vertical axis.

The two nose-end straight pipe sections are centrally symmetrical with respect to the snail-shaped structure section.

The draft water pipe adopts a straight conical structure, and the water outlet of the draft water pipe is used to communicate with the water pipe of the circulating water system of the cooling tower.

Example 1:

Taking the Francis turbine with double inlet volute proposed by the present invention as an example in a cooling tower, the rated shaft power of the fan of the cooling tower is 98kW, and the surplus head of circulating cooling water is 14m.

The parameters optimized by the present invention are as follows: the two nose-end straight pipe sections in the circumferential direction of the scroll-shaped structure section are arranged symmetrically with respect to the scroll-shaped structure section, the inlet section of the scroll-shaped structure section is an elliptical section, and the length of the elliptical section is The ratio of shafts is 1.1:1; the number of movable guide vanes is 16; the diameters of the inlet and outlet of the Francis runner are 1200mm and 800mm respectively; 12° straight conical draft tube.

Example 2:

The parameters optimized by the present invention are as follows: the two nose-end straight pipe sections in the circumferential direction of the scroll-shaped structure section are arranged symmetrically with respect to the scroll-shaped structure section, the inlet section of the scroll-shaped structure section is an elliptical section, and the length of the elliptical section is The ratio of shafts is 1.05:1; the number of movable guide vanes is 16; the diameters of the inlet and outlet of the Francis runner are 1200mm and 800mm respectively; 12° straight conical draft tube.

Example 3:

The parameters optimized by the present invention are as follows: the two nose-end straight pipe sections in the circumferential direction of the scroll-shaped structure section are arranged symmetrically with respect to the scroll-shaped structure section, the inlet section of the scroll-shaped structure section is an elliptical section, and the length of the elliptical section is The ratio of shafts is 1.15:1; the number of movable guide vanes is 16; the diameters of the inlet and outlet of the Francis runner are 1200mm and 800mm respectively; 14° straight conical draft tube.

Example 4:

The specific application process of the present invention is as follows: the straight pipe sections of the two nose ends of the double inlet volute are directly connected to the water inlet pipe of the cooling tower, the water flows into the runner through the water guiding mechanism, drives the runner to rotate, converts the potential energy of the water into mechanical energy, drives the When the turbine is running, the draft water pipe is directly connected to the water pipe of the circulating water system of the cooling tower.

The descriptions not involved in the specific embodiments of the present invention belong to the well-known technology in the art, and can be implemented with reference to the well-known technology.

The above is only the preferred embodiment of the present invention, it should be pointed out that: for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can also be made, and these improvements and modifications are also It should be regarded as the protection scope of the present invention.

Claims (9)

1. a Francis turbine with a double inlet volute that is applicable to a cooling tower, it is characterized in that: comprise a double inlet volute, the inner annular opening of the double inlet volute is sleeved with a seat ring, the seat ring A circle of movable guide vanes is arranged inside, a runner is sleeved at the inner ring of the seat ring, and a drain cone is sleeved at the inner ring of the runner; the bottom of the runner is provided with a draft tube. 2. A Francis turbine with a double inlet volute suitable for a cooling tower according to claim 1, wherein the double inlet volute comprises: a volute structure section, the circumferential direction of the volute structure section is Two nose-end straight pipe sections are respectively arranged, and the inlet section of the snail-shaped structure section is an oval section; the two nose-end straight pipe sections are centrally symmetrically arranged with respect to the snail-shaped structure section. 3. A Francis turbine with double inlet volute suitable for cooling tower according to claim 2, characterized in that: the ratio of the length of the long semi-axis to the short semi-axis of the elliptical section is 1.05-1.5 :1. 4. A Francis turbine with double inlet volute suitable for cooling towers according to claim 1, characterized in that the runner is a Francis runner. 5. A Francis turbine with a double inlet volute suitable for a cooling tower according to claim 1, characterized in that: the blades of the runner adopt an unequal thickness twisted structure, and the front and back of the blades are Top to bottom are smoothly connected by surfaces of different curvatures. 6 . The Francis turbine with a double inlet volute suitable for cooling towers according to claim 5 , wherein the number of the blades is 14-19. 7 . 7. A Francis turbine with a double inlet volute suitable for a cooling tower according to claim 1, wherein the center of the double inlet volute, the seat ring, the runner and the draft tube is at the center of the on the same vertical axis. 8 . The Francis turbine with double inlet volute according to claim 1 , wherein the draft water pipe adopts a straight conical structure. 9 . 9. A Francis turbine with double inlet volute suitable for a cooling tower according to claim 5, characterized in that: the cross-sectional airfoil curve of the curved surface from top to bottom on the front and back of the blade is set as follows : At a distance of 100mm from the lower edge of the drain cone in the transverse axis, the cross-sectional airfoil curve formula of the curved surface of the blade front is as follows: y=0.0018x ² -1.44395x+390.86743 The cross-sectional airfoil curve formula of the curved surface on the opposite side of the blade is as follows: y=0.00187x ² -1.50257x+399.45313 At a distance of 150mm from the lower edge of the drain cone in the transverse axis, the cross-sectional airfoil curve formula of the curved surface of the front of the blade is as follows: y=3.922×10 ^-6 x ³ -0.0021x ² -0.09877x+213.81885 The cross-sectional airfoil curve formula of the curved surface on the opposite side of the blade is as follows: y=3.22687×10 ^-6 x ³ -0.00137x ² -0.36516x+243.22 At a distance of 200mm from the lower edge of the drain cone in the transverse axis, the cross-sectional airfoil curve formula of the curved surface of the front of the blade is as follows: y=2.2885×10 ^-6 x ³ -2.64996×10 ^-4 x ² -0.70085x+261.97 The cross-sectional airfoil curve formula of the curved surface on the opposite side of the blade is as follows: y=3.5575×10 ^-6 x ³ -0.00185x ² -0.087x+182.41278 The cross-sectional airfoil curve formula of the curved surface of the blade front at a distance of 250mm from the lower edge of the drain cone in the transverse direction is as follows: y= ^7.71574 × ^{10-7x3 +} 0.00168x2-1.48645x+360.08014 The cross-sectional airfoil curve formula of the curved surface on the opposite side of the blade is as follows: y ⁼ 6.81816x10-6x3-0.00653x2 ^{+ 2.15092x} -174.62416.

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