Adjustable tailrace internal guide vane and adjustment method

Abstract

The adjustable internal guide plate of the draft tube and the adjusting method disclosed by the application comprise a draft tube cone section, a plurality of connecting grooves are opened on the draft tube cone section, the connecting grooves are evenly distributed along the circumference of the draft tube cone section, and the connecting grooves are opened along the extension direction of the inclined surface of the draft tube cone section; a guide plate is penetrated into the connecting groove, a motor support frame is arranged outside the draft tube cone section, a lead screw stepping motor is arranged on the motor support frame opposite to the guide plate, and the lead screw stepping motor is connected with the guide plate. The specific steps of the method are as follows: step 1, the relative power P' of the water turbine is calculated based on the operating power P1 of the water turbine; step 2, the penetration length L of the guide plate penetrated into the draft tube cone section is determined according to the relative power P' P ; step 3, the lead screw stepping motor is controlled to make the penetration length of the guide plate into the draft tube cone section reach the penetration length L P determined in step 2. The application relieves the flow field distribution in the draft tube, weakens the generation of vortex belts, and improves the efficiency of the water turbine.

Description

Technical Field

[0001] This invention belongs to the field of water turbine technology, specifically relating to an adjustable guide plate inside the tailrace pipe, and also to a method for adjusting the aforementioned guide plate. Background Technology

[0002] Hydropower generation for grid stability requires renewable energy to operate more frequently under off-design conditions. Flow instability in these conditions reduces turbine efficiency. Partial load operation also impacts unit stability; as fluid enters the runner, the developing vortex structure causes periodic pressure pulsations in the draft tube, jeopardizing turbine performance.

[0003] Under partial load operation of the turbine, low-frequency oscillations relative to the runner frequency occur in the turbine's draft tube. The flow development under these conditions affects the turbine's power output, thus reducing efficiency. Residual vortices entering the draft tube under partial load conditions exhibit high tangential velocities near the wall, leading to a low-velocity region at the center of the draft tube's conical section. Simultaneously, the high shear force between the recirculation and vortex regions makes it easier to form vortex bands, increasing pressure oscillations, exacerbating draft tube losses, and reducing the turbine unit's efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide an adjustable guide vane inside the tailrace tube to alleviate the flow field distribution inside the tailrace tube, reduce the generation of vortices, and improve turbine efficiency.

[0005] Another object of the present invention is to provide a method for adjusting the internal guide plate of the adjustable tailpipe.

[0006] The first technical solution adopted in this invention is an adjustable tailwater pipe internal guide plate, including a tailwater pipe cone section, on which a plurality of connecting grooves are opened, the plurality of connecting grooves being evenly distributed along the circumference of the tailwater pipe cone section, and the connecting grooves being opened along the inclined extension direction of the tailwater pipe cone section.

[0007] A guide plate passes through the connecting groove, and a motor support frame is set on the outside of the tailwater conical section. A lead screw stepper motor is set on the motor support frame relative to the guide plate, and the lead screw stepper motor is connected to the guide plate. The lead screw stepper motor controls the radial extension and retraction of the guide plate relative to the tailwater conical section.

[0008] The first technical solution of the present invention is further characterized in that,

[0009] The lead screw of the lead screw stepper motor is riveted to the guide plate.

[0010] The guide plate is in the shape of a right trapezoid, and the inclination angle of the inclined surface on the guide plate is the same as the inclination angle of the inclined surface of the tailrace cone section.

[0011] The ratio of the distance between the guide vane and the inlet of the tailrace cone section to the inlet diameter of the tailrace cone section is H1:D = 1:10 to 3:10;

[0012] Where H1 is the distance between the guide plate and the inlet of the tailrace cone section, and D is the inlet diameter of the tailrace cone section.

[0013] The ratio of the height of the guide vane to the inlet diameter of the tailrace cone section is H2:D = 7:10 to 8:10;

[0014] Where H2 is the height of the deflector.

[0015] The ratio of the maximum length L of the guide plate penetrating the tailrace cone section to the inlet diameter of the tailrace cone section is L:D = 1:4 to 1:3;

[0016] The minimum length L2 of the guide plate inserted into the tailrace cone section is 5cm.

[0017] The second technical solution adopted in this invention is a method for adjusting the internal guide plate of the adjustable tailwater pipe, the specific steps of which are as follows:

[0018] Step 1: Obtain the operating power P1 of the water turbine, and calculate the relative power P′ of the water turbine based on the operating power P1;

[0019] Step 2: Determine the insertion length L of the guide plate into the tailrace cone section based on the relative power P′. P ;

[0020] Step 3: Control the lead screw stepper motor to push the guide plate to extend and retract, so that the guide plate penetrates the tailrace cone section to the penetration length L determined in Step 2. P .

[0021] The first technical solution of the present invention is further characterized in that,

[0022] In step 1, the relative power P′ of the turbine is calculated based on the turbine's operating power P1, as shown in the following formula:

[0023]

[0024] Where P1 is the current operating power of the turbine, P r P' is the rated power of the turbine, and P′ is the relative power of the turbine.

[0025] In step 2, determine the insertion length L of the guide plate into the tailrace cone section. P Specifically:

[0026] When 40% < P′ < 60%, the insertion length L P The length L of the maximum length of the guide plate inserted into the tailrace cone section is half of the length of the guide plate.

[0027] When 60% ≤ P′ < 75%, the insertion length L P It is equal to the maximum length L of the cone section inserted into the tailrace pipe;

[0028] When 75% ≤ P′ < 100%, the insertion length L P It is equal to the minimum length L2 of the cone section inserted into the tailrace pipe.

[0029] The beneficial effects of this invention are that the adjustable draft tube internal guide plate, by setting four guide plates that can extend and retract relative to the draft tube cone section, can stabilize the flow state within the draft tube cone section under partial load conditions, reduce pressure oscillations of water entering the draft tube, reduce pressure pulsation inside the draft tube, slow down the formation of vortices, alleviate and suppress vortices near the inner wall of the draft tube, and simultaneously reduce the vortex nucleus at the center of the draft tube cone section. In other words, it reduces the low-pressure area, improves draft tube performance, reduces water flow energy loss, and thus improves the turbine's operating efficiency. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the adjustable tailwater pipe internal guide plate of the present invention;

[0031] Figure 2 This is a schematic diagram of the connection between the lead screw stepper motor and the guide plate in this invention;

[0032] Figure 3 This is a cross-sectional view of the tailrace cone section of the present invention.

[0033] In the diagram, 1. Tailwater conical section, 2. Baffle plate, 3. Screw stepper motor, 4. Motor support frame, 5. Screw, 6. Connecting groove. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] like Figure 1 As shown, the adjustable tailwater pipe internal guide plate of the present invention includes a tailwater pipe cone section 1, and a plurality of connecting grooves 6 are opened on the tailwater pipe cone section 1. The plurality of connecting grooves 6 are evenly distributed around the circumference of the tailwater pipe cone section 1, and the connecting grooves 6 are opened along the inclined surface extension direction of the tailwater pipe cone section 1.

[0037] A guide plate 2 passes through the connecting groove 6. A motor support frame 4 is set on the outside of the tailrace cone section 1. The motor support frame 4 is fixed to the basic parts around the tailrace in the turbine. A lead screw stepper motor 3 is set on the motor support frame 4 relative to the guide plate 2. The lead screw stepper motor 3 is connected to the guide plate 2. Specifically, the lead screw 5 of the lead screw stepper motor 3 is riveted to the guide plate 2.

[0038] In this invention, a lead screw stepper motor 3 is connected to a guide plate 2 on the outer side of the tailwater conical section 1. The lead screw 5 on the lead screw stepper motor 3 is controlled to rotate, and the lead screw 5 moves relative to the lead screw stepper motor 3, thereby driving the guide plate 2 to move radially and extend and retract relative to the tailwater conical section 1, so as to adjust the length of the guide plate 2 inside the tailwater conical section 1.

[0039] Example 2

[0040] like Figure 2 As shown, this embodiment is based on embodiment 1. The guide plate 2 is generally in the shape of a right trapezoid, and the inclination angle of the inclined surface of the guide plate 2 is the same as the inclination angle of the inclined surface of the tailwater conical section 1.

[0041] Preferably, several guide plates 2 are inserted into the tailwater conical section 1 to form a frustum-shaped inner cavity, and the taper of the frustum-shaped inner cavity is the same as the taper of the tailwater conical section 1.

[0042] The guide plate 2 of the present invention can stabilize the flow in the straight conical section of the tailpipe under partial load conditions, reduce the low-speed region in the center of the straight conical section, reduce the high shear force between the backflow zone and the vortex zone, weaken pressure oscillation and reduce the generation of vortex bands, so that the water flows out more smoothly.

[0043] Example 3

[0044] The adjustable tailwater pipe internal guide plate in this embodiment includes a tailwater pipe cone section 1, on which a plurality of connecting grooves 6 are opened. The plurality of connecting grooves 6 are evenly distributed around the tailwater pipe cone section 1, and the connecting grooves 6 are opened along the inclined extension direction of the tailwater pipe cone section 1.

[0045] A guide plate 2 passes through the connecting groove 6, such as Figure 3 As shown, the guide plate 2 is generally in the shape of a right trapezoid, and the inclination angle of the inclined surface of the guide plate 2 is the same as the inclination angle of the inclined surface of the tailwater conical section 1.

[0046] Preferably, the ratio of the distance between the guide plate 2 and the inlet of the tailrace cone section 1 to the inlet diameter of the tailrace cone section 1 or the outlet diameter of the impeller is H1:D = 1:10 to 3:10;

[0047] Where H1 is the distance between the guide plate 2 and the inlet of the tailrace cone section 1, and D is the inlet diameter of the tailrace cone section 1 or the outlet diameter of the impeller.

[0048] The ratio of the height of the guide plate 2 to the inlet diameter of the tailrace cone section 1 or the outlet diameter of the impeller is H2:D = 7:10 to 8:10;

[0049] Where H2 is the height of the guide vane 2.

[0050] The ratio of the maximum length L of the guide plate 2 inserted into the tailrace cone section 1 to the inlet diameter of the tailrace cone section 1 or the outlet diameter of the impeller is L:D = 1:4 to 1:3;

[0051] The minimum length L2 of the guide plate 2 inserted into the tailwater conical section 1 is 5cm.

[0052] A motor support frame 4 is installed on the outside of the tailrace cone section 1. The motor support frame 4 is fixed to the foundation parts around the tailrace in the turbine. A lead screw stepper motor 3 is installed on the motor support frame 4 relative to the guide plate 2, and the lead screw stepper motor 3 is connected to the guide plate 2.

[0053] Specifically, the lead screw 5 of the lead screw stepper motor 3 is riveted to the guide plate 2.

[0054] The adjustment method of the adjustable tailwater pipe internal guide plate of the present invention adopts the adjustable tailwater pipe internal guide plate described in Example 3, and the specific steps are as follows:

[0055] Step 1: Obtain the operating power P1 of the water turbine, and calculate the relative power P′ of the water turbine based on the operating power P1;

[0056] Specifically, as shown in the following formula:

[0057]

[0058] Where P1 is the current operating power of the turbine, P r P' is the rated power of the turbine, and P′ is the relative power of the turbine.

[0059] Step 2: Determine the insertion length L of the guide plate 2 into the tailrace cone section 1 based on the relative power P′. P Specifically:

[0060] When 40% < P′ < 60%, the insertion length L P The length of the guide plate 2 inserted into the tailrace cone section 1) is half of the maximum length L;

[0061] When 60% ≤ P′ < 75%, the insertion length L P Equal to the maximum length L of the cone section inserted into the tailrace pipe;

[0062] When 75% ≤ P′ < 100%, the insertion length L P =Equal to the minimum length L2 of the conical section inserted into the tailrace pipe 1).

[0063] Step 3: Control the lead screw stepper motor 3 to push the guide plate 2 to extend and retract, so that the guide plate 2 penetrates the tailwater conical section 1 to the penetration length L determined in step 2. P Complete the adjustment of guide vane 2.

[0064] The present invention ensures that the flow pattern inside the tailrace pipe is basically undisturbed when the turbine is under high load or close to the optimal operating condition by shortening the length of the guide plate 2 extending into the tailrace cone section 1.

[0065] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made under the concept of the present invention using the description and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for adjusting the internal guide plate of an adjustable tailwater pipe, characterized in that, A number of connecting grooves (6) are opened on the tailwater conical section (1). The connecting grooves (6) are evenly distributed around the tailwater conical section (1) and are opened along the inclined surface extension direction of the tailwater conical section (1). The connecting groove (6) is fitted with a guide plate (2), and a motor support frame (4) is provided on the outside of the tailwater pipe cone section (1). A screw stepper motor (3) is provided on the motor support frame (4) relative to the guide plate (2), and the screw stepper motor (3) is connected to the guide plate (2). The screw stepper motor (3) controls the radial extension and retraction of the guide plate (2) relative to the tailwater pipe cone section (1). The guide plate (2) is in the shape of a right trapezoid, and the inclination angle of the upper slope of the guide plate (2) is the same as the inclination angle of the slope of the tailwater conical section (1). The ratio of the maximum length L of the guide plate (2) inserted into the tailwater conical section (1) to the inlet diameter of the tailwater conical section (1) is L:D=1:4~1:3; The minimum length L2 of the guide plate (2) inserted into the tailwater conical section (1) is 5cm. The specific steps are as follows: Step 1: Obtain the operating power P1 of the turbine, and calculate the relative power of the turbine based on the operating power P1. ; Step 2, based on relative power Determine the insertion length L of the guide plate (2) into the tailrace cone section (1). P ; Step 3: Control the lead screw stepper motor (3) to push the guide plate (2) to extend and retract, so that the guide plate (2) penetrates the tailwater conical section (1) to the penetration length L determined in step 2. P ; In step 2, the insertion length L of the guide plate (2) into the tailrace cone section (1) is determined. P Specifically: When 40% < When <60%, the insertion length L P The length L of the guide plate (2) inserted into the tailwater conical section (1) is half of the maximum length L. When 60%≤ When <75%, the insertion length L P Equal to the maximum length L of the cone section (1) inserted into the tailrace pipe; When 75%≤ When <100%, the insertion length L P =Equal to the minimum length L2 of the conical section (1) inserted into the tailwater pipe.

2. The method for adjusting the adjustable tailwater pipe internal guide plate according to claim 1, characterized in that, The lead screw (5) of the lead screw stepper motor (3) is riveted to the guide plate (2).

3. The adjustment method for the adjustable tailwater pipe internal guide plate according to claim 1, characterized in that, The ratio of the distance between the guide plate (2) and the inlet of the tailwater conical section (1) to the inlet diameter of the tailwater conical section (1) is H1:D=1:10~3:10; Where H1 is the distance between the guide plate (2) and the inlet of the tailwater conical section (1), and D is the inlet diameter of the tailwater conical section (1).

4. The method for adjusting the adjustable tailwater pipe internal guide plate according to claim 1, characterized in that, The ratio of the height of the guide plate (2) to the inlet diameter of the tailwater conical section (1) is H2:D=7:10~8:10; Where H2 is the height of the guide plate (2).

5. The method for adjusting the adjustable tailwater pipe internal guide plate according to claim 1, characterized in that, In step 1, the relative power of the turbine is calculated based on the turbine's operating power P1. As shown in the following formula: ； Where P1 is the current operating power of the turbine, P r This refers to the rated power of the water turbine. This represents the relative power of the water turbine.

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