A design method of adjustable moving blade axial flow fan back guide vane

Abstract

The application discloses a design method of a rear guide vane of an adjustable moving blade axial flow fan, and comprises the following steps: firstly, determining the number N of profile sections of the rear guide vane along the blade height section; secondly, for the N profile sections, the profile method of the blade profile curve of each section is given respectively; and finally, the blade profile curves of the N blade height sections are stacked along the blade height direction to complete the three-dimensional model profiling of the rear guide vane, and the number of the rear guide vane is determined. Under the premise of keeping the moving blade wheel of the adjustable moving blade axial flow fan unchanged, the rear guide vane is re-optimized and designed after the fan moving blade wheel, so that the dual purposes of improving the operation pressure of the fan and the actual operation efficiency of the fan can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of adjustable blade axial flow fan, in particular to a design method of adjustable blade axial flow fan back guide vane. BACKGROUND

[0002] The adjustable blade axial flow fan can adjust the blade angle, change the blade installation angle to adapt to the flow change, so that it can run in a wider flow range, and it also has the characteristics of energy saving and low noise. Therefore, in recent years, the adjustable blade axial flow fan has been widely used in large thermal power generating units. The back guide vane is usually arranged behind the adjustable blade axial flow fan impeller, which can fully recover the swirling kinetic energy at the outlet of the adjustable blade axial flow fan impeller, so as to improve the operating pressure of the fan and the actual operating efficiency of the fan.

[0003] However, the back guide vane of the adjustable blade axial flow fan usually adopts a single circular arc blade type, which cannot fully utilize the potential of the back guide vane to recover the swirling kinetic energy at the outlet of the adjustable blade axial flow fan impeller, so the actual operating performance of the fan cannot reach the best. SUMMARY

[0004] In order to solve the problems in the prior art, the present application provides a design method of adjustable blade axial flow fan back guide vane, which can improve the operating pressure and the actual operating efficiency of the fan by re-optimizing the design of the back guide vane behind the fan impeller under the premise of keeping the adjustable blade axial flow fan impeller unchanged. At the same time, this design method of adjustable blade axial flow fan back guide vane has the advantages of low investment cost, short reconstruction period, remarkable reconstruction effect, etc., and is suitable for large-scale popularization and application in the market.

[0005] The present application is realized by adopting the following technical scheme:

[0006] A design method of adjustable blade axial flow fan back guide vane, comprising:

[0007] Firstly, the number N of profile sections of the back guide vane along the blade height section is determined; secondly, for the N profile sections, the profile curve modeling method of each section is given; finally, the profile curve of the N blade height sections is stacked along the blade height direction to complete the three-dimensional model of the back guide vane, and the number of the back guide vanes is determined.

[0008] The present application further improves the method by implementing the following steps:

[0009] 1) Determine the number N of profile sections of the back guide vane along the blade height section, and uniformly divide the back guide vane along the blade height direction into N profile sections in the polar coordinate system, wherein the first section is the blade root section, and the Nth section is the blade tip section;

[0010] 2) For N shaped sections, give the shaping method of the airfoil section curve for each section. The shaping method of each airfoil section is the same for N airfoil sections.

[0011] 3) Stack the airfoil profiles of the N airfoil sections along the blade height direction to generate a single three-dimensional shape of the guide vane; based on the airfoil profile of the i-th airfoil section obtained in step 2), pass through point B on the center line of each airfoil. i Stacking is performed along the leaf height direction to generate a single three-dimensional model of the rear guide vane;

[0012] 4) Determine the number of guide vanes and complete the overall shape of the guide vanes.

[0013] A further improvement of the present invention is that, in step 1), 3≤N≤5, and N is an integer.

[0014] A further improvement of this invention is that, in step 2), for the i-th airfoil section, i = 1, ..., N, the method for shaping the airfoil section of the guide vane is as follows:

[0015] 201) Determine the centerline MC of the i-th airfoil section of the guide vane. i Center line MC i It consists of two circular arcs and one straight line segment;

[0016] 202) Determine the airfoil profile of the i-th airfoil section of the rear guide vane; First, the centerline MC of the i-th airfoil section of the rear guide vane is obtained through step 201). i Along the center line MC i Equal thickness δ is offset to both sides i The upper and lower surface profiles of the i-th airfoil section of the guide vane are obtained; then, the airfoil leading edge point A is used to obtain the profiles. i Leaf-shaped trailing edge point D i Construct the common tangent arcs of the upper and lower surface profiles of the i-th airfoil section obtained earlier, with the radius of the arc being r. i In this way, we obtain the leading edge arc curve, the trailing edge arc curve, and the upper and lower surface profiles of the airfoil, which is the airfoil profile of the guide vane at the i-th airfoil section.

[0017] A further improvement of the present invention is that, in step 201), the centerline MC i The specific method for determination is as follows:

[0018] First, at the i-th airfoil section, with O 1,i Centered on A i Starting from point θ, draw a circle with a central angle of θ. 1,i The radius is R 1,i The arc, with its endpoint at point B. i This completes the circular arc curve. The structure; in which, the circular arc curve At destination B i It is tangent to the axis at point B. i Circular curve The axial length is l 1,i Then, with B i Starting from a point along the axial direction, extend for a length of l. 2,i The line segment, whose endpoint is C. i straight line segment Length l 2,i Satisfy: 0.5·l 1,i ≤l 2,i ≤1.5·l 1,i Finally, with C i Starting from point θ, draw a circle with a central angle of θ. 2,i The radius is R 2,i The arc, with its endpoint at D. i This completes the circular arc curve. The structure; in which, the circular arc curve At starting point C i Located on the axial straight segment Tangent, with the point of tangency at C i Circular curve The axial length is l 3,i The center of the circle is O 2,i ; circular curve straight segment and circular curves The trailing ends are connected sequentially to form the centerline MC of the i-th airfoil section of the guide vane. i .

[0019] A further improvement of the present invention is that the central angle θ 1,i Satisfy: θ 1,i ∈[15°, 60°], radius R 1,i Satisfy: R 1,i ∈[500,3500]mm; Central angle θ 2,i Satisfy: θ 2,i ∈[5°,15°], radius R 2,i Satisfy: R 2,i ∈[500,2500]mm.

[0020] A further improvement of the present invention is that, in step 202), δ i ∈[3,12]mm.

[0021] A further improvement of the present invention is that, in step 202), r i =δ i ∈[3,12].

[0022] The further improvement of the present application is that in step 202), the airfoil section curve is divided into two curves of upper side and lower side, the upper side curve of the airfoil is the suction surface profile SC of the airfoil i , and the lower side curve of the airfoil is the pressure surface profile PC of the airfoil i . i i .

[0023] The further improvement of the present application is that in step 4), the number of the rotor blades of the rotor-adjustable axial flow fan is N R , the number of the guide vane blades is N S , which is determined as follows: 0.7·N R ≤N S ≤1.3·N R , and N S and N R do not have common multiples; after the number of the guide vane blades N S is determined, the guide vanes are arranged evenly on the hub behind the impeller in the number of N S .

[0024] The present application has at least the following beneficial technical effects:

[0025] The present application provides a design method of the guide vanes of the rotor-adjustable axial flow fan, which can improve the operating pressure and the actual operating efficiency of the fan by re-optimizing the design of the guide vanes behind the impeller of the fan under the premise of keeping the impeller unchanged.

[0026] The design method of the guide vanes of the rotor-adjustable axial flow fan improves the traditional design method by optimizing and upgrading the single circular-arc airfoil structure to the multi-segment composite airfoil structure, so that the optimized and upgraded composite airfoil guide vanes can fully exploit the potential of recovering the rotational kinetic energy at the outlet of the impeller, thereby significantly improving the actual operating performance of the rotor-adjustable axial flow fan. Meanwhile, the present application has the advantages of technical safety and reliability, strong implementability, low investment cost, short reconstruction period, and remarkable reconstruction effect, and is suitable for large-scale popularization and application in the market. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a schematic diagram of the airfoil section of the guide vanes of the present application.

[0028] Wherein, N is the total number of the airfoil sections of the guide vanes, i is the serial number of the airfoil section, N R is the number of the blades of the impeller of the fan, and N S is the number of the blades of the guide vanes of the fan.

[0029] Figure 1 ​MCi is the parameter of the i-th blade profile section of the rear guide vane, wherein, MCi i is the first circular arc curve of the blade profile section center line, is the first circular arc curve of the blade profile section center line, is the straight line segment of the blade profile section center line, is the second circular arc curve of the blade profile section center line, A i is the leading edge point of the blade profile section center line, B i is the starting point of the straight line segment of the blade profile section center line, which is also the blade profile section area center point, C i is the ending point of the straight line segment of the blade profile section center line, D i is the trailing edge point of the blade profile section center line, O 1,i is the turning center of the first circular arc curve of the blade profile section center line, O 2,i is the turning center of the second circular arc curve of the blade profile section center line, SC i is the blade suction surface profile, PC i is the blade pressure surface profile.

[0030] θ 1,i is the turning angle of the first circular arc curve of the blade profile section center line, θ 2,i is the turning angle of the second circular arc curve of the blade profile section center line, all of the above units are °.

[0031] l 1,i is the axial length of the first circular arc curve of the blade profile section center line, l 2,i is the length of the straight line segment of the blade profile section center line, l 3,i is the axial length of the second circular arc curve of the blade profile section center line, δ i is the superimposed thickness of the blade profile section center line, r i is the radius of the leading edge and trailing edge circular arc curve of the blade profile section, R 1,i is the radius of curvature of the first circular arc curve of the blade profile section center line, R 2,i is the radius of curvature of the second circular arc curve of the blade profile section center line, all of the above units are mm. DETAILED DESCRIPTION

[0032] Exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be accurately conveyed to those skilled in the art. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict. The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0033] AsFigure 1 As shown, the application provides a design method for the rear guide vane of an adjustable blade axial flow fan. First, the number N of profile sections of the rear guide vane along the blade height section is determined. Second, the profile curve of each section is given for the N profile sections. Finally, the profile curves of the N blade height sections are stacked along the blade height direction to complete the three-dimensional modeling of the rear guide vane and determine the number of the rear guide vane.

[0034] The specific implementation method is as follows:

[0035] 1. Determine the number N of profile sections of the rear guide vane along the blade height section. In the polar coordinate system, the rear guide vane is evenly divided into N blade profile sections along the blade height direction, 3≤N≤5, N is an integer, wherein the first section is the blade root section and the Nth section is the blade tip section.

[0036] 2. For the N profile sections, the profile curve of each section is given. For the N blade profile sections, the profile method of each blade profile section is the same. The following describes the profile method of the i-th blade profile section, i=1,…,N.

[0037] (1) Determine the center line MC of the i-th blade profile section of the rear guide vane i . The center line MC i is composed of two circular arc curves and a straight line segment. The specific determination method is as follows: first, in the i-th blade profile section, take O 1,i as the center, take A i as the starting point, draw a circular arc with a central angle of θ 1,i and a radius of R 1,i , and the end point of the circular arc is B i . In this way, the circular arc curve is constructed. The circular arc curve is tangent to the axial direction at the end point B i , the tangent point is B i , the length of the circular arc curve in the axial direction is l 1,i , the central angle θ 1,i satisfies: θ 1,i ∈[15°,60°], the radius R 1,i satisfies: R 1,i ∈[500,3500]mm. Then, take B i as the starting point and extend a straight line segment with a length of l 2,i along the axial direction, and the end point of the line segment is C i , the length l 2,i of the straight line segment satisfies: 0.5·l 1,i ≤l 2,i ≤1.5·l 1,iFinally, with C i Starting from point θ, draw a circle with a central angle of θ. 2,i The radius is R 2,i The arc, with its endpoint at D. i This completes the circular arc curve. The structure. Among them, the circular arc curve. At starting point C i Located on the axial straight segment Tangent, with the point of tangency at C i Circular curve The axial length is l 3,i The center of the circle is O 2,i Central angle θ 2,i Satisfy: θ 2,i ∈[5°,15°], radius R 2,i Satisfy: R 2,i ∈[500,2500]mm. Circular curve. straight segment and circular curves The trailing ends are connected sequentially to form the centerline MC of the i-th airfoil section of the guide vane. i .

[0038] (2) Determine the airfoil profile of the i-th airfoil section of the rear guide vane. First, through the above steps, the centerline MC of the i-th airfoil section of the rear guide vane is obtained. i Along the center line MC i Equal thickness δ is offset to both sides i δ i ∈[3,12]mm, obtain the upper and lower surface profiles of the i-th airfoil section of the rear guide vane. Then, through the leading edge point A of the airfoil... i Leaf-shaped trailing edge point D i Construct the common tangent arcs of the upper and lower surface profiles of the i-th airfoil section obtained earlier, with the radius of the arc being r. i r i =δ i ∈[3,12], thus obtaining the leading edge arc curve, the trailing edge arc curve, and the upper and lower surface profiles of the airfoil, which in turn yields the airfoil profile of the i-th airfoil section. The airfoil section curve is defined by the leading edge point A. i Leaf-shaped trailing edge point D i The blade profile is divided into two curves, upper and lower. The upper curve of the blade profile is the suction surface profile SC. i The lower side curve of the airfoil is the airfoil pressure surface profile PC. i .

[0039] 3. The profile lines of the N profile sections of the back guide vane are stacked along the blade height direction to generate a single back guide vane three-dimensional model. According to the profile lines of the i-th profile section of the back guide vane obtained in the above step, the points B i on the center line of each profile are stacked along the blade height direction to generate a single back guide vane three-dimensional model.

[0040] 4. The number of back guide vane blades is determined to complete the overall modeling of the back guide vane. The number of blades of the movable vane of the movable vane adjustable axial flow fan is N R , and the number of back guide vane blades is N S . The number of back guide vane blades is determined as follows: 0.7·N R ≤N S ≤1.3·N R , and N S and N R cannot be mutual multiples. After determining the number of back guide vane blades N S , the back guide vane is installed on the impeller hub with N S uniformly arranged, so that the overall modeling of the back guide vane of the movable vane adjustable axial flow fan is completed.

[0041] Embodiment

[0042] A 600MW unit induced draft fan in China is a movable vane adjustable axial flow fan, and the number of single-stage movable vanes is 18. The design and modeling of the back guide vane of the movable vane adjustable axial flow fan are implemented in the following steps:

[0043] 1. The number of modeling profile sections of the back guide vane along the blade height direction is determined to be N=3.

[0044] 2. For the three modeling profile sections, the modeling method of the profile curve of each section is given respectively:

[0045] (1) The parameters required for modeling the profile lines of each profile section are determined: R 1,1 =R 2,1 =R 3,1 =1200mm, R 1,2 =R 2,2 =R 3,2 =800mm, l 1,1 =600mm, l 2,1 =507mm, l 3,1 =410mm, l 1,2 =l 2,2 =l 3,2 =300mm, l 1,3 =l 2,3 =l 3,3 =139mm, δ1=δ2=δ3=5mm, r1=r2=r3=6mm, θ 1,1 =30°, θ 2,1= 25°, θ 1,1 = 20°, θ 2,1 = θ 2,2 = θ 2,3 = 10°.

[0046] (2) According to each blade profile section blade profile line parameter determined above, the modeling of the first to third blade profile sections is completed according to the modeling method of the present application.

[0047] 3. The blade profile line of the i-th blade profile section of the back guide vane obtained according to the above steps is stacked along the blade height direction at each blade profile section B i i = 1,..., 3, thus completing the three-dimensional modeling of a single back guide vane.

[0048] 4. The number of fan moving vane blades N rotor = 18, the number of fan back guide vane blades N S = 19, the three-dimensional modeling of a single back guide vane obtained in the above step is arranged along a plane perpendicular to the axial direction of the fan, and 19 back guide vane blades are evenly arranged between the fan hub and the casing according to the principle of equal solidity.

[0049] After the above steps, the overall modeling of the adjustable moving vane axial flow fan back guide vane is completed. The application of the new multi-section back guide vane of the present application to the adjustable moving vane axial flow fan not only increases the pressure coefficient of the fan by 5%, but also increases the operating efficiency of the fan. The fan can meet the output requirements of the unit and operate safely and reliably. The design of the adjustable moving vane axial flow fan back guide vane has achieved the expected improvement effect.

[0050] Although the present application has been described in detail above with general description and specific implementation, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application are within the scope of the present application.

Claims

1. A method for designing the rear guide vanes of an adjustable axial flow fan, characterized in that, include: First, determine the number of profile sections along the blade height of the rear guide vane. N ; Secondly, targeting N Each section has a specific shape, and the method for shaping the blade profile curve for each section is given; finally, N The airfoil profile curves of each blade height section are stacked along the blade height direction to complete the three-dimensional model of the guide vane and determine the number of guide vanes. The specific implementation steps of this method are as follows: 1) Determine the number of profile sections along the blade height of the rear guide vane. N In the polar coordinate system, the rear guide vane is evenly divided along the blade height direction into... N There are several blade-shaped cross-sections, where the first cross-section is the blade root cross-section, and the second... N One section is the blade tip section; 3≤ N ≤5, N It is an integer; 2) Targeting N For each of the several airfoil cross-sections, the method for creating the airfoil cross-section curve is given. N The airfoil section is shaped in the same way for each airfoil section; for the ... One leaf-shaped cross section, The method for shaping the airfoil section of the guide vane is as follows: 201) Determine the first guide vane Centerline of each airfoil section center line It consists of two circular arcs and one straight line segment; centerline The specific method for determination is as follows: First, in the A leaf-shaped cross section, with With the center as the center, Starting from point A, draw the central angle as... , radius is The arc, the endpoint of the arc is This completes the circular arc curve. The structure; in which, the circular arc curve At the finish line It is tangent to the axis at the point of tangency. Circular curve The length in the axial direction is Then, with Starting from the axis, the length extended along the axial direction is The line segment, the endpoint of the line segment is straight line segment length satisfy: Finally, with Starting from point A, draw the central angle as... , radius is The arc, the endpoint of the arc is This completes the circular arc curve. The structure; in which, the circular arc curve At the starting point Located on the axial straight segment Tangent, the point of tangency is Circular curve The length in the axial direction is The center of the circle is ; circular curve straight line segment and circular curves The tails are connected in sequence to form the first rear guide leaf. Centerline of each airfoil section ; Central angle satisfy: ,radius satisfy: mm; central angle satisfy: ,radius satisfy: mm; 202) Determine the first guide vane The airfoil profile of the first airfoil section; firstly, the airfoil of the rear guide vane was obtained through step 201). Centerline of each airfoil section Along the center line Equal thickness offset to both sides After obtaining the first leaf The upper and lower surface profiles of each airfoil section; then, through the leading edge point of the airfoil. Leaf-shaped tail edge point The first and second guide leaves obtained above are respectively... The common tangent arcs of the upper and lower surface profiles of each leaf-shaped section have radii of... In this way, we obtain the leading edge arc curve, the trailing edge arc curve, and the upper and lower surface profiles of the airfoil, thus obtaining the first... The airfoil profile of the guide vane at each airfoil section; among which mm, ; The airfoil section curve is affected by the airfoil leading edge point. Leaf-shaped tail edge point The blade profile is divided into two curves, upper and lower. The upper curve of the blade profile is the suction surface profile. The lower side curve of the airfoil is the pressure surface profile of the airfoil. ; 3) The rear guide vane N The airfoil profiles of each airfoil section are stacked along the airfoil height direction to generate a single three-dimensional shape of the guide vane; based on the airfoil obtained in step 2), the first airfoil section... The airfoil profile of each airfoil section passes through a point on the center line of each airfoil. Stacking is performed along the leaf height direction to generate a single three-dimensional model of the rear guide vane; 4) Determine the number of guide vane blades, complete the overall shape of the guide vanes, and determine the number of blades for the adjustable axial flow fan impeller. Number of rear guide vane blades Determine according to the following requirements: ,and Not with The number of guide vane blades should be a common multiple of each other; after determining the number of guide vane blades... Then, install the number of rear guide vanes on the impeller rear hub. Distribute evenly.

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