CN112131720B - Method for calculating unit load of fan blade icing - Google Patents
Method for calculating unit load of fan blade icing Download PDFInfo
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Abstract
The embodiment of the invention provides a method for calculating unit load of fan blade icing, which adopts load simulation calculation software based on a first standard of a fan, wherein the first standard is modeled by a first icing quality model. The method comprises the following steps: correcting the airfoil shape of the fan blade in the software based on a second standard, wherein the second standard is modeled by a second icing quality model; calculating a first icing mass moment of the fan blade based on a first criterion; calculating a second icing mass moment of the fan blade based on a second criterion; finding out the minimum blade tip icing chord length of the fan blade when the calculated first icing mass moment is equal to the second icing mass moment; inputting the found minimum blade tip icing chord length into the software, and establishing an icing model of the fan blade in the software based on a second standard; and calculating and obtaining the unit load of the fan blade icing through the software based on the icing working condition of the second standard. Therefore, the unit load of the fan blade after icing can be calculated more accurately.
Description
Technical Field
The embodiment of the invention relates to the technical field of wind power, in particular to a method for calculating unit load of fan blade icing.
Background
At present, a relevant method given in GL2010 standard is generally adopted for unit load simulation calculation of icing of wind turbine generator unit blades, and an icing quality model adopted by the GL2010 standard is shown in fig. 1. And calculating the minimum icing chord length Cmin of the blade tip according to the blade tip shape interpolation, and further calculating the maximum linear density mu E of the blade icing. The calculation formula of the maximum linear density mu E of the blade ice coating is as follows:
μE＝ρEk Cmin(Cmin+Cmax)
wherein, the ice density ρ E＝700kg/m3; the coefficient k=0.00675+0.3exp (-0.32R), C max is the maximum chord length.
As can be seen from the icing quality model shown in fig. 1, the icing linear density from the rotor center O to the rotor radius intermediate distance S increases linearly from zero to a maximum linear density value μ E, after which the maximum linear density μ E value is maintained to the blade tip B. The icing quality of the fan blade can be calculated according to the icing quality model of the fan blade and the ice density.
However, the icing quality obtained by the blade icing quality calculation method in the GL2010 specification is more conservative, so that the ice load limit and the fatigue load are larger, the influence of icing on the aerodynamic performance of the blade is not considered, and the calculation result is inaccurate.
The fourth edition of IEC61400-1 standard provides a new method for calculating the icing quality of the blade. The icing quality model adopted by the fourth edition of the IEC61400-1 standard is shown in figure 2. The ice-coating linear density M (r) of the blades at each section is increased linearly from the wind wheel center O to the blade tip B to M. The calculation formula of the ice-coating linear density M (r) of the blade at each section is as follows:
M(r)＝0.125×C85×r
Wherein C 85 is the chord length at the position of the impeller radius of 85%, and r is the distance between each section of the blade and the hub center O.
In addition, due to the pneumatic performance attenuation of the blade after icing, the fourth edition of IEC61400-1 standard also defines a correction method of pneumatic performance parameters (coefficient of resistance to rise) of the icing airfoil, namely penalty factors. Moreover, the manner in which blade icing quality for different load analysis types, such as limit load and fatigue load, is considered is different, as shown in the following table:
| Analysis type | Blade 1 | Blade 2 | Blade 3 | Penalty factor |
| Ultimate load | 2×M(r) | 2×M(r) | - | Is that |
| Fatigue load | M(r) | M(r) | M(r)×0.5 | Is that |
The blade icing quality calculation method and the icing wing profile aerodynamic performance parameter (lift drag coefficient) correction method proposed by the fourth edition of IEC61400-1 standard are more reasonable. However, since the default icing quality model in the Bladed load simulation calculation software adopts the setting of the GL2010 standard, the modeling of the icing of the fourth version of the IEC61400-1 standard cannot be realized in the Bladed load simulation calculation software at present, and further, the accurate and reasonable ice-load working condition assumption and calculation analysis work cannot be carried out.
Disclosure of Invention
The embodiment of the invention aims to provide a method for calculating the unit load of the fan blade ice coating, which can more accurately calculate the unit load of the fan blade ice coating.
One aspect of the embodiment of the invention provides a method for calculating unit load of ice coating of a fan blade, which adopts load simulation calculation software based on a first standard of the fan, wherein the first standard is modeled by a first ice coating quality model of the fan blade. The method comprises the following steps: modifying an airfoil of the fan blade in the load simulation calculation software based on a second criterion, wherein the second criterion is modeled with a second icing quality model of the fan blade; calculating a first icing mass moment of the fan blade based on the first criterion; calculating a second icing mass moment of the fan blade based on the second criterion; finding out the minimum blade tip icing chord length of the fan blade when the calculated first icing mass moment is equal to the second icing mass moment; inputting the found minimum blade tip icing chord length into the load simulation calculation software, and establishing an icing model of the fan blade in the load simulation calculation software based on the second standard; and calculating and obtaining the unit load of the fan blade icing through the load simulation calculation software based on the icing working condition of the second standard.
Further, the load simulation calculation software comprises Bladed software.
Further, the first standard of the fan comprises GL2010 specifications, and the second standard of the fan comprises IEC61400-1 standard, fourth edition.
Further, modifying the airfoil of the fan blade in the load simulation calculation software based on the second criteria includes: and correcting the aerodynamic performance parameters of the fan blade in the load simulation calculation software based on the second standard.
Further, the modifying the aerodynamic performance parameters of the fan blade in the load simulation calculation software based on the second criteria includes: a penalty factor is used to modify the aerodynamic performance parameter of the fan blade.
Further, the modifying the aerodynamic performance parameter of the fan blade using the penalty factor includes: the lift coefficient penalty factor and the drag coefficient penalty factor are respectively used for obtaining the lift coefficient and the drag coefficient after the fan blade is corrected; and obtaining the lift coefficient and the drag coefficient of the fan blade after correction by using an extrapolation method at an attack angle ranging from-180 degrees to 180 degrees except from a minimum attack angle to a stall attack angle.
Further, the calculating a first icing mass moment of the fan blade based on the first criterion comprises: the first icing mass moment of the blade is calculated based on a first icing linear density of the blade in the first icing mass model.
Further, the second icing mass moment includes a second limit single blade icing mass moment, and the calculating the second icing mass moment of the fan blade based on the second criterion includes: the second limited single blade icing mass moment of the fan blade is calculated based on 2 times a second icing linear density of blades in the second icing mass model.
Further, the finding the minimum tip icing chord length of the fan blade when the calculated first icing mass moment and the calculated second icing mass moment are equal includes: finding out the minimum blade tip icing chord length of the fan blade when the calculated first icing mass moment is equal to the second limit single-blade icing mass moment, wherein the building of the icing model of the fan blade comprises the following steps: establishing a limit icing model of the fan blade, wherein the calculating to obtain the icing load of the fan blade comprises the following steps: and calculating to obtain the unit load of the limit icing of the fan blade.
Further, the second icing mass moment includes a second fatigue single blade icing mass moment, and the calculating the second icing mass moment of the fan blade based on the second criterion includes: the second fatigue single blade icing mass moment of the fan blade is calculated based on 0.5 times a second icing linear density of blades in the second icing mass model.
Further, the finding the minimum tip icing chord length of the fan blade when the calculated first icing mass moment and the calculated second icing mass moment are equal includes: finding out the minimum blade tip icing chord length of the fan blade when the calculated first icing mass moment is equal to the second fatigue single-blade icing mass moment, wherein the building of the icing model of the fan blade comprises the following steps: establishing a fatigue icing model of the fan blade, wherein the calculating to obtain the icing load of the fan blade comprises the following steps: and calculating to obtain the fatigue ice-covered unit load of the fan blade.
Further, the establishing the icing model of the fan blade includes: and increasing the original linear density of the fan blade by 0.5 times of the second icing linear density in the load simulation calculation software.
The method for calculating the unit load of the fan blade icing adopts the load simulation calculation software based on the first standard of the fan, and realizes modeling in the load simulation calculation software of the blade icing quality calculation method based on the second standard and the airfoil correction method of the fan blade based on the second standard. Therefore, the unit load of the fan blade after icing can be calculated more accurately.
Drawings
FIG. 1 is a schematic diagram of an icing quality model employed in the GL2010 Specification;
FIG. 2 is a schematic diagram of an icing quality model employed in the fourth edition of the IEC61400-1 standard;
FIG. 3 is a flow chart of a method of calculating unit load for fan blade icing in accordance with an embodiment of the present invention;
FIG. 4 is a schematic view of a fan blade.
Detailed Description
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus consistent with aspects of the invention as detailed in the accompanying claims.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless defined otherwise, technical or scientific terms used in the embodiments of the present invention should be given the ordinary meaning as understood by one of ordinary skill in the art to which the present invention belongs. The terms first, second and the like in the description and in the claims, are not used for any order, quantity or importance, but are used for distinguishing between different elements. Likewise, the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. "plurality" or "plurality" means two or more. Unless otherwise indicated, the terms "front," "rear," "lower," and/or "upper" and the like are merely for convenience of description and are not limited to one location or one spatial orientation. The word "comprising" or "comprises", and the like, means that elements or items appearing before "comprising" or "comprising" are encompassed by the element or item recited after "comprising" or "comprising" and equivalents thereof, and that other elements or items are not excluded. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.
The embodiment of the invention provides a method for calculating the unit load of fan blade icing, which adopts load simulation calculation software based on a first standard of a fan to realize modeling in the load simulation calculation software of a blade icing quality calculation method based on a second standard and an airfoil correction method of a fan blade based on the second standard. The first standard is modeled by a first icing quality model of the fan blade, and the second standard is modeled by a second icing quality model of the fan blade.
FIG. 1 discloses a flow chart of a method for calculating unit load of fan blade icing in accordance with an embodiment of the present invention. As shown in FIG. 1, the method for calculating the unit load of the fan blade icing according to one embodiment of the present invention may include steps S11-S16.
In step S11, the airfoil of the fan blade in the load simulation calculation software is modified based on the second criterion.
In step S12, a first icing mass moment of the fan blade is calculated based on the first criterion.
In step S13, a second icing mass moment of the fan blade is calculated based on a second criterion.
In step S14, the minimum Tip icing chord length Tip chord of the fan blade when the calculated first icing mass moment is equal to the second icing mass moment is found.
In step S15, the found minimum Tip icing chord length Tip chord is input into the load simulation calculation software, and an icing model of the fan blade is built in the load simulation calculation software based on the second standard.
In step S16, the unit load for obtaining the icing of the fan blade is calculated through the load simulation calculation software based on the icing working condition of the second standard.
As shown in fig. 3, the method for calculating the unit load of the fan blade ice coating according to the embodiment of the present invention includes the above steps, but the method for calculating the unit load of the fan blade ice coating according to the embodiment of the present invention may further include additional steps before, after and between the steps listed. In some embodiments, one or more of the enumerated steps may be performed in a different order than shown in fig. 3.
In one embodiment, the load simulation calculation software of the embodiment of the invention may comprise Bladed software, the first standard of the blower may comprise the GL2010 specification, and the second standard of the blower may comprise the fourth version of the IEC61400-1 standard. The GL2010 standard adopts a first ice coating quality model shown in fig. 1, and the fourth version of the IEC61400-1 standard adopts a second ice coating quality model shown in fig. 2. However, the embodiments of the present invention are not limited thereto.
In some embodiments, modifying the airfoil of the fan blade in the load simulation calculation software based on the second criteria of step S11 includes: and correcting the aerodynamic performance parameters of the fan blade in the load simulation calculation software based on the second standard. For example, in an embodiment in which the second standard is the fourth version of the IEC61400-1 standard, the penalty factor may be used to modify the aerodynamic performance parameters of the fan blade.
How to use penalty factors to modify the aerodynamic performance parameters of a fan blade based on the fourth version of the IEC61400-1 standard will be described in detail below.
The lift coefficient and drag coefficient penalty factors may be used to obtain the corrected lift coefficient and drag coefficient of the fan blade at an angle of attack in the range of the minimum angle of attack α 0 to the stall angle of attack α s, i.e., α 0～αs, respectively.
The penalty factor formula is as follows:
CL,pen(α)＝-0.0014α2-0.0017α+0.9509
CD,pen(α)＝0.0191α+3.1151
Wherein, C L,pen is a lift coefficient penalty factor, C D,pen is a drag coefficient penalty factor, and alpha is an attack angle.
The lift coefficient and drag coefficient after fan blade correction, i.e. the icing airfoil drag coefficient, can be expressed as:
CL,Iced＝CL,pen×CL,clean
CD,Iced＝CD,pen×CD,clean
Wherein, C L,Iced is the lift coefficient of the ice-covered airfoil, and C L,clean is the original lift coefficient of the airfoil; c D,Iced is the ice-covered airfoil drag coefficient, and C D,clean is the airfoil original drag coefficient.
Therefore, at an attack angle in the range of alpha 0～αs, the lift coefficient C L,Iced and the drag coefficient C D,Iced of the fan blade after correction (namely after the blade is iced) can be obtained according to the products of the original lift coefficient C L,clean and the original drag coefficient C D,clean of the fan blade airfoil and the lift coefficient penalty factor C L,pen and the drag coefficient penalty factor C D,pen respectively.
In addition to the minimum angle of attack α 0 to the stall angle of attack α s, within the range of-180 to 180 degrees, extrapolation methods, such as Viterna methods, may be used to extrapolate to obtain the corrected lift and drag coefficients of the fan blade, with no modification to the bending moment coefficient C M. The details are as follows.
In the range of alpha s -90 degrees of attack, the lift coefficient C L,Iced and the drag coefficient C D,Iced of the fan blade after correction can be obtained by the following formula:
CL,Iced＝CDMAXsin(2α)/2+A2cos2(α)/sin(α)
CD,Iced＝CDMAXsin2(α)+B2cos(α)
where C DMAX represents the drag coefficient at angle of attack α=90°, C DMAX can be derived according to the following formula:
CDMAX＝min(1.11+0.018AR,2.01)
Wherein AR is the aspect ratio of the blade and represents the ratio of the radius of the wind wheel to the chord length at the radius of the 80% wind wheel.
A2＝(CLs-CDMAXsin(αs)cos(αs))sin(αs)/cos2(αs)
B2＝(CDs-CDMAXsin2(αs))/cos(αs)
Wherein C Ls is the lift coefficient corresponding to stall angle of attack alpha s; c Ds is the corresponding drag coefficient at stall angle of attack α s.
For the angle of attack range of 90 deg. -180 deg. -alpha s、-180°+αs～-αs deg., the lift coefficient of the airfoil can be obtained by scaling and mirroring the lift coefficient curve of alpha s deg. -90 deg.. For an asymmetric airfoil, the scaling factor C LAdj is 0.7. When the attack angle is + -180 DEG, the lift coefficient is 0. The missing part (-180 degrees to-180 degrees+alpha s、-αs～α0、180°-αs to 180 degrees) of other lift coefficient curves can be obtained through linear interpolation. The drag coefficient of the airfoil is not scaled and can be directly mirrored. Thus, the first and second substrates are bonded together,
In the attack angle range of-180 degrees to-180 degrees +alpha s, the lift coefficient C L,Iced and the drag coefficient C D,Iced after fan blade correction are as follows:
CL,Iced＝(180+α)/αsCLsCLAdj
CD,Iced＝CDMAXsin2(180+α)+B2cos(180+α)
In the attack angle range of-180 degrees+alpha s to-90 degrees, the lift coefficient C L,Iced and the drag coefficient C D,Iced of the fan blade after correction are as follows:
CL,Iced＝CLAdj(CDMAXsin(2(α+180))/2+A2cos2(180+α)/sin(180+α))
CD,Iced＝CDMAXsin2(180+α)+B2cos(180+α)
in the attack angle range of-90 degrees to-alpha s degrees, the lift coefficient C L,Iced and the drag coefficient C D,Iced of the fan blade after correction are as follows:
CL,Iced＝CLAdj(-CDMAXsin(2(-α))/2-A2cos2(-α)/sin(-α))
CD,Iced＝CDMAXsin2(-α)+B2cos(-α)
in the angle of attack range of-alpha s～α0, the lift coefficient C L,Iced and the drag coefficient C D,Iced after fan blade correction are as follows:
CL,Iced＝-CLsCLAdj+(α+αs)/(α0+αs)(CLsCLAdj+CL0)
CD,Iced＝CD0+(-α+α0)(CDs–CD0)/(αs+α0)
Wherein C L0 is the lift coefficient corresponding to the minimum attack angle alpha 0; c D0 is the corresponding drag coefficient at the minimum angle of attack α 0. C L0 and C D0 may be derived from the penalty factor correction method mentioned above.
In the attack angle range of 90-180-alpha s, the lift coefficient C L,Iced and the drag coefficient C D,Iced of the fan blade after correction are as follows:
CL,Iced＝CLAdj(-CDMAXsin(2(180-α))/2-A2cos2(180-α)/sin(180-α))
CD,Iced＝CDMAXsin2(180-α)+B2cos(180-α)
In the range of 180 ° -alpha s -180 ° attack angle, the lift coefficient C L,Iced and drag coefficient C D,Iced after fan blade correction are as follows:
CL,Iced＝(α-180)/αsCLsCLAdj
CD,Iced＝CDMAXsin2(α-180)+B2cos(α-180)
In some embodiments, calculating the first icing mass moment of the fan blade based on the first criterion of step S12 comprises: a first icing mass moment of the blade is calculated based on a first icing linear density of the blade in the first icing mass model.
How to calculate the first icing mass moment of the blade based on the GL2010 specifications employing the first icing mass model shown in fig. 1 will be described in detail below taking the first standard as the GL2010 specification as an example.
(A1) Impeller radius: r=0.5d, where D is the impeller diameter;
(b1) Half radius position of impeller: s=0.5R;
(c1) Minimum icing chord length of blade tip: cmin=tip chord, which represents the minimum icing chord length of the blade Tip, and this value is related to the blade Tip shape, so after the blade is selected, the blade Tip shape is unchanged, and this value is a constant, where Tip chord is a parameter input in the blade software interface;
(d1) The first icing linear density of the blade, i.e. the icing unit length mass μ E, is as follows:
μE＝ρEk Cmin(Cmin+Cmax)
wherein: ice density ρ E＝700kg/m3; the coefficient k=0.00675+0.3exp (-0.32R), C max is the maximum chord length;
(e1) Array of distances of each section of the blade from the hub center O: rr=r+l, where r is an array of distances from each section of the blade to the blade root a, and L is the distance from the blade root a to the hub center O;
(f1) Putting the position S into an array rr, and arranging the array rr from small to large, wherein the newly arranged array is rrr;
For example, consider a leaf model:
r can be obtained from a blade model, and r is an array of distances from each section of the blade to the blade root a, and is a series of discrete values, such as: 0. 0.4, 1.4, 2.4, 3.4 … … 70.67, 71.69, L is a fixed value, 1.668 is read from the model, rr is 1.668, 2.068, 3.068, 4.068, 5.068 … … 72.338, 73.348, s=0.5r=0.5× 73.348 = 36.674 because rr=r+l, then S is combined with the array rr to: 1.668, 2.068, 3.068, 4.068, 5.068 … … 72.338, 73.348, 36.674, to obtain a new array rrr:1.668, 2.068, 3.068, 4.068, 5.068 … … 36.674 (S) … … 72.338, 73.348.
(G1) After the position S is added, the distance array q=rrr-L between each section of the blade and the blade root A;
(h1) The mass array of the icing unit length from the blade root A position to the blade root S in the array rrr is as follows:
μE1＝rrr1μE/rrr1(S)
Fig. 4 discloses a schematic view of a blade. As shown in fig. 4, 1 to N in fig. 4 represent N sections of the blade, respectively. In the above formula, rrr 1 is an array of distances from the hub center O of each section of the blade from position 1 to position S, where position 1 represents the position of blade root a, i.e. the first number in array rrr; rrr 1 (S) is the distance of position S from hub center O;
(i1) The mass array of the ice coating unit length from the position S+1 in the array rrr to the position B of the blade tip is as follows:
μE2＝μE
(j1) The mass array of the ice coating unit length from the blade root A position to the blade tip B position is as follows:
mGL＝[μE1,μE2]
(k1) The mass moment array of the ice coating unit length is as follows:
iGL＝mGL×q
(l 1) i GL is the icing mass moment of each section of the blade, which is a series of discrete values. Since the blade is a continuous object, i GL needs to be integrated in order to obtain a continuous moment of icing by a series of discrete values i GL of the moment. The first icing mass moment of a blade may be expressed as:
IGL＝∫iGLdq
thus, through the above steps, the first icing mass moment I GL of the blade may be obtained.
In some embodiments, the second icing mass moment comprises a second extreme single blade icing mass moment. Thus, calculating a second icing mass moment for the fan blade based on the second criterion of step S13 comprises: and calculating the second limit single-blade icing mass moment of the fan blade based on 2 times of the second icing linear density of the blade in the second icing mass model.
How to calculate the second extreme single blade icing mass moment of the blade based on the fourth version of the IEC61400-1 standard using the second icing mass model shown in fig. 2 will be described in detail below taking the fourth version of the IEC61400-1 standard as the second standard as an example.
(A2) Impeller radius: r=0.5d, where D is the impeller diameter;
(b2) 85% impeller radius position: c 85_P =0.85R;
(c2) Array of distances of each section of the blade from the hub center O: rr=r+l, where r is an array of distances from each section of the blade to the blade root a, and L is the distance from the blade root a to the hub center O;
(d2) Chord length at 85% impeller radius position:
C85＝(C85_P–rr(t))(C(t+1)–C(t))/(rr(t+1)-rr(t))+C(t)
Wherein rr (t) represents a position before the 85% impeller radius position, rr (t+1) represents a position after the 85% impeller radius position, C (t) represents a chord length corresponding to the position before the 85% impeller radius position, and C (t+1) represents a chord length corresponding to the position after the 85% impeller radius position;
(e2) The second icing linear density of the blade, i.e. the icing unit length mass M 1, is as follows:
M1＝2×0.125×C85×R
(f2) The mass array of the icing unit length from the blade root A position to the blade tip B position is as follows:
mIEC1＝rr M1/rr(tip)
Wherein rr (tip) is the distance from the tip B to the hub center O;
(g2) The mass moment array of the ice coating unit length is as follows:
iIEC1＝mIEC1×r
(h2) i IEC1 is the icing mass moment of each section of the blade, which is a series of discrete values. Since the blade is a continuous object, i IEC1 needs to be integrated in order to obtain a continuous moment of icing by a series of discrete values i IEC1 of the moment. Thus, the second limit single blade icing mass moment can be expressed as:
IIEC1＝∫iIEC1dr
therefore, through the steps, the second extreme single blade icing mass moment I IEC1 of the blade can be obtained.
When calculating the limit working condition, the minimum blade tip icing chord length of the fan blade when the calculated first icing mass moment is equal to the calculated second icing mass moment in the step S14 comprises the following steps: and finding out the minimum Tip icing chord length Tip chord of the fan blade when the calculated first icing mass moment I GL is equal to the second limit single-blade icing mass moment I IEC1. Accordingly, the building of the icing model of the fan blade in step S15 comprises: and establishing a limit icing model of the fan blade. The calculating in step S16 to obtain the icing load of the fan blade includes: and calculating to obtain the unit load of the limit icing of the fan blade.
Specifically, the minimum blade Tip icing chord value when the first icing mass moment I GL and the second limit single-blade icing mass moment I IEC1 are equal is input into Bladed software, two-blade icing is checked, and ice density ρ E＝700kg/m3 is input. And (5) saving the model, and completing the ultimate load analysis icing modeling. And carrying out working condition assumption and Bladed simulation calculation according to the established limit icing Bladed model and the icing working condition requirement of the fourth version of IEC61400-1 standard, and carrying out post-processing on a load calculation result. Therefore, the unit load of the limit icing of the fan blade can be finally obtained.
In other embodiments, the second icing mass moment comprises a second fatigue single blade icing mass moment. Thus, calculating a second icing mass moment for the fan blade based on the second criterion of step S13 comprises: a second fatigue single-blade icing mass moment of the fan blade is calculated based on 0.5 times the second icing linear density of the blade in the second icing mass model.
How to calculate the second fatigue single blade icing mass moment of the blade based on the fourth version of the IEC61400-1 standard using the second icing mass model shown in fig. 2 will be described in detail below taking the fourth version of the IEC61400-1 standard as the second standard as an example.
(A3) Impeller radius: r=0.5d, where D is the impeller diameter;
(b3) 85% impeller radius position: c 85_P =0.85R;
(c3) Array of distances of each section of the blade from the hub center O: rr=r+l, where r is an array of distances from each section of the blade to the blade root a, and L is the distance from the blade root a to the hub center O;
(d3) Chord length at 85% impeller radius position:
C85＝(C85_P–rr(t))(C(t+1)–C(t))/(rr(t+1)-rr(t))+C(t)
Wherein rr (t) represents a position before the 85% impeller radius position, rr (t+1) represents a position after the 85% impeller radius position, C (t) represents a chord length corresponding to the position before the 85% impeller radius position, and C (t+1) represents a chord length corresponding to the position after the 85% impeller radius position;
(e3) The second icing linear density of the blade, i.e. the icing unit length mass M 2, is as follows:
M2＝0.5×0.125×C85×R
(f3) The mass array of the icing unit length from the blade root A position to the blade tip B position is as follows:
mIEC2＝rr M2/rr(tip)
Wherein rr (tip) is the distance from the tip B to the hub center O;
(g3) The mass moment array of the ice coating unit length is as follows:
iIEC2＝mIEC2×r
(h3) The second fatigue single blade icing mass moment can be expressed as:
IIEC2＝∫iIEC2dr
Thus, through the above steps, a second fatigue single blade icing mass moment I IEC2 of the blade can be obtained.
Under the fatigue working condition, the minimum blade tip icing chord length of the fan blade when the calculated first icing mass moment and the calculated second icing mass moment are equal in the step S14 comprises the following steps: and finding out the minimum Tip icing chord length Tip chord of the fan blade when the calculated first icing mass moment I GL is equal to the second fatigue single-blade icing mass moment I IEC2. Accordingly, the building of the icing model of the fan blade in step S15 comprises: establishing a fatigue ice coating model of the fan blade, wherein the establishing the ice coating model of the fan blade in the step S15 further comprises the following steps: and increasing the primary linear density of the fan blade by 0.5 times of the second icing linear density in load simulation calculation software. The raw linear density refers to the linear density of the blade itself, i.e. the linear density before icing. The calculating in step S16 to obtain the icing load of the fan blade includes: and calculating to obtain the fatigue ice-covered unit load of the fan blade.
Specifically, the minimum blade Tip icing chord value when the first icing mass moment I GL and the second fatigue single-blade icing mass moment I IEC2 are equal is input into Bladed software, two-blade icing is checked, and ice density ρ E＝700kg/m3 is input. Then, the original linear density in the Bladed software model is modified, and the second icing linear density is increased by 0.5 times on the basis of the original linear density. And (5) saving the model, and completing the fatigue load analysis icing modeling. And carrying out working condition assumption and Bladed simulation calculation according to the established fatigue ice coating Bladed model and the ice coating working condition requirement of the fourth version of IEC61400-1 standard, and carrying out post-processing on a load calculation result. Thereby, the fatigue ice-covered unit load of the fan blade can be finally obtained.
The embodiment of the invention builds a reasonable and effective ice coating working condition Bladed model based on the blade ice coating quality calculation method and the blade aerodynamic performance parameter (lift drag coefficient) correction method after ice coating in the IEC61400-1 standard fourth edition, and fills the blank of calculating and analyzing the influence of the blade ice coating load on each component according to the IEC61400-1 standard fourth edition.
The method for calculating the unit load of the fan blade icing realizes modeling in the Bladed software based on the blade icing quality calculation method and the icing airfoil pneumatic performance parameter (lifting resistance coefficient) correction method in the IEC61400-1 standard fourth edition, avoids the problems of larger ice load limit and fatigue load caused by the conservation of icing quality in the GL2010 standard, and solves the problem that the fourth edition cannot perform ice load calculation and analysis according to the IEC61400-1 standard.
The method for calculating the unit load of the fan blade icing provided by the embodiment of the invention is described in detail. Specific examples are applied to illustrate the method for calculating the unit load of the fan blade icing in the embodiment of the present invention, and the description of the above embodiment is only used to help understand the core idea of the present invention, and is not intended to limit the present invention. It should be noted that it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the spirit and principles of the invention, which should also fall within the scope of the appended claims.
Claims (12)
1. A method for calculating unit load of fan blade icing adopts load simulation calculation software based on a first standard of a fan, wherein the first standard is modeled by a first icing quality model of the fan blade, and is characterized in that: the method comprises the following steps:
modifying an airfoil of the fan blade in the load simulation calculation software based on a second criterion, wherein the second criterion is modeled with a second icing quality model of the fan blade;
calculating a first icing mass moment of the fan blade based on the first criterion;
calculating a second icing mass moment of the fan blade based on the second criterion;
finding out the minimum blade tip icing chord length of the fan blade when the calculated first icing mass moment is equal to the second icing mass moment;
inputting the found minimum blade tip icing chord length into the load simulation calculation software, and establishing an icing model of the fan blade in the load simulation calculation software based on the second standard; and
And calculating and obtaining the unit load of the fan blade icing through the load simulation calculation software based on the icing working condition of the second standard.
2. The method of claim 1, wherein: the load simulation calculation software comprises Bladed software.
3. The method of claim 1, wherein: the first standard of the fan comprises GL2010 specifications, and the second standard of the fan comprises IEC61400-1 standard fourth edition.
4. A method as claimed in claim 3, wherein: the modifying the airfoil of the fan blade in the load simulation calculation software based on the second criteria includes:
and correcting the aerodynamic performance parameters of the fan blade in the load simulation calculation software based on the second standard.
5. The method of claim 4, wherein: the modifying aerodynamic performance parameters of the fan blade in the load simulation calculation software based on the second criteria includes:
A penalty factor is used to modify the aerodynamic performance parameter of the fan blade.
6. The method of claim 5, wherein: the using a penalty factor to modify the aerodynamic performance parameter of the fan blade includes:
Respectively using a lift coefficient penalty factor and a drag coefficient penalty factor to obtain a lift coefficient and a drag coefficient after the fan blade is corrected in the range from the minimum attack angle to the stall attack angle; and
Extrapolation methods are used to obtain the corrected lift coefficient and drag coefficient for the fan blade at angles of attack in the range-180 degrees to 180 degrees, except for the range of minimum angle of attack to stall angle of attack.
7. A method as claimed in claim 3, wherein: the calculating a first icing mass moment of the fan blade based on the first criterion comprises:
The first icing mass moment of the blade is calculated based on a first icing linear density of the blade in the first icing mass model.
8. A method as claimed in claim 3, wherein: the second icing mass moment comprises a second limit single-blade icing mass moment, and the calculating the second icing mass moment of the fan blade based on the second criterion comprises:
the second limited single blade icing mass moment of the fan blade is calculated based on 2 times a second icing linear density of blades in the second icing mass model.
9. The method as recited in claim 8, wherein: the finding out the minimum tip icing chord length of the fan blade when the calculated first icing mass moment is equal to the second icing mass moment comprises: finding out the minimum blade tip icing chord length of the fan blade when the calculated first icing mass moment is equal to the second limit single blade icing mass moment,
The establishing the icing model of the fan blade comprises the following steps: establishing a limit icing model of the fan blade,
The calculating to obtain the icing load of the fan blade comprises the following steps: and calculating to obtain the unit load of the limit icing of the fan blade.
10. A method as claimed in claim 3, wherein: the second icing mass moment comprises a second fatigue single blade icing mass moment, and the calculating the second icing mass moment of the fan blade based on the second criterion comprises:
the second fatigue single blade icing mass moment of the fan blade is calculated based on 0.5 times a second icing linear density of blades in the second icing mass model.
11. The method of claim 10, wherein: the finding out the minimum tip icing chord length of the fan blade when the calculated first icing mass moment is equal to the second icing mass moment comprises: finding out the minimum blade tip icing chord length of the fan blade when the calculated first icing mass moment is equal to the second fatigue single blade icing mass moment,
The establishing the icing model of the fan blade comprises the following steps: establishing a fatigue ice-coating model of the fan blade,
The calculating to obtain the icing load of the fan blade comprises the following steps: and calculating to obtain the fatigue ice-covered unit load of the fan blade.
12. The method of claim 11, wherein: the establishing the icing model of the fan blade comprises the following steps:
And increasing the original linear density of the fan blade by 0.5 times of the second icing linear density in the load simulation calculation software.
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| CN106368913A (en) * | 2015-07-15 | 2017-02-01 | 成都阜特科技股份有限公司 | Method for measuring ice cover mass of blades of wind generating set |
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| CN106368913A (en) * | 2015-07-15 | 2017-02-01 | 成都阜特科技股份有限公司 | Method for measuring ice cover mass of blades of wind generating set |
| CN107194059A (en) * | 2017-05-19 | 2017-09-22 | 国网河南省电力公司电力科学研究院 | A kind of ice coating wire based on icing wobbler action waves method for numerical simulation |
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