Novel blade tip loss correction calculation method based on Shen blade tip loss model

Abstract

The invention provides a novel blade tip loss correction calculation method based on a Shen blade tip loss model. The method comprises the steps that 1, parameters input by a user are read; 2, the Shen blade tip loss correction model is coupled to a wind turbine simulation tool OpenFAST; 3, calculating a general correction factor according to the parameters input by the user; 4, according to the blade tip loss correction requirement, one of the Shen blade tip loss correction model and the Prandtt model in the wind turbine simulation tool OpenFAST is selected, the stress and displacement of the blade tip position under the condition of the high blade tip speed ratio are corrected in combination with the universal correction factor, and blade tip loss correction calculation is completed. The Shen blade tip loss correction model is coupled to the OpenFAST, a new blade tip loss correction calculation method is provided, the stress and displacement of the blade tip position are calculated more accurately under the condition of the high blade tip speed ratio, and the blank of the OpenFAST in the field is filled.

Description

Technical Field

[0001] The invention relates to a novel blade tip loss correction calculation method based on a Shen blade tip loss model, and belongs to the technical field of wind turbine aerodynamic design and optimization. Background Art

[0002] OpenFAST is an open source software tool for comprehensive design and analysis of wind turbines. It is widely used in the simulation and optimization of aerodynamics, structural dynamics and control systems in the field of wind power generation. The tool mainly uses the blade element momentum theory to calculate the aerodynamic performance of wind turbine blades, and on this basis introduces the Prandtl tip loss correction model to consider the influence of the tip effect on aerodynamic performance. However, in the case of high tip speed ratio, its calculation accuracy has certain limitations, which can easily lead to inaccurate prediction of aerodynamic performance.

[0003] To address this problem, the Shen tip loss correction model came into being. Compared with the traditional correction model, the Shen correction model can more accurately describe the force and resistance conditions near the blade tip, thereby improving the prediction accuracy of the aerodynamic performance of the wind turbine under this operating condition.

[0004] The focus of this invention is to couple the Shen tip loss correction model to OpenFAST, optimizing the aerodynamic computing capabilities of existing tools so that more accurate simulation and analysis can be achieved under high tip speed ratio conditions. This innovation not only fills the gap in OpenFAST in this field, but also provides new technical support for the design and performance optimization of large blades, especially floating wind turbines. Summary of the invention

[0005] The present invention aims to solve the technical problem that the calculation accuracy of the wind turbine simulation tool OpenFAST is limited under high tip speed ratio, resulting in inaccurate prediction of aerodynamic performance, and further proposes a new tip loss correction calculation method based on the Shen tip loss model.

[0006] The technical solution adopted by the present invention to solve the above problems is: the present invention proposes a new blade tip loss correction calculation method based on the Shen blade tip loss model, including:

[0007] Step 1: Read user input parameters;

[0008] Step 2: Couple the Shen tip loss correction model to the wind turbine simulation tool OpenFAST;

[0009] Step 3: Calculate the universal correction factor based on the user input parameters;

[0010] Step 4: According to the tip loss correction requirements, select one of the Shen tip loss correction model and the Prandtl model in the wind turbine simulation tool OpenFAST, and use the universal correction factor to correct the force and displacement of the tip position under high tip speed ratio to complete the tip loss correction calculation.

[0011] Optionally, the user input parameters in step 1 include blade inflow wind parameters, airfoil parameters, lift and drag coefficients corresponding to the airfoil parameters, the number of blades, blade rotation speed, blade radius, blade geometry, blade element node position, the number of blades, blade inflow angle, and blade local velocity components.

[0012] Optionally, the step of obtaining the universal correction factor in step 3 includes:

[0013] Step 3.1: Read the blade inflow wind parameters, airfoil parameters and lift and drag coefficients corresponding to the airfoil parameters, initialize the fan speed, and calculate the average inflow wind speed;

[0014] Step 3.2: Calculate the tip speed ratio λ based on the average inflow wind speed, blade speed and blade radius;

[0015] Step 3.3: Calculate the tip loss correction constant based on the blade geometry, blade node position, and blade number;

[0016] Step 3.4: Calculate the universal correction factor based on the tip loss correction constant and the blade inflow angle;

[0017] The calculation formula for the average flow velocity is:

[0018]

[0019] In formula (1), V 0 is the average inflow velocity, V xi corresponds to the local velocity component of the blade along the thrust direction, B is the number of blades;

[0020] The calculation formula of tip speed ratio λ is:

[0021]

[0022] In formula (2), Ω is the blade speed, and R is the blade radius;

[0023] The calculation formula of the tip loss correction constant is:

[0024]

[0025] In formula (3), t is the tip loss correction constant, and r is the length of the node to be calculated in the blade;

[0026] The correction factor is calculated as:

[0027]

[0028] In formula (4), f is the universal correction factor and Φ is the blade inflow angle.

[0029] Optionally, the step of selecting the Shen tip loss correction model in step 4 to correct the force and displacement of the tip position under the high tip speed ratio includes:

[0030] Step 4.1: Calculate the Shen correction factor g based on the number of blades and the tip speed ratio λ;

[0031] Step 4.2: Calculate the tip loss correction factor F based on the Shen correction factor g and the universal correction factor;

[0032] Step 4.3: Correct the force and displacement at the tip position under high tip speed ratio based on the tip loss correction factor F;

[0033] The calculation formula of Shen correction factor g is:

[0034] g=e -0.125(Bλ-21)+0.1 (5);

[0035] The calculation formula of the tip loss correction factor F is:

[0036]

[0037] Optionally, in step 4, the Prandtl model is selected to correct the force and displacement of the blade tip position under the condition of high blade tip speed ratio, specifically including:

[0038] The universal correction factor is input into the Prandtl model, and combined with the simulation function of the wind turbine simulation tool OpenFAST, the force and displacement at the tip position under high tip speed ratio are corrected.

[0039] The beneficial effects of the present invention are:

[0040] 1. The present invention couples the Shen tip loss correction model into OpenFAST and proposes a new tip loss correction calculation method, which can more accurately calculate the force and displacement of the tip position under high tip speed ratio conditions, filling the gap of OpenFAST in this field.

[0041] 2. After coupling the Shen tip loss correction model to OpenFAST, the present invention can be applied to multiple fields for accurate prediction of aerodynamic performance through integration with other simulation software, providing new technical support for the design and performance optimization of large blades, especially floating wind turbines. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A flow chart of a novel blade tip loss correction calculation method based on the Shen blade tip loss model provided by the present invention;

[0043] Figure 2 A comparison diagram of blade tip displacements in two different directions of flapping and shimmying calculated by using the Shen blade tip loss model and the Wilson blade tip loss model provided by the present invention;

[0044] Figure 3 This is a blade force comparison diagram of the no tip loss result provided by the present invention, the Wilson tip loss model calculation result, and the Shen tip loss model calculation result. DETAILED DESCRIPTION

[0045] Combination Figure 1 This embodiment is described as follows. Figure 1 As shown, the steps of the novel blade tip loss correction calculation method based on the Shen blade tip loss model described in this embodiment include:

[0046] S1: Couple the Shen tip loss correction model to the wind turbine simulation tool OpenFAST and read user input data;

[0047] The user input parameters include blade inflow wind parameters, airfoil parameters, lift and drag coefficients corresponding to the airfoil parameters, number of blades, blade speed, blade radius, blade geometry, blade node position, number of blades, blade inflow angle, and blade local velocity component.

[0048] S2: Read the blade inflow wind parameters, airfoil parameters and their corresponding lift and drag coefficients, initialize the fan speed, and calculate the average inflow wind speed;

[0049] The calculation formula for the average flow velocity is:

[0050]

[0051] In formula (1), V 0 is the average inflow velocity, V xi corresponds to the local velocity component of the blade along the thrust direction, B is the number of blades;

[0052] S3: Calculate the tip speed ratio λ;

[0053] The calculation formula of tip speed ratio λ is:

[0054]

[0055] In formula (2), Ω is the blade speed and R is the blade radius.

[0056] S4: Calculate tip loss correction constant;

[0057] The tip loss correction constant can also be applied to other tip loss correction methods. The calculation formula of the tip loss correction constant is:

[0058]

[0059] In formula (3), t is the tip loss correction constant, and r is the length of the node to be calculated in the blade.

[0060] S5: Calculate the general correction factor;

[0061] The general correction factor is related to the blade geometry, blade node position and number of blades. The calculation formula of the general correction factor is:

[0062]

[0063] In formula (4), f is the universal correction factor and Φ is the blade inflow angle.

[0064] S6: Select one of the Shen tip loss correction model and the Prandtl model in the wind turbine simulation tool OpenFAST to correct the force and displacement of the tip position under high tip speed ratio to complete the tip loss correction calculation;

[0065] Among them, the Shen tip loss correction model corrects the force and displacement of the tip position under high tip speed ratio, specifically including: calculating the Shen correction factor g;

[0066] The calculation formula of Shen correction factor g is:

[0067] g=e -0.125(Bλ-21)+0.1 (5);

[0068] Calculate the tip loss correction factor F;

[0069] The calculation formula of the tip loss correction factor F is:

[0070]

[0071] The Prandtl model corrects the forces and displacements at the tip position under high tip speed ratios, including:

[0072] The universal correction factor is input into the Prandtl model, and combined with the simulation function of the wind turbine simulation tool OpenFAST, the force and displacement at the tip position under high tip speed ratio are corrected.

[0073] The present invention couples the Shen tip loss correction model into OpenFAST and proposes a new tip loss correction calculation method, which can more accurately calculate the force and displacement of the tip position under high tip speed ratio conditions, filling the gap of OpenFAST in this field.

[0074] Example

[0075] Combination Figure 2-3 This embodiment is described. To verify the technical effect of the present invention, this embodiment adopts the following experiment:

[0076] This embodiment uses the DTU-10MW wind turbine model to calculate the blade tip displacements in two different directions of flapping and shimmying using the Wilson blade tip loss model and the Shen blade tip loss model at a wind speed of 11.4 m / s and a rotation speed of 9.6 rpm. The results are as follows: Figure 2 As shown in the figure, it is explained that there are differences in the blade tip displacements calculated by the two tip loss correction models under the same operating conditions.

[0077] The normal force and tangential force at different blade span positions when the tip speed ratio is 7.86 and 11.2 are calculated by applying the Wilson tip loss model and the Shen tip loss model. The values ​​at spans of 10%, 22%, 31%, 53%, 60%, 93%, 95% are calculated respectively, and the results without tip loss, the calculation results of the Wilson tip loss model and the calculation results of the Shen tip loss model are compared. Figure 3 By calculating the normal force and tangential force results at different span positions of 10MW wind turbine blades under different tip speed ratios, it is concluded that in the case of small tip speed ratio, the calculation results of Wilson tip loss model and Shen tip loss model are basically consistent. In the case of large tip speed ratio, the settlement results of Shen tip loss model are closer to the actual blade force than Wilson tip loss model.

[0078] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A new blade tip loss correction calculation method based on Shen blade tip loss model, characterized in that: The steps of the novel blade tip loss correction calculation method based on the Shen blade tip loss model include: Step 1: Read user input parameters; Step 2: Couple the shen blade tip loss correction model to the wind turbine simulation tool OpenFAST; Step 3: Calculate a universal correction factor according to the user input parameters; Step 4: According to the tip loss correction requirements, select one of the Shen tip loss correction model and the Prandtl model in the wind turbine simulation tool OpenFAST, and use the universal correction factor to correct the force and displacement of the tip position under high tip speed ratio to complete the tip loss correction calculation.

2. The novel blade tip loss correction calculation method based on Shen blade tip loss model according to claim 1 is characterized in that: The user input parameters in step 1 include blade inflow wind parameters, airfoil parameters, lift and drag coefficients corresponding to the airfoil parameters, number of blades, blade speed, blade radius, blade geometry, blade node position, number of blades, blade inflow angle, and blade local velocity component.

3. The novel blade tip loss correction calculation method based on Shen blade tip loss model according to claim 1 is characterized in that: The steps for obtaining the universal correction factor in step 3 include: Step 3.1: reading the blade inflow wind parameters, airfoil parameters and lift and drag coefficients corresponding to the airfoil parameters, initializing the fan speed, and calculating the average inflow wind speed; Step 3.2: Calculate the tip speed ratio λ based on the average inflow wind speed, blade rotation speed and blade radius; Step 3.3: Calculate the tip loss correction constant based on the blade geometry, blade node position, and blade quantity; Step 3.4: Calculate a universal correction factor based on the tip loss correction constant and the blade inflow angle; The calculation formula for the average flow velocity is: In formula (1), V0 is the average inflow velocity, V xi corresponds to the local velocity component of the blade along the thrust direction, B is the number of blades; The calculation formula of tip speed ratio λ is: In formula (2), Ω is the blade speed, and R is the blade radius; The calculation formula of the tip loss correction constant is: In formula (3), t is the tip loss correction constant, and r is the length of the node to be calculated in the blade; The general correction factor is calculated as: In formula (4), f is the universal correction factor and Φ is the blade inflow angle.

4. The novel blade tip loss correction calculation method based on Shen blade tip loss model according to claim 1 is characterized in that: The steps of selecting the Shen tip loss correction model in step 4 to correct the force and displacement of the tip position under high tip speed ratio include: Step 4.1: Calculate the Shen correction factor g based on the number of blades and the tip speed ratio λ; Step 4.2: Calculate the tip loss correction factor F based on the Shen correction factor g and the universal correction factor; Step 4.3: Correcting the force and displacement of the blade tip position under the condition of high tip speed ratio based on the blade tip loss correction factor F; The calculation formula of Shen correction factor g is: g=e -0.125(Bλ-21)+0.1 (5); The calculation formula of blade tip loss correction factor F is:

5. The novel blade tip loss correction calculation method based on Shen blade tip loss model according to claim 1 is characterized in that: In step 4, the Prandtl model is selected to correct the force and displacement of the blade tip position under high tip speed ratio, including: The universal correction factor is input into the Prandtl model, and combined with the simulation function of the wind turbine simulation tool OpenFAST, the force and displacement of the blade tip position under the condition of high blade tip speed ratio are corrected.

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