Low-resistance propeller hub fairing aerodynamic configuration optimization design method
By combining optimized algorithms and CFD calculations in aerodynamic shape design, the problem of aerodynamic interference affecting the fuselage in helicopter rotor hub fairing design was solved, achieving a more effective drag reduction effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-03-27
AI Technical Summary
Existing helicopter rotor hub fairing design methods fail to effectively consider the effects of fuselage aerodynamic interference, resulting in poor drag reduction performance in practical applications.
An aerodynamic shape optimization design method based on optimization algorithms is adopted. By parameterizing the fairing shape and combining CFD calculation and Kriging surrogate model, the optimal sample point set is generated, and the fairing shape is optimized to meet the design objectives and constraints, taking into account the aerodynamic interference of the fuselage.
The drag reduction effect of the propeller hub fairing has been improved, making the design scheme more practical and of high engineering value.
Smart Images
Figure CN121744488A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of helicopter aerodynamic design technology, and discloses a method for optimizing the aerodynamic shape of a low-drag rotor hub fairing. Background Technology
[0002] A helicopter rotor hub fairing is a shell-like structure installed at the helicopter rotor hub. Its streamlined surface reduces rotor hub drag during forward flight. However, existing rotor hub fairing aerodynamic design methods generally consider the rotor hub size and motion constraints when designing an isolated rotor hub. While this can achieve a rotor hub fairing shape with low drag, it fails to consider the aerodynamic interference of other components. In practical applications, the drag reduction effect of the rotor hub fairing is weakened in some flight conditions, or even fails to meet drag reduction requirements. Summary of the Invention
[0003] Purpose of the invention: This paper proposes a method for optimizing the aerodynamic shape of a low-drag propeller hub fairing.
[0004] The technical solution is as follows: A method for optimizing the aerodynamic shape of a low-drag propeller hub fairing, comprising the following steps: Step 1: Analyze the design task of the low-drag rotor hub fairing to determine the design status and design objectives; Step 2: Parameterize the shape of the propeller hub fairing and determine the parameter range; Step 3: Design experiments for the fairing shape parameters within the parameter range and generate a sample point set; Step 4: Generate the aerodynamic shape of the elliptical rotating rotor hub fairing based on the sample points in the sample point set, and check whether the shape meets the rotor hub fairing constraint conditions. If it does not meet the constraints, the sample point is removed, and the filtered sample point set is obtained. Step 5: Use CFD calculation methods to calculate and evaluate the selected aerodynamic shape schemes, and calculate the design target values of all sample points under the design state after selection. Step 6: Based on the sample dataset consisting of the filtered sample points and the calculated target values, build a Kriging surrogate model, and use an optimization point addition strategy on the surrogate model to generate new optimal sample points; Step 7: Repeat the process in Steps 4 and 5 to check, screen, and evaluate the newly generated sample points using CFD calculations, and update the results to the sample dataset. Step 8: Determine if convergence has occurred; if not, return to Step 6. Step 9: Generate the fairing shape from the optimal sample points.
[0005] Furthermore, in step one, the design state is taken as the helicopter's maximum level flight speed state, and the design target is taken as the sum of the drag of the helicopter's rotor hub, fuselage, and rotor hub support arm.
[0006] Furthermore, in step two, the rotor hub fairing is a body of revolution with a cross-section that is an ellipse cut from the lower plane. The formula for the elliptical shape is as follows:
[0007] The origin of the coordinate system is the center of the propeller hub, and the direction upwards along the propeller hub axis is... y Positive axis, x The plane of the square grinding disc faces outwards; a The length of the semi-major axis of the ellipse. b The length of the minor semi-axis of the ellipse. p The center of the elliptical gyro and the center of the propeller hub y Offset; The area below the propeller hub fairing is equipped with... y The cut is made in a plane perpendicular to the rotor shaft fairing, and a safety margin must be maintained between the plane and the fairing. The diameter of the fairing aperture after cutting is [missing information]. D The value range is 1.0. a ~1.5 a ; The specific method for determining the parameter range in step two is as follows: 1) Use the radial length of the connection point between the outrigger and the waving limiting device as a parameter. a The lower limit of the value is determined by using the radial length of the blade pin as the value. a The upper limit of the possible values; 2) Upper and lower limit devices on the propeller hub y The maximum distance along the axis is used as a parameter b Lower bound of the value, parameter b upper limit and parameters a Consistent; 3) Parameters p The range is 0 to 0.05. a .
[0008] Furthermore, in step three, the process of generating the sample point set is as follows: The Latin hypercube sampling method was used, with parameters... a , b , p Take no fewer than 6 initial sample points from the range of the three parameters to form a sample point set.
[0009] Furthermore, in step four, the constraints are as follows: 1) Within the upper and lower flapping limits of the propeller hub support arm, there is no interference between the propeller hub fairing and the upper and lower flapping limiting devices, and the clearance meets the safety margin. 2) The moving parts of the variable pitch rocker arm and damper do not interfere with the propeller hub fairing within the range of motion, and the clearance meets the safety margin. 3) The diameter D of the fairing after cutting should not be less than the diameter of the rotor shaft fairing.
[0010] Furthermore, in step five, the specific calculation and evaluation process is as follows: Using a high-precision CFD analysis method, an analytical model was established for the elliptical rotor hub fairing after planar cutting, the fuselage shape, and the rotor hub support arm. The sum of the drag of the rotor hub, fuselage, and rotor hub support arm under a given wind speed was calculated.
[0011] Furthermore, in step six, the specific process for generating new optimal sample points is as follows: Based on the sample dataset consisting of the selected sample points and the calculated target values, a Kriging surrogate model with objective and constraint functions is established. Then, the Improvement Expectation Criterion (EI plus point criterion) is used to perform sub-optimization on the surrogate model in order to find the optimal solution under the surrogate model.
[0012] Furthermore, in step seven, the specific process of updating the results to the sample dataset is as follows: The newly selected sample points and their CFD evaluation values are added to the original sample dataset, which increases the size of the sample dataset with the number of iterations, thereby making the established surrogate model more accurate.
[0013] Furthermore, in step eight, the process for determining convergence is as follows: The target value of the new sample points was evaluated by CFD calculation. Compared with the surrogate model predictions The difference meets the preset requirements: .
[0014] An aerodynamic shape for a propeller hub fairing, wherein the propeller hub fairing is a rotating body with an elliptical cross-section cut from the lower plane:
[0015] parameter a The value is 750mm, parameter b The value is 280mm, parameter p The value is 36mm, which is the diameter of the fairing aperture after planar cutting. D It is 1028mm.
[0016] In summary, the beneficial effects of the present invention are as follows: The core of this invention lies in solving the problem of reduced drag reduction effect of rotor hub fairings designed by existing helicopter rotor hub fairing design methods in practical applications. It proposes a low-drag rotor hub fairing aerodynamic shape optimization design method. This method adopts rotor hub fairing aerodynamic shape optimization design based on optimization algorithm. The aerodynamic interference of the fuselage is taken into account in the optimization process, which makes the evaluation of the design scheme more accurate and the design scheme more valuable for engineering applications. Attached Figure Description
[0017] Figure 1 This is a flowchart of a low-drag propeller hub fairing aerodynamic shape optimization design method; Figure 2 This is a schematic diagram showing the relationship between the propeller hub fairing and components such as the propeller hub and support arms. Figure 3 This is a diagram illustrating the drag reduction effect of a design obtained using conventional helicopter rotor hub fairing methods. Figure 4 This is a comparison chart of the drag reduction effects of the optimized scheme and the baseline scheme obtained by this method at different fuselage pitch angles; Figure 5 This is a comparison chart of the fuselage and rotor hub drag results obtained by this method for the optimized scheme and the benchmark scheme at a fuselage pitch angle of 0°; in: 1 represents a schematic diagram of the optimized rotor hub fairing; 2 represents a schematic diagram of the downward swing limiting device; 3 represents a schematic diagram of the upper waving motion restriction device; 4 represents a schematic diagram of the propeller hub support arm; 5 represents a schematic diagram of the rotor shaft fairing; 6 indicates the diameter of the rotor shaft fairing aperture; 7 indicates the aperture of the rotor hub fairing after the lower part is cut with a plane. Detailed Implementation
[0018] This invention addresses the problem that existing helicopter rotor hub fairing aerodynamic shape design methods cannot account for the influence of aerodynamic interference, resulting in rotor hub fairings that fail to meet design requirements. It proposes a low-drag rotor hub fairing aerodynamic shape optimization design method. This method employs an optimization algorithm-based aerodynamic shape optimization design for the rotor hub fairing. The design process not only satisfies constraints such as rotor hub size and the motion of related components, but also incorporates the aerodynamic interference influence of the fuselage during optimization. This makes the drag reduction effect of the designed rotor hub fairing more closely aligned with practical applications, demonstrating high engineering practical value.
[0019] The technical solution of the present invention: Step 1: Analyze the design task of the low-drag rotor hub fairing to determine the design state and design objectives; the design state is the maximum level flight speed of the helicopter, and the design objectives are the sum of the drag of the helicopter rotor hub, fuselage, and rotor hub support arms.
[0020] Step 2: Parametrically configure the rotor hub fairing shape and determine the parameters. a , b , p The range; the rotor hub fairing is a body of revolution, with a cross-section of an ellipse cut by a lower plane. The formula for the elliptical shape is as follows:
[0021] The origin of the coordinate system is the center of the propeller hub, and the direction upwards along the propeller hub axis is... y Positive axis, x The plane of the square grinding disc faces outwards; a The length of the semi-major axis of the ellipse. b The length of the minor semi-axis of the ellipse. p The center of the elliptical gyro and the center of the propeller hub y Offset; The area below the propeller hub fairing is equipped with... y The cut is made in a plane perpendicular to the rotor shaft fairing, and a safety margin must be maintained between the plane and the fairing. The diameter of the fairing aperture after cutting is [missing information]. D The value range is 1.0. a ~1.5 a .
[0022] 1) Use the radial length of the connection point between the outrigger and the waving limiting device as a parameter. a The lower limit of the value is determined by using the radial length of the blade pin as the value. a The upper limit of the possible values; 2) Upper and lower limit devices on the propeller hub y The maximum distance along the axis is used as a parameter b Lower bound of the value, parameter b upper limit and parameters a Consistent; 3) Parameters p The range is 0 to 0.05. a ; Step 3: Design experiments for the fairing shape parameters within the parameter range to generate a sample point set. The process is as follows: Use the Latin hypercube sampling method within the parameter range... a , b , p Take no fewer than 6 initial sample points from the range of the three parameters to form a sample point set.
[0023] Step 4: Generate the aerodynamic shape of the elliptical rotating rotor hub fairing based on the sample points in the sample point set. Check whether the shape meets the rotor hub fairing constraints. If not, remove the sample point to obtain the filtered sample point set. The constraints are as follows: 1) Within the upper and lower flapping limits of the propeller hub support arm, there is no interference between the propeller hub fairing and the upper and lower flapping limiting devices, and the clearance meets the safety margin. 2) The moving parts of the variable pitch rocker arm and damper do not interfere with the propeller hub fairing within the range of motion, and the clearance meets the safety margin. 3) The diameter D of the fairing after cutting should not be less than the diameter of the rotor shaft fairing.
[0024] Step 5: Use CFD calculation methods to evaluate the selected aerodynamic shape schemes and calculate the design target values of all sample points under the design state. Use high-precision CFD analysis and calculation methods to establish an analysis model for the elliptical rotor hub fairing, fuselage shape and rotor hub support after planar cutting, and solve the sum of the drag of rotor hub, fuselage and rotor hub support under a given wind speed.
[0025] Step Six: Based on the sample dataset consisting of the selected sample points and the calculated target values, establish a Kriging surrogate model, and use an optimization point-addition strategy to generate new optimal sample points on the surrogate model; Based on the sample dataset consisting of the selected sample points and the calculated target values, establish a Kriging surrogate model with objective function and constraint function, and then use the Improved Expectation Criterion (EI point-addition criterion) to perform sub-optimization on the surrogate model to find the optimal solution under the surrogate model; Step 7: Using the methods described in Steps 4 and 5, check, filter, and evaluate the newly generated sample points using CFD calculations, and update the results to the sample dataset; add the filtered new sample points and their CFD evaluation values to the original sample dataset, so that the sample dataset increases with the number of iterations, thereby making the established surrogate model more accurate.
[0026] Step 8: Determine if convergence has occurred; if not, return to Step 6; the convergence determination process is as follows: The target value of the new sample points was evaluated by CFD calculation. Compared with the surrogate model predictions The difference meets the preset requirements:
[0027] Step 9: Generate the fairing shape from the optimal sample points.
[0028] An aerodynamic shape for a propeller hub fairing, wherein the propeller hub fairing is a rotating body with an elliptical cross-section cut from the lower plane:
[0029] parameter a The value is 750mm, parameter b The value is 280mm, parameter p The value is 36mm. This is the aperture of the fairing after planar cutting. D It is 1028mm.
[0030] The optimization design method of the present invention is as follows: Figure 1 As shown in the diagram, the relationship between the propeller hub fairing and components such as the propeller hub and support arms is as follows: Figure 2 As shown.
[0031] The drag reduction effect of the conventional helicopter rotor hub fairing design method is as follows: Figure 3 As shown, the drag reduction effects of the optimized scheme and the baseline scheme obtained by this method at different fuselage pitch angles are compared. Figure 4 As shown, the method obtains the fuselage and rotor hub drag results of the optimized and baseline schemes at a fuselage pitch angle of 0°, for example... Figure 5 As shown.
[0032] Obviously, the embodiments described in the specific implementation details of this application are merely for the purpose of more clearly explaining the technical solutions in the specification, and are only a part of the embodiments of this application, and are not intended to limit this application. All other embodiments obtained by those skilled in the art based on the embodiments in the specific implementation details without creative effort should fall within the protection scope of this application.
Claims
1. A low-drag hubcap fairing aerodynamic shape optimization design method, characterized by: The steps are as follows: Step one: analyze the design task of low-resistance hub fairing, determine the design state and design target; Step two: parameterize the hub fairing shape and determine the parameter range; Step three: design the hub fairing shape parameters in the parameter range, generate a sample point set; Step four: generate an elliptical rotary body hub fairing aerodynamic shape according to the sample points in the sample point set, and use the check shape to determine whether it meets the hub fairing constraint conditions, if not, eliminate the sample point, and obtain the screened sample point set; Step five: use CFD calculation method to calculate and evaluate the screened aerodynamic shape scheme, calculate the design target value of all screened sample points in the design state; Step six: based on the sample data set composed of the screened sample points and the calculated target values, establish a Kriging surrogate model, and generate a new optimal sample point on the surrogate model using an optimization adding strategy; Step seven: repeat the process in steps four and five, check and screen the new sample points and perform CFD calculation and evaluation, and update the results to the sample data set; Step eight: determine whether to converge; if not, return to step six; Step nine: generate the fairing shape from the optimal sample point.
2. The method of claim 1, wherein: In step one, the design state is taken as the maximum straight flight speed state of the helicopter, and the design target is taken as the sum of the resistances of the hub, fuselage and hub arm.
3. The method of claim 2, wherein: In step two, the hub fairing shape is a rotary body with an elliptical cross-section cut by a plane, and the elliptical shape formula is as follows: The coordinate system origin is the hub center, and the upward direction along the hub axis is y the shaft positive direction, x the shaft positive direction, a is the length of the major axis of the ellipse, b is the length of the minor axis of the ellipse, p is the distance between the center of the elliptical runner and the center of the hub, y is the amount of skew. The area below the propeller hub fairing is equipped with... y The cut is made in a plane perpendicular to the rotor shaft fairing, and a safety margin must be maintained between the plane and the fairing. The diameter of the fairing aperture after cutting is [missing information]. D The value range is 1.
0. a ~1.5 a ; The parameter range determination method in step two is as follows: 1) the radial length of the position of connection of the arm with the flap check device as parameter of the lower limit of the value of a the radial length of the blade pin as parameter of the upper limit of the value of a the radial length of the blade pin 2) the maximum distance in the axial direction between the upper and lower pitch limiting devices as a parameter y the lower limit of the value taken by the parameter b the upper limit value of the parameter b coincides with the parameter a . 3) Parameters p ranging from 0 to 0.05 a .
4. The method of claim 3, wherein: In step three, the sample point set generation process is as follows: The Latin hypercube sampling method is used to take no less than 6 initial sample points in the range of the three parameters a , b , p to form a sample point set.
5. The method of claim 4, wherein: In step four, the constraint conditions are as follows: 1) The hub arm is within the upper and lower flapping limit range, the hub fairing does not interfere with the upper and lower flapping limit devices, and the clearance meets the safety margin; 2) The variable pitch rocker arm and damper moving parts are within the movement range and do not interfere with the hub fairing, and the clearance meets the safety margin; 3) The diameter of the cut fairing should not be less than the diameter of the rotor shaft fairing.
6. The method of claim 5, wherein: In step five, the calculation and evaluation process is as follows: A high-precision CFD analysis and calculation method is used to establish an analysis model for the elliptical hub fairing, fuselage shape and hub arm after cutting, and to solve the sum of the resistances of the hub, fuselage and hub arm under a given wind speed.
7. The method of claim 6, wherein: In step six, the process of generating a new optimal sample point is as follows: Based on the sample data set composed of the screened sample points and the calculated target values, a Kriging surrogate model of the objective function and constraint function is established, and then an improved expectation criterion is used to optimize the surrogate model to find the optimal solution under the surrogate model.
8. The method of claim 7, wherein: In step seven, the process of updating the results to the sample data set is as follows: The new sample points and their CFD evaluation values are added to the original sample data set, so that the sample data set increases with the number of iterations, making the established surrogate model more accurate.
9. The method of claim 8, wherein: In step eight, the convergence judgment process is as follows: Target values of new sample points evaluated by CFD calculation Difference between the agent model prediction value satisfies a preset requirement: 。 10. A hub fairing aerodynamic shape designed by the method of any one of claims 1-9, characterized by: The boss fairing is a rotary body, and the cross section is an oval cut by a horizontal plane: Parameter a is 750 mm, parameter b is 280 mm, parameter p is 36 mm, aperture of the fairing after planar cutting D is 1028 mm.