Method and testing device for testing rotor blades

Patent metadata

Field	Value
Publication number	US-11885299-B2
Application number	US-201917288623-A
Country	US
Kind code	B2
Filing date	Oct 24, 2019
Priority date	Oct 29, 2018
Publication date	Jan 30, 2024
Grant date	Jan 30, 2024

Abstract

A method for testing a rotor blade of a wind turbine may include predefining a setpoint bending moment distribution. At least two active load-introducing means may be provided which each engage on a load frame. A first of the at least two active load-introducing means may be configured for introducing load in a pivot direction of the rotor blade and a second of the at least two active load-introducing means may be configured for introducing load in an impact direction of the rotor blade. Also provided is at least one passive load-introducing means. A cyclic introduction of load is effected by the at least two active load-introducing means, where a load introduction frequency of the first active load-introducing means and a load introduction frequency of the second active load-introducing means are selected such that the ratio thereof is rational. A testing device for carrying out the method is also provided.

First claim

What is claimed is:

1. A method for testing a rotor blade of a wind turbine, wherein a setpoint bending moment distribution is predetermined, comprising at least the steps:
clamping the rotor blade in a clamping device so that a longitudinal axis of the rotor blade extends from a clamping point of the rotor blade,
attaching one or more load frames to the rotor blade,
providing at least two active load-introducing means which each engage on one of the load frames, wherein a first of the at least two active load-introducing means is set up for introducing load in a pivot direction of the rotor blade and a second of the at least two active load-introducing means is set up for introducing load in an impact direction of the rotor blade,
providing at least one passive load-introducing means engaging one of said load frames, wherein for a system comprising said rotor blade and said at least one passive load-introducing means, a system natural frequency for the pivot direction and/or for the impact direction is changed by said at least one passive load-introducing means,
a cyclic introduction of load is effected by the at least two active load-introducing means, wherein a load introduction frequency of the first active load-introducing means and a load introduction frequency of the second active load-introducing means are selected such that the ratio thereof is rational, and wherein
the load frames and the at least two active load-introducing means and the at least one passive load-introducing means are arranged at previously determined positions which are selected in such a way that a bending moment distribution introduced during cyclic load introduction does not fall below the setpoint bending moment distribution and does not exceed it by more than 20%.

2. The method according to claim 1 , wherein the at least one passive load-introducing means is arranged such that the system natural frequency in the impact direction matches the load introduction frequency in the impact direction or, for applying an additional load, deviates no more than 10%, from the system natural frequency in the impact direction.

3. The method according to claim 1 , wherein the at least one passive load-introducing means is arranged such that the system natural frequency in the pivot direction coincides with the load introduction frequency in the pivot direction or, for introducing an additional load, deviates no more than 10%, from the system natural frequency in the pivot direction.

4. The method according to claim 1 , wherein the at least two active load-introducing means are controlled or regulated for adjusting and maintaining the ratio between the load introduction frequency of the first active load applying means and the load-introduction frequency of the second active load-introducing means.

5. The method according to claim 1 , wherein at least one passive load-introducing means is provided for adjusting the system natural frequency in the impact direction and at least one passive load-introducing means is provided for adjusting the system natural frequency in the pivot direction.

6. The method according to claim 1 , wherein the rotor blade is clamped such that the longitudinal axis of the rotor blade extends substantially horizontally and the pivot direction is oriented horizontally.

7. The method according to claim 1 , wherein the at least two active load-introducing means and/or the at least one passive load-introducing means are externally anchored.

8. The method according to claim 1 , wherein the at least one passive load-introducing means is selected from fixed masses, decoupled masses and elastic elements.

9. The method according to claim 1 , wherein at least one of the at least one passive load-introducing means is chosen as a decoupled mass or as an elastic element.

10. The method according to claim 1 , wherein the ratio between the load introduction frequency of the first load-introducing means and the load introduction frequency of the second load-introducing means is 1:1, 2:1 or 1:2.

11. The method according to claim 1 , wherein a distribution of moment vector paths occurring in the field is determined, via an aeroservoelastic multi-body simulation, and a setpoint middle bending moment is set by the passive load-introducing means by the decoupled masses and/or by a bias of the elastic elements, such that a midpoint of moment vector paths generated by means of the active load-introducing means lies within the distribution of moment vector paths occurring in the field.

12. The method according to claim 11 , wherein the moment vector paths generated by the active load-introducing means are adapted to a contour of the distribution of the moment vector paths occurring in the field by adjusting the rotor blade clockwise or counterclockwise about its longitudinal axis.

13. The method according to claim 12 , wherein the moment vector paths generated by the active load-introducing means are matched to a contour of the distribution of the moment vector paths occurring in the field by adjusting a phase angle between the load introduction in the pivot direction and the load introduction in the impact direction.

14. The method according to claim 1 , wherein the ratio between the load introduction frequencies is 1:1 and a phase angle between the load introduction in the pivot direction and the load introduction in the impact direction is between 00 and 180.

15. The method according to claim 1 , wherein the ratio between the load introduction frequencies is 1:2 or 2:1 and a phase angle between the load introduction in the pivot direction and the load introduction in the impact direction is 00 or 1800.

16. The method according to claim 1 , wherein a minimum distance between adjacent load frames is 1 m.

17. A testing device for testing a rotor blade, comprising:
a clamping device for clamping a rotor blade at a clamping point of the rotor blade, so that a longitudinal axis of the rotor blade extends substantially horizontally starting from the clamping point,
one or more load frames to be attached to the rotor blade,
at least two active load-introducing means, each of which is attached to one of the load frames,
at least one passive load-introducing means attached to one of the load frames,
wherein
at least one of the at least two active load-introducing means is configured for introducing loads into the rotor blade in a pivot direction, and at least one of the at least two active load-introducing means is configured for introducing loads into the rotor blade in an impact direction,
and wherein the at least one passive load-introducing means is externally anchored and comprises an elastic element and/or a decoupled mass and is adapted to adjust a system natural frequency in the pivot direction and/or in the impact direction, for a system comprising the rotor blade and the at least one passive load-introducing means.

18. The testing device of claim 17 , further comprising a control device adapted to control a load introduction frequency of the first active load-introducing means and a load introduction frequency of the second active load-introducing means such that a ratio between these two load introduction frequencies is rational.

19. The testing device according to claim 17 , wherein the active load-introducing means is in the form of a hydraulic, or pneumatic or electric actuator and is externally anchored.

20. The testing device according to claim 17 , wherein the elastic element is designed as a spring or torsion spring or beam or leaf spring

Assignees

• Fraunhofer Ges Forschung
• Fraunhofer Ges Forschung

Inventors

• Batge Moritz
• Rosemeier Malo
• Haller Bernd
• Ha Kwangtae
• Wroblewski Willi
• Sayer Florian

Classifications

• F03D13/30 Primary

  Commissioning, e.g. inspection, testing or final adjustment before releasing for production · CPC title

• G01M5/0058 Primary

  of elongated objects, e.g. pipes, masts, towers or railways · CPC title

• G01M7/022

  Vibration control arrangements, e.g. for generating random vibrations · CPC title

• G01M7/06

  Multidirectional test stands · CPC title

• F03D17/00

  Monitoring or testing of wind motors, e.g. diagnostics (testing during commissioning of wind motors F03D13/30) · CPC title