Physical-numerical hybrid scale model test method for floating fan

Abstract

The invention provides a physical-numerical hybrid scale model test method for a floating fan, and belongs to the technical field of offshore wind power generation. The test method comprises the steps that the floating fan is modeled into a physical model and a numerical model, and besides the physical model and the numerical model, a test platform further comprises a measuring system and a loading system; real-time interaction is carried out on actual measurement signals of the measurement system and calculation results of the numerical model through the computer, loading of the signals is achieved through the loading system, and building and closed-loop control of the hybrid test platform are achieved. And finally, required information is extracted through visual interface monitoring. According to the method, the dynamic response performance of the key structure can be accurately captured, and a series of problems of scale effect, scale criterion incompatibility caused by the scale effect, difficulty in indoor test simulation of the offshore floating fan and the like can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of offshore wind power generation and relates to a physical-numerical hybrid scaled model test method for a floating wind turbine. Background Art

[0002] Offshore wind power is one of the important renewable energy sources, playing an important role in optimizing energy structure and mitigating climate change. With the improvement of science and technology and economic level, global wind power equipment has gradually shown a significant trend of large-scale and offshore development. Offshore floating wind turbines include blades, nacelles, towers, floating platforms and mooring systems. The floating platform is connected to the seabed through a mooring system to suppress the movement of the floating body caused by environmental loads such as wind, waves and currents, and is adapted to different water depths and soil conditions. Compared with floating oil and gas platforms in marine engineering, floating wind turbines need to withstand greater aerodynamic loads. Therefore, when analyzing the dynamic response of floating wind turbines, in addition to considering hydrodynamic forces and mooring forces, the coupling of aerodynamic forces should also be considered. The most widely used method to obtain the dynamic response of floating wind turbines is to establish motion control equations based on potential flow, blade element momentum and multi-body dynamics theory, and combine automatic control algorithms to perform aerodynamic-hydrodynamic-servo-elastic coupling numerical simulations. However, there is uncertainty in floating wind turbines under highly nonlinear conditions, and high-reliability model tests are required to verify and correct the numerical simulation results.

[0003] Compared with fixed offshore wind turbines, the dynamic response of floating wind turbines is more significant, so it is crucial to simulate aerodynamics and hydrodynamics synchronously and accurately in model tests. However, due to the incompatibility of the Reynolds number and the Froude number, it is difficult to meet the similarity of aerodynamics and hydrodynamics at the same time. Most of the existing floating wind turbine model tests are water tank tests. The tests are equivalent based on the Froude number similarity criterion, and only simulate the main aerodynamic loads, such as the axial thrust of the impeller under steady wind speed, which will bring certain errors to the test. In addition, due to the limited water depth of the water tank laboratory, it is difficult to conduct large-scale tests, and the quality of wind generation in the water tank is poor. The distortion of wind field simulation will also affect the wave morphology, which has certain limitations. Therefore, how to solve the incompatibility of similarity criteria in floating wind turbine model tests and the accurate simulation of scaled aerodynamic loads is an urgent problem to be solved in this field.

[0004] Chinese patent application CN117386568A discloses a real-time hybrid model test method for multi-fan drive of an offshore floating wind turbine. The invention proposes to divide the hybrid model into a platform physical substructure and a wind turbine numerical substructure. The physical substructure refers to the floating wind turbine platform model, and the numerical substructure is a computer-based numerical simulation of the wind turbine aerodynamic load. At each time step, the force command derived from the numerical substructure is applied to the platform physical substructure through the multi-fan drive system, and the motion from the floating platform test is fed back to the numerical substructure for calculating subsequent time steps. The invention enables the test to accurately simulate aerodynamic loads under the Froude scaling law, which is beneficial to laboratory-scale wind turbine load simulation and has better static and dynamic response performance. However, this patented technology uses traditional water tank tests to simulate hydrodynamic loads, which cannot overcome the limitations of traditional water tank tests.

[0005] Chinese patent application CN116011193A discloses a hybrid model test method for offshore wind turbines that can be used for a variety of basic types, including the following steps: (1) determining the test scale ratio and processing the physical model; (2) selecting an indoor wave pool and calibrating the wave conditions; (3) hoisting the physical model and actuator to the site; (4) arranging the optical measurement system; (5) iterative calculation of the blade element momentum model in aerodynamics and overall test implementation. Through the information interaction of the blade element momentum model, physical model, and actuator in aerodynamics at the truncation point, the load and motion response of the real wind turbine can be reflected. However, this patented technology requires customized frames for different wind turbine models due to the large mass of the multi-degree-of-freedom loading brake itself, and this method does not take into account the gyroscopic effect of offshore wind turbines. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a floating wind turbine physical-numerical hybrid scaled model test method. The test method provided by the present invention can not only accurately capture the dynamic response of key structures, but also solve a series of problems such as incompatibility of scale criteria and the scale effect caused by them. This method can more accurately simulate aerodynamic loads and hydrodynamic loads, ensure the authenticity and reliability of floating wind turbine model tests, and provide theoretical guidance and technical support for the construction of offshore floating wind turbine generators.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A floating wind turbine physical-numerical hybrid scaled model test method is disclosed. The test method models the floating wind turbine into two parts, a physical model and a numerical model, according to the scaled criterion. In addition to the physical model and the numerical model, the test platform also includes a measurement system composed of a three-dimensional force sensor and a six-dimensional force sensor, and a loading system composed of a six-rotor propeller and a six-degree-of-freedom platform. The measured signal of the measurement system is interacted with the calculation result of the numerical model in real time through a computer, and the signal is loaded through the loading system, finally realizing the construction and closed-loop control of the hybrid test platform.

[0009] First, the multi-body / multi-physics field collaborative scaling criteria of floating wind turbines are established according to the dimensional analysis method, and the physical model and numerical model are designed according to the scaling criteria. Secondly, the physical model of the floating wind turbine is bolted and assembled with the measurement system composed of sensors and the loading system composed of a six-degree-of-freedom platform and a six-rotor propeller. The measurement system is connected to the computer through the data acquisition system and the data cable, and then the computer is connected to the loading system to realize the transmission of the loading signal, and finally a physical-numerical hybrid test platform is built. Thirdly, the load calculation of different working conditions is carried out according to the numerical model, the physical model is loaded through the loading system, the shear force and bending moment information at the bottom of the tower are measured through the measurement system, and the measured data are transmitted to the computer. Finally, the measured data at the bottom of the tower is transmitted to the numerical floating body through the computer, thereby calculating the additional floating body movement caused by the tower acting on the platform, and feeding it back to the numerical wind wheel, thereby realizing the recalculation of the load, and realizing closed-loop control through the loading system acting on the physical model. Through the visual monitoring interface, the relevant information of the test process is extracted according to actual needs. Specifically, the following steps are included:

[0010] Step (1) establishes the multi-body / multi-physics field collaborative scaling criterion for the floating wind turbine and divides the overall structure of the floating wind turbine into a physical model and a numerical model, specifically:

[0011] Step 1.1, equate the aerodynamic load to the rotor thrust, equate the hydrodynamic load to the floating body motion, derive the load-structure-response similarity law based on dimensional analysis theory, and establish the multi-body / multi-physics field collaborative scaling criterion for floating wind turbines to ensure that the response of the scaled model can be returned to the original scale model through the scaling criterion.

[0012] Step 1.2, determine the scale ratio according to the established scale criterion and the prototype size of the floating wind turbine, and design the physical model and numerical model of the floating wind turbine, wherein the physical model includes blades, nacelle, tower and connection structure, and the numerical model includes numerical float and numerical wind wheel.

[0013] Step (2) integrates the physical model, numerical model, loading system and measurement system to build a floating wind turbine physical-numerical hybrid test platform, specifically:

[0014] Step 2.1, connect the hardware of the test platform, and connect the physical model to the measurement system and the loading system respectively through flange and other connection structures. The measurement system includes a three-dimensional force sensor and a six-dimensional force sensor, and the loading system includes a six-rotor propeller and a six-degree-of-freedom motion platform.

[0015] Step 2.2, establish the data transmission channel of the test platform, integrate the sensor data interface, numerical model calculation result file and the input end of the loading system into the same information storage device of the computer, and establish a data closed-loop transmission channel of "measurement system-numerical model-loading system-physical model-measurement system" through the computer.

[0016] Step (3), data interaction and closed-loop control of the physical-numerical hybrid test platform, specifically:

[0017] The six-degree-of-freedom motion platform is controlled by a computer to apply the floating body motion to the physical model, and the six-rotor propeller is controlled to apply the wind wheel thrust to the physical model. The measurement system records the measurement data in real time and sends it to the computer. The computer receives the signal from the data acquisition board in the measurement system. The collected signal is used as the input of the numerical model for calculation to obtain the additional floating body motion under the action of the tower bottom load, and the numerical model calculation results are sent to the loading system through the computer. Based on the calculation results of the numerical model, the real-time loading signals of the six-degree-of-freedom motion platform and the six-rotor propeller are changed, and the load data at the bottom of the tower is recorded by the measurement system to realize the data interaction and closed-loop control of the physical-numerical hybrid test platform.

[0018] Step (4), information monitoring and extraction during the physical-numerical hybrid experiment, specifically:

[0019] The operation status of the physical-numerical hybrid test platform is monitored through a visual interface. Furthermore, the visual interface is used to monitor the operation status of the physical-numerical hybrid test platform in real time and display information such as the motion data of the floating body and the aerodynamic load data of the wind wheel. The required information is extracted in real time, and the extracted information is analyzed and processed to evaluate the dynamic response performance of the floating wind turbine.

[0020] The beneficial effects of the present invention are:

[0021] (1) The present invention divides the overall structure of the floating wind turbine into two parts: a physical model and a numerical model. The physical model includes a scaled model of the wind turbine of blades, nacelle and tower, which is an actual structure that bears aerodynamic and hydrodynamic loads. The numerical model is a system that performs real-time calculation of equivalent loads based on computers and scale criteria. It can calculate the motion response of the floating body under the action of waves and tower bottom loads, as well as the rotor thrust of the blades under different wind speeds and rotation speeds. At each time step, the numerical model calculates the rotor thrust and floating body motion at that moment, acts on the physical model through the loading system, records the tower bottom load data through the measurement system, and transmits it to the numerical model through the computer, forming real-time interaction and closed-loop control of the floating wind turbine physical-numerical hybrid test data.

[0022] (2) The present invention uses a physical-numerical hybrid test to equate aerodynamic loads and hydrodynamic loads to wind rotor thrust and floating body motion, respectively, thereby achieving independent scaling of aerodynamic loads and hydrodynamic loads, solving the incompatibility problem of scaling of the two types of loads in water tank tests, getting rid of the limitations of traditional water tank tests, and establishing a more adaptable scaling criterion.

[0023] (3) The test method proposed by the present invention uses a low-cost numerical model, which can achieve the reconstruction of the numerical wind wheel and the numerical floating body at a very low test cost, which has a significant effect on the design of the blades and floating body of the floating wind turbine. Designers can optimize the design of the floating wind turbine through the test method proposed by the present invention, which significantly reduces the design cycle and design cost of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a three-dimensional model of the floating wind turbine tower of the present invention;

[0025] Figure 2 It is a three-dimensional model of the floating wind turbine cabin of the present invention;

[0026] Figure 3 It is a three-dimensional model of the floating wind turbine connection structure of the present invention;

[0027] Figure 4 It is a schematic diagram of the overall layout of the system of the present invention. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0030] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0031] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] The present invention is further described below with reference to the accompanying drawings. A floating wind turbine physical-numerical hybrid scale model test method, the specific implementation of the present invention comprises the following steps:

[0033] Step (1), establishing the multi-body / multi-physics field scaling criteria for floating wind turbines, specifically:

[0034] Through similarity theory, the scaled proportional relationship of each physical quantity in the hybrid test was determined by dimensional analysis, and then the target parameters were derived. For example, the conversion coefficients of physical quantities such as length, area, volume, mass, time, frequency, speed, acceleration, force, torque, and moment of inertia between the scaled model and the prototype were obtained based on dimensional analysis, thereby determining the target parameters of the physical model such as tower thickness, nacelle-blade mass and center of gravity position, equivalent wind rotor thrust, and floating body motion.

[0035] Step (2), designing and processing the physical model according to the established scaling criteria, specifically:

[0036] The physical model includes the blades, nacelle, tower and the connection structure between the components of the floating wind turbine. After the scaling criteria are established, the scaling ratio needs to be determined according to the prototype size of the floating wind turbine and the test conditions. The present invention makes a physical model with a scale of 1:40, and the physical model meets the following similarity conditions: 1) Geometric similarity: The physical model should be completely proportionally reduced according to the prototype size according to the scaling ratio; 2) Dynamic similarity: After the physical model is made according to the geometric similarity, reinforcement and counterweight are performed at appropriate locations to make its weight, center of gravity position, moment of inertia and other related parameters meet the similarity law. The tower of the physical model is as follows: Figure 1 As shown, the cabin is Figure 2 As shown, the connection structure is as Figure 3 shown.

[0037] Step (3), designing and establishing a numerical model according to the established scaling criteria, specifically:

[0038] The numerical model includes a numerical wind wheel and a numerical floating body. The numerical wind wheel is modeled and solved using the blade element-momentum theory, combined with the established scaling criteria, to achieve the purpose of inputting "wind speed-floating body motion" at the current time step and outputting "wind wheel thrust". The numerical floating body is modeled and solved using the three-dimensional potential flow theory and Morrison equation, combined with the established scaling criteria, to achieve the purpose of inputting "wave information-tower bottom shear force and bending moment" at the current time step and outputting "floating body motion".

[0039] Step (4), establishing a loading system for a floating wind turbine physical-numerical hybrid test platform, specifically:

[0040] In order to apply the wind turbine thrust and floating body motion calculated by the numerical model to the physical model, a loading system of the hybrid test platform was established, which consists of a six-rotor propeller and a six-degree-of-freedom platform. The six-rotor propeller was modified on the ZD850 UAV frame, and the six motor speeds were independently controlled through the secondary development and control of the pixhawk4 flight control system, so as to accurately load the wind turbine thrust calculated by the numerical wind turbine. The floating body motion calculated by the numerical floating body was loaded using the MG6-10 / 12EP six-degree-of-freedom motion platform, and the software was installed on the same computer to achieve synchronous control of the two, thus forming a loading system for the floating wind turbine physical-numerical hybrid test platform.

[0041] Step (5) is to establish a measurement system for a floating wind turbine physical-numerical hybrid test platform, specifically:

[0042] In order to obtain the actual thrust loaded on the top of the physical model and the shear force and bending moment borne at the bottom, a measurement system of the hybrid test platform was established. The measurement system consists of a three-dimensional force sensor, a six-dimensional force sensor and a data acquisition system. The three-dimensional force sensor model is Naichuang FC3D80, the six-dimensional force sensor model is Kunwei KWR200E, and the data acquisition system is Donghua DH5922D dynamic signal test and analysis system. The three-dimensional force sensor and the six-dimensional force sensor are connected to the data acquisition system through data cables, and the data acquisition system is connected to the computer through data cables to realize the establishment of the measurement system.

[0043] Step (6), building a floating wind turbine physical-numerical hybrid test platform, specifically:

[0044] In order to combine the physical model, numerical model, loading system and measurement system into a coupled closed-loop system, it is necessary to build a floating wind turbine physical-numerical hybrid test platform. The construction of the test platform mainly consists of two parts: the hardware installation of the model and sensors and the establishment of a data transmission channel. After the tower-nacelle-blade is formed into a physical model, the three-dimensional force sensor and the six-dimensional force sensor of the measurement system are installed on the top and bottom of the physical model respectively, and are connected to the six-rotor propeller and the six-degree-of-freedom platform respectively. The hardware part is installed by bolt connection. The established numerical model is installed in the computer, and a data transmission communication channel is established with the measurement system and the loading system. Data interaction and closed-loop control are realized in the computer, specifically: the data transmission cycle of "numerical model-loading system-physical model-measurement system-numerical model". The above steps realize the real-time interaction of the various parts of the hybrid test platform at each time step. The overall layout of the system is as follows: Figure 4 shown.

[0045] Step (7), monitoring and extracting test information, specifically:

[0046] The operation status of the physical-numerical hybrid test platform is monitored through a visual interface. Furthermore, the movement of the numerical floating body and the aerodynamic load of the numerical wind wheel are displayed, the required information is extracted in real time, and the extracted information is analyzed and processed to evaluate the dynamic response performance of the floating wind turbine.

[0047] In summary, the present invention proposes a physical-numerical hybrid test method for offshore floating wind turbines, which develops a physical-numerical hybrid test technology for floating wind turbines by combining physical models with numerical models, accurately realizes the real-time dynamic coupling of numerical models and physical models in the test, and establishes a set of effective test methods and processes that can make up for the shortcomings of existing model test methods and can truly and reliably predict the motion and dynamic response of floating wind turbines.

[0048] The above specific embodiments are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can make various modifications and variations without departing from the scope of protection of the present invention and the claims, which all fall within the scope of protection of the present invention.

Claims

1. A floating wind turbine physical-numerical hybrid scale model test method, characterized in that: The test method models the floating wind turbine into two parts: a physical model and a numerical model. In addition to the physical model and the numerical model, the test platform also includes a measurement system and a loading system. The measured signal of the measurement system interacts with the calculation result of the numerical model in real time through a computer, and the signal is loaded through the loading system, and finally the construction and closed-loop control of the hybrid test platform are realized. The test method includes the following steps: Step (1), establishing a multi-body / multi-physics field collaborative scaling criterion for a floating wind turbine according to a dimensional analysis method, and dividing the overall structure of the floating wind turbine into a physical model and a numerical model; Step (2), integrating the physical model, the numerical model, the loading system and the measurement system, building a physical-numerical hybrid test platform for floating wind turbines, connecting the measurement system to a computer through a data acquisition system, and then connecting the computer to the loading system to achieve transmission of loading signals, thereby building a physical-numerical hybrid test platform; Step (3), data interaction and closed-loop control of the physical-numerical hybrid test platform; Carry out load calculations for different working conditions according to the numerical model, load the physical model through the loading system, measure the shear force and bending moment information at the bottom of the tower through the measurement system, and transmit the measured data to the computer; transmit the measured data of the tower to the numerical float through the computer, calculate the additional float movement caused by the tower acting on the platform, and feed it back to the numerical wind wheel to realize the recalculation of the load, and realize closed-loop control by acting on the physical model through the loading system; Step (4): information monitoring and extraction during the physical-numerical hybrid experiment.

2. A floating wind turbine physical-numerical hybrid scale model test method according to claim 1, characterized in that: The step (1) is specifically as follows: Step 1.1, equate the aerodynamic load to the rotor thrust, equate the hydrodynamic load to the floating body motion, derive the load-structure-response similarity law based on the dimensional analysis theory, and establish the multi-body / multi-physics field collaborative scaling criterion for floating wind turbines to ensure that the response of the scaled model can be returned to the original scale model through the scaling criterion; Step 1.2, determine the scale ratio according to the established scale criterion and the prototype size of the floating wind turbine, and design the physical model and numerical model of the floating wind turbine, wherein the physical model includes blades, nacelle, tower and connection structure, and the numerical model includes numerical float and numerical wind wheel.

3. A floating wind turbine physical-numerical hybrid scale model test method according to claim 1, characterized in that: The step (2) is specifically as follows: Step 2.1, connect the hardware of the test platform, connect the physical model to the measurement system and the loading system respectively, the measurement system includes a three-dimensional force sensor and a six-dimensional force sensor, and the loading system includes a six-rotor propeller and a six-degree-of-freedom motion platform; Step 2.2, establish the data transmission channel of the test platform, integrate the sensor data interface, numerical model calculation result file and the input end of the loading system into the computer, and establish the data closed-loop transmission channel of "measurement system-numerical model-loading system-physical model-measurement system" through the computer.

4. A floating wind turbine physical-numerical hybrid scale model test method according to claim 1, characterized in that: The step (3) is specifically as follows: Step (3), data interaction and closed-loop control of the physical-numerical hybrid test platform, specifically: The six-degree-of-freedom motion platform is controlled by a computer to apply floating body motion to the physical model, and the six-rotor propeller is controlled to apply wind wheel thrust to the physical model. The measurement data is recorded in real time by the measurement system and sent to the computer, and the computer receives the signal from the data acquisition board in the measurement system; The collected signals are used as inputs of the numerical model for calculation to obtain the additional movement of the floating body under the tower bottom load, and the calculation results of the numerical model are sent to the loading system through a computer; The real-time loading signals of the six-degree-of-freedom motion platform and the six-rotor thruster are changed based on the calculation results of the numerical model. The load data at the bottom of the tower is recorded by the measurement system to realize data interaction and closed-loop control of the physical-numerical hybrid test platform.

5. The floating wind turbine physical-numerical hybrid scale model test method according to claim 1, characterized in that: The step (4) is specifically as follows: The operating status of the physical-numerical hybrid test platform is monitored through a visual interface; the visual interface is used to monitor the operating status of the physical-numerical hybrid test platform in real time, and display the motion data of the floating body and the aerodynamic load data information of the wind wheel; the extracted information is extracted, analyzed and processed in real time to evaluate the dynamic response performance of the floating wind turbine.

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