Fan electric pulse deicing simulation method based on deicing criterion of cohesive zone composite structure model

Abstract

The invention provides a fan electric pulse deicing simulation method based on a deicing criterion of a cohesive zone composite structure model. The fan electric pulse deicing simulation method comprises the following steps: S1, obtaining icing parameters of fan blades under actual working conditions; s2, inputting the icing parameters into simulation software to construct an icing composite structure simulation model based on the cohesive region; and S3, applying an electric pulse load to the skin in the simulation model, judging whether an ice layer in the simulation model falls off or not, if so, recording the current electric pulse load, and applying the current electric pulse load to the actual deicing working condition, and if not, changing the electric pulse load of the skin. According to the method, the actual icing is simulated based on the icing parameters under the actual working condition, the icing is simulated to determine the cohesion parameters between the icing and the surface of the fan blade, and then the corresponding electric pulse load when the icing falls off is judged; therefore, the electric pulse load is applied to an actual deicing system, and ice covering the fan blade is effectively removed.

Description

Technical Field

[0001] The invention relates to a deicing simulation method, in particular to a fan electric pulse deicing simulation method based on an ice-shedding criterion of a composite structure model of a cohesive zone. Background Art

[0002] Wind turbine blades are the core components that convert the kinetic energy of air into mechanical energy during wind power generation. Their working status determines the power generation capacity of the wind farm. Considering factors such as work efficiency, noise, safety, and ecological protection, large wind farms are usually built in hilly, mountainous, and offshore areas far away from urban areas. Usually, these areas have high altitudes, higher density of cold air than warm air, and faster wind speeds. However, the high humidity and low temperature microclimate environment of the microtopography makes wind turbine blades more susceptible to ice.

[0003] Ice has a huge impact on the airfoil structure including the wind turbine blades, which seriously endangers production safety. When ice is applied, the load on the wind turbine blades is increased, and it is easy to cause an imbalance in the load of the wind turbine, resulting in damage to the wind turbine unit. In addition, the difference in the thermal process of ice application between different regions will cause the force of ice on the blades to be uneven, and it will fall off the blades under the action of complex external forces such as centrifugal force and gravity, which is easy to cause damage to the unit itself, the tower bottom equipment (radiator / box transformer) and the supporting transmission lines. At the same time, it poses a safety hazard to the operation and maintenance personnel. Once the ice on the wind turbine blades is not handled in time, it is very likely to cause wind abandonment and shutdown.

[0004] In the prior art, electric pulse deicing technology is generally used for deicing fan blades. As a mechanical active deicing technology, electric pulse deicing has the advantages of low energy consumption, simple structure, light weight, strong versatility, and high reliability. It can meet the requirements of aircraft deicing safety and low energy consumption and environmental protection, and has broad application potential.

[0005] Electric pulse deicing is to fix several skins (such as aluminum skins) on the fan blades, and set an excitation coil at the skin. The excitation coil is set between the skin and the fan blades. When the pulse excitation current is input, the current induces the coil to generate an electromagnetic field, thereby instantly stimulating a pulse repulsive force of hundreds of thousands of Newtons on the fan skin. The fan skin deforms under the stimulation of the electric pulse repulsive force, and transmits the impact and vibration loads to the ice on the skin surface, causing the ice layer to fall off, ultimately achieving the purpose of deicing.

[0006] However, in the prior art, how to determine the size of the pulse excitation current of the excitation coil and the duty cycle of the pulse has become a technical problem. If the pulse current is too small, good deicing cannot be achieved, and if the pulse current is too large, the surface of the wind turbine blades will be damaged.

[0007] Therefore, in order to solve the above technical problems, it is urgent to propose a new technical means. Summary of the invention

[0008] In view of this, the purpose of the present invention is to provide a fan electric pulse de-icing simulation method based on the de-icing criterion of the composite structure model of the cohesion zone, simulate the actual icing based on the icing parameters under actual working conditions, and simulate the icing to determine the cohesion parameters between the ice and the surface of the fan blade, and then judge the corresponding electric pulse load (i.e. the corresponding pulse current) when the ice falls off, so as to apply the electric pulse load to the actual de-icing system, so that the ice on the fan blades can be effectively removed, the impact on the fan blades is reduced, and the power generation loss of the unit caused by blade icing is reduced, and the fan icing shutdown time is shortened.

[0009] The present invention provides a fan electric pulse deicing simulation method based on the deicing criterion of the cohesive zone composite structure model, comprising the following steps:

[0010] S1. Obtaining ice coating parameters of wind turbine blades under actual working conditions;

[0011] S2. Inputting the icing parameters into the simulation software to construct a simulation model of the icing composite structure based on the cohesive zone;

[0012] S3. Apply an electric pulse load to the skin in the simulation model to determine whether the ice layer in the simulation model has fallen off. If so, record the current electric pulse load and apply the current electric pulse load to the actual deicing condition. If not, change the electric pulse load of the skin.

[0013] Further, in step S1, the icing parameters include wind turbine blade geometry, skin thickness, skin material, ice layer thickness, ice layer density and icing shape.

[0014] Further, judging whether the ice layer in the simulation model has fallen off specifically includes:

[0015] The surface of the fan blade is divided into a number of grid units, each grid unit corresponds to a skin;

[0016] Determine the relative displacement of ice cover δ for each grid cell m and the relative displacement of the failure interface between the ice cover of the grid unit and the wind turbine blade

[0017] when When the ice cover of the grid cell falls off.

[0018] Furthermore, the relative displacement of ice cover δ is determined by the following method: m :

[0019]

[0020] Where: δ3 represents the normal tensile displacement of the ice covering the current grid unit, δ1 represents the lateral shear displacement of the ice covering the current grid unit, and δ2 represents the longitudinal shear displacement of the ice covering the current grid unit; <·> represents the operator, and the expression is:

[0021]

[0022] Furthermore, the relative displacement at failure is determined by the following method:

[0023]

[0024] Where: β = δ sheat / δ3,δ shear represents the total shear relative displacement of the ice covering the current grid cell, K p represents the initial stiffness of the adhesion between the ice covering the current grid unit and the wind turbine blades, represents the relative displacement of ice cover in the current grid cell under mixed failure, G IC , G IIC are the critical failure energies of single transverse shear fracture failure and single longitudinal shear fracture failure interfaces respectively; They are the relative displacements of interface failure when single transverse shear fracture fails and single longitudinal shear fracture fails respectively; the index α is the mixed coefficient of fracture mode, and its value is usually 1 or 2. In order to comprehensively consider the mixed failure, the value of α is 2.

[0025] Further, the relative displacement is determined by the following method:

[0026]

[0027] in: N represents the transverse shear cohesive strength, and S represents the longitudinal shear cohesive strength.

[0028] The beneficial effects of the present invention are as follows: Through the present invention, actual icing is simulated based on icing parameters under actual working conditions, and the icing is simulated to determine the adhesion parameters between the icing and the surface of the fan blades, and then the corresponding electric pulse load (i.e., the corresponding pulse current) when the ice falls off is judged, so that the electric pulse load is applied to the actual de-icing system, so that the ice on the fan blades can be effectively removed, the impact on the fan blades is reduced, and the power generation loss of the unit caused by blade icing is reduced, and the fan icing shutdown time is shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0030] Figure 1 It is a schematic diagram of the process of the present invention.

[0031] Figure 2 Schematic diagram of ice shedding.

[0032] Figure 3 Schematic diagram of the relationship between the skin-ice interface under the mixed effects of transverse shear, longitudinal shear and normal tension. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below:

[0034] The present invention provides a fan electric pulse deicing simulation method based on the deicing criterion of the cohesive zone composite structure model, comprising the following steps:

[0035] S1. Obtaining icing parameters of wind turbine blades under actual working conditions; wherein the icing parameters include wind turbine blade geometry, skin thickness, skin material, ice thickness, ice density, and icing shape, so as to perform corresponding simulation;

[0036] S2. Input the icing parameters into the simulation software to construct a simulation model of the icing composite structure based on the cohesive zone; wherein the simulation software uses Ansys / Ls-Dyna and Abaqus, which can automatically solve the parameters such as the normal tensile displacement, the transverse shear displacement and the longitudinal shear displacement;

[0037] S3. Apply an electric pulse load to the skin in the simulation model to determine whether the ice layer in the simulation model has fallen off. If so, record the current electric pulse load, including the current excitation current and the duty cycle of the pulse current, and apply the current electric pulse load to the actual deicing condition. If not, change the electric pulse load of the skin. Through the above method, the actual icing is simulated based on the icing parameters under the actual working conditions, and the icing is simulated to determine the adhesion parameters between the icing and the surface of the fan blade, and then determine the corresponding electric pulse load (i.e., the corresponding pulse current) when the ice falls off, so that the electric pulse load is applied to the actual deicing system, so that the ice on the fan blades is effectively removed, the impact on the fan blades is reduced, and the power generation loss of the unit caused by blade icing is reduced, and the fan icing downtime is shortened.

[0038] In this embodiment, determining whether the ice layer in the simulation model has fallen off specifically includes:

[0039] The surface of the fan blade is divided into a number of grid units, each grid unit corresponds to a skin;

[0040] Determine the relative displacement of ice cover δ for each grid cell m and the relative displacement of the failure interface between the ice cover of the grid unit and the wind turbine blade

[0041] when When the ice cover of the grid cell falls off.

[0042] Specifically: Determine the relative displacement of ice by the following method: m :

[0043]

[0044] Where: δ3 represents the normal tensile displacement of the ice covering the current grid unit, δ1 represents the lateral shear displacement of the ice covering the current grid unit, and δ2 represents the longitudinal shear displacement of the ice covering the current grid unit; <·> represents the operator, and the expression is:

[0045] The transverse direction mentioned above refers to the chord direction of the fan blade, that is, the length direction of the fan blade, the longitudinal direction refers to the width direction of the fan blade, and the normal direction is the vertical direction of the surface of the fan blade.

[0046] The relative displacement at failure is determined by the following method:

[0047]

[0048] Where: β = δ sheat / δ3,δ shear represents the total shear relative displacement of the ice covering the current grid cell, K p represents the initial stiffness of the adhesion between the ice covering the current grid unit and the wind turbine blades, represents the relative displacement of ice cover in the current grid cell under mixed failure, G IC , G IIC are the critical failure energies of single transverse shear fracture failure and single longitudinal shear fracture failure interfaces respectively; They are the relative displacements of interface failure when single transverse shear fracture fails and single longitudinal shear fracture fails respectively; the index α is the mixed coefficient of fracture mode, and its value is usually 1 or 2. In order to comprehensively consider the mixed failure, the value of α is 2.

[0049] The relative displacement is determined by

[0050]

[0051] in: N represents the transverse shear cohesive strength, and S represents the longitudinal shear cohesive strength.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A fan electric pulse deicing simulation method based on the deicing criterion of the composite structure model of the cohesive zone, characterized by: The following steps are involved: S1. Obtaining ice coating parameters of wind turbine blades under actual working conditions; S2. Inputting the icing parameters into the simulation software to construct a simulation model of the icing composite structure based on the cohesive zone; S3. Apply an electric pulse load to the skin in the simulation model to determine whether the ice layer in the simulation model has fallen off. If so, record the current electric pulse load and apply the current electric pulse load to the actual deicing condition. If not, change the electric pulse load of the skin.

2. The wind turbine electric pulse deicing simulation method based on the deicing criterion of the composite structure model of the cohesive zone according to claim 1 is characterized in that: In step S1, the icing parameters include the geometric shape of the wind turbine blade, the skin thickness, the skin material, the ice layer thickness, the ice layer density and the icing shape.

3. The wind turbine electric pulse deicing simulation method based on the deicing criterion of the composite structure model of the cohesive zone according to claim 1 is characterized in that: Determining whether the ice layer in the simulation model has fallen off specifically includes: The surface of the fan blade is divided into a number of grid units, each grid unit corresponds to a skin; Determine the relative displacement of ice cover δ for each grid cell m and the relative displacement of the failure interface between the ice cover of the grid unit and the wind turbine blade when When the ice cover of the grid cell falls off.

4. The wind turbine electric pulse deicing simulation method based on the deicing criterion of the composite structure model of the cohesive zone according to claim 3 is characterized in that: The relative displacement of ice cover δ is determined by the following method m : Where: δ3 represents the normal tensile displacement of the ice covering the current grid unit, δ1 represents the lateral shear displacement of the ice covering the current grid unit, and δ2 represents the longitudinal shear displacement of the ice covering the current grid unit; <·> represents the operator, and the expression is:

5. The wind turbine electric pulse deicing simulation method based on the deicing criterion of the composite structure model of the cohesive zone according to claim 4 is characterized in that: The relative displacement at failure is determined by the following method: Where: β = δ sheat / δ3,δ shear represents the total shear relative displacement of the ice covering the current grid cell, K p represents the initial stiffness of the adhesion between the ice covering the current grid unit and the wind turbine blades, represents the relative displacement of ice cover in the current grid cell under mixed failure, G IC , G IIC are the critical failure energies of single transverse shear fracture failure and single longitudinal shear fracture failure interfaces respectively; are the relative displacements of interface failure when single transverse shear fracture fails and single longitudinal shear fracture fails respectively; the exponent α is the fracture mode mixing coefficient.

6. The wind turbine electric pulse deicing simulation method based on the deicing criterion of the composite structure model of the cohesive zone according to claim 5 is characterized by: The relative displacement is determined by in: N represents the transverse shear cohesive strength, and S represents the longitudinal shear cohesive strength.

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