Method for determining parameters of first-gear winding model of transformer added with micro guide structure, winding model and oil flow observation experiment platform of winding model

Abstract

The invention discloses a method for determining parameters of a one-gear winding model of a transformer added with a micro-guiding structure, a winding model and an oil flow observation experiment platform of the winding model. The method comprises the following steps: establishing a two-dimensional CFD model of a three-gear winding area of the transformer, and obtaining an oil flow proportional relational expression in the winding of the transformer based on a dimensional analysis method; establishing a transformer three-gear winding area two-dimensional CFD model added with different micro-guiding structures, and performing data fitting to determine an oil flow proportion function expression in the transformer three-gear winding area added with the micro-guiding structures; and further determining the flow proportion at the third gear inlet, and determining the length, width and angle of the inlet according to the flow proportion relational expression of the first-gear winding at the inlet. Compared with the prior art, the method has the advantages that a conventional three-gear type transformer winding model is replaced by the one-gear type transformer winding model, materials and complex procedures required by the winding model are saved, the inlet flow velocity of a winding area can be changed more simply and conveniently, and the inhibition effect of a micro-guiding structure on reverse oil flow can be reflected more visually.

Description

Technical Field

[0001] The invention belongs to the field of electrical equipment, and in particular relates to a method for determining parameters of a transformer single-stage winding model with a micro-guide structure added, a winding model and an oil flow observation experimental platform thereof. Background Art

[0002] The on-board traction transformer of an EMU (referred to as "on-board transformer") is the core equipment in the EMU electrical system. Its efficient cooling is the key link in achieving the speed increase of the EMU, ensuring that various equipment on the train, such as traction motors, lighting, and control, can operate efficiently and safely.

[0003] Compared with the existing highest speed EMUs, the power of EMUs with a speed of 400 kilometers per hour or above will increase by 50%, and the loss will also increase simultaneously, but the assembly space of the on-board transformer has not been expanded accordingly, which further increases the difficulty of cooling design and insulation layout. In the current research and development, the expected cooling effect has not been achieved by increasing the output of the oil pump and adjusting the flow rate. It is even found that although increasing the inlet flow rate can reduce the average temperature rise, some oil channels in the winding area have reverse flow, resulting in the temperature rise of the hottest point rising instead of falling. Even if the abnormal phenomena under several typical working conditions such as rated load and stable operation can be avoided during design, the large changes in oil viscosity and speed will trigger reverse flow in the changeable and diverse actual working conditions. The resulting local overheating threatens the long-term reliability of the insulation, and the area where it is located is also the weak insulation point of the whole machine. After research, it was found that the reverse oil flow in the three-speed winding area of ​​the transformer is prone to appear in the first and second oil channels of the third gear of the winding. Therefore, in view of the internal cooling design of the on-board transformer under the harsh condition of higher loss density, it is proposed to simulate the oil flow streamline at the entrance of the third gear, and realize the observation by using a one-gear winding experimental platform to replace the three-gear winding experimental platform, so as to obtain the flow direction and velocity of the oil flow in the transformer winding area, restore the flow in the on-board transformer winding, verify the correctness of the oil channel flow proportional function, explore the inhibitory effect of the micro-guide structure on the reverse oil flow, and then improve the cooling design of the transformer winding area.

[0004] Patent publication number CN112903244B "Device and method for observing internal flow and temperature distribution of a horizontal transformer" can observe the internal flow and temperature distribution of a horizontal transformer, but still uses a three-stage transformer winding model and cannot observe transformers with added micro-guide structures. Summary of the invention

[0005] Purpose of the invention: In response to the problems in the background technology, the present invention discloses a method for determining the parameters of a one-stage winding model of a transformer with an added micro-guide structure, a winding model and an oil flow observation experimental platform. By establishing one-stage and three-stage transformer winding area simulation models with added micro-guide structures, and based on the oil flow proportional function formula and fluid mechanics equations in the transformer winding with added micro-guide structures, the inlet length and angle of the one-stage transformer winding experimental model are obtained, and then a one-stage transformer winding area oil flow observation device with added micro-guide structures is built.

[0006] Technical solution: The present invention discloses a method for determining parameters of a transformer single-stage winding model with a micro-guide structure, comprising the following steps:

[0007] Step 1: Establish a two-dimensional CFD model of the three-stage winding area of ​​the transformer, and obtain the proportional relationship of the oil flow in the transformer winding based on the dimensional analysis method;

[0008] Step 2: A two-dimensional CFD model of the transformer three-stage winding area with different micro-guide structures added is established in Ansys Icem software, and imported into Ansys Fluent finite element simulation software to extract the flow ratio of each oil channel, and after parametric scanning, a function formula of the oil flow ratio in the transformer three-stage winding area with the micro-guide structure added is obtained;

[0009] Step 3: Determine the flow ratio at the third gear entrance based on the oil flow ratio function in the three-gear winding area of ​​the transformer with the micro-guide structure added, and then determine the entrance length, width and angle based on the one-gear winding flow ratio relationship at the entrance.

[0010] Furthermore, the flow rate ratio in the oil channel in step 1 is:

[0011]

[0012] Where: k fi It is the flow rate ratio of the i-th horizontal oil channel in the winding, i = 1, 2, ..., n, n 1 is the number of windings in each gear; v in is the average oil velocity at the inlet; W oin and W oout H are the widths of the inner and outer vertical oil passages respectively; o is the height of the horizontal oil channel; H d and W d are the height and width of the winding cake respectively; R in R is the length from the center of the micro-guide structure to the upper side of the second-gear oil guide gasket; w is the radius of the micro-guide structure; D w is the depth of the micro-guide structure.

[0013] Furthermore, in step 2, different dimensionless parameters of windings with different micro-guide structures are scanned, and the simulation results are substituted into the flow ratio function for iteration to obtain the oil flow ratio function formula in the transformer winding:

[0014]

[0015] Where: k fi is the flow rate ratio of the i-th horizontal oil channel; a ij 、b ijk 、c ijkm is the virtual coefficient introduced, and k of each oil channel is fitted fi Several d coefficients will be generated; α is the ratio of the radius of the micro-guide structure to the height of the winding cake; β is the ratio of the depth of the micro-guide structure to the height of the winding cake; γ is the ratio of the length from the center of the micro-guide structure to the upper side of the second-stage oil guide gasket to the height of the winding cake.

[0016] Furthermore, in step 3, the flow ratio at the third gear entrance of the three-gear winding area is first determined according to the oil flow ratio function in the transformer winding, and then the entrance length, width and angle are determined according to the one-gear winding flow ratio relationship at the entrance. The calculation formula of the one-gear winding flow ratio relationship at the entrance is:

[0017]

[0018] Where: is the average oil channel flow ratio of the oil channel; is the average oil speed at the inlet of the first-gear winding; K L is the angle correction coefficient; L is the length of the single-stage winding entrance; W is the width of the single-stage winding entrance; θ is the angle of the single-stage winding entrance.

[0019] Furthermore, it also includes building a transformer one-stage winding model with determined parameters and a three-stage model for simulation comparison to determine the equivalent correctness of the one-stage model, as follows:

[0020] According to the inlet length, width and angle of the one-stage winding model of the transformer winding area determined in step 3, a two-dimensional CFD model is established in the Ansys Icem software. Then the one-stage winding model is imported into Ansys Fluent for simulation, and the velocity cloud map and the oil channel flow ratio data at the inlet are exported. The velocity cloud map of the one-stage winding model in the transformer winding area is compared with the velocity cloud map of the corresponding three-stage winding model in the transformer winding area to observe whether the oil flow streamlines at the inlet are consistent. Then, the oil channel flow ratio data at the inlet are compared to verify the equivalent substitutability of the one-stage winding model in the transformer winding area.

[0021] The present invention also discloses a transformer one-stage winding model with a micro-guide structure added thereto, and the transformer one-stage winding model is constructed according to the inlet length, width and angle determined by the above-mentioned method for determining parameters of the transformer one-stage winding model with a micro-guide structure added thereto, and the specific model structure is made as follows:

[0022] According to the calculated length, width and angle of the entrance, a one-stage transformer winding model drawing with a micro-guide structure is made in CAD and the file is exported. The exported file is input into the milling machine, and the winding cake groove and oil channel are milled downward from the entire transparent acrylic plate. The micro-guide structure and winding cake are cut out, and the inner and outer winding walls and the micro-guide structure are polished. The winding cake is embedded in the winding cake groove, and the transparent acrylic sheet is encapsulated on the upper part of the model to verify the airtightness.

[0023] The present invention also discloses an oil flow observation experimental platform based on the above-mentioned method for determining parameters of a transformer one-stage winding model with a micro-guide structure, comprising a transformer one-stage winding model, a flow meter, an oil pump, a valve, an oil tank, a heat sink, a micro-guide structure, an oil circulation outer pipeline and a particle image velocimetry system PIV, wherein the transformer one-stage winding model provided with the micro-guide structure is sequentially connected to an oil pump and a heat sink through an oil circulation outer pipeline, the valve is provided on the heat sink inlet pipeline, and the flow meter is provided on the oil pump inlet pipeline;

[0024] The particle image velocimetry system PIV is composed of a synchronizer, a computer, a laser source, a laser sheet, and a CCD camera;

[0025] Aim the laser sheet at the transformer single-stage winding model and place it horizontally to ensure that the measurement plane illuminated by the light source is two-dimensional. Adjust the position so that the light source after irradiating the laser sheet is facing the micro-guide structure of the transformer single-stage winding model. Place the CCD camera perpendicular to the measurement plane, turn on the CCD camera and laser source, set the frame rate and exposure time, record and save the original flow field image obtained by shooting; perform post-processing on the image to obtain the speed of the oil flow in each oil channel, and derive the vector diagram and cloud diagram of the oil flow speed.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention models the single-stage winding area of ​​the transformer and proposes a proportional relationship formula for the single-stage winding flow at the inlet, which can replace the conventional three-stage transformer winding model with a single-stage transformer winding model, saving the materials and complex processes required for the winding model. At the same time, it can also more easily change the inlet flow velocity of the winding area, and more intuitively reflect the inhibitory effect of the micro-guide structure on the reverse oil flow.

[0028] 2. The present invention builds a transformer first-stage winding area oil flow observation experimental platform with an added micro-guide structure, which can obtain the streamline and flow velocity of the oil flow in the transformer winding area, restore the flow in the vehicle-mounted transformer winding, verify the correctness of the oil channel flow proportional function, and explore the inhibitory effect of the micro-guide structure on the reverse oil flow, thereby improving the cooling design of the transformer winding area and increasing the service life of the transformer, providing an experimental data basis for the design of the next generation of vehicle-mounted transformers for EMUs with a speed of 400 kilometers per hour and above. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the process flow of determining the parameters of a transformer single-stage winding model with a micro-guide structure added, i.e., the simulation process;

[0030] Figure 2 Schematic diagram of the transformer three-stage winding model with added micro-guide structure;

[0031] Figure 3 Establish a 2D CFD model of transformer winding with micro-guide structure in Ansys Icem;

[0032] Figure 4 This is a comparison chart of oil flow rate simulation of two-dimensional CFD models of three-stage transformer winding and one-stage transformer winding in Ansys Fluent;

[0033] Figure 5 Schematic diagram of the platform of the transformer one-stage winding area oil flow observation experimental device with added micro-guide structure;

[0034] Figure 6 Create CAD drawings for the windings of a single-stage transformer;

[0035] Figure 7 This is a three-layer explosion design diagram of a single-stage transformer winding;

[0036] Figure 8 This is the experimental diagram of oil flow observation in the first-stage winding area of ​​a transformer with a micro-guide structure;

[0037] Fig. 9 The oil velocity vector diagram at the inlet of the transformer winding derived by the PIV system;

[0038] Fig.10 The oil flow velocity contour at the inlet of the transformer winding derived from the PIV system. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0040] The present invention discloses a method for determining parameters of a transformer winding model with a micro-guide structure, a winding model and an oil flow observation experimental platform thereof, which is aimed at suppressing reverse oil flow inside the transformer winding and determining the arrangement of the transformer winding oil flow observation experimental platform with a micro-guide structure, such as Figure 1 As shown, the method for determining the parameters of the transformer single-stage winding model includes:

[0041] S1: Establish a two-dimensional CFD model of the three-stage winding area of ​​the transformer, and obtain the proportional relationship of the oil flow in the transformer winding based on the dimensional analysis method.

[0042] First, the average oil velocity at the inlet is related to the following variables:

[0043]

[0044] Where: n 1 is the number of winding cakes in each gear; is the average oil velocity at the inlet; W oin and W oout H are the widths of the inner and outer vertical oil passages respectively; o is the height of the horizontal oil channel; H d and W d are the height and width of the winding cake respectively; R in R is the length from the center of the micro-guide structure to the upper side of the second-gear oil guide gasket; w is the radius of the micro-guide structure; D w is the depth of the micro-guide structure.

[0045] Then ρ and W oout Set as the control parameter, and convert the dimensional expression into dimensionless form according to the theorem as follows:

[0046]

[0047] Then replace the ratio of the average oil channel velocity with the product of the horizontal oil channel height and the inlet vertical oil channel width to obtain the flow rate ratio in the oil channel:

[0048]

[0049] Where: k fi It is the flow rate ratio of the i-th horizontal oil channel in the winding, i = 1, 2, ..., n. The schematic diagram of each parameter can be shown as Figure 2 As shown, in this embodiment, the flow ratio of 7 horizontal oil channels is studied, that is, i=1,2,...,7 is selected.

[0050] Then, a two-dimensional CFD model of the three-stage winding area of ​​the transformer with different micro-guide structures was established in Ansys Icem software, and then imported into Ansys Fluent finite element simulation software to extract the flow ratio of each oil channel and observe the oil flow streamlines; the two-dimensional CFD winding model mode was set to steady, the solver was set to Pressure-Based mode, and the solution algorithm was set to Implicit. Since the model is an axisymmetric model, the two-dimensional space attribute was set to Axisymmetric, the viscosity model was set to Laminar, the pressure-velocity coupling mode was SIMPLE, and the pressure was set to PRESTO.

[0051] Finally, different dimensionless parameters of windings with different micro-guide structures were scanned, and a total of 560 simulations were obtained; the geometric parameters α, β and position parameters γ can generate multiple sets of models with different structures, all of which need to be modified and meshed again in CFD; the simulation results are substituted into the flow ratio relationship and iterated to obtain the oil flow ratio function of the transformer winding:

[0052]

[0053] Where: k fi is the flow rate ratio of the i-th horizontal oil channel; a ij 、b ijk 、c ijkm is the virtual coefficient introduced, and k of each oil channel is fitted fi Several d coefficients will be generated; α is the ratio of the radius of the micro-guide structure to the height of the winding cake; β is the ratio of the depth of the micro-guide structure to the height of the winding cake; γ is the ratio of the length from the center of the micro-guide structure to the upper side of the second-stage oil guide gasket to the height of the winding cake.

[0054] In this embodiment, the flow ratio of 7 horizontal oil channels is studied, that is, i=1, 2, ..., 7 is selected, and when generating a plurality of d coefficients, d ijkm1 d ijkm2 d ijkm3 That is the 64 d coefficients generated.

[0055] S2: Determine the flow ratio at the entrance, and then determine the entrance length, width and angle according to the first-stage winding flow ratio relationship at the entrance.

[0056] First, the flow ratio at the entrance of the third gear of the three-gear winding area is determined according to the oil flow ratio function in the transformer winding, and then the entrance length, width and angle are determined according to the one-gear winding flow ratio relationship at the entrance, see Figure 3 The calculation formula for the proportional relationship of the first-stage winding flow at the inlet is:

[0057]

[0058] Where: is the average oil channel flow ratio of the oil channel; is the average oil speed at the inlet of the first-gear winding; K L is the angle correction coefficient; L is the length of the single-stage winding entrance; W is the width of the single-stage winding entrance; θ is the angle of the single-stage winding entrance.

[0059] S3: Build a single-stage winding model and a three-stage model of the transformer with determined parameters for simulation comparison.

[0060] According to the inlet length, width and angle of the transformer one-stage winding model determined by S2, a two-dimensional CFD model is established in Ansys Icem software, and then the model is imported into Ansys Fluent for simulation, and the velocity cloud map and the oil channel flow ratio data at the inlet are exported. The velocity cloud map of the transformer one-stage winding model is compared with the velocity cloud map of the corresponding transformer three-stage winding model, as shown in Figure 2. Figure 4 As shown, observe whether the oil flow streamlines at the inlet are consistent, and then compare the oil channel flow ratio data at the inlet to verify the equivalent substitutability of the transformer's single-stage winding model.

[0061] S4: Build a transformer first-stage winding area oil flow observation experimental device platform with added micro-guide structure.

[0062] The transformer single-stage winding area oil flow observation experimental device platform with added micro-guide structure is composed of a transformer single-stage winding model 1, a flow meter 2, an oil pump 3, a valve 4, an oil tank 5, a heat sink 6, a micro-guide structure 7, an oil circulation outer pipeline 9 and a particle image velocimetry system PIV9. The particle image velocimetry system PIV9 is composed of a synchronous machine 901, a computer 902, a laser source 903, a laser sheet 904 and a CCD camera 905. The schematic diagram of the experimental device platform is shown in the figure. Figure 5 shown.

[0063] The transformer one-stage winding model 1 provided with a micro-guide structure 7 is connected to an oil pump 3 and a heat sink 6 in sequence through an oil circulation outer pipeline 8, a valve 4 is provided on the heat sink 6 inlet pipeline, and a flow meter 2 is provided on the oil pump 3 inlet pipeline. The production of the transformer one-stage winding model includes the following steps:

[0064] The first step is to make a one-stage transformer winding model drawing with a micro-guide structure in CAD according to the calculated length, width and angle at the entrance and export the file. The CAD drawing is as follows: Figure 6 shown.

[0065] The second step is to input the exported file into the milling machine, mill out the winding cake groove and oil channel of the entire transparent acrylic plate, cut out the micro-guide structure and winding cake, and the three-layer explosion design diagram of the one-stage transformer winding model is as follows: Figure 7 shown.

[0066] The third step is to polish the inner and outer winding walls and the micro-guide structure.

[0067] Step 4: Embed the winding cake into the winding cake groove, seal the transparent acrylic sheet to the upper part of the model, and verify the airtightness.

[0068] The arrangement of the particle image velocimetry system PIV9 includes the following steps:

[0069] The first step is to align the laser sheet (904) with the transformer single-stage winding model (1) and place it horizontally to ensure that the measurement plane illuminated by the light source is two-dimensional. The position is adjusted so that the light source (903) illuminates the laser sheet (904) and faces the micro-guide structure (7) of the transformer single-stage winding model (1) to ensure that the light can completely pass through the acrylic plate. The CCD camera 905 is placed perpendicular to the measurement plane. The specific observation experiment is shown in the figure below. Figure 8 shown.

[0070] The second step is to turn on the CCD camera 905 and the laser source (903), set a suitable frame rate and exposure time, and record and save the captured original flow field image.

[0071] The third step is to perform post-processing of the images in the Qianyanlang RFlow3.0 software to obtain the speed of the oil flow in each oil channel, and derive the vector diagram and cloud diagram of the oil flow speed, such as Fig. 9 and Fig.10 shown.

[0072] The above content is merely an illustration of the structure of the present invention. Various modifications or additions made by technicians in the technical field to the specific structure described shall be protected by the present invention as long as they do not deviate from the structure of the invention or exceed the scope defined by the claims.

Claims

1. A method for determining parameters of a transformer single-stage winding model with a micro-guide structure, characterized in that: The steps include: Step 1: Establish a two-dimensional CFD model of the three-stage winding area of ​​the transformer, and obtain the proportional relationship of the oil flow in the transformer winding based on the dimensional analysis method; Step 2: A two-dimensional CFD model of the transformer three-stage winding area with different micro-guide structures added is established in Ansys Icem software, and imported into Ansys Fluent finite element simulation software to extract the flow ratio of each oil channel, and after parametric scanning, a function formula of the oil flow ratio in the transformer three-stage winding area with the micro-guide structure added is obtained; Step 3: Determine the flow ratio at the third gear entrance based on the oil flow ratio function in the three-gear winding area of ​​the transformer with the micro-guide structure added, and then determine the entrance length, width and angle based on the one-gear winding flow ratio relationship at the entrance.

2. The method for determining parameters of a transformer single-stage winding model with a micro-guide structure added according to claim 1, characterized in that: The flow rate ratio relation in the oil channel in step 1 is: Where: k fi It is the flow rate ratio of the i-th horizontal oil channel in the winding, i = 1, 2, ..., n, n1 is the number of winding cakes in each gear; v in is the average oil velocity at the inlet; W oin and W oout H are the widths of the inner and outer vertical oil passages respectively; o is the height of the horizontal oil channel; H d and W d are the height and width of the winding cake respectively; R in R is the length from the center of the micro-guide structure to the upper side of the second-gear oil guide gasket; w is the radius of the micro-guiding structure; D w is the depth of the micro-guide structure.

3. The method for determining parameters of a transformer single-stage winding model with a micro-guide structure added according to claim 1, characterized in that: In step 2, different dimensionless parameters of windings with different micro-guide structures are scanned, and the simulation results are substituted into the flow ratio function for iteration to obtain the oil flow ratio function formula in the transformer winding: Where: k fi is the flow rate ratio of the i-th horizontal oil channel; a ij , b ijk 、c ijkm is the virtual coefficient introduced, and k for each oil channel fitted fi Several d coefficients will be generated; α is the ratio of the radius of the micro-guide structure to the height of the winding cake; β is the ratio of the depth of the micro-guide structure to the height of the winding cake; γ is the ratio of the length from the center of the micro-guide structure to the upper side of the second-stage oil guide gasket to the height of the winding cake.

4. The method for determining parameters of a transformer single-stage winding model with a micro-guide structure added according to claim 1, characterized in that: In step 3, the flow ratio at the third gear entrance of the three-gear winding area is first determined according to the oil flow ratio function in the transformer winding, and then the entrance length, width and angle are determined according to the one-gear winding flow ratio relationship at the entrance. The calculation formula of the one-gear winding flow ratio relationship at the entrance is: Where: is the average oil channel flow rate ratio of the oil channel; is the average oil speed at the inlet of the first-gear winding; K L is the angle correction coefficient; L is the length of the first-stage winding entrance; W is the width of the first-stage winding entrance; θ is the angle of the first-stage winding entrance.

5. The method for determining parameters of a transformer single-stage winding model with a micro-guide structure added according to claim 4, characterized in that: It also includes building a transformer one-stage winding model with determined parameters and a three-stage model for simulation comparison to determine the equivalent correctness of the one-stage model, as follows: According to the inlet length, width and angle of the one-stage winding model of the transformer winding area determined in step 3, a two-dimensional CFD model is established in the Ansys Icem software. Then the one-stage winding model is imported into Ansys Fluent for simulation, and the velocity cloud map and the oil channel flow ratio data at the inlet are exported. The velocity cloud map of the one-stage winding model in the transformer winding area is compared with the velocity cloud map of the corresponding three-stage winding model in the transformer winding area to observe whether the oil flow streamlines at the inlet are consistent. Then, the oil channel flow ratio data at the inlet are compared to verify the equivalent substitutability of the one-stage winding model in the transformer winding area.

6. A transformer single-stage winding model with a micro-guide structure added, characterized in that: According to the method for determining parameters of a transformer one-stage winding model with a micro-guide structure added according to claim 4, the transformer one-stage winding model constructed by the inlet length, width and angle is specifically manufactured as follows: According to the calculated length, width and angle of the entrance, a one-stage transformer winding model drawing with a micro-guide structure is made in CAD and the file is exported. The exported file is input into the milling machine, and the winding cake groove and oil channel are milled downward from the entire transparent acrylic plate. The micro-guide structure and winding cake are cut out, and the inner and outer winding walls and the micro-guide structure are polished. The winding cake is embedded in the winding cake groove, and the transparent acrylic sheet is encapsulated on the upper part of the model to verify the airtightness.

7. An oil flow observation experimental platform based on the method for determining parameters of a transformer single-stage winding model with a micro-guide structure added as claimed in any one of claims 1 to 4, characterized in that: The invention comprises a transformer single-stage winding model (1), a flow meter (2), an oil pump (3), a valve (4), an oil tank (5), a heat sink (6), a micro-guide structure (7), an oil circulation external pipeline (8) and a particle image velocimetry system PIV (9); the transformer single-stage winding model (1) provided with the micro-guide structure (7) is connected to the oil pump (3) and the heat sink (6) in sequence through the oil circulation external pipeline (8); the valve (4) is arranged on the heat sink (6) inlet pipeline; and the flow meter (2) is arranged on the oil pump (3) inlet pipeline; The particle image velocimetry system PIV is composed of a synchronizer (901), a computer (902), a laser source (903), a laser sheet (904), and a CCD camera (905); A laser sheet (904) is aligned with the transformer single-stage winding model (1) and placed horizontally, ensuring that the measurement plane illuminated by the light source is two-dimensional, and the position is adjusted so that the light source after the laser source (903) illuminates the laser sheet (904) is directly facing the micro-guide structure (7) of the transformer single-stage winding model (1), and a CCD camera (905) is placed perpendicular to the measurement plane, the CCD camera (905) and the laser source (903) are turned on, and the frame rate and exposure time are set, and the original flow field image obtained by shooting is recorded and saved; Post-processing of the images is performed to obtain the velocity of the oil flow in each oil channel, and the vector diagram and cloud diagram of the oil flow velocity are derived.

Images