A Static Pressure Measurement Method for Turbine Stator Blades Based on 3D Printing Technology

Abstract

The present invention discloses a static pressure measurement method for a turbine stator blade based on 3D printing technology. The method includes constructing a three-dimensional model of a static pressure test channel and a static pressure lead-out channel; 3D forming the static pressure test channel and the static pressure lead-out channel according to the three-dimensional model; welding a capillary tube at the static pressure lead-out channel; and connecting a pressure measurement module to the other end of the capillary tube. The technical solution of the present invention utilizes the characteristics of simple surface forming in 3D printing to form static pressure test holes on the surface of the blade body and static pressure lead-out holes inside the blade body through 3D printing. Since 3D printing technology directly prepares and forms based on a three-dimensional model, the position and angle errors of the test points are only related to the model and no other processing errors will be introduced. Therefore, the test accuracy of the technical solution of the present invention is higher and the applicable range is wider. At the same time, the curved surface formed by 3D printing can make full use of the space of the blade body, and more static pressure measurement points on the blade body can be measured.

Description

Technical Field

[0001] The present invention relates to the technical field of blade static pressure measurement, and in particular to a method for measuring the static pressure of a turbine stator blade based on 3D printing technology. Background Art

[0002] At present, many blowing performance tests of turbine stator blades have been carried out in the industry. Through these tests, the characteristics of the change of aerodynamic performance parameters such as the loss coefficient, exit Mach number, and flow function of the stator blade with the mainstream Mach number are obtained. At the same time, we also hope to obtain the static pressure distribution on the blade body of the stator blade, as Figure 1 shown. Through these data, it can be judged whether there is an air flow separation phenomenon on the surface of the blade body, providing a reference basis for the optimal design of the stator blade profile. In the existing static pressure test scheme of the blade body, the stator blade is obtained by machining (casting or numerical milling), and the static pressure measuring points on the blade body surface are arranged by drilling holes in the blade body through electrical discharge machining, and then led out from the blade tip through electrical discharge machining.

[0003] The existing technology uses electrical discharge machining for the static pressure holes on the blade body surface and leading out the static pressure holes, which requires high position accuracy and angle accuracy for the electrical discharge machining. The positions of all static pressure measurement points are calculated through prior simulation, and the direction of the static pressure test hole passage on the blade body surface must be along the normal direction of the surface of the test point to accurately measure the static pressure of the blade body at this point. For the existing electrical discharge machining method for workpieces with complex curved surface shapes, the position accuracy and angle accuracy of the alignment points are not high, and it is easy to introduce position deviation and angle deviation of the test points, affecting the test accuracy. Moreover, for some more complex workpieces, such as inter-stage guides, transition sections and other parts, due to the possible interference between the electrical discharge machining equipment and adjacent blades or flange edges, it is difficult to position and machine the electrical discharge machining. Summary of the Invention

[0004] Aiming at the above problems, for workpieces with complex curved surface shapes, a method capable of directly and accurately positioning the position accuracy and angle accuracy of the alignment points is needed. The present invention utilizes the characteristics of simple 3D printing surface forming, directly constructs and forms based on the three-dimensional model. Since the position and angle errors of the test points are only related to the model and no other machining errors are introduced, the test accuracy of the technical solution of the present invention is higher, and there is no interference problem in machining in the technical solution of the present invention, which can be applied to a wider range. To achieve the above object, the present invention provides the following technical solutions:

[0005] A method for measuring the static pressure of a turbine stator blade based on 3D printing technology, the method comprising: constructing a three-dimensional model of a static pressure test channel and a static pressure lead-out channel; 3D forming the static pressure test channel and the static pressure lead-out channel according to the three-dimensional model; welding a capillary at the static pressure lead-out channel; connecting a pressure measurement module to the other end of the capillary.

[0006] Preferably, the construction of the three-dimensional model of the static pressure test channels and the static pressure lead-out channels includes: determining the number of blade body test points, establishing the positions of the blade body test points, the directions of the test channels, and the sizes of the test channels.

[0007] Preferably, the test channels include a first channel, and the static pressure lead-out channels include a second channel and a third channel. Among them, the second channel is connected to the end of the first channel, and the other end of the second channel extends near the casing wall surface; the third channel is connected to the end of the second channel, and the other end of the third channel extends to the casing wall surface.

[0008] Preferably, the first channel is used to provide the static pressure measurement information of the blade body test points on the blade body; the second channel is used to lead out the static pressure measurement information of the blade body to near the casing wall surface; the third channel is used to externally connect an inserted capillary tube for transmitting the static pressure measurement information of the blade body to the pressure measurement module.

[0009] Preferably, the first channel is constructed along the normal direction of the blade profile surface through the static pressure test points on the blade body; the direction of the second channel is perpendicular to the first channel; the direction of the third channel is the same as the direction of the second channel.

[0010] Preferably, the depth of the first channel is greater than twice the channel diameter.

[0011] Preferably, the second channel is a curved channel; the first channel and the third channel are straight channels.

[0012] Preferably, the diameter of the second channel is greater than the diameter of the first channel; the diameter of the third channel is greater than the diameter of the second channel.

[0013] Preferably, the other end of the second channel extends near the casing wall surface, where the casing wall surface includes the inner casing wall surface and the outer casing wall surface.

[0014] Preferably, a capillary tube is welded at the static pressure lead-out channel inside the blade body, the capillary tube is inserted into the third channel, and is welded at the casing wall surface.

[0015] Preferably, the capillary tube is made of stainless steel.

[0016] Preferably, the diameter of the capillary tube is smaller than the third channel.

[0017] Preferably, the pressure measurement module is connected to the capillary tube through a threaded static pressure nozzle.

[0018] Preferably, the threaded static pressure nozzle is a general-purpose pressure measurement interface; the threaded static pressure nozzle and the capillary tube are connected by welding.

[0019] Preferably, the static pressure measurement information is led out to the vicinity of the outer wall surface of the casing, which is applicable to the static pressure measurement in the middle and top of the blade body; the static pressure measurement information is led out to the vicinity of the inner wall surface of the casing, which is applicable to the static pressure measurement at the root of the blade body near the inner wall surface of the casing.

[0020] The technical effects and advantages of the present invention:

[0021] 1. Based on the characteristics of simple forming of complex curved surfaces by 3D printing, the internal measurement channels of the blade are formed by using 3D printing technology. At the same time, the position and angle errors of the test points are only related to the model and will not introduce other machining errors. Therefore, the test accuracy of the technical solution of the present invention is better than that of the prior art;

[0022] 2. The static pressure measurement information is led out by welding a capillary at the casing wall surface through the head-to-tail connection of the first channel, the second channel and the third channel;

[0023] 3. The design that the aperture of the test channel gradually increases along the measurement stroke;

[0024] 4. To ensure the measurement accuracy, the direction of the first channel is constructed along the normal direction of the blade surface from the static pressure test point of the blade body, and the depth of the channel is not less than 2 times the diameter of the channel;

[0025] 5. The curved surface shape formed by 3D printing can make full use of the space of the blade body and can realize the measurement of more static pressure measurement points on the blade body;

[0026] Through actual application, the present invention has realized the static pressure measurement of a total of 96 static pressure measurement points on three blade body sections of a certain stage guide vane, and the use effect has reached the expectation. At the same time, there is no interference problem in mechanical processing in the present invention, and the applicable range is wider.

[0027] In summary, the technical solution of the present invention utilizes the characteristics of simple forming of the 3D printed curved surface, forms the static pressure test channels on the blade surface and the static pressure leading channels inside the blade body through 3D printing, leads out the static pressure measurement information on the blade surface to the outer wall surface or the inner wall surface of the part casing, and then welds a capillary to lead it out to the pressure measurement module.

[0028] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained by the structures pointed out in the specification and the drawings. Brief Description of the Drawings

[0029] Figure 1 It is a schematic diagram for test structure;

[0030] Figure 2 It is a schematic diagram of the static pressure test holes and the leading holes;

[0031] Figure 3 is a schematic diagram of the pore structure;

[0032] Figure 4 is a schematic diagram of the capillary welded to the casing wall;

[0033] In the figure: 1. The capillary tube led out from the static pressure measurement point in the middle of the blade body; 2. The capillary tube led out from the static pressure measurement point at the top of the blade body; 3. The capillary tube led out from the static pressure measurement point at the root of the blade body; 4. The outer wall of the casing; 5. The inner wall of the casing; 6. The static pressure measurement point; 7. The first pore; 8. The second pore; 9. The third pore. Specific implementation mode

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] To solve the deficiencies of the prior art, the present invention discloses a method for measuring the static pressure of a turbine stator blade based on 3D printing technology. The method includes constructing a three-dimensional model of the static pressure test pore and the static pressure lead-out pore; according to the three-dimensional model, 3D forming the static pressure test pore and the static pressure lead-out pore; welding a capillary at the static pressure lead-out pore; connecting a pressure measurement module to the other end of the capillary, forming a test structure schematic diagram as shown in Figure 1 shown, where

[0036] The construction of the three-dimensional model of the static pressure test pore and the static pressure lead-out pore shall be set according to the experimental requirements, including determining the number of test points on the blade body surface, establishing the positions of the test points on the blade body surface, the direction of the test pore, and the size of the test pore, etc. As shown in the schematic diagram of the static pressure test pore and the lead-out pore in Figure 2 the static pressure test pore is a straight pore extending along the normal direction of the surface at the static pressure measurement point on the blade body surface, and one end of the static pressure lead-out pore is connected to the static pressure test pore, and the other end extends to the outer wall surface or the inner wall surface of the casing of the part.

[0037] The test pore includes a first pore, and the static pressure lead-out pore includes a second pore and a third pore. As shown in Figure 3As shown, the first channel is used to provide static pressure measurement information at the selected pressure measurement point position. The second channel is used to lead out the blade static pressure measurement information to the casing wall hole channel. The third channel is used to externally connect a capillary tube to transmit the blade static pressure measurement information. Both the first channel and the third channel are straight channels. To avoid interference between the test channels of different measurement points, the second channel is designed as a complex curved channel. To prevent pressure throttling loss in the measurement channel, the diameter of the third channel is larger than that of the second channel, and the diameter of the second channel is larger than that of the first channel.

[0038] The first channel is constructed along the normal direction of the blade profile surface through the blade static pressure test point. To ensure the pressure measurement effect, the depth of the first channel is required to be not less than 2 times the channel diameter.

[0039] The second channel is used to lead out the blade static pressure measurement information to the casing wall hole channel. The second channel is connected to the end of the first channel, and the other end extends to the vicinity of the inner wall surface or the outer wall surface of the casing. The direction of the second channel is perpendicular to that of the first channel.

[0040] The third channel is used to externally connect and insert a capillary tube, and transmit the blade static pressure measurement information to the pressure test module through the capillary tube. The direction of the third channel is the same as that of the second channel. The third channel is connected to the extended end of the second channel, and the other end of the third channel extends to the casing wall surface.

[0041] The capillary tube is made of stainless steel. Figure 4 For the schematic diagram of welding the capillary tube on the casing wall, refer to Figure 4 It can be seen that the capillary tube is inserted into one end of the third channel extending to the outer wall surface or the inner wall surface of the casing and welded at the casing wall surface. The diameter of the capillary tube is smaller than that of the third channel. The other end of the capillary tube is connected to the static pressure nozzle with threads through welding. The other end of the static pressure nozzle is connected to the pressure measurement module through threads, so as to realize the measurement of pressure. The threaded static pressure nozzle is a commonly used pressure measurement interface.

[0042] In the prior art, electrical discharge machining is used to machine the static pressure holes and the static pressure lead-out holes on the blade body surface, and then the static pressure is led out from the blade tip through electrical discharge machining. High requirements are imposed on the position accuracy and angular accuracy of the electrical discharge machining. The positions of all static pressure measurement points are calculated through prior simulation, and the direction of the static pressure test channel on the blade body surface must be along the surface normal direction of the test point in order to accurately measure the static pressure of the blade body at this point. For the existing electrical discharge machining method, for workpieces with complex curved surface shapes, the position accuracy and angular accuracy of the alignment points are not high, and it is easy to introduce position deviation and angular deviation of the test points, affecting the test accuracy. Moreover, for some more complex workpieces, such as inter-stage guides, transition sections and other parts, due to the possible interference between the electrical discharge machining equipment and adjacent blades or flange edges, it is difficult to position and machine the electrical discharge machining.

[0043] Compared with the prior art, the technical solution of the present invention takes advantage of the simple characteristics of 3D printing curved surface forming, and forms the static pressure test channels on the blade body surface and the static pressure lead-out channels inside the blade body through 3D printing, and leads out the static pressure measurement information on the blade body surface to the outer wall surface or the inner wall surface of the part casing, and then welds the capillary to lead it to the pressure measurement module. Since the 3D printing technology directly constructs and forms based on the three-dimensional model, the position and angular errors of the test points are only related to the model and no other machining errors will be introduced. Therefore, the test accuracy of the technical solution of the present invention is higher. The technical solution of the present invention does not have the problem of mechanical machining interference and has a wider application range. At the same time, the curved surface shape formed by 3D printing can make full use of the blade body space and can realize the measurement of more static pressure measurement points on the blade body.

[0044] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0045] Embodiment 1

[0046] This embodiment is applicable to the static pressure measurement of the middle part and the top part of the blade body. By using modeling software to construct a three-dimensional model, the number of test points on the blade body surface is determined according to the experimental requirements, and the test points on the blade body surface, the direction of the test channels and the size of the test channels are established. The specific steps are as follows:

[0047] Determine the number of test points on the blade body surface.

[0048] Furthermore, select the test points and construct the first channel: The first channel extends along the surface normal direction of the blade profile from the static pressure test point on the blade body. The direction of the channel is constructed along the surface normal direction in the modeling software, which can ensure the function of the channel. To ensure the pressure measurement effect, the depth of the first channel is required to be not less than 2 times the channel diameter, and the diameter of the first channel is set to 0.5 mm.

[0049] Further, a second channel is constructed: the direction of the second channel is perpendicular to the first channel, the second channel is connected to the end of the first channel, and the other end of the second channel extends near the outer wall surface of the casing. The function of the second channel is to lead out the blade body static pressure measurement information to the channel on the outer wall surface of the casing. To avoid interference of the test channels at different measuring points, the second channel can be designed as a complex curved channel. At the same time, to prevent pressure throttling loss in the measurement channel, the aperture of the measurement channel should increase along the measurement stroke. Therefore, it is required that the diameter of the second channel is larger than that of the first channel. Thus, the diameter of the second channel is set to 0.8 mm.

[0050] Further, a third channel is constructed: the direction of the third channel is the same as that of the second channel, and the third channel is connected to the extended end of the second channel. The other end of the third channel extends to the outer wall surface of the casing. Similarly, to prevent pressure throttling loss in the measurement channel, the aperture of the measurement channel should increase along the measurement stroke. So, it is required that the diameter of the third channel is larger than that of the second channel. Therefore, the diameter of the third channel is set to 1.3 mm.

[0051] Further, after the three-dimensional graph construction is completed, the above-mentioned blade body surface static pressure test channels and the static pressure lead-out channels inside the blade body are formed by 3D printing technology.

[0052] Further, a capillary with an outer diameter of 1.2 mm is taken. The material of the capillary is stainless steel. The capillary is inserted into one end of the third channel that extends to the outer wall surface of the casing after forming and is welded at the casing wall surface. The other end of the capillary is connected to the pressure measurement module through a threaded static pressure nozzle, thereby realizing the measurement of pressure. Among them, the threaded static pressure nozzle is welded on the capillary, and the threaded static pressure nozzle is a commonly used pressure measurement interface.

[0053] This embodiment is applicable to measuring the static pressure at the middle part and the top of the blade body, and the lead-out method is from the outer wall surface of the casing.

[0054] Embodiment 2

[0055] This embodiment is applicable to measuring the static pressure of the static pressure measuring point at the root of the blade body near the inner wall surface of the casing. Determine the number of test points on the root of the blade body near the inner wall surface, establish the test points on the surface of the blade body near the inner wall surface of the casing, the direction of the test channels, the size of the test channels, etc. according to the experimental requirements. The specific steps are as follows:

[0056] Determine the number of test points on the root of the blade body on the inner wall surface.

[0057] Furthermore, select the test points and construct the first channel: The first channel extends along the normal direction of the blade profile surface from the static pressure test point on the blade body. The direction of the channel is constructed along the normal direction of the surface in the modeling software, which can ensure the hole function. To ensure the pressure measurement effect, the depth of the first channel is required to be not less than 2 times the channel diameter. Set the diameter of the first channel to 0.5 mm.

[0058] Furthermore, construct the second channel: The direction of the second channel is perpendicular to the first channel. The second channel is connected to the end of the first channel, and the other end of the second channel extends to the vicinity of the casing inner wall surface. The function of the second channel is to lead out the static pressure measurement information on the blade body to the hole on the casing inner wall surface. To avoid interference between the test channels at different measurement points, the second channel is designed as a complex curved channel. At the same time, to prevent pressure throttling loss in the measurement channel, the aperture of the measurement channel should increase along the measurement stroke. Therefore, it is required that the diameter of the second channel is larger than that of the first channel. Thus, set the diameter of the second channel to 0.8 mm.

[0059] Furthermore, construct the third channel: The direction of the third channel is the same as that of the second channel, and the third channel is connected to the extended end of the second channel. The other end of the third channel extends to the casing inner wall surface. Similarly, to prevent pressure throttling loss in the measurement channel, the aperture of the measurement channel should increase along the measurement stroke. So, it is required that the diameter of the third channel is larger than that of the second channel. Therefore, set the diameter of the third channel to 1.3 mm.

[0060] Furthermore, after completing the construction of the 3D graphics, the static pressure test holes on the blade body surface and the static pressure lead-out holes inside the blade body are formed by 3D printing technology.

[0061] Furthermore, take a capillary with an outer diameter of 1.2 mm. The capillary is made of stainless steel. Insert the capillary into the end of the third channel extending to the casing wall after forming and weld it at the casing wall surface. The other end of the capillary is connected to the pressure measurement module through a threaded static pressure nozzle, thereby realizing the measurement of pressure. Among them, the threaded static pressure nozzle is welded on the capillary, and the threaded static pressure nozzle is a commonly used pressure measurement interface.

[0062] This embodiment is applicable to measuring the static pressure at the root of the blade body on the casing inner wall surface, and its lead-out method is from the casing inner wall surface, so the required distance of the measurement channels is the shortest.

[0063] In summary, based on the characteristics of simple forming of complex curved surfaces by 3D printing, the present invention uses 3D printing technology to form the internal measurement channels of the blade; a static pressure measurement extraction method of welding a capillary tube at the casing wall surface through the head-to-tail connection of the first channel, the second channel and the third channel; a design principle that the aperture of the test channel gradually increases along the measurement stroke; to ensure the measurement accuracy, the direction of the first channel needs to be along the normal direction of the curved surface at this point, and the depth of the channel is not less than twice the diameter of the channel. There is no interference problem in machining for the present invention, so the position accuracy and angular accuracy of the alignment point can be accurately positioned and machined. Even the present invention can be applied to a wider range; at the same time, the curved surface modeling by 3D printing can make full use of the blade space and can realize the measurement of more static pressure measurement points on the blade.

[0064] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent substitution on some of the technical features. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A static pressure measurement method for a turbine stator blade based on 3D printing technology, characterized in that, The method includes: Constructing a three-dimensional model of a static pressure test channel and a static pressure extraction channel; wherein, the test channel includes a first channel, and the static pressure extraction channel includes a second channel and a third channel, wherein the second channel is connected to the end of the first channel, and the other end of the second channel extends to the casing wall surface; the third channel is connected to the end of the second channel, and the other end of the third channel extends to the casing wall surface; The first channel is for the blade static pressure measurement information of the blade test points; the second channel leads the blade static pressure measurement information to the casing wall surface; the third channel is externally connected to an inserted capillary tube to transfer the blade static pressure measurement information to the pressure measurement module; 3D forming the static pressure test channel and the static pressure extraction channel according to the three-dimensional model; Welding a capillary tube at the static pressure extraction channel; connecting the pressure measurement module to the other end of the capillary tube.

2. The method according to claim 1, wherein The constructing of the three-dimensional model of the static pressure test channel and the static pressure extraction channel includes: Determining the number of blade test points, establishing the positions of the blade test points, the direction of the test channel, and the size of the test channel.

3. The method according to claim 1, wherein The first channel is constructed along the normal direction of the blade profile surface through the blade static pressure test points; The direction of the second channel is perpendicular to the first channel; The direction of the third channel is the same as the direction of the second channel.

4. The method according to claim 1, wherein The depth of the first channel is greater than twice the channel diameter.

5. The method according to claim 1, wherein The second channel is a curved channel; the first channel and the third channel are straight channels.

6. The method according to claim 1, wherein The diameter of the second channel is greater than the diameter of the first channel; The diameter of the third channel is greater than the diameter of the second channel.

7. The method according to claim 1, wherein The other end of the second channel extends to the casing wall surface, wherein, The casing wall surface includes a casing inner wall surface and a casing outer wall surface.

8. The method according to any one of claims 1 to 3, characterized in that, A capillary tube is welded at the static pressure extraction channel inside the blade, the capillary tube is inserted into the third channel, and is welded at the casing wall surface.

9. The method according to claim 8, wherein The capillary tube is made of stainless steel.

10. The method according to claim 8, wherein The diameter of the capillary tube is smaller than the third channel.

11. The method according to claim 1, wherein The pressure measurement module is connected to the capillary tube through a threaded static pressure nozzle.

12. The method according to claim 11, characterized in that, The threaded static pressure nozzle includes a general pressure measurement interface; the threaded static pressure nozzle is connected to the capillary tube by welding.

13. According to the method described in claim 7, wherein, When the static pressure measurement information is led to the casing outer wall surface, the static pressure at the middle and top of the blade can be measured; When the static pressure measurement information is led to the casing inner wall surface, the static pressure at the blade root near the casing inner wall surface can be measured.

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