Measuring Device and Measuring Method for Axial Gas Force of Casing

Abstract

The present invention provides a measuring device and a measuring method for the axial gas force of a casing to obtain accurate experimental data. The measuring device for the axial gas force of the casing is used to measure the axial gas force borne by an adjacent pair of casing mounting edges, and includes a measuring frame, a measuring rod, and a measuring circuit. Among them, the measuring frame includes a first end, a second end, and a bridging portion. The first end has a connecting portion for connecting with the pair of casing mounting edges. The bridging portion is arranged to span the pair of casing mounting edges to connect the first end and the second end. The measuring rod has a head for pressing against the casing mounting edge to generate strain and a bottom portion provided at the second end. The measuring circuit includes a strain sensor provided on the measuring rod.

Description

Technical Field

[0001] The invention relates to a device and a method for measuring the axial force of casing gas of an aero-engine or a gas turbine. Background Art

[0002] To ensure the stable and reliable operation of aircraft engines, it is necessary to measure and monitor the gas axial force on the mounting edges of each casing, and obtain accurate experimental data to improve design capabilities and avoid structural failure near the mounting edges. At present, the measurement of gas axial force in China is mainly converted into strain measurement at a special position through a certain structural form. For example, the measurement of axial force at the bearing position of an aircraft engine is generally completed by designing a specific force ring auxiliary device. The patent specification with the publication number "CN111238711A" mentions this type of measurement method. However, there is no mature and reliable method for the axial force of the mounting edge of the aircraft engine casing in China. This is mainly due to the small measurement area, large vibration strain, high axial stiffness of the casing and high operating temperature, which makes measurement difficult and has large errors. Summary of the Invention

[0003] The purpose of the present invention is to provide a device for measuring the axial force of casing gas to obtain accurate experimental data.

[0004] Another object of the present invention is to provide a measurement method, which adopts the above-mentioned measurement device.

[0005] To achieve the aforementioned purpose, a device for measuring the axial gas force of a casing is provided, which is used to measure the axial gas force exerted on a pair of adjacent casing mounting edges. The device comprises a measuring frame, a measuring rod, and a measuring circuit. The measuring frame comprises a first end, a second end, and a bridge portion. The first end comprises a connecting portion for connecting to the pair of casing mounting edges, and the bridge portion is configured to span the pair of casing mounting edges and connect the first and second ends. The measuring rod comprises a head portion for bearing against the casing mounting edges to generate strain, and a base portion disposed at the second end. The measuring circuit comprises a strain sensor disposed on the measuring rod.

[0006] In one embodiment, the bottom portion of the measuring rod is detachably arranged at the second end.

[0007] In one embodiment, a measuring rod mounting hole is provided at the second end, and the circumferential position of the bottom of the measuring rod in the measuring rod mounting hole is adjustable.

[0008] In one embodiment, a measuring rod mounting hole is provided at the second end, and the bottom of the measuring rod is provided in the measuring rod mounting hole. The measuring device also includes a distance adjusting bolt, which is threadedly connected to the second end, extends into the measuring rod mounting hole, and presses against the bottom of the measuring rod.

[0009] In one embodiment, at least two of the measuring rods are disposed on the measuring frame.

[0010] In one embodiment, the measuring device further includes a bolt. The connecting portion provides a bolt connection hole, and the bolt is used to pass through the bolt connection hole and the connection holes of the pair of casing mounting edges to fix the measuring device on the pair of casing mounting edges.

[0011] In one embodiment, the head of the measuring rod is flat-shaped, and the bottom is cylindrical. The bottom and the measuring frame are arranged as rigid bodies relative to the head.

[0012] In one embodiment, the bottom has sufficient roughness to prevent relative sliding between the measuring rod and the measuring rod mounting hole during the measurement process of the measuring device.

[0013] In one embodiment, the measuring frame and the measuring rod are made of the same material as the casing.

[0014] For the method of measuring the axial gas force of the casing to achieve the above object, any one of the above measuring devices is used, and it includes:

[0015] Fix the measuring device on one side of the pair of casing mounting edges, so that the head of the measuring rod abuts against the lower edge of the other side on the other side of the pair of casing mounting edges;

[0016] Adjust the contact between the measuring rod and the lower edge, so that when the casing bears the axial gas force, the strain generated by the lower edge compresses the head of the measuring rod;

[0017] By obtaining the temperature and strain of the head of the measuring rod, the compression amount of the measuring rod at this time is obtained, and the axial gas force borne by the pair of mounting edges is calculated inversely.

[0018] In one embodiment, the arithmetic mean of the strains measured by the two measuring rods is used to calculate the axial gas force inversely.

[0019] The measuring device is set for an appropriate measuring position, and the deformation of the lower edge of the mounting edge caused by the axial force is transmitted to the head of the measuring rod in the form of pressure, so that accurate experimental data can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other features, properties, and advantages of the present invention will become more apparent from the following description in conjunction with the drawings and embodiments, wherein:

[0021] Figure 1 is a perspective view of the measuring frame device.

[0022] Figure 2 is a cross-sectional view of the measuring frame.

[0023] Figure 3 It is a perspective view of the measuring rod.

[0024] Figure 4 It is a side view of the measuring device mounted on a pair of casing mounting edges.

[0025] Figure 5 It is a cross-sectional view of the measuring device mounted on a pair of casing mounting edges.

[0026] Figure 6 It is a front view of the measuring rod provided with strain sensors.

[0027] Figure 7 It is a top view of the measuring rod provided with strain sensors.

[0028] Figure 8 It is an operation flow chart for measuring the axial force of gas by the measuring device. Detailed implementation manners

[0029] The present invention will be further described below in conjunction with specific embodiments and the accompanying drawings. More details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from this description. Those skilled in the art can make similar generalizations and deductions according to the actual application situation without departing from the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0030] It should be noted that these and subsequent other drawings are only examples, and they are not drawn under the condition of equal proportions, and should not be used to limit the actual claimed protection scope of the present invention.

[0031] As Figure 1 shown, the measuring device for the axial force of gas in the casing includes a measuring frame 1 and a measuring rod 3. The measuring frame 1 includes a first end 11, a second end 12 and a bridging portion 13, and the first end 11 has a connecting portion 110. As Figure 4 and Figure 5 shown, the bridging portion 13 is arranged to span a pair of casing mounting edges 91, 92 to connect the first end 11 and the second end 12. The casing 9 has a casing mounting edge 91, and the casing 10 has a casing mounting edge 92, and is used to support or contain a fluid machine inside the casing 9 or 10. As Figure 1 and Figure 2As shown, the connecting portion 110 is a bolt connection hole. The specific structure of the connecting portion 110 is related to the specific structure of the casing mounting edges 91 and 92. The advantage of setting the connecting portion 110 as a bolt connection hole is that the bolt 4 passes through the connecting portion 110 and the casing mounting edges 91 and 92, and is then tightened by the nut 41. When the casing mounting edges 91 and 92 are connected by bolts, the measuring device can directly use the bolts used to connect the casing mounting edges to each other. Even if the original bolt length is insufficient, an extension bolt can be used. There are many aircraft engine casing mounting edges and they vary in shape. Setting the connecting portion 110 as a bolt connection hole makes the measuring device more versatile and simple to install and disassemble. In addition, the structure of the engine is complex, and the aforementioned structure also allows the measuring device to avoid modifying the original structure of the engine. Generally, the positions available for measurement are mainly the casing mounting edge and the outer surface of the casing. The flange edge of the receiver mounting area is short and the bolts are densely distributed. Due to the high axial stiffness of the bolts, the area available for measurement is very limited to the lower edge of the flange edge. Furthermore, the axial stiffness of the receiver is high and unevenly distributed in the circumferential direction. Therefore, the strain on the receiver's outer surface caused by axial force is small and irregular, and the ideal measurement area on the outer surface of the receiver is also quite limited. Therefore, the measurement device is fixed to the mounting edge of the receiver, and a suitable measurement position is selected to facilitate accurate measurement data and simplify calibration.

[0032] like Figure 3 As shown, the measuring rod 3 includes a head 31 and a bottom 32. Accordingly, the second end 12 of the measuring frame 1 provides a measuring rod mounting hole 120, such as Figure 5 As shown, the bottom portion 32 is fixed in the measuring rod mounting hole 120 .

[0033] exist Figure 4 In the embodiment shown, the measuring device further comprises a distance adjusting bolt 2, the distance adjusting bolt 2 and the threaded hole 121 (such as Figure 2 The measuring device (as shown) is connected to the measuring rod mounting hole 120 and abuts the bottom 32 of the measuring rod 3, thereby pushing the measuring rod 3 to the lower edge of the casing mounting edge 92. The head 31 of the measuring rod 3 presses against this lower edge. In this way, the measuring device transmits the deformation of the lower edge of the mounting edge caused by the axial force of the gas to the head 31 of the measuring rod 3 in the form of pressure, which generates strain in the head 31. By measuring the strain on the head 31, the axial force of the gas on the mounting edges 91 and 92 can be indirectly measured.

[0034] like Figure 6 and Figure 7As shown, the measuring device further includes a measuring circuit, which includes strain sensors 51, 52, 53, 54. The strain sensors 51 and 54 are arranged on both sides of the head 31 of the measuring rod 3, and the strain sensors 53 and 54 are arranged on both sides of the bottom 32 of the measuring rod 3. The four strain sensors form a full-bridge circuit. The measuring circuit can also be replaced with other circuit structure forms. The advantage of using a full-bridge circuit is that the full-bridge form has the function of temperature self-compensation.

[0035] As shown in Figure 5 As shown, the head 31 of the measuring rod 3 is flat, while the bottom 32 is cylindrical. The thickness of the bottom 32 is much greater than that of the head 31. Similarly, the thickness of the measuring frame 1 is also much greater than that of the head 31. In this way, the bottom 32 and the measuring frame 1 are set as rigid bodies relative to the head 31. The advantage of this setting is that since the stiffness of the measuring frame 1 and the bottom 32 of the measuring rod 3 is large enough and rigidly fixed to the left mounting edge 91, it can be considered that the strain of the head 32 of the measuring rod 3 is basically equal to the strain of the lower edge of the right mounting edge 92. Thus, the accurate measurement of the gas axial force can be achieved through a simple structure.

[0036] In some embodiments, the adjusting bolt 2 can be omitted. The contact pre-tightening force between the head 31 of the measuring rod 3 and the lower edge of the mounting edge 92 can be applied by other means. For example, the fastening between the connecting portion 11 of the measuring frame 1 and the mounting edge 91 does not only rely on the nut 41. A wedge block is inserted between the connecting portion 11 and the mounting edge 91. By adjusting the degree of intervention of the wedge block, the fastening force of the connecting portion 11 of the measuring frame 1 on the mounting edge 91 is achieved. When the wedge block pushes the connecting portion 11 to the left to move the measuring frame 1, the head 31 of the measuring rod 3 contacts the lower edge of the mounting edge 92. Through pre-design, the contact pre-tightening force between the head 31 of the measuring rod 3 and the lower edge of the mounting edge 92 can reach synchronously with the fastening force of the connecting portion 11 of the measuring frame 1 on the mounting edge 91. However, by using the adjusting bolt 2 to adjust the distance of the measuring rod 3 and the contact pre-tightening force, the structure and operation are simpler.

[0037] In the embodiment shown in the figure, the bottom 32 of the measuring rod 3 is arranged to be detachable in the measuring rod mounting hole 120 of the second end 12. Since the measuring rod 3 is detachable, the measuring rod 3 can be formed separately, which is convenient for processing and also convenient for the installation of the measuring device.

[0038] Optionally, the circumferential position of the bottom 32 of the measuring rod 3 in the measuring rod mounting hole 120 is arranged to be adjustable. Since the circumferential position is adjustable, the contact direction between the measuring rod and the mounting edge is adjustable, which can adapt to each mounting edge of the engine. For some very complex mounting edges, a targeted measuring rod can also be customized to complete the measurement. Therefore, the applicability of the measuring device is relatively high. In addition, in the embodiment using the adjusting bolt 2, the extending length of the measuring rod 3 is also adjustable, which can better enhance the applicability.

[0039] Aero-engine casings generally operate at relatively high temperatures. On the one hand, the strain caused by temperature is large, far exceeding the strain caused by axial force (taking the connecting mounting edge between the combustion chamber casing and the high-pressure turbine as an example, the highest temperature in the area exceeds 600 °C, causing 8,000 - 9,800 microstrains). On the other hand, the measurement error of the sensor will also be amplified at high temperatures (at 600 °C, the thermal output error of the high-temperature strain gauge is 20 - 100 microstrains, and the measurement error of the temperature sensor thermocouple is 0.25% - 1%). In a preferred embodiment, the measuring frame 1 and the measuring rod 3 of the measuring device are made of the same material as the casing, which can ensure that when the temperature of the casing changes, the entire device expands uniformly with the casing, basically eliminating the influence caused by temperature.

[0040] During the operation of an aero-engine casing, it will be subjected to various excitation loads (such as rotor imbalance, incomplete combustion), and these excitation loads will cause considerable dynamic strain, affecting the measurement of axial force. The triggering causes of dynamic strain are complex and lack strong regularity. As Figure 1 and Figure 4 shown, the measuring frame 1 of the measuring device is fixed by two bolts 4, which can make the measuring frame 1 have better stability. The measuring device also has two measuring rods 3 arranged on the measuring frame 1, and the two measuring rods measure the strain at different circumferential positions simultaneously, effectively reducing the influence of vibration.

[0041] Combined with Figure 8 , the method for measuring the axial gas force of the casing uses the aforementioned measuring device, including the following steps:

[0042] (1) Estimate the approximate strain range. The estimation method can be achieved through computer simulation calculation. Then, according to the measurable area of the casing mounting edge, the size of the strain sensor, and the buckling theory, determine the cross-sectional width, height, and length of the head 31 of the measuring rod 3, and then determine the diameter of the bottom 32 of the measuring rod 3 and the size of the adjusting bolt 2. In this step, by estimating the approximate strain range and calculating with the buckling theory, buckling of the measuring device is avoided during the design stage.

[0043] (2) According to the size of the measuring rod 3, the thickness of the casing mounting edges 91, 92, and the size of the bolt 4, determine the opening diameter, depth, and main body size of the measuring frame 1. It is recommended that when designing the measuring frame 1 and the bottom of the measuring rod 3, sufficient stiffness should be ensured so that the head 31 of the measuring rod 3 can directly and accurately reflect the strain of the lower edge of the casing mounting edge 92.

[0044] (3) As Figure 4 and Figure 5As shown, install the measuring frame 1 on the left casing mounting edge 91 through bolts 4, and tighten it to the designed torque to ensure that the connection between the measuring frame 1 and the casing has sufficient stiffness. For some models of the invention engine, since the connecting part 11 of the measuring frame 1 has a certain thickness, if the original bolt length is not enough, it can be replaced with a lengthened bolt of the same specification.

[0045] (4) As Figure 4 and Figure 5 shown, insert the measuring rod 3 into the measuring rod mounting hole 120 of the measuring frame 1, and rotate it to an appropriate angle according to the distribution of the mounting bolts on the right casing mounting edge 92 so that the pressure-receiving surface of the head 31 of the measuring rod 3 can fully fit with the lower edge of the outer surface of the right casing mounting edge 92. A head 31 is provided at the lower edge of the mounting edge 92 because the strain is the largest here and is easy to measure.

[0046] (5) Adjust the distance-adjusting bolt 2 so that the pressure-receiving surface of the head 31 of the measuring rod 3 fits with the outer surface of the right casing mounting edge 92, and apply a certain pre-tightening force to the distance-adjusting bolt 2 so that the fit between the head 31 and the mounting edge 92 also has a certain pre-tightening force, avoiding measurement errors caused by initial gaps and making the overall device stable. During the operation, the pre-tightening forces of the distance-adjusting bolts of the two measuring rods 3 are the same, and the initial strains of the heads of the two measuring rods are the same. An optional method is to provide a certain roughness on the outer surface of the bottom 32 of the measuring rod 3 to avoid relative sliding with the measuring frame 1 during the measurement process. This kind of sliding is usually caused by the impact, vibration and other factors that the measuring rod will be affected when the aero-engine is running.

[0047] (6) As Figure 6 、 Figure 7 shown, paste 4 strain gauges at the marked positions of each measuring rod 3 to form a full-bridge circuit to achieve the effect of temperature self-compensation.

[0048] (7) When the casing bears the axial gas force, the strain generated at the measuring position of the mounting edge causes the head of the measuring rod to be compressed. By measuring the temperature and strain of the measuring rod, the compression amount of the measuring rod at this time can be obtained, and theoretically the axial force can be calculated inversely.

[0049] In an embodiment, during actual calibration, the arithmetic mean of the strains measured by the two measuring rods can be used for calibration with the axial force. This method can improve the reliability of the measuring device to obtain more stable results, and also effectively weakens the influence of structural vibration and the like.

[0050] The aforementioned measuring device can be applied to the casing mounting edge with high working temperature and complex vibration environment. At the same time, the rotatable and adjustable measuring rod makes the device of the present invention have strong versatility and can be used for the measurement of the casing mounting edges at different positions of the engine. In addition, the device has the characteristics of simple structure, convenient loading and unloading, low calibration difficulty and high measurement accuracy.

[0051] Although the present invention is disclosed above in preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modifications, equivalent changes and decorations made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention all fall within the protection scope defined by the claims of the present invention.

Claims

1. A device for measuring the axial gas force of a casing, used to measure the axial gas force borne by a pair of adjacent casing mounting edges, characterized in that: include: The measuring frame includes a first end, a second end, and a bridge portion, wherein the first end has a connecting portion for connecting with the pair of casing mounting edges, and the bridge portion is configured to connect the first end and the second end across the pair of casing mounting edges; a measuring rod having a head for bearing against a mounting edge of the receiver to generate strain and a bottom disposed at the second end; as well as The measuring circuit includes a strain sensor arranged on the measuring rod.

2. The measuring device according to claim 1, wherein The bottom portion of the measuring rod is detachably arranged at the second end.

3. The measuring device according to claim 2, wherein The second end is provided with a measuring rod mounting hole, and the circumferential position of the bottom of the measuring rod in the measuring rod mounting hole is adjustable.

4. The measuring device according to claim 3, wherein The bottom is provided with sufficient roughness to prevent the measuring rod and the measuring rod mounting hole from sliding relative to each other during the measuring process of the measuring device.

5. The measuring device according to claim 1, wherein The second end is provided with a measuring rod mounting hole, and the bottom of the measuring rod is provided in the measuring rod mounting hole. The measuring device also includes a distance adjusting bolt, which is threadedly connected to the second end, extends into the measuring rod mounting hole, and presses against the bottom of the measuring rod.

6. The measuring device according to claim 1, wherein At least two measuring rods are arranged on the measuring frame.

7. The measuring device according to claim 1, wherein The measuring device also includes a bolt, the connecting portion provides a bolt connecting hole, and the bolt is used to pass through the bolt connecting hole and the connecting holes of the pair of casing mounting edges to fix the measuring device on the pair of casing mounting edges.

8. The measuring device according to claim 1, wherein The head of the measuring rod is flat, the bottom is cylindrical, and the bottom and the measuring frame are arranged to form a rigid body relative to the head.

9. The measuring device according to any one of claims 1 to 8, characterized in that The measuring frame and the measuring rod are made of the same material as the casing.

10. A method for measuring the axial force of casing gas, using the measuring device according to any one of claims 1 to 9, characterized in that: include: Fixing the measuring device on one side of the pair of casing mounting edges so that the head of the measuring rod abuts against the lower edge of the other side of the pair of casing mounting edges; Adjusting the contact between the measuring rod and the lower edge so that when the casing is subjected to the axial force of the gas, the strain generated by the lower edge causes the head of the measuring rod to be compressed; By acquiring the temperature and strain of the head of the measuring rod, the compression amount of the measuring rod at this time is obtained, and the gas axial force borne by the pair of casing mounting edges is inversely calculated.

11. The measuring method according to claim 10, wherein: The arithmetic mean of the strains measured by the two measuring rods is used to inversely calculate the gas axial force.

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