A blade blasting and cutting device for aero-engine containment test

Abstract

This application belongs to the technical field of aero-engine containment test, and particularly relates to a blade bursting and cutting device for aero-engine containment test. The device includes a back surface groove (1) formed on the back surface side of the blade along the chordwise direction of the blade; a front surface groove (2) formed on the front surface side of the blade along the chordwise direction of the blade, and the end of the front surface groove (2) penetrates through the blade along the thickness direction of the blade and forms two perforations (6) on the back surface side of the blade; two cutting cables (3) are respectively fixedly laid in the back surface groove (1) and the front surface groove (2), and the cutting direction of the cutting cable (3) points to the connection part (5) between the back surface groove (1) and the front surface groove (2) of the blade; a detonator (4) is arranged at one of the perforations on the back surface side, one end of which is connected to the detonation signal switch through a lead wire, and the other end is respectively connected to the two cutting cables. This application realizes the flying break of the blade at a specified rotational speed and ensures the effectiveness of the test results.

Description

Technical Field

[0001] This application belongs to the technical field of aero-engine containment tests, and particularly relates to a blade blasting and cutting device for aero-engine containment tests. Background Art

[0002] With the continuous development of aero-engines, the rotor speed is getting higher and higher, and the failure of blades is increasing day by day. If the broken blade cannot be contained by the casing, it may penetrate the cabin and cause harm to passengers. If it hits the oil pipeline or fuel tank, it will also cause a fire, resulting in a serious accident of plane crash and death. To ensure flight safety, it is particularly important to ensure that the failed blade can be effectively contained by the casing. Therefore, the military and civilian gas turbine engine specifications worldwide all have relevant requirements for containment without exception, and the content is basically the same. Generally speaking, a single blade should be contained by the casing after breaking at a cross-section outside the tenon, or for an integral bladed disk, at least a single blade should be contained by the casing after breaking at 80% of the blade height. The resulting engine damage should not cause any dangerous engine effects. Generally speaking, airworthiness specifications require conducting casing containment verification work on the entire engine, but directly conducting a full-scale test is very risky and extremely costly. Therefore, before the full-scale containment test, a component-level casing containment test is usually carried out on a rotor test rig to preliminarily verify the containment ability of the casing.

[0003] In the containment test, the blade break-off speed directly affects the test conclusion. Therefore, it is very necessary to accurately control the blade break-off speed. Currently, there are mainly three commonly used methods for controlling the break-off speed: the prefabricated notch method, the local rapid heating method, and the blasting and cutting method. The prefabricated notch method uses wire cutting technology to prefabricate a notch at the break-off cross-section, reducing the blade load-bearing area so that it is broken under the action of centrifugal load; the local rapid heating combined method drills a hole at the root of the blade tenon to install an electric heating rod, and powers the electric heating rod through a slip ring to rapidly increase the local temperature at the tenon. The tensile strength of the blade decreases as the temperature rises until the centrifugal load breaks the blade; the blasting and cutting method drills a cylindrical hole at the root of the blade tenon, and installs a detonator and explosive (or cutting cord) in the hole. During the test, when the rotor reaches the predetermined speed, the blade is cut by detonating the explosive through the detonator.

[0004] Technically, the existing prefabricated incision method is affected by material dispersion, processing errors, and incision sensitivity, resulting in low precision in controlling the flying-off speed. For blades without a root extension section, only the method of cutting on the blade profile can be adopted. The complex geometric dimensions of the blade profile make it even more difficult to control the remaining area, and it is impossible to ensure that the blade flies off within the predetermined speed range. The method of local rapid heating is only suitable for blade materials whose tensile strength decreases with increasing temperature, so its scope of application is relatively limited. The existing explosive cutting method requires the blade structure to have an obvious root extension section for drilling and burying explosives. For blades without a root extension section, as well as the currently more advanced rotors using integral bladed disks, the blades and disks are integrated, without tenons and mortises. Since the blades do not have a root extension section with regular shape, the existing technology of drilling and burying explosives for blasting cannot be used.

[0005] In terms of cost, the poor precision in controlling the flying-off speed of the existing prefabricated incision method will lead to repeated loading and unloading of test pieces or premature flying-off of the blades. If the blades fly off prematurely, the containment capacity of the casing cannot be effectively verified, resulting in test failure and huge economic costs. In terms of efficiency, the incision size of the existing incision technology is relatively conservative, often requiring repeated disassembly and assembly, and the test efficiency is very poor. Summary of the Invention

[0006] To solve the above problems, the present application provides a blade explosive cutting device for aero-engine containment tests, which is applied to the cutting of blades without a root extension section, enabling the blades to fly off at a specified speed. The blade explosive cutting device mainly includes:

[0007] The back blade groove is opened on the back side of the blade along the chord direction of the blade;

[0008] The front blade groove is opened on the front side of the blade along the chord direction of the blade. The front blade groove includes two ends along the extending direction of the groove. Each end penetrates through the blade along the thickness direction of the blade and forms two perforations on the back side of the blade. The back blade groove opened on the back side is located between the two perforations;

[0009] The cutting cords include two. The two cutting cords are respectively fixedly laid in the back blade groove and the front blade groove. The cutting direction of the cutting cord points to the connection part between the back blade groove and the front blade groove of the blade;

[0010] The detonator is arranged at one of the perforations on the back side. One end of the detonator is connected to the detonation signal switch through a lead wire, and the other end is respectively connected to the two cutting cords.

[0011] Preferably, the cutting cords are fixed in the back blade groove and the front blade groove by resin glue.

[0012] Preferably, the outside of the cutting cord is coated with a fiber cloth.

[0013] Preferably, the cutting cable includes a metal outer shell and an explosive covered by the metal outer shell. The explosive is cyclonite, and the metal outer shell is made of lead-antimony alloy.

[0014] Preferably, the perforation is a round hole.

[0015] Preferably, the cross-sections of the back leaf grooves and the front leaf grooves are arc-shaped structures.

[0016] This application is a method for machining arc-shaped grooves on the surface of the flying break cross-section at the root of the blade and drilling holes on the blade profile. A flexible cutting cable is placed in the grooves to cut the reserved part of the blade. After blasting, the reserved part in the middle of the blade is cut off by the cutting cable, and only the leading edge and trailing edge of the blade are connected. It can no longer bear the centrifugal load of the blade. Under the action of the centrifugal load, the blade is broken, realizing the flying break of the blade at a specified speed. Description of the Drawings

[0017] Figure 1 is a schematic diagram of the back leaf slotting of the blade in a preferred embodiment of the blade blasting cutting device for aero-engine containment test in this application.

[0018] Figure 2 is this application Figure 1 schematic diagram of the front leaf slotting of the blade in the shown embodiment.

[0019] Figure 3 is this application Figure 1 schematic diagram of the blade cutting in the shown embodiment.

[0020] Figure 4 is this application Figure 2 schematic diagram of the A-A section in the shown embodiment.

[0021] Figure 5 is a schematic diagram of the cutting cable.

[0022] Figure 6 is a schematic diagram of the detonator and cutting cable arrangement.

[0023] Figure 7 is a schematic diagram of the wireless detonation system.

[0024] Among them, 1-back leaf groove, 2-front leaf groove, 3-cutting cable, 4-detonator, 5-connection part, 6-perforation, 7-leading edge, 8-trailing edge, 9-fan blade, 10-lead wire, 11-fan disc, 12-lead wire hole, 13-wireless signal receiving device, 14-wireless signal transmitting device, 15-bottom of the test chamber, 16-drive shaft. Detailed Embodiments

[0025] To make the purpose, technical solution and advantages of the present application more clear, the technical solutions in the embodiments of the present application will be described in more detail below in conjunction with the accompanying drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The described embodiments are some, but not all, of the embodiments of the present application. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present application, and should not be construed as a limitation of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application. The embodiments of the present application will be described in detail below in conjunction with the accompanying drawings.

[0026] The present application provides a blade blasting and cutting device for aeroengine containment tests, as Figures 1 - 6 shown, which is applied to the cutting of blades without root extension sections, enabling the blades to fly off at a specified speed. The blade blasting and cutting device mainly includes:

[0027] A back surface groove, which is opened on the back surface side of the blade along the chord direction of the blade;

[0028] A front surface groove, which is opened on the front surface side of the blade along the chord direction of the blade. The front surface groove includes two ends along the extending direction of the groove, and each end penetrates through the blade in the thickness direction of the blade and forms two perforations on the back surface side of the blade. The back surface groove opened on the back surface side is located between the two perforations;

[0029] Cutting ropes, including two. The two cutting ropes are respectively fixedly laid in the back surface groove and the front surface groove, and the cutting direction of the cutting ropes points to the connecting part between the back surface groove and the front surface groove of the blade;

[0030] A detonator, which is arranged at one of the perforations on the back surface side. One end of the detonator is connected to the detonation signal switch through a lead wire, and the other end is respectively connected to the two cutting ropes.

[0031] The present application proposes a method of machining an arc-shaped groove on the surface of the blade root fly-off section and combining it with drilling on the blade profile. A flexible cutting rope is placed in the groove to cut the reserved part of the blade. After blasting, the reserved part in the middle of the blade is cut off by the cutting rope, and only the front and rear edges of the blade are connected. It can no longer bear the centrifugal load of the blade, and the blade is pulled off under the action of the centrifugal load, realizing the fly-off of the blade at a specified speed.

[0032] Refer to Figure 1 and Figure 2 , an arc-shaped chordal through groove is opened on the back surface side of the blade fly-off section, and a perforation is machined near the front surface side. After the perforation penetrates through the front surface profile, a groove is formed on the front surface side, and only the perforations are reserved at the front and rear edges. After grooving, the blade fly-off section is asFigure 3 and Figure 4 As shown, the remaining area is shown as the shaded part in the figure.

[0033] In some alternative embodiments, the cutting cord includes a metal casing and an explosive coated by the metal casing. The explosive is cyclonite, and the metal casing is made of lead-antimony alloy.

[0034] Figure 5 and Figure 6 The schematic diagram of the cutting cord and detonator arrangement is given. A flexible cutting cord is selected, which has the characteristic of being easily deformed and is laid closely along the groove on the blade surface. The cutting cord is processed by a drawing process. The material of the metal casing is lead-antimony alloy, and the explosive used inside is cyclonite. The schematic diagram of the cutting cord structure is as Figure 5 shown. A detonator is installed in the cylindrical hole at the blade edge. The cutting cords are arranged on both sides of the blade respectively, and the cutting direction points to the connecting part 5 in the middle of the blade. Among them, the cutting cord on the back side of the blade is laid along the blade surface to the detonator, and the cutting cord on the basin side of the blade is in direct contact with the end of the detonator, so as to achieve the purpose of detonating two cutting cords simultaneously with one detonator. During the test, when the reserved part of the blade is cut off by the metal jet generated by the cutting cord, only the leading edge 7 and the trailing edge 8 of the blade are left connected, and it can no longer bear the centrifugal load of the blade. It is broken and flies out under the action of the centrifugal load, effectively avoiding the additional kinetic energy added to the blade due to the blasting effect.

[0035] In some alternative embodiments, the cutting cord is fixed in the groove on the back of the blade and the groove on the basin of the blade by resin glue.

[0036] In some alternative embodiments, the outside of the cutting cord is coated with a fiber cloth.

[0037] After the cutting cord is placed, it is coated with a fiber cloth and fixed by resin glue, which not only ensures the reliable fixation of the cutting cord in the groove under the rotating condition, but also prevents the fire generated during the blasting of the cutting cord from affecting the high-speed imaging effect.

[0038] In some alternative embodiments, the perforation is a round hole.

[0039] In some alternative embodiments, the cross sections of the groove on the back of the blade and the groove on the basin of the blade are arc-shaped structures.

[0040] Figure 7 The schematic diagram of the initiation system is given. The initiation system is composed of a wireless signal transmitting device 14, a wireless signal receiving device 13 and an initiation lead 10, as Figure 7As shown, the wireless signal transmitting device 14 is fixed to the bottom 15 of the test chamber and leads through the cabin to the test control room; the wireless signal receiving device 13 is installed at the front end of the test rotor drive shaft 16 through rabbet fitting and fastened with screws. The lead wire 10 of the detonating detonator is designed as follows: the detonation power supply wire leads inward from the wheel disc tenon groove, the front end face, the journal lead hole 12 of the fan disc 11, and the rotor drive shaft lead hole to the wireless receiving device 13 in sequence, and the lead wire is fixed with resin glue. During the test, the wireless signal transmitting device 14 emits a signal, and after the wireless signal receiving device 13 receives the signal, it is transmitted to the detonator 4 embedded in the blade, and the cutting cable is cut by detonating the detonator to cut the blade.

[0041] In the above two embodiments, through the round holes and arc-shaped grooves, the blade can still maintain a certain strength after grooving. To prevent the blade from breaking prematurely due to grooving, the strength of the grooved blade is checked. Considering the strength dispersion of the blade, through the methods of analysis and verification under the rotating state, it is ensured that the blade will not fail due to the action of centrifugal load at 122% of the rotational speed, so that the grooved blade has a strength reserve of more than 1.5 times.

[0042] Compared with the prior art, the main advantages of the present application are as follows:

[0043] 1. The present application solves the problem of poor control accuracy of the breaking speed, enabling the blade to break at the specified rotational speed;

[0044] 2. In the present application, the breaking mode of the blade is tensile fracture under centrifugal load, which solves the problem of easy generation of additional kinetic energy in the blasting cutting technology and ensures the effectiveness of the test results;

[0045] 3. The flexible cutting cable selected in the present application can be laid closely along the blade surface, which solves the problem of installing the blasting device on the complex blade profile. The blasting device is installed reliably and avoids large stress concentration, and can be widely applied in the containment test of the same type of blade.

[0046] The present application is a method of machining an arc-shaped groove on the surface of the breaking cross-section at the blade root and combining with drilling holes on the blade profile. A flexible cutting cable is placed in the groove to cut the reserved part of the blade. After blasting, the reserved part in the middle of the blade is cut by the cutting cable, and only the front and rear edges of the blade are connected, and it can no longer bear the centrifugal load of the blade. Under the action of the centrifugal load, the blade is pulled off, realizing the breaking of the blade at the specified rotational speed.

[0047] Although the present application has been described in detail above with general descriptions and specific implementation schemes, based on the present application, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present application all fall within the scope protected by the present application.

Claims

1. A blade blasting and cutting device for aero-engine containment test, which is applied to the cutting of blades without root extension sections, is characterized in that The blade blasting and cutting device includes: A back - blade groove (1) is formed on the back - blade side of the blade along the chord - wise direction of the blade; A front - blade groove (2) is formed on the front - blade side of the blade along the chord - wise direction of the blade. The front - blade groove (2) includes two ends along the extending direction of the groove. Each end penetrates through the blade along the thickness direction of the blade and forms two perforations (6) on the back - blade side of the blade. The back - blade groove (1) formed on the back - blade side is located between the two perforations; Cutting cables (3), including two. The two cutting cables (3) are respectively fixedly laid in the back - blade groove (1) and the front - blade groove (2). The cutting direction of the cutting cable (3) points to the connecting part (5) between the back - blade groove (1) and the front - blade groove (2) of the blade; A detonator (4) is arranged at one of the perforations on the back - blade side. One end of the detonator (4) is connected to the detonation signal switch through a lead wire, and the other end is respectively connected to the two cutting cables.

2. The blade blasting and cutting device for aero-engine containment test according to claim 1, wherein, The cutting cable (3) is fixed in the back - blade groove (1) and the front - blade groove (2) by resin glue.

3. The blade blasting and cutting device for aero-engine containment test according to claim 1, characterized in that, The outer surface of the cutting cable (3) is covered with a fiber cloth.

4. The blade blasting and cutting device for aeroengine containment test according to claim 1, wherein, The cutting cable (3) includes a metal shell and an explosive covered by the metal shell. The explosive is cyclonite, and the metal shell is made of lead - antimony alloy.

5. The blade blasting and cutting device for aero-engine containment test according to claim 1, characterized in that, The perforation (6) is a round hole.

6. The blade bursting and cutting device for aero-engine containment test according to claim 1, characterized in that, The cross - sections of the back - blade groove (1) and the front - blade groove (2) are arc - shaped structures.

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