Mobile protective device and engine testing system

Abstract

This invention discloses a mobile protective device and an engine testing system, applicable to the whole-engine testing of aero-engines. The aero-engine test bench has a shielded chamber and an exhaust ejector tube installed in the shielded chamber to connect the inside and outside of the shielded chamber. The mobile protective device includes: a first protective cover, movably installed at the exhaust ejector tube position, for moving to cover the side wall of the exhaust ejector tube or moving to a position where its first end matches the front end of the exhaust ejector tube; a second protective cover, movably fitted onto the first protective cover, for moving to cover the first protective cover or moving to a position where its two ends match the second end of the first protective cover and the air intake end of the aero-engine, respectively; and an electromagnetic shielding structure, installed on the outer wall of the second protective cover, for electromagnetic shielding and absorption of the tail nozzle during the whole-engine electromagnetic test, where the first protective cover moves to cover the exhaust ejector tube and the second protective cover moves to cover the first protective cover.

Description

Technical Field

[0001] This invention relates to the field of aero-engine testing technology, and in particular, to a mobile protective device. Furthermore, this invention also relates to an engine testing system including the aforementioned mobile protective device. Background Technology

[0002] When conducting electromagnetic compatibility (EMC) tests on an aero-engine, the high-temperature exhaust gas generated after the engine ignites and runs needs to be collected through the exhaust ejector tube on the test stand and discharged into the atmosphere outside the shielded room. The exhaust ejector tube is usually located close to the rear of the engine exhaust nozzle and is typically made of metals such as carbon steel or stainless steel. For the shielded room, the directly exposed metal surface will reflect the electromagnetic signals directed at the metal surface a second time, polluting and damaging the electromagnetic environment of the test inside the shielded room, thus affecting the test results of the EMC test.

[0003] Meanwhile, during the whole-engine testing of aero engines, a certain concentration of oil mist, soot, and other pollutants may be generated around the engine. After these pollutants diffuse in the air, a large portion of them will eventually settle on the surface of the equipment and floor in the test room and accumulate. For the whole-engine electromagnetic compatibility test bench with high cleanliness requirements, in order to reduce the accumulation of oil mist, soot, and other pollutants on the electromagnetic testing environment equipment in the dark room, a test protection device needs to be installed around the test bench during the whole-engine test and commissioning phase before the whole-engine electromagnetic compatibility test. This protection device can block most of the oil mist, soot, and other pollutants near the engine from diffusing outward during the test, and also has a certain ejection effect, which can eject most of the oil mist, soot, and other pollutants near the engine into the exhaust tower.

[0004] Existing protective devices are generally movable structures, with a semi-enclosed outer shell as their main body. During testing, the protective device can be moved to the vicinity of the test piece to cover it and provide protection. After the test, the protective device can be moved away from the test piece, thus not affecting the inspection, disassembly, or other operations of the test piece. However, existing movable protective devices have the following disadvantages:

[0005] a) Existing fully enclosed mobile protective devices completely cover and enclose the test piece or equipment to prevent the external environment from affecting the test piece or equipment, and also prevent test piece or equipment parts from flying out into the external environment. However, existing fully enclosed mobile protective devices cannot meet the air intake requirements for engine whole-machine testing because they are isolated from the external environment.

[0006] (b) To meet the test air intake requirements, the engine cannot be completely sealed. A semi-enclosed mobile protective device is used to partially cover and enclose the test piece or equipment to prevent external personnel or equipment from contacting the test piece or equipment inside the protective device. It also prevents test pieces or equipment parts from flying into the external environment. However, since the exhaust pipe of the shielded room and even the existing semi-enclosed mobile protective device are exposed metal structures, the exposed metal surfaces will cause secondary reflection of electromagnetic signals during the whole-machine electromagnetic test after the ignition operation test, affecting the test environment inside the shielded room and thus affecting the results of the electromagnetic compatibility test. For example, the technical solution of patent application number 202210886443.X discloses an electromagnetic shielding high-temperature exhaust device, which uses a movable ejector tube installed outside the shielded room to extend into the shielded room and can be sleeved on the outside of the engine tail nozzle to achieve exhaust ejection. Its structure cooperates with the outer wall of the shielded room to achieve electromagnetic shielding and isolation of the shielded room to meet the test requirements. However, it cannot solve the problem of secondary reflection of electromagnetic signals caused by the exposed metal surfaces of the exhaust pipe and protective device inside the shielded room. Summary of the Invention

[0007] This invention provides a mobile protective device and an engine testing system to solve the technical problem that the use of only semi-enclosed mobile protective devices to meet the requirements of engine whole-machine testing results in exposed metal surfaces such as exhaust pipes, leading to secondary reflection of electromagnetic signals and electromagnetic signal disorder in the dark chamber during electromagnetic testing.

[0008] According to one aspect of the present invention, a mobile protective device is provided for use in the testing of an aero-engine. The test bench for the aero-engine has a shielded chamber and an exhaust ejector tube disposed in the shielded chamber for connecting the inside and outside of the shielded chamber. The mobile protective device includes:

[0009] A first protective cover is disposed in the shielding chamber. The first protective cover is movably disposed at the position of the exhaust ejector tube in the shielding chamber, and is used to move to cover the side wall of the exhaust ejector tube or to move to match the front end of the exhaust ejector tube.

[0010] The second protective cover is disposed in the shielding room. The second protective cover is movable and covers the outside of the first protective cover. The second protective cover is used to move to cover the outside of the first protective cover or to move to match the second end position of the first protective cover and the air intake position of the aero-engine, respectively.

[0011] An electromagnetic shielding structure is disposed on the outer wall of the second protective cover, and is used to electromagnetically shield and absorb the exhaust ejector tube when the first protective cover moves to cover the exhaust ejector tube and the second protective cover moves to cover the first protective cover during the electromagnetic test of the engine.

[0012] As a further improvement to the above technical solution, the mobile protective device also includes an installation structure disposed in the shielding chamber for movably installing the first protective cover and the second protective cover along the axial direction of the exhaust ejector tube.

[0013] As a further improvement to the above technical solution, the installation structure includes a first guide rail arranged axially on both sides of the exhaust ejector tube and a second guide rail arranged axially on both sides of the exhaust ejector tube; the spacing of the first guide rail matches the bottom spacing on both sides of the first protective cover, and the spacing of the second guide rail matches the bottom spacing on both sides of the second protective cover; a first slider for cooperating with the first guide rail is provided on the bottom of both sides of the first protective cover; a second slider for cooperating with the second guide rail is provided on the bottom of the second protective cover.

[0014] As a further improvement to the above technical solution, the mobile protective device further includes a first sealing structure and a second sealing structure. The first sealing structure is used to seal the first protective cover and the exhaust ejector tube when the first protective cover moves to a position where the first end matches the front end of the exhaust ejector tube. The second sealing structure is used to seal the second protective cover and the previous protective cover when the second protective cover moves to a position where the first end matches the second end of the previous protective cover.

[0015] As a further improvement to the above technical solution, the first sealing structure includes a limiting plate disposed on the outer wall of the front end of the exhaust ejector tube and a first sealing ring disposed on the inner end face of the first end of the first protective cover, and the second sealing structure includes a mating edge formed on the outer wall of the second end of the preceding protective cover of the second protective cover and a second sealing ring disposed on the inner end face of the first end of the second protective cover.

[0016] As a further improvement to the above technical solution, the inner walls of the first protective cover and the second protective cover are respectively provided with reinforcing ribs.

[0017] As a further improvement to the above technical solution, the axial dimension of the first protective cover is greater than or equal to the axial dimension of the exhaust ejector tube located inside the shielding chamber, and the axial dimension of the second protective cover is greater than or equal to the axial dimension of the exhaust ejector tube; the sum of the axial dimensions of the first protective cover and the second protective cover is greater than or equal to the axial distance between the exhaust ejector tube and the air intake end of the aero-engine.

[0018] As a further improvement to the above technical solution, one or more intermediate protective covers are provided between the first protective cover and the second protective cover.

[0019] As a further improvement to the above technical solution, the electromagnetic shielding structure includes an electromagnetic shielding layer disposed on the outer wall of the second protective cover and an absorbing wedge disposed outside the electromagnetic shielding layer.

[0020] According to another aspect of the invention, an engine testing system is also provided, which includes the aforementioned mobile protective device.

[0021] The present invention has the following beneficial effects:

[0022] This mobile protective device consists of a movable first protective cover and a second protective cover installed within a shielded chamber, with an electromagnetic shielding structure installed outside the second protective cover. During ignition operation tests, the first and second protective covers are moved so that the second end of the second protective cover aligns with the engine's air intake, the first end of the second protective cover aligns with the second end of the first protective cover, and the first end of the first protective cover aligns with the position of the exhaust ejector tube within the shielded chamber. During the test, this ensures air intake at the front of the test piece and blocks most of the oil mist, soot, and other contaminants near the test piece from diffusing into the shielded chamber. It also has a certain ejection effect, drawing most of the oil mist, soot, and other contaminants near the engine's exhaust nozzle through the ejector. The exhaust ejector tube discharges into the exhaust tower, thus protecting the test environment equipment inside the shielded room. During electromagnetic compatibility (EMC) testing, the first protective cover is moved outside the exhaust ejector tube, and the second protective cover is moved outside the first protective cover. The electromagnetic shielding structure of the second protective cover shields and absorbs electromagnetic signals emitted towards the outer surface of the exhaust ejector tube, thereby preventing secondary reflection of electromagnetic signals generated by the test piece or test equipment during EMC testing through the outer surface of the exhaust ejector tube, which would pollute and damage the electromagnetic test environment inside the shielded room. This ensures stable telecommunication signals inside the shielded room and accurate test results. After the ignition operation test or the whole machine EMC test, the first and second protective covers can be moved away from the test piece, thus not affecting the inspection, disassembly, and other operations of the test piece.

[0023] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0025] Figure 1 This is a schematic diagram of a preferred embodiment of the present invention;

[0026] Figure 2This is a top view of the preferred embodiment of the present invention under the ignition operation test state.

[0027] Figure 3 This is a top view of the machine in use under electromagnetic compatibility testing conditions according to a preferred embodiment of the present invention.

[0028] Legend:

[0029] 1. Exhaust ejector tube; 2. Limiting plate; 3. First sealing ring; 4. Mounting structure; 5. First guide rail; 6. First slider; 7. First connector; 8. First protective cover; 9. Second sealing ring; 10. Second guide rail; 11. Second slider; 12. Second connector; 13. Second protective cover; 14. Limiting mechanism; 15. Electromagnetic shielding layer; 16. Wave absorbing wedge. Detailed Implementation

[0030] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0031] Figure 1 This is a schematic diagram of a preferred embodiment of the present invention; Figure 2 This is a top view of the preferred embodiment of the present invention under the ignition operation test state. Figure 3 This is a top view of the machine in use under electromagnetic compatibility testing conditions according to a preferred embodiment of the present invention;

[0032] like Figures 1 to 3 As shown, the mobile protective device of this embodiment is applied to the whole-engine testing of an aero-engine. The test bench of the aero-engine has a shielded room and an exhaust ejector 1 installed in the shielded room for connecting the inside and outside of the shielded room. The mobile protective device includes:

[0033] The first protective cover 8 is installed in the shielding room. The first protective cover 8 is movably installed at the position of the exhaust ejector tube 1 in the shielding room, and is used to move to cover the side wall of the exhaust ejector tube 1 or to move to match the first end with the front end of the exhaust ejector tube 1.

[0034] The second protective cover 13 is installed in the shielding room. The second protective cover 13 is movable and installed outside the first protective cover. The second protective cover 13 is used to move to be installed outside the first protective cover or to move to match the second end position of the first protective cover and the air intake end position of the aircraft engine, respectively.

[0035] An electromagnetic shielding structure is installed on the outer wall of the second protective cover 13. It is used to perform electromagnetic shielding and electromagnetic absorption on the exhaust ejector tube 1 by moving the first protective cover 8 to cover the exhaust ejector tube 1 and the second protective cover to cover the first protective cover 8 during the electromagnetic test of the engine.

[0036] It should be understood that, in this embodiment, the end of each component facing the engine intake is the front end or the second end, and the other end is the rear end, the tail end, or the first end; the axial position of the exhaust ejector tube 1 of the shielding chamber matches or tends to match the axial position of the tail nozzle of the test piece installed on the test bench, so as to ensure that the second protective cover 13 can cover the first protective cover and the exhaust ejector tube 1 simultaneously without being too large.

[0037] It should be noted that the mobile protective device includes at least two protective covers. In this embodiment, the first protective cover 8 and the second protective cover 13 are used as examples. In other embodiments, one or more protective covers may be arranged between the first protective cover 8 and the second protective cover 13 in sequence; that is, the height and width of the protective cover increase sequentially from the first protective cover 8, the intermediate protective covers to the second protective cover 13.

[0038] Understandably, this mobile protective device, by setting up movable first protective cover 8 and second protective cover 13 respectively in the shielded room and setting an electromagnetic shielding structure outside the second protective cover 13, moves the first protective cover 8 and second protective cover 13 respectively during ignition operation tests. This ensures that the second end of the second protective cover 13 matches the air intake end of the engine, the first end of the second protective cover 13 matches the second end of the first protective cover 8, and the first end of the first protective cover 8 matches the position of the exhaust ejector 1 in the shielded room. During the test of the test piece, this ensures air intake at the front end of the test piece and blocks most of the oil mist, soot, and other pollutants near the test piece from diffusing into the shielded room. It also has a certain ejection effect, capable of drawing most of the oil mist, soot, and other pollutants near the engine exhaust nozzle into the shielded room. Under the influence of the ejector, the electromagnetic signal is discharged into the exhaust tower through the exhaust ejector tube 1, thereby protecting the test environment equipment in the shielded room. When conducting electromagnetic compatibility tests, the first protective cover 8 is moved outside the exhaust ejector tube 1, and the second protective cover 13 is moved outside the first protective cover 1. The electromagnetic shielding structure of the second protective cover 13 is used to shield and absorb the electromagnetic signals emitted towards the outer surface of the exhaust ejector tube 1, thereby preventing the electromagnetic signals generated by the test piece or test equipment during the electromagnetic compatibility test from being reflected twice through the outer surface of the exhaust ejector tube 1, which would cause pollution and damage to the electromagnetic test environment in the shielded room. This ensures the stability of the telecommunications signal in the shielded room and the accuracy of the test results. After the ignition operation test or the whole machine electromagnetic compatibility test, the first protective cover and the second protective cover can be moved away from the test piece, so as not to affect the inspection, disassembly and assembly of the test piece.

[0039] In some preferred embodiments, the mobile protective device further includes an installation structure 4 disposed in the shielding chamber for movably installing the first protective cover 8 and the second protective cover 13 along the axial direction of the exhaust ejector tube 1. If there is an intermediate protective cover, the installation structure 4 is also used to install the intermediate protective cover. By setting the installation structure 4, the first protective cover 8 and the second protective cover 13 can be moved along the axial direction of the exhaust ejector tube 1, and the installation structure 4 restricts the first protective cover 8 and the second protective cover 13 to be moved only along the axial direction, making the operation more convenient and efficient.

[0040] In some preferred embodiments, the mounting structure 4 includes a first guide rail 5 axially disposed on both sides of the exhaust ejector tube 1 and a second guide rail 10 axially disposed on both sides of the exhaust ejector tube 1; the spacing of the first guide rail 5 matches the bottom spacing on both sides of the first protective cover 8, and the spacing of the second guide rail 10 matches the bottom spacing on both sides of the second protective cover 13; a first slider 6 for cooperating with the first guide rail 5 is respectively disposed on the bottom of both sides of the first protective cover 8; a second slider 11 for cooperating with the second guide rail 10 is respectively disposed on the bottom of the second protective cover 13; it should be understood that the width and height of the first protective cover 8 are both smaller than the width and height of the second protective cover 13, ensuring... The second protective cover 13 can be installed outside the first protective cover 8; the first protective cover 8 is connected to the first slider 6 through the first connector 7, and the second protective cover 13 is connected to the second slider 11 through the second connector 12; by setting the first guide rail 5 and the second guide rail 10 on both sides of the exhaust ejector tube 1 along the axial direction and matching the bottom spacing of the corresponding protective cover, and setting the slider at the bottom of the protective cover to cooperate with the guide rail, the protective cover can move along the guide rail direction, that is, move along the axial direction of the exhaust ejector tube 1, which is convenient for operation, installation and maintenance, and smooth movement; it should be understood that when an intermediate protective cover is set, an intermediate guide rail with matching position and number is also set between the first guide rail 5 and the second guide rail 10;

[0041] In some preferred embodiments, the mobile protective device further includes a first sealing structure and a second sealing structure. The first sealing structure is used to seal the first protective cover 8 with the exhaust ejector tube 1 when the first end of the first protective cover 8 moves to a position that matches the front end of the exhaust ejector tube 1 of the aero-engine. The second sealing structure is used to seal the second protective cover 13 with the first protective cover when the first end of the second protective cover moves to a position that matches the second end of the previous protective cover. By setting the sealing structure, a sealing fit is achieved between each protective cover and between each protective cover and the outer wall of the exhaust ejector tube 1 during the ignition test to prevent pollutants from spreading towards the engine. The exhaust gas is guided to the exhaust ejector tube 1 for discharge by its ejection effect.

[0042] In some preferred embodiments, the first sealing structure includes a limiting plate 2 disposed on the outer wall of the front end of the exhaust ejector tube 1 and a first sealing ring 3 disposed on the inner end face of the first end of the first protective cover 8. The second sealing structure includes a mating edge formed on the outer wall of the second end of the first protective cover 8 and each intermediate protective cover and a second sealing ring 9 disposed on the inner end face of the first end of each intermediate protective cover and the second protective cover 13. In this embodiment, taking only the first protective cover 8 and the second protective cover 13 as an example, when it moves to the limit position in the direction of the second end, the first sealing ring 3 on the inner end face of the first end of the first protective cover 8 is pressed against the limiting plate 2 on the outer wall of the tail nozzle 1, and the second sealing ring 9 on the inner end face of the first end of the second protective cover 13 is pressed against the second sealing ring 9 on the outer wall of the second end of the first protective cover 8. It has both a sealing function and a limiting function.

[0043] In some preferred embodiments, the inner walls of the first protective cover 8 and the second protective cover 13 are respectively provided with reinforcing ribs to increase their strength and prevent them from being deformed or damaged by impacts from the exhaust of the tailpipe 1.

[0044] In some preferred embodiments, the mobile protective device further includes a limiting mechanism 14 for limiting the axial position of the second protective cover 13. The limiting mechanism 14 can also be provided at the second end of the mounting structure 4 with a locking member for cooperating with the second connecting member 12 provided at the bottom of the second protective cover 13 near the second end. When it moves to the extreme position of the second end, the locking member engages with the second connecting member 12 to fix the position of the second protective cover 13. Under the action of the sealing structure, the front protective covers are axially limited, thereby fixing the overall position of the device, avoiding movement during the test, and making the structure simple and easy to operate.

[0045] In some preferred embodiments, the axial dimension of the first protective cover 8 is greater than or equal to the axial dimension of the exhaust ejector tube 1, and the axial dimension of the second protective cover 13 is greater than or equal to the axial dimension of the exhaust ejector tube 1, and preferably greater than the axial dimension of the exhaust ejector tube 1, to ensure that it is covered outside the exhaust ejector tube and thus ensures electromagnetic shielding and absorption effects; the sum of the axial dimensions of the first protective cover 8 and the second protective cover 13 is greater than or equal to the axial distance between the exhaust ejector tube 1 and the air inlet end of the test piece; specifically, the axial dimensions of each protective cover are preferably set to be consistent or close to consistent and matched with the axial dimension of the exhaust ejector tube 1, to ensure that when each protective cover moves to the first end limit position, it is sequentially covered and completely covered outside the side wall of the exhaust ejector tube 1, thus ensuring electromagnetic shielding and absorption effects. At the same time, after each protective cover moves to the corresponding limit position of the second end, the first protective cover 8 and the second protective cover 13 can be covered outside the aero-engine, that is, whether to set an intermediate protective cover or the number of intermediate protective covers set is matched according to the axial distance between the exhaust ejector tube 1 and the air inlet end of the test piece.

[0046] In some preferred embodiments, the electromagnetic shielding structure includes an electromagnetic shielding layer 15 disposed on the outer wall of the second protective cover 13 and an absorbing wedge 16 disposed outside the electromagnetic shielding layer 15. It is understood that the electromagnetic shielding structure is disposed on both outer walls of the second protective cover 13, the electromagnetic shielding layer 15 is a ferrite shielding layer, and the absorbing wedge 16 adopts the existing technology of absorbing wedge 16. Based on the three-layer shielding structure of the metal steel plate structure of the side wall of the second protective cover 13, the electromagnetic shielding layer 15 and the absorbing wedge 16, the electromagnetic signals emitted toward the outer surface of the exhaust ejector tube 1 are shielded and absorbed, thereby preventing the electromagnetic signals generated by the test piece or test equipment during electromagnetic compatibility testing from being reflected twice through the outer surface of the exhaust ejector tube, and avoiding pollution and damage to the electromagnetic test environment inside the shielding room.

[0047] On the other hand, a preferred embodiment of the present invention also provides an engine testing system that incorporates the aforementioned mobile protective device.

[0048] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A mobile shielding device for aero-engine overall test, wherein a test bed of an aero-engine has a shielding chamber and an exhaust injection cylinder (1) arranged in the shielding chamber for connecting the inside and outside of the shielding chamber, characterized in that, The mobile shielding device comprises: a first shielding cover (8) arranged in the shielding chamber, the first shielding cover (8) being arranged at the position of the exhaust injection cylinder (1) in the shielding chamber and being movable to cover the side wall of the exhaust injection cylinder (1) or to match the front end of the exhaust injection cylinder (1); a second shielding cover (13) arranged in the shielding chamber, one or more intermediate shielding covers being arranged between the first shielding cover (8) and the second shielding cover (13), the second shielding cover (13) being movable to cover the previous shielding cover, and the second shielding cover (13) being used to move to cover the previous shielding cover or to match the second end of the previous shielding cover and the air intake end of the aero-engine respectively; an electromagnetic shielding structure arranged on the outer wall of the second shielding cover (13), which is used to shield and absorb the electromagnetic waves of the exhaust injection cylinder (1) when the first shielding cover (8) is moved to cover the exhaust injection cylinder (1) and the second shielding cover is moved to cover the first shielding cover (8) during the electromagnetic test of the engine.

2. The mobile shield of claim 1, wherein, The mobile shielding device further comprises a mounting structure (4) arranged in the shielding chamber, which is used to move the first shielding cover (8) and the second shielding cover (13) along the axial direction of the exhaust injection cylinder (1).

3. The mobile shield of claim 2, wherein, The mounting structure (4) comprises first guide rails (5) arranged on both sides of the exhaust injection cylinder (1) in the axial direction and second guide rails (10) arranged on both sides of the exhaust injection cylinder (1) in the axial direction; the arrangement interval of the first guide rails (5) matches the interval of the bottom of the first shielding cover (8), and the arrangement interval of the second guide rails (10) matches the interval of the bottom of the second shielding cover (13); the bottom of the first shielding cover (8) is respectively provided with a first sliding block (6) used to cooperate with the first guide rail (5); and the bottom of the second shielding cover (13) is respectively provided with a second sliding block (11) used to cooperate with the second guide rail (10).

4. The mobile shield of claim 1, wherein, The mobile shielding device further comprises a first sealing structure and a second sealing structure, the first sealing structure being used to seal the first shielding cover (8) and the exhaust injection cylinder (1) when the first shielding cover is moved to match the front end of the exhaust injection cylinder (1); and the second sealing structure being used to seal the second shielding cover (13) and the previous shielding cover when the second shielding cover (13) is moved to match the second end of the previous shielding cover.

5. The mobile shield of claim 4, wherein, The first sealing structure comprises a limiting plate (2) arranged on the outer wall of the front end of the exhaust injection cylinder (1) and a first sealing ring (3) arranged on the inner end face of the first end of the first shielding cover (8); and the second sealing structure comprises a cooperating edge formed on the outer wall of the second end of the previous shielding cover of the second shielding cover (13) and a second sealing ring (9) arranged on the inner end face of the first end of the second shielding cover (13).

6. The mobile shield of claim 1, wherein, The inner wall of the first protective cover (8) and the inner wall of the second protective cover (13) are respectively provided with reinforcing ribs.

7. The mobile shield of claim 1, wherein, The axial dimension of the first protective cover (8) is greater than or equal to the axial dimension of the exhaust injection cylinder (1) located in the shielding chamber, the axial dimension of the second protective cover (13) is greater than or equal to the axial dimension of the exhaust injection cylinder (1), and the sum of the axial dimensions of the first protective cover (8) and the second protective cover (13) is greater than or equal to the axial spacing between the exhaust injection cylinder (1) and the air intake end of the aero-engine.

8. The mobile shield of any of claims 1-7, wherein, The electromagnetic shielding structure comprises an electromagnetic shielding layer (15) arranged on the outer wall of the second protective cover (13) and a wave-absorbing wedge (16) arranged outside the electromagnetic shielding layer (15).

9. An engine test system characterized by, The application has the mobile protective device of any one of claims 1-8.

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