Aero-engine inlet duct dynamic hammer wave and surge wave simulation device and simulation method

Abstract

The application discloses an aero-engine inlet duct dynamic hammering wave and surge wave simulation device, which comprises a main body pipeline, a high-speed rotating valve and a high-pressure gas source system. The high-speed rotating valve is composed of a fixed hollow inner shaft and a rotatable hollow outer shaft which are coaxially arranged and transversely penetrate the main body pipeline, and the center lines of the two shafts are along the spanwise direction which is perpendicular to the airflow direction. The inner and outer shafts are provided with gas discharge holes with the same shape and area on the pipe wall, and the centers of the gas discharge holes coincide with the center of the pipeline. The high-pressure gas source system comprises a high-pressure cabin, a pressure stabilizing cabin and a valve and a pressure diaphragm arranged between the outlet of the pressure stabilizing cabin and the inlet of the inner shaft. By controlling the rotating state of the rotatable outer shaft, the device can simulate two pressure pulsation modes of single hammering wave and periodic surge wave. The application has the characteristics of compact structure, flexible control, accurate reproduction of dynamic pressure load with high pressure ratio and millisecond rise time, and is suitable for simulation verification of the structural strength of the inlet duct in the wind tunnel test, and has the characteristics of high fidelity, high repeatability and convenient operation.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine air intake technology, and particularly relates to a device for simulating dynamic hammer waves and surge waves in air intakes based on a high-speed rotary valve and diaphragm rupture triggering. Background Technology

[0002] The air intake is a critical component of an aircraft's propulsion system, responsible for compressing and rectifying the incoming airflow to provide a stable air supply for the engine. Its structural integrity directly affects flight safety and engine stability. Among the various loads borne by the air intake, hammer wave load plays a significant role and is the primary factor to consider in the design of the air intake structure. Hammer waves are usually caused by compressor surge. When the downstream compressor enters an unstable state, it induces a severe transient pressure rise at the air intake outlet. This pressure wave then propagates upstream against the flow, forming a phenomenon of a rapid pressure jump in a short period of time, i.e., a hammer wave. This transient overpressure, which forms within milliseconds, can have a peak value exceeding twice the total incoming pressure, severely impacting the air intake system structure and causing failures such as intake valve damage, bulkhead rupture, and connection structure failure.

[0003] To fully verify the strength of the air intake structure under hammer wave loads during the model development phase, reliable ground simulation tests must be conducted. However, directly using a real engine for surge testing is not only costly and risky, but also difficult to precisely control test conditions and has poor repeatability. Therefore, developing a dedicated device capable of accurately simulating hammer wave loads on a scaled-down wind tunnel model has become an urgent need in the field of aerospace engineering. The main technical challenges of hammer wave and surge wave simulation are that the device must be able to reproduce the high pressure ratio and millisecond-level pressure rise time of real surge, while also flexibly simulating single impacts or periodic waveforms; its structure must be compact, easy to install on a scaled-down wind tunnel model, and interfere with the original air intake flow field as little as possible; in addition, it must meet the stringent engineering requirements for high repeatability, low cost, and safe and reliable operation.

[0004] Therefore, the aviation industry urgently needs a hammer wave and surge wave simulation device that combines high fidelity, good repeatability, low cost, and easy integration, so as to accurately reproduce the dynamic pressure load generated by engine surge in wind tunnel tests and provide reliable data support for the structural strength design and verification of the air intake. Summary of the Invention

[0005] To address the challenges of reproducing high pressure ratio and millisecond-level pressure rise time in hammer wave simulation, and the difficulty of adjusting specific test frequencies and waveforms in surge wave simulation, while also considering the stringent requirements for structural compactness in wind tunnel scale-down model installation and the practical engineering requirements of high repeatability, low cost, and safety and reliability, this invention provides a dynamic hammer wave and surge wave simulation device for aero-engine inlet, which can accurately, easily, and economically simulate the above two dynamic pressure loads in wind tunnel tests.

[0006] The present invention also provides a simulation method using a dynamic hammer wave and surge wave simulation device for an aero-engine inlet, for simulating single hammer waves and periodic surge waves in wind tunnel tests.

[0007] The dynamic hammer wave and surge wave simulation device for aero-engine inlet provided by this invention can adopt the following technical solutions:

[0008] A dynamic hammer wave and surge wave simulation device for an aero-engine inlet includes: a main duct, a rotatable hollow outer shaft passing through the main duct, a fixed hollow inner shaft located within the rotatable hollow outer shaft, an air source connected to the inlet end of the fixed hollow inner shaft, and a pressure diaphragm located within the fixed hollow inner shaft and close to its inlet. The fixed hollow inner shaft has a first vent hole on its sidewall facing the interior of the main duct, and the rotatable hollow outer shaft has a second vent hole on its sidewall. When the rotatable hollow outer shaft rotates to make the first vent hole coincide with the second vent hole, the fixed hollow inner shaft is connected to the main duct.

[0009] Furthermore, the axis of the main pipe is perpendicular to the axis of the rotatable hollow outer shaft.

[0010] Furthermore, the rotatable hollow outer shaft is coaxial with the fixed hollow inner shaft and has a clearance fit; one end of the fixed hollow inner shaft is closed while the other end is connected to an air source.

[0011] Furthermore, the gas source includes a high-pressure chamber, a pressure-stabilizing chamber connected to the high-pressure chamber, and a valve installed between the outlet of the pressure-stabilizing chamber and the inlet of the fixed hollow inner shaft.

[0012] Furthermore, a first gear is fitted onto one end of the rotatable hollow outer shaft extending out of the main pipe, and a drive motor and a second gear self-mounted on the output shaft of the drive motor are provided on the outer shell of the main pipe, with the second gear meshing with the first gear.

[0013] Furthermore, the centers of the first and second vent holes coincide with the axis of the main pipe; the first and second vent holes are racetrack-shaped, and the total area of ​​the second vent hole connected to the main pipe is between 0.5% and 5% of the flow cross-sectional area of ​​the main pipe.

[0014] Furthermore, a plurality of second vent holes are uniformly opened along the circumferential direction on the wall of the rotatable hollow outer shaft.

[0015] Furthermore, it also includes an intake duct model that is connected to the main duct.

[0016] Beneficial Effects: This invention proposes a dynamic hammer wave and surge wave simulation device for aero-engine inlets. It presents a mechanical design based on the relative rotation of inner and outer shafts to achieve periodic opening and closing of airflow. This device can simulate single hammer waves and periodic surge waves, improving the accuracy, repeatability, and ease of operation of hammer wave simulation. The simulation device can accurately reproduce dynamic pressure loads with high pressure ratios and millisecond-level rise times, making it suitable for simulating and verifying the structural strength of inlets in wind tunnel tests. It features high fidelity, high repeatability, and ease of operation.

[0017] The simulation method using the aforementioned dynamic hammer wave and surge wave simulation device for aero-engine inlet provided by this invention adopts the following technical solution:

[0018] This includes methods for simulating single-impact waves and methods for simulating periodic surge waves;

[0019] The single-wave hammer impact simulation method is as follows: First, rotate the rotatable hollow outer shaft to align the second vent hole with the first vent hole; then, use high-pressure gas supplied by the gas source to trigger the pressure diaphragm to rupture, and the high-pressure gas is injected into the main pipe through the second vent hole; then, rotate the rotatable hollow outer shaft again to offset the second vent hole from the first vent hole, thereby terminating the gas release and forming a single pressure pulse.

[0020] The method for simulating the periodic surge wave is as follows: First, the rotatable hollow outer shaft is accelerated to the target speed and maintained at the target speed; then, the high-pressure gas supplied by the gas source triggers the pressure diaphragm to rupture, and the high-pressure gas is continuously supplied to the fixed hollow inner shaft; during the constant rotation of the rotatable hollow outer shaft, the second vent hole periodically passes over the first vent hole, thereby intermittently releasing high-pressure gas into the main pipeline, generating periodic surge pressure waves in the main pipeline.

[0021] Furthermore, in the single-hammer wave simulation method, after triggering the membrane rupture, there is a delay of about 2ms, and then the rotatable hollow outer shaft is rotated by a predetermined angle so that the two vent holes are completely offset.

[0022] Beneficial effects: Based on the structure of the aforementioned dynamic hammer wave and surge wave simulation device for aero-engine inlet, this simulation method can realize two simulation methods: single hammer wave simulation method and periodic surge wave simulation method. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the dynamic hammer wave and surge wave simulation device for the air intake of an aero-engine provided by the present invention.

[0024] Figure 2 This is a schematic diagram of a scaled-down model of the air intake in the dynamic hammer wave and surge wave simulation device for aero-engine air intakes provided by the present invention.

[0025] Figure 3 This is a cross-sectional schematic diagram of the fixed hollow inner shaft and the rotatable hollow outer shaft provided by the present invention.

[0026] Figure 4 This is a schematic diagram of the runway-shaped vent provided by the present invention.

[0027] Figure 5 This is a schematic diagram of the expected pressure waveform of a typical single hammer impact wave mode provided by the present invention.

[0028] Figure 6 This is a schematic diagram of the expected pressure waveform of a typical periodic surge wave mode provided by the present invention. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] This embodiment provides a specific implementation scheme for a dynamic intake maneuver and surge wave simulation device based on a high-speed rotary valve and diaphragm rupture triggering. Please refer to [link to relevant documentation]. Figure 1 The device includes a main pipeline, a high-speed rotary valve, a high-pressure gas source system, and a drive system. The high-speed rotary valve comprises a fixed hollow inner shaft and a rotatable hollow outer shaft arranged coaxially. The high-pressure gas source system includes a high-pressure chamber and a pressure-stabilizing chamber connected in sequence by pipelines, as well as a valve and pressure diaphragm installed between the outlet of the pressure-stabilizing chamber and the inlet of the fixed hollow inner shaft. The drive motor drives the rotatable hollow outer shaft to rotate via a gear transmission mechanism.

[0031] The main duct is a straight pipe with a circular cross-section, its axis aligned with the airflow direction, used to connect to the outlet of the scaled-down inlet model 12. Its internal flow cross-section diameter is designed to be equal to the inlet outlet diameter of the model. In this embodiment, this diameter is 100 mm. Please refer to... Figure 2 The main pipeline is coaxially and sealed to the intake duct scale model 12 via a flange, and the connection surface is rectified to minimize interference with the downstream flow field at the connection.

[0032] The core of this device is a high-speed rotary valve that runs transversely through the pipeline along its longitudinal direction. This valve consists of a coaxial, fixed hollow inner shaft and a rotatable hollow outer shaft. Please refer to [link / reference]. Figure 3 The fixed hollow inner shaft has an inner diameter r1 of 10 mm and a wall thickness of 2 mm. A first vent hole is formed on the side facing upstream of the airflow. The rotatable hollow outer shaft has an inner diameter r2 of 12.05 mm and an outer diameter r3 of 15 mm. Two second vent holes, 180° apart and of equal shape and area, are formed at corresponding positions on both shafts. Please refer to [link / reference]. Figure 4Both vents are designed in a racetrack shape, with the following dimensions: long side w = 16mm, short side h = 6mm, and corner radius R = 3mm. The centers of the two vents coincide with the center of the pipe, and the total area of ​​the vents accounts for approximately 1.58% of the pipe's flow area. The area of ​​the rotatable hollow outer shaft that runs across the pipe accounts for approximately 38% of the pipe's flow area.

[0033] A rotatable hollow outer shaft is supported on the outside of the main pipe wall by a pair of bearings, and a dynamic sealing structure is provided between the outer shaft and the pipe wall, and between the inner and outer shafts, to prevent gas leakage. A servo drive motor with continuously adjustable speed is installed above the main pipe, and a drive gear is mounted on its output shaft. A driven gear is mounted on one end of the rotatable hollow outer shaft, and the rotatable hollow outer shaft is driven to rotate through the meshing of the drive gear and the driven gear. In this embodiment, the drive gear has 104 teeth, a module m = 1 mm, and a pitch circle diameter of 104 mm; the driven gear has 52 teeth, a module m = 1 mm, and a pitch circle diameter of 52 mm. Thus, the center distance between the two gears is 78 mm, the gear ratio is 0.5, and the rotational speed of the rotatable hollow outer shaft is twice the speed of the drive motor. The speed range of the drive motor is 0-2000 rpm.

[0034] The high-pressure gas source system provides a high-pressure gas source for the hammer wave simulation and controls its release. The system includes a high-pressure chamber and a pressure-stabilizing chamber connected sequentially by pipelines. The high-pressure chamber stores the high-pressure gas; its volume in this embodiment is 1 m³, pressurized to 0.149 MPa (gauge pressure) during the experiment. For example, under standard atmospheric conditions, the inlet outlet pressure p0 is 101325 Pa, at which point the driving pressure ratio is approximately 2.47. The pressure-stabilizing chamber stabilizes and regulates the release pressure; its volume is 0.1 m³. The pressure-stabilizing chamber outlet is connected to the inlet of a fixed hollow inner shaft via a pipeline. A valve is installed on this pipeline to control the opening and closing of the gas path; a pressure diaphragm is installed between the valve outlet and the inner shaft inlet. When gas needs to be released, a trigger mechanism breaks the pressure diaphragm, achieving rapid release of the high-pressure gas.

[0035] This device achieves two operating modes by coordinating the triggering of the drive motor, valves, and pressure diaphragm. In the single-impact wave mode, the control process is as follows: First, the drive motor is controlled to align the second vent hole of the rotatable hollow outer shaft with the first vent hole of the fixed hollow inner shaft, and the valve is opened to allow high-pressure gas to accumulate upstream of the pressure diaphragm. After the wind tunnel flow stabilizes and the designed flow field is established in the intake duct, the pressure diaphragm is actively triggered to rupture. The instantaneous rupture of the diaphragm allows the high-pressure gas passage to be fully established in a very short time, and the gas is injected into the mainstream through the vent hole, thereby generating a transient pressure pulse in the pipeline. The pressure rise time and peak pressure of this pulse are mainly determined by the vent hole area, the driving pressure difference, and the incoming flow conditions. Under the conditions of a vent hole area of ​​approximately 124 mm² and a driving pressure ratio of 2.47 given in this embodiment, the pressure rise time is estimated to be approximately 1-1.3 ms. To ensure that the generated pressure wave can fully develop and completely enter the intake duct model, the rotary valve must close after the pressure wave has propagated a certain distance forward. After triggering membrane rupture, a delay of approximately 2ms is observed. Then, the drive motor is controlled to rotate the rotatable hollow outer shaft at 1000 rpm by a predetermined angle, completely misaligning the two vent holes, thereby cutting off the air supply and creating a transient, single pressure impact. This angle is determined by the inner diameter r2 of the hollow outer shaft and the height h of the vent hole. In this embodiment, the rotation angle of the outer shaft is 28.1°, and the rotation speed of the hollow outer shaft is 2000 rpm, indicating a pressure drop time of approximately 2.34ms. The device in this embodiment can generate... Figure 5 The typical expected waveform of a single hammer-wave is shown, characterized by a rapid rise on the order of milliseconds and a single-peak shape.

[0036] In the periodic surge wave mode, the control process is as follows: First, based on the target surge frequency f and the number N of the second vent holes on the rotatable hollow outer shaft, the target rotational speed n = 60 * f / N (rpm) of the outer shaft is calculated and set. In this embodiment, the target surge frequency is selected as 50Hz, and the number of second vent holes is 2, so the target rotational speed of the outer shaft is 1500rpm. Next, the high-pressure chamber and the pressure stabilizing chamber are pressurized to the target pressure of 0.149Mpa (gauge pressure), and the drive motor is started at a speed of 750rpm to accelerate the rotatable hollow outer shaft to the target rotational speed of 1500rpm and maintain a uniform rotational speed. After the wind tunnel is running normally and the flow field in the air intake is established, the pressure diaphragm is actively triggered to rupture. The role of the pressure diaphragm in this mode is that its one-time rupture realizes the instantaneous switching of the high-pressure gas path from sealed to unobstructed. This design is the physical basis for reproducing the millisecond-level pressure rise time. After the pressure diaphragm ruptures, high-pressure gas begins to be continuously supplied to the fixed hollow inner shaft, while the rotating outer shaft provides a periodic release window, generating a pressure pulse. For the first pulse, the rapid pressure rise is achieved through the combined action of two instantaneous events: "instantaneous diaphragm rupture establishing a clear airflow path" and "initial alignment of the rotary valve opening the release window." While subsequent pulses do not involve a second rupture of the pressure diaphragm, the airflow path, already established and maintained as a clear path due to the initial rupture, is momentarily disturbed when the high-speed rotating valve periodically aligns, thus generating a rapid pressure rise front with characteristics essentially identical to the first pulse. The volumetric design of the pressure stabilizing chamber ensures relatively stable supply pressure during the pulse sequence. The rise time of the first pulse includes the transient process of initial airflow path establishment, while the pressure rise time of subsequent pulses mainly depends on the vent parameters and rotational speed. Under the parameters of this embodiment, the theoretically estimated rise time of subsequent pulses is approximately 3.12 ms, the generated surge pressure pulse frequency is 50 Hz, and the pulse interval is 20 ms (corresponding to an external shaft rotational speed of 1500 rpm and two vents). Its expected theoretical waveform is as follows: Figure 6 As shown. At the end of the test, first close the valve to cut off the upstream gas supply, then stop the drive motor.

[0037] This invention proposes a dynamic hammer wave and surge wave simulation device for the intake duct based on a high-speed rotary valve and diaphragm rupture triggering. It provides a mechanical method for achieving periodic opening and closing of airflow based on the relative rotation of inner and outer shafts, matching design parameters for the vent holes of the inner and outer shafts, control timing of single and periodic pressure waves, and a method for achieving coordinated operation of high-pressure air source, pressure diaphragm, and rotary valve. This effectively improves the accuracy, repeatability, and ease of operation of hammer wave simulation.

[0038] Furthermore, there are many ways and methods to implement the present invention, and the above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention. All components not explicitly stated in this embodiment can be implemented using existing technology and theory.

Claims

1. A device for simulating dynamic hammer waves and surge waves in an aero-engine inlet, characterized in that, include: Main pipe (1), rotatable hollow outer shaft (3) that runs through the main pipe (1), fixed hollow inner shaft (2) located inside the rotatable hollow outer shaft (3), air source connected to the inlet end of the fixed hollow inner shaft (2), and pressure diaphragm (6) located inside the fixed hollow inner shaft (2) and close to the inlet of the fixed hollow inner shaft (2). The fixed hollow inner shaft (2) has a first vent hole (21) on its side wall facing the inside of the main pipe (1), and the rotatable hollow outer shaft (3) has a second vent hole (31) on its side wall; when the rotatable hollow outer shaft (3) rotates so that the first vent hole (21) and the second vent hole (31) coincide, the fixed hollow inner shaft (2) and the main pipe (1) are connected.

2. The dynamic hammer wave and surge wave simulation device for aero-engine inlet according to claim 1, characterized in that, The axis of the main pipe (1) is perpendicular to the axis of the rotatable hollow outer shaft (3).

3. The dynamic hammer wave and surge wave simulation device for aero-engine inlet according to claim 1, characterized in that, The rotatable hollow outer shaft (3) is coaxial with the fixed hollow inner shaft (2) and has a clearance fit; one end of the fixed hollow inner shaft (2) is closed and the other end is connected to the air source.

4. The dynamic hammer wave and surge wave simulation device for aero-engine inlet according to claim 1 or 3, characterized in that, The gas source includes a high-pressure chamber (4), a pressure stabilizing chamber (5) connected to the high-pressure chamber (4), and a valve (8) installed between the outlet of the pressure stabilizing chamber (5) and the inlet of the fixed hollow inner shaft (2).

5. The dynamic hammer wave and surge wave simulation device for aero-engine inlet according to claim 1, characterized in that, The rotatable hollow outer shaft (3) extends out of the main pipe and is fitted with a first gear. The outer shell of the main pipe is provided with a drive motor and a second gear that is self-mounted on the output shaft of the drive motor. The second gear meshes with the first gear.

6. The dynamic hammer wave and surge wave simulation device for aero-engine inlet according to claim 5, characterized in that, The center of the first vent (21) and the second vent (31) coincides with the axis of the main pipe (1); the first vent (21) and the second vent (31) are in the shape of a racetrack, and the total area of ​​the second vent (31) connected to the main pipe (1) is between 0.5% and 5% of the cross-sectional area of ​​the main pipe (1).

7. The dynamic hammer wave and surge wave simulation device for aero-engine inlet according to claim 1, characterized in that, Multiple second vent holes (31) are evenly opened along the circumference on the wall of the rotatable hollow outer shaft (3).

8. The dynamic hammer wave and surge wave simulation device for aero-engine inlet according to claim 1, characterized in that, It also includes an intake duct model connected to the main duct (1).

9. A simulation method using the dynamic hammer wave and surge wave simulation device for an aero-engine inlet as described in any one of claims 1 to 8, characterized in that, This includes methods for simulating single-impact waves and methods for simulating periodic surge waves; The single-wave hammer simulation method is as follows: First, rotate the rotatable hollow outer shaft (3) to align the second vent hole (31) with the first vent hole (21); then, the high-pressure gas supplied by the gas source triggers the pressure diaphragm (6) to rupture, and the high-pressure gas is injected into the main pipe (1) through the second vent hole (31); then, rotate the rotatable hollow outer shaft (3) again to rotate the second vent hole (31) and the first vent hole (21) to offset each other, thereby terminating the gas release and forming a single pressure pulse; The method for simulating the periodic surge wave is as follows: First, the rotatable hollow outer shaft (3) is accelerated to the target speed and kept rotating at the target speed; then, the high-pressure gas supplied by the gas source triggers the pressure diaphragm (6) to break open, and the high-pressure gas is continuously supplied to the fixed hollow inner shaft (2); during the constant rotation of the rotatable hollow outer shaft (3), the second vent hole (31) periodically passes over the first vent hole (21), thereby intermittently releasing high-pressure gas into the main pipe (1) and generating periodic surge pressure waves in the main pipe (1).

10. The simulation method according to claim 9, characterized in that, In the single hammer wave simulation method, after triggering the membrane rupture, there is a delay of about 2ms, and then the rotatable hollow outer shaft is rotated by a predetermined angle so that the two vent holes are completely offset.

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