Auxiliary power system hub containment test method

Abstract

The invention belongs to the field of aviation aircrafts, and particularly relates to an auxiliary power system hub containment test method which comprises the following steps: determining test control parameters; determining the most dangerous rotor; determining the working state of the auxiliary power system; determining hub gap parameters; determining a test criterion; modifying the auxiliary power system according to the test control parameters and the hub gap parameters; building a test bed according to the modified auxiliary power system; and carrying out an auxiliary power system hub containment test according to the hub failure rotating speed and the working state of the auxiliary power system, and judging a containment test result according to the test criterion. The method can be used for the complete machine hub containment test of the auxiliary power system, effective parameters are provided for design and manufacturing of the auxiliary power system, and therefore the safety of the auxiliary power system is improved.

Description

Technical Field

[0001] The present invention belongs to the field of aircraft, and particularly relates to a method for conducting a hub containment test on an auxiliary power system. Background Art

[0002] The main purpose of an Auxiliary Power Unit (APU) is to supply power without relying on ground equipment when the main engine is stopped. The APU is a complete independent system within the power plant, but it is integrated with the entire aircraft in terms of control. On modern large and medium-sized airliners, the APU is the main equipment to ensure the restart of the engine after an in-flight shutdown, and it directly affects the flight safety of the aircraft.

[0003] The APU needs to have the hub containment ability. Specifically, the auxiliary power system needs to meet the requirements of containing the maximum kinetic energy debris generated by the failure of the hub, the installation joints not failing, and no continuous external ignition occurring. Therefore, it is necessary to conduct a hub containment test on the auxiliary power system.

[0004] The existing containment test methods (such as Chinese Patent Application CN116776467A) are mainly for turbofan engines, while for turboshaft engines, it is for the containment of power turbine blades. The structure of a turboshaft engine is as Figure 1 shown in the figure. In the figure, 1 is the detached blade. After the blade of the turboshaft engine is lost, the rotor system will not be damaged. The detached blade directly impacts the outer casing of the engine, and there is an intermediate casing isolation between the failure part and the combustion rotor and the combustion chamber.

[0005] Currently, only the full-scale containment test of the blades of the turboshaft engine has been achieved, and the full-scale containment test of the hub of the auxiliary power system has not been realized.

[0006] A typical auxiliary power system is as Figure 2 shown in the figure. In the figure, 2 is the load compressor, 3 is the power compressor, 4 is the combustion chamber, 5 is the containment ring, and 6 is the turbine rotor. The structure of the auxiliary power system is different from that of the turboshaft engine. Specifically:

[0007] (1) The auxiliary power system has a single-rotor structure, and all rotors are compressed by a central tie rod.

[0008] (2) The auxiliary power system is hub containment. After the hub fails, the entire rotor loses axial restraint, and the response of other rotors cannot be predicted.

[0009] (3) The compressor of the auxiliary power system is made of titanium alloy, and titanium fire may occur after bursting and impacting the casing.

[0010] (4) The containment ring of the turbine rotor is directly below the combustion chamber. When the containment ring absorbs energy and deforms, it will rub against the combustion chamber, posing a risk of combustion chamber rupture and gas leakage, and even a risk of deflagration.

[0011] Since the structure of the auxiliary power system is different from that of the turboshaft engine, and the turboshaft engine is for the blade whole-engine containment test, with its failure mode and system response after failure being quite different from those of the APU hub failure; therefore, the containment test method for the turboshaft engine is not applicable to the auxiliary power system.

[0012] In view of this, the present invention is specifically proposed. Summary of the Invention

[0013] In order to solve the technical problems existing in the prior art, the present invention provides a method for the whole-engine hub containment test of an auxiliary power system. The method of the present invention can be used for the whole-engine hub containment test of the auxiliary power system, providing effective parameters for the design and manufacture of the auxiliary power system, thereby improving the safety of the auxiliary power system.

[0014] The present invention includes the following technical solutions:

[0015] The present invention provides a method for the hub containment test of an auxiliary power system, including the following steps:

[0016] Determine the test control parameters;

[0017] Determine the most dangerous-level rotor;

[0018] Determine the operating state of the auxiliary power system;

[0019] Determine the hub notch parameters;

[0020] Determine the test criteria;

[0021] Modify the auxiliary power system according to the test control parameters, the most dangerous-level rotor, and the hub notch parameters;

[0022] Build a test bench according to the modified auxiliary power system;

[0023] Conduct the hub containment test of the auxiliary power system according to the operating state of the auxiliary power system and the modified auxiliary power system, and judge the results of the containment test according to the test criteria.

[0024] Further, the hub failure speed is the highest speed caused by a single-point failure of the auxiliary power system.

[0025] Further, the most dangerous-level rotor is determined according to the maximum unbalanced load generated after the hub failure of each stage of the rotor, the harmful consequences generated by each stage of the rotor, and / or the containment coefficient of each stage of the rotor.

[0026] Further, the operating state of the auxiliary power system is the rated operating state of the auxiliary power system.

[0027] Furthermore, the hub notch parameters are determined according to the temperature, aerodynamic load, size, and material of the most dangerous-level rotor.

[0028] Furthermore, the hub notch parameters include the hub notch position and the hub notch depth.

[0029] Furthermore, the test criteria include: no continuous external fire occurs and the auxiliary power system casing is not penetrated.

[0030] Furthermore, modifying the auxiliary power system includes the following steps:

[0031] Modify the control logic of the control system of the auxiliary power system by test control parameters;

[0032] Grind the tip of each rotor of the auxiliary power system.

[0033] Furthermore, the test control parameters include the hub failure speed, the physical speed protection value, and the speed increase step value;

[0034] Among them, the hub failure speed is less than the physical speed protection value; the hub failure speed is the speed at which the disk ruptures in the containment test, the physical speed protection value is the maximum speed of the auxiliary power system in the containment test, and the speed increase step value is the set of speeds in the speed increase stage of the auxiliary power system in the containment test.

[0035] Furthermore, the construction of the test bench includes the following steps:

[0036] Fix the modified auxiliary power system on the mounting strut;

[0037] Set a protective cover outside the auxiliary power system.

[0038] Adopting the above technical solutions, the present invention has the following advantages:

[0039] 1. The method of the present invention provides effective parameters for the design and manufacture of the auxiliary power system through the whole-machine hub containment test of the most dangerous-level rotor of the auxiliary power system, thereby improving the safety of the auxiliary power system.

[0040] 2. The method for the whole-machine hub containment test of the auxiliary power system of the present invention can successfully implement the whole-machine hub containment test of the auxiliary power device to fill the blank of the hub containment test.

[0041] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained by the structure pointed out in the specification and the drawings. Description of the Drawings

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0043] Figure 1 It is a schematic structural diagram of a turboshaft engine in the background art;

[0044] Figure 2 It is a schematic structural diagram of an auxiliary power system;

[0045] Figure 3 It is a flowchart of a method for a hub containment test of an auxiliary power system in an embodiment of the present invention;

[0046] Figure 4 It is a schematic structural diagram of a hub in an embodiment of the present invention;

[0047] Figure 5 It is a schematic structural diagram of a rotor in an embodiment of the present invention;

[0048] In the figure, 1 - shed blade, 2 - load compressor, 3 - power compressor, 4 - combustion chamber, 5 - containment ring, 6 - turbine rotor, 7 - hub, 71 - notch. Specific Embodiments

[0049] The following description provides many different embodiments or examples for implementing different features of the present invention. The elements and arrangements described in the following specific examples are only used to concisely express the present invention, and they are only examples and are not intended to limit the present invention.

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0051] This embodiment provides a method for a hub containment test of an auxiliary power system, as Figure 3 shown, including the following steps:

[0052] Determine the hub failure speed; determine the most dangerous stage rotor; determine the operating state of the auxiliary power system; determine the hub notch parameters; determine the test criterion. It should be noted that, Figure 1It is only a schematic diagram of an example. The actual order of determining the wheel hub failure speed, determining the most dangerous stage rotor, determining the operating state of the auxiliary power system, determining the wheel hub notch parameters, and determining the test criterion is uncertain; however, for the adjustment of the order, it is also necessary to ensure that the most dangerous stage rotor is determined before the wheel hub notch parameters are determined, because different most dangerous stage rotors will result in different determined wheel hub notch parameters.

[0053] Modify the auxiliary power system according to the most dangerous stage rotor and the wheel hub notch parameters; specifically, if in an auxiliary power system with a single rotor and a four-stage wheel hub, the most dangerous stage rotor is obtained, set a notch on the wheel hub of this most dangerous stage rotor, and there are no restrictions on the other three rotors. As Figure 4 shown, it is the wheel hub with a notch. In the figure, 7 is the wheel hub and 71 is the notch.

[0054] Build a test bench according to the modified auxiliary power system;

[0055] Conduct an auxiliary power system wheel hub containment test according to the wheel hub failure speed and the operating state of the auxiliary power system, and judge all the containment test results according to the test criterion. Specifically, the auxiliary power system operates at the wheel hub failure speed until the wheel hub ruptures; after the wheel hub ruptures, compare the state of the auxiliary power system with the test criterion. If the state of the auxiliary power system meets the test criterion, the wheel hub is contained; if the state of the auxiliary power system does not meet the test criterion, the wheel hub is not contained.

[0056] Furthermore, according to Article 6.8 "Inclusiveness" of the "Technical Standard for Gas Turbine Auxiliary Power System (APU)" (CTSO-C77b), the wheel hub failure speed is the highest speed caused by a single point failure of the auxiliary power system.

[0057] Furthermore, the most dangerous stage rotor is determined according to the maximum unbalanced load generated after the wheel hub failure of each stage rotor, the harmful consequences generated by each stage rotor, and / or the containment coefficient of each stage rotor. Exemplarily, if the auxiliary power system has four-stage rotors, and the maximum unbalanced loads generated after the failure of these four rotors are obtained respectively, the rotor corresponding to the maximum value of these four maximum unbalanced loads is the most dangerous stage rotor. The harmful consequences generated by each stage rotor include the harmful consequences of the failure of each stage device to the whole machine, such as deflagration, fuel and lubricating oil leakage, etc. The rotor with the most harmful consequences generated by each stage rotor is the most dangerous stage rotor. Exemplarily, if the auxiliary power system has four-stage rotors, and the containment coefficients of these four rotors at each stage are obtained respectively, the rotor with the smallest containment coefficient is the most dangerous stage rotor.

[0058] The maximum unbalanced load generated after the failure of the rotor hubs at all levels, the harmful consequences generated by the rotors at all levels, and / or the containment coefficients of the rotors at all levels can be separately used to determine the most dangerous-level rotor, or can be used simultaneously for determination, which improves the accuracy of determination.

[0059] Further, the operating state of the auxiliary power system is the rated operating state of the auxiliary power system.

[0060] Further, the hub notch parameters are determined according to the temperature, aerodynamic load, size, and material of the most dangerous-level rotor. It should be noted that the size should be understood as a set of data that can enable those skilled in the art to manufacture the rotor, such as the length, width, diameter, rotational degree, etc. of the rotor marked on the engineering drawing.

[0061] Further, the hub notch parameters include the hub notch position and the hub notch depth.

[0062] Further, the test criteria include: no continuous external ignition and no penetration of the auxiliary power system casing.

[0063] Further, the modification of the auxiliary power system includes the following steps:

[0064] Modify the control logic of the control system of the auxiliary power system through test control parameters; by setting the control logic, the automation of the containment test can be realized, which has the advantages of improving the accuracy and efficiency of the test.

[0065] Because the hub failure speed is higher than the actual operating speed of the auxiliary dynamic system, in order to avoid the stator rubbing of the auxiliary power system during the test and affecting the test; so the tip of each rotor of the auxiliary power system is ground; as Figure 5 shown, a in the figure indicates the position of the tip grinding; it should be noted that how to specifically grind the tip is known to those skilled in the art and will not be elaborated here in detail.

[0066] Further, the test control parameters include the hub failure speed, the physical speed protection value, and the speed increase step value; wherein, the hub failure speed is less than the physical speed protection value; the hub failure speed is the speed at which the wheel disc ruptures in the containment test, the physical speed protection value is the maximum speed of the auxiliary power system in the containment test, and the speed increase step value is the set of speeds in the speed increase stage of the auxiliary power system in the containment test. By setting the speed increase step value, the speed of the auxiliary power system is slowly increased during the test, ensuring the stability of the auxiliary power system, which has the advantage of improving the accuracy of the test.

[0067] If resonance surge occurs in the rotor during the test, it will cause the auxiliary power system to fail to work. Therefore, preferably, the rotational speed increase step value is not equal to the resonance rotational speed of any rotor to avoid resonance surge of the rotor.

[0068] During the containment test, the control logic controls the rotational speed of the auxiliary power system to climb according to the rotational speed increase step value until the rotational speed of the auxiliary power system reaches the hub failure speed.

[0069] During the containment test, the disk of the most dangerous stage rotor of the auxiliary power system experiences hub rupture at the hub failure speed; according to the test criterion, all containment test results are judged, and the containment test is ended.

[0070] Exemplarily, taking the auxiliary power system with a four-stage rotor as an example, if the most dangerous stage rotor is the fourth-stage rotor, the hub failure speed (single-point failure of the control system) for the containment test is 50,000 r / min, and the actual operating speed of the auxiliary power system is 45,000 r / min. Then, the rupture speeds of the hubs corresponding to each stage rotor are analyzed as N1, N2, N3, and N4 respectively, where N4 is the rupture speed of the hub corresponding to the most dangerous stage rotor (the fourth-stage rotor), and N1, N2, and N3 are all greater than N4. Then, the physical rotational speed protection value is Nr, and N4 + A < Nr < min(95%(N1, N2, N3)). Exemplarily, A = 2,000 r / min, and the rotational speed during the test preferably does not exceed the physical rotational speed protection value. The resonance rotational speeds of each stage rotor are analyzed as N11, N22, N33, and N44, and the rotational speed during the rotational speed increase stage of the test needs to avoid staying at the resonance rotational speed; then, the rotational speed increase steps can be n1, n2, n3, n4, n5, where n1 < n2 < n3 < n4 < n5 < 50,000 r / min, and n1, n2, n3, n4, and n5 are not equal to any one of N11, N22, N33, and N44; during the containment test, after the rotational speed of the auxiliary power system reaches the operating speed (45,000 r / min), it gradually climbs to 50,000 r / min according to n1, n2, n3, n4, and n5.

[0071] Furthermore, the test control parameters further include a temperature alarm limit value, a fuel alarm limit value, a lubricating oil alarm limit value, and a vibration alarm limit value; during the test, if any of the temperature, fuel, lubricating oil, and vibration exceeds the limit value, an alarm will be issued, thereby terminating the test, which has the advantage of specifically improving the test safety.

[0072] Furthermore, the auxiliary dynamic installation further includes the following steps:

[0073] Arrange thermocouples and strain gauges on the stator components of the hub rupture load transfer path, observe the response of the stator system of the auxiliary power system after the hub ruptures, obtain the temperature distribution and load magnitude during the test, and provide inputs for subsequent designs.

[0074] Further, the construction of the test bench includes the following steps:

[0075] Fix the modified auxiliary power system on the mounting struts; the installation method of the auxiliary power system should simulate the typical nacelle installation form, and the stiffness of each mounting strut should be consistent with the actual one.

[0076] Set up a protective cover outside the auxiliary power system to improve the safety of the test.

[0077] Further, the construction of the test bench also includes the following steps:

[0078] Set up a debris collection device at the exhaust port for collecting debris;

[0079] Set up a high-speed camera for recording the test process. This is convenient for tracing back the test process in order to improve the test and obtain more accurate test results.

[0080] The walls of the test room should meet the inclusiveness requirements to prevent high-energy debris that may fly out during the test from piercing the walls and causing casualties to the test personnel.

[0081] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a connection that allows mutual communication; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside multiple components or the interaction relationship between multiple components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0082] In the description of the present invention, it should be understood that all terms indicating orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as a limitation of the present invention.

[0083] Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing the wheel hub containment of an auxiliary power system, characterized in that: The steps include: Determine test control parameters; Determine the most dangerous rotor; Determine the auxiliary power system operating status; Determine the hub gap parameters; Determine the test criteria; Modifying the auxiliary power system according to the test control parameters, the most dangerous rotor and the hub gap parameters; The test bench is constructed according to the modified auxiliary power system; An auxiliary power system wheel hub containment test is performed according to the auxiliary power system working state and the modified auxiliary power system, and the containment test result is judged according to the test criterion.

2. The auxiliary power system hub containment test method according to claim 1, characterized in that: The hub failure speed is the maximum speed caused by a single point failure of the auxiliary power system.

3. According to the auxiliary power system hub containment test method described in claim 1, the most dangerous level rotor is determined based on the maximum unbalanced load generated after the failure of each level of the rotor hub, the harmful consequences generated by each level of the rotor and / or the containment coefficient of each level of the rotor.

4. The auxiliary power system hub containment test method according to claim 1, characterized in that: The auxiliary power system operating state is the rated operating state of the auxiliary power system.

5. The auxiliary power system hub containment test method according to claim 1, characterized in that: The hub gap parameters are determined according to the temperature, aerodynamic load, size and material of the most dangerous rotor.

6. The auxiliary power system hub containment test method according to claim 5, characterized in that: The hub gap parameters include the hub gap position and the hub gap depth.

7. The auxiliary power system hub containment test method according to claim 1, characterized in that: The test criteria include: no sustained external fire and no penetration of the auxiliary power system casing.

8. The auxiliary power system hub containment test method according to claim 1, characterized in that: Modification of the auxiliary power system includes the following steps: Modify the control logic of the control system of the auxiliary power system by testing control parameters; Grind the blade tips of each rotor of the auxiliary power system.

9. The auxiliary power system hub containment test method according to claim 8, characterized in that: The test control parameters include hub failure speed, physical speed protection value, and speed boost step value; Among them, the wheel hub failure speed is less than the physical speed protection value; the wheel hub failure speed is the speed that causes the wheel disc to rupture in the containment test, the physical speed protection value is the maximum speed of the auxiliary power system in the containment test, and the speed boost step value is the speed set of the auxiliary power system speed boost stage in the containment test.

10. The auxiliary power system hub containment test method according to claim 1, characterized in that: The test bench construction includes the following steps: Fix the modified auxiliary power system on the mounting bracket; A protective cover is provided outside the auxiliary power system.

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