Coupling type critical rotation speed optimization method based on rigidity-adjustable interstage supporting structure

Abstract

The invention belongs to the field of aviation dynamics design, and particularly relates to a coupling type critical rotation speed optimization method based on an adjustable rigidity interstage supporting structure. The method comprises the following steps: step 1, carrying out rotor dynamics analysis on a double-rotor system, judging whether a coupling type criticality exists in a working rotating speed range of the double-rotor system, and if so, entering step 2; 2, the installation position and the initial rigidity parameter of the interstage supporting structure are determined; step 3, adjusting a stiffness parameter of an interstage support structure by taking reduction of the strain energy ratio of the excitation rotor and the interstage bearing as a target, and performing rotor dynamics analysis on the adjusted dual-rotor system; and 4, according to the rotor dynamics analysis result of the adjusted double-rotor system, judging whether the strain energy ratio of the excitation rotor and the interstage bearing meets the harmless critical standard, if not, returning to the step 3, and if yes, obtaining the interstage support structure meeting the harmless critical standard. The optimization space is large, and the workload is remarkably reduced.

Description

Technical Field

[0001] The present application belongs to the field of aerodynamic design, and in particular relates to a coupled critical speed optimization method based on an adjustable stiffness interstage support structure. Background Art

[0002] In aircraft engines and gas turbines, dynamic design often faces the critical speed of the two-rotor coupling type within the operating speed range. This type of critical speed is specifically manifested as: the strain energy of the exciting rotor and the interstage bearing (intermediate bearing) accounts for a high proportion. According to industry standards, this type of critical speed is a harmful critical speed, which can easily lead to serious vibration problems and bearing damage in the engine. It is a critical speed that must be targeted for optimization design.

[0003] At present, only some theoretical research has been carried out on the optimization of the coupled critical speed of the dual-rotor system, and there is a lack of effective methods for the optimization of the coupled critical speed of the dual-rotor system. In order to solve the problem of insufficient margin of the coupled critical speed of the dual-rotor system, the industry usually chooses the conventional solution of reducing the weight of the rotor and the turntable, increasing the stiffness of the shaft section, and increasing the stiffness of the support point, with the aim of increasing the critical speed of this order to meet the margin requirements. However, in general, the weight reduction solution is not conducive to the strength reserve of the components, and the strength reserve of the components needs to be compressed. The scheme of changing the stiffness of the shaft section and the support point is limited by the weight and geometric size requirements of the engine, and the optimization space is very limited, and the optimization cost is high. In addition, in the optimization process, it is necessary not only to carry out the calculation of the rotor dynamics, but also to carry out the iterative analysis and calculation of the strength of multiple components (including blades, disks, shafts and other key components). In summary, the conventional weight reduction and adjustment of the shaft section and support stiffness scheme has a small overall benefit and a large iterative workload, which greatly restricts the optimization design of the engine rotor dynamics. It is urgent to establish a fast optimization method for the coupled critical speed of the two rotors.

[0004] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned defects of the prior art. Summary of the invention

[0005] The purpose of the present application is to provide a coupled critical speed optimization method based on an adjustable stiffness interstage support structure to solve at least one problem existing in the prior art.

[0006] The technical solution of this application is:

[0007] A coupled critical speed optimization method based on an adjustable stiffness interstage support structure comprises:

[0008] Step 1: Perform rotor dynamics analysis on the dual-rotor system to determine whether there is a coupling criticality within the operating speed range of the dual-rotor system. If so, proceed to step 2;

[0009] Step 2: Determine the installation position and initial stiffness parameters of the interstage support structure;

[0010] Step 3: With the goal of reducing the strain energy ratio of the excitation rotor and the interstage bearing, the stiffness parameters of the interstage support structure are adjusted, and the rotor dynamics analysis of the adjusted dual-rotor system is performed;

[0011] Step 4: According to the rotor dynamics analysis results of the adjusted dual-rotor system, determine whether the strain energy ratio of the excitation rotor and the interstage bearing meets the harmless critical standard. If not, return to step 3. If so, obtain the interstage support structure that meets the harmless critical standard.

[0012] In at least one embodiment of the present application, in step 2, determining the installation position and initial stiffness parameters of the interstage support structure includes:

[0013] The installation position of the interstage support structure is located on the non-excited rotor of the coupled critical type;

[0014] The initial stiffness of the interstage support structure is a median value of the stiffness adjustment range.

[0015] In at least one embodiment of the present application, the interstage support structure has an L-shaped cross-section and includes a first support portion and a second support portion, wherein the first support portion is fixedly connected to the non-excited rotor, and the second support portion is fixedly connected to the outer ring of the interstage bearing.

[0016] In at least one embodiment of the present application, the first support portion is fixedly connected to the non-excited rotor by bolts.

[0017] In at least one embodiment of the present application, in step three, the stiffness parameters of the interstage support structure are adjusted by adjusting the length, width and / or thickness of the first support portion and / or the second support portion.

[0018] In at least one embodiment of the present application, the method further includes step five, designing the structural parameters of the dual-rotor system according to the interstage support structure of the harmless criticality standard and performing strength verification.

[0019] The invention has at least the following beneficial technical effects:

[0020] The coupled critical speed optimization method based on the adjustable stiffness interstage support structure of the present application is easy to achieve the optimal design of the coupled critical speed by adjusting the stiffness of the interstage support structure, because the coupled critical speed is most sensitive to the stiffness near the interstage bearing, and the optimization space is large; the optimization process only involves the adjustment of the cage bar parameters of the interstage support structure, so it will not reduce the strength reserve of key components such as blades, disks, and shafts, and there is no need to carry out iterative strength analysis and calculation of multiple components. It only needs to refer to the squirrel cage spring support strength design method to carry out the strength design work of the interstage support structure, and the workload is significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of a coupled critical speed optimization method based on an adjustable stiffness interstage support structure according to an embodiment of the present application;

[0022] Figure 2 It is a schematic diagram of a dual-rotor system with an interstage support structure according to an embodiment of the present application.

[0023] in:

[0024] 1-Excited rotor; 2-Non-excited rotor; 3-Interstage bearing; 4-Interstage support structure. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0026] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present application.

[0027] The following is combined with Figure 1 to Figure 2 This application is described in further detail.

[0028] The present application provides a coupled critical speed optimization method based on an adjustable stiffness interstage support structure, comprising the following steps:

[0029] Step 1: Perform rotor dynamics analysis on the dual-rotor system to determine whether there is a coupling criticality within the operating speed range of the dual-rotor system. If so, proceed to step 2.

[0030] Step 2: Determine the installation position and initial stiffness parameters of the interstage support structure;

[0031] Step 3: With the goal of reducing the strain energy ratio of the exciting rotor and the interstage bearing, the stiffness parameters of the interstage support structure are adjusted, and the rotor dynamics analysis of the adjusted dual-rotor system is performed;

[0032] Step 4: According to the rotor dynamics analysis results of the adjusted dual-rotor system, determine whether the strain energy ratio of the excitation rotor and the interstage bearing meets the harmless critical standard. If not, return to step 3. If so, obtain the interstage support structure that meets the harmless critical standard.

[0033] The coupled critical speed optimization method based on the adjustable stiffness interstage support structure of this application firstly, in step 1, the rotor dynamics analysis of the initial scheme of the dual-rotor system is carried out. The critical speed, vibration mode, and strain energy ratio are extracted, and according to the strain energy distribution calculation results, it is judged whether there is a coupled criticality within the working speed range in reference to the design standard. If there is no coupled criticality, the coupled criticality optimization design is not carried out. If there is a coupled criticality, the next step needs to be carried out.

[0034] In the coupled critical speed optimization method based on the adjustable stiffness interstage support structure of the present application, in step 2, the installation position and initial stiffness parameters of the interstage support structure are determined. The interstage support structure installation position is selected according to the specific structural characteristics of the dual-rotor system. It is recommended to select the installation on the coupled critical non-excited rotor. The initial stiffness is recommended to select the median value of the interstage support structure stiffness adjustment range to ensure that the stiffness parameters can be adjusted up and down. In the preferred embodiment of the present application, the dual-rotor system with an interstage support structure is as follows Figure 2 As shown, the system includes an excited rotor 1, a non-excited rotor 2, an interstage bearing 3 and an interstage support structure 4. The interstage support structure 4 has an L-shaped cross section and includes a first support portion and a second support portion. The first support portion is fixedly connected to the non-excited rotor 2, and the second support portion is fixedly connected to the outer ring of the interstage bearing 3. The interstage support structure 4 can be fixed to the non-excited rotor 2 by bolt connection and rotates together with the non-excited rotor 2. The inner ring of the interstage bearing 3 is fixed to the excited rotor 1 and rotates together with the excited rotor 1.

[0035] The coupled critical speed optimization method based on the adjustable stiffness interstage support structure of the present application, in step three, analyzes the relationship between the stiffness parameter adjustment of the interstage support structure and the change in the strain energy distribution of the coupled critical speed, adjusts the stiffness parameters of the interstage support structure with the goal of reducing the strain energy proportion of the exciting rotor and the interstage bearing, and conducts rotor dynamics analysis of the adjusted scheme. In a preferred embodiment of the present application, the stiffness parameters of the interstage support structure are adjusted by adjusting the length, width and / or thickness of the first support part and / or the second support part. By means of adjusting the stiffness of the interstage support structure, the strain energy distribution of the system is adjusted, the strain energy proportion of the exciting rotor and the interstage bearing is reduced, and the coupled vibration mode in which the exciting rotor participates is adjusted to the non-exciting rotor vibration mode, that is, the harmful coupled critical is adjusted to the harmless critical.

[0036] Furthermore, in the coupled critical speed optimization method based on the adjustable stiffness interstage support structure of the present application, in step four, according to the rotor dynamics analysis results of the adjusted scheme, it is judged whether the strain energy ratio of the exciting rotor and the interstage bearing meets the harmless critical standard. If not, it is necessary to return to the previous step to continue adjusting the stiffness parameters of the interstage support structure until the harmless critical standard is met. If it is met, the interstage support structure that meets the harmless critical standard is obtained.

[0037] The coupled critical speed optimization method based on the adjustable stiffness interstage support structure of the present application also includes step 5, designing the structural parameters of the dual-rotor system according to the interstage support structure of the harmless critical standard and conducting strength verification. Here, the squirrel cage spring support design method can be referred to to complete the structural design. After the strength verification is completed, the solidified optimized solution is obtained, and the optimization design work is completed.

[0038] The coupled critical speed optimization method based on the adjustable stiffness interstage support structure of the present application adds an interstage support structure at the interstage bearing position of the original dual-rotor system. The interstage support structure adopts a structural scheme similar to the squirrel-cage elastic support. By adjusting the cage bar parameters (the length, width, thickness, etc. of the first support part and the second support part), a wide range adjustment of the stiffness can be achieved (usually arbitrary adjustment of the stiffness within one order of magnitude can be achieved).

[0039] The coupled critical speed optimization method based on the adjustable stiffness interstage support structure of the present application has the following advantages:

[0040] 1. Since the coupled critical speed is most sensitive to the stiffness near the interstage bearing, it is easy to achieve the optimal design of the coupled critical speed by adjusting the stiffness of the interstage support structure, and there is a large optimization space;

[0041] 2. Since the optimization process only involves the adjustment of the cage bar parameters of the interstage support structure, the strength reserve of key components such as blades, disks, and shafts will not be reduced, and there is no need to carry out iterative strength analysis and calculation of multiple components. It is only necessary to refer to the squirrel cage elastic support strength design method to carry out the strength design of the interstage support structure, which significantly reduces the workload.

[0042] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A coupled critical speed optimization method based on an adjustable stiffness interstage support structure, characterized in that: include: Step 1: Perform rotor dynamics analysis on the dual-rotor system to determine whether there is a coupling criticality within the operating speed range of the dual-rotor system. If so, proceed to step 2; Step 2: Determine the installation position and initial stiffness parameters of the interstage support structure; Step 3: With the goal of reducing the strain energy ratio of the excitation rotor and the interstage bearing, the stiffness parameters of the interstage support structure are adjusted, and the rotor dynamics analysis of the adjusted dual-rotor system is performed; Step 4: According to the rotor dynamics analysis results of the adjusted dual-rotor system, determine whether the strain energy ratio of the excitation rotor and the interstage bearing meets the harmless critical standard. If not, return to step 3. If so, obtain the interstage support structure that meets the harmless critical standard.

2. The coupled critical speed optimization method based on the adjustable stiffness interstage support structure according to claim 1 is characterized in that: In step 2, the installation position and initial stiffness parameters of the interstage support structure are determined, including: The installation position of the interstage support structure is located on the non-excited rotor of the coupled critical type; The initial stiffness of the interstage support structure is a median value of the stiffness adjustment range.

3. The coupled critical speed optimization method based on the adjustable stiffness interstage support structure according to claim 2 is characterized in that: The interstage support structure has an L-shaped cross section and comprises a first support portion and a second support portion, wherein the first support portion is fixedly connected to the non-excited rotor, and the second support portion is fixedly connected to the outer ring of the interstage bearing.

4. The coupled critical speed optimization method based on the adjustable stiffness interstage support structure according to claim 3 is characterized in that: The first support portion is fixedly connected to the non-excited rotor by bolts.

5. The coupled critical speed optimization method based on the adjustable stiffness interstage support structure according to claim 3 is characterized in that: In step three, the stiffness parameters of the inter-stage support structure are adjusted by adjusting the length, width and / or thickness of the first support portion and / or the second support portion.

6. The coupled critical speed optimization method based on an adjustable stiffness interstage support structure according to claim 1 is characterized in that: It also includes step five, designing the structural parameters of the dual-rotor system according to the interstage support structure of the harmless criticality standard and carrying out strength verification.

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