A method for calculating rotor axial force based on the physical condition of an aero-engine

Abstract

This application provides a method for calculating rotor axial force based on the actual condition of an aero-engine, belonging to the field of aero-engine technology. The method includes: acquiring the boundary cavities and associated boundaries of each flow path in the air system; calculating the similarity coefficient between the design pressure of each cavity and the design pressure of the associated boundary at different conversion speeds; calculating the theoretical test pressure of the cavity based on the similarity coefficient; conducting sensitivity analysis on the changes in grate clearance and chamber pressure to obtain the relationship between the cavity pressure correction coefficient and the grate clearance deviation for each grate in each cavity; calculating the average change in pressure of each cavity relative to its own design value under the change in grate clearance, and determining whether there is a correlation between cavity pressure and grate clearance; and calculating the actual pressure of each cavity based on the correlation determination results, the theoretical test pressure of the cavity, and the relationship, further obtaining the rotor axial force under the current grate clearance. This application considers the grate clearance, improving the accuracy of axial force assessment.

Description

Technical Field

[0001] This application relates to the field of aero-engine technology, and in particular to a method for calculating rotor axial force based on the physical condition of an aero-engine. Background Technology

[0002] When calculating the axial force of an aero-engine rotor, the total axial force can be considered as the sum of the axial force in the flow channel and the axial force in the cavity. The cavity axial force is the axial load generated by the interaction between the airflow pressure and the structure within each cavity of the engine, and its magnitude is mainly affected by factors such as the clearance of the cavity sealing grates and the size of the cavity. In actual engines, due to manufacturing and assembly factors, the cold-state clearance of throttling elements such as grates often has a certain deviation, causing them not to operate at the designed clearance. Simultaneously, during different stages of engine commissioning and operation, the mainstream performance parameters will also change slightly, and the bleed and exhaust pressures in the rotor cavity flow path will also change, thus causing the rotor cavity pressure to deviate from the design value to a certain extent. Changes in cavity pressure will cause changes in the actual axial force of the engine, which in severe cases may lead to a deviation of the actual axial force from the design value, resulting in extreme consequences such as reverse axial force and bearing overload / underload.

[0003] Currently, methods for calculating axial force are mainly divided into empirical formula methods, finite element / numerical simulation methods, and data coupling methods. Patent CN118153238A, "A Method and System for Aerodynamic Axial Force Analysis of Aero-engines Based on Data Coupling," ensures the matching of upstream and downstream professional data through data coupling verification and analysis calculations, improving the efficiency and reliability of aerodynamic axial force analysis. However, this method suffers from drawbacks such as strong subjectivity in threshold setting, high model accuracy requirements, and large computational resource demands. Patent CN114692309B, "A Real-time Calculation Method for Axial Force of Low-Pressure Turbine Rotor of Aero-engine," selects parameters strongly correlated with the axial force of the low-pressure turbine rotor flow channel and, combined with experimental data, constructs and corrects the axial force calculation model of the flow channel and internal cavity. This method has good real-time performance, but the calculation model is complex and requires large real-time computational resources.

[0004] Meanwhile, none of the above methods take into account the impact of the actual change in the gap between the engine teeth relative to the design value on the axial force calculation. The calculation results deviate from the actual values ​​and cannot meet the requirements for axial force assessment and debugging before the test. Summary of the Invention

[0005] In view of this, embodiments of this application provide a method for calculating the rotor axial force based on the actual condition of an aero-engine. The theoretical value of the chamber pressure is determined by using the similarity relationship between the chamber pressure design value and the boundary conditions. Based on the theoretical value, the actual chamber pressure can be obtained by correcting the chamber pressure using the actual tooth clearance. The axial force of the engine rotor is then calculated based on the obtained actual chamber pressure.

[0006] This application provides a method for calculating the rotor axial force based on the physical condition of an aero-engine, including:

[0007] Based on the design network diagram of the aero-engine air system, obtain the boundary disks of each flow path in the air system and the corresponding associated boundaries of each disk. Calculate the similarity coefficient between the design pressure of each disk cavity and the design pressure of the corresponding associated boundary of the disk cavity under different conversion speeds; For each disc cavity, the theoretical test pressure of the disc cavity is calculated based on the similarity coefficient; Based on air system engineering analysis software, sensitivity analysis was conducted on the flow rate and chamber pressure changes of the corresponding flow path when the gap of each grate tooth changed, and the relationship between the chamber pressure correction coefficient and the grate tooth gap deviation value of each grate tooth in each disc cavity was obtained. Based on the aforementioned formula, calculate the average change in pressure in each chamber relative to its own design value under a preset gap change in the sieve teeth; Based on the average change, determine whether there is a correlation between the cavity pressure and the tooth clearance; Based on the correlation judgment results, the theoretical pressure of the disc cavity test, and the aforementioned relationship, the actual pressure of each disc cavity is calculated. The rotor axial force of the engine under the current tooth clearance is calculated based on the actual pressure of each cavity.

[0008] According to a specific implementation of an embodiment of this application, the boundary cavity is located at the intake boundary or the exhaust boundary, and the associated boundary is the boundary with the weakest throttling effect between the cavity and the boundary.

[0009] According to a specific implementation of an embodiment of this application, the expression for the similarity coefficient is: , in, Design pressure for cavity A, Design pressure for the boundary of cavity A. The similarity coefficients are calculated for different rotational speeds.

[0010] According to a specific implementation of an embodiment of this application, the expression for the theoretical pressure of the disc cavity test is: , in, The theoretical pressure for cavity A is given. This represents the actual pressure at the associated boundary.

[0011] According to a specific implementation of this application, obtaining the relationship between the cavity pressure correction coefficient and the tooth gap deviation value corresponding to each tooth in each disk cavity includes: Set the preset gap variation of the comb teeth; For each tooth in each disc cavity, calculate the cavity pressure correction coefficient and tooth gap deviation value of each tooth gap when the tooth gap changes under the preset gap change amount. A polynomial fitting function is constructed, and the polynomial fitting function is solved based on the cavity pressure correction coefficients and the deviation values ​​of the tooth gaps under multiple sets of tooth gaps to obtain the relationship.

[0012] According to a specific implementation of this application, the expression for the cavity pressure correction coefficient is: , The expression for the deviation value of the tooth gap is: , The expression for the polynomial fitting function is: , in, P is the cavity pressure correction coefficient corresponding to the i-th tooth of cavity A. A The pressure in the lower cavity of the tooth gap is output by the air system engineering analysis software. Let be the deviation value of the gap between the i-th tooth ferrules. Let be the actual clearance of the i-th tooth. The design clearance for the i-th tooth is given by 'a', where 'a' is the first coefficient and 'b' is the second coefficient.

[0013] According to a specific implementation of an embodiment of this application, determining whether there is a correlation between the disk cavity pressure and the tooth gap based on the average change includes: The expression for the average change is: , Wherein, β is the average change; When the gap between the teeth changes by a preset amount, if the average change is no greater than 0.01%, it is determined that there is no correlation between the pressure in the cavity and the gap between the teeth; if the average change is greater than 0.01%, it is determined that there is a correlation between the pressure in the cavity and the gap between the teeth.

[0014] According to a specific implementation of an embodiment of this application, the expression for the actual pressure of each disc cavity is: , in, Let A be the actual pressure, and k be the number of grates that are correlated with the pressure in the disk cavity. This is the correction factor for the actual cavity pressure.

[0015] According to a specific implementation of an embodiment of this application, the step of calculating the rotor axial force of the engine under the current grate tooth clearance based on the actual pressure of each disc cavity includes: For each disc cavity, the total axial force of the rotor cavity is calculated based on the actual pressure of the disc cavity and the cavity area. The rotor axial force is obtained from the total axial force in the rotor cavity and the axial force in the rotor flow channel.

[0016] According to a specific implementation of an embodiment of this application, the total axial force of the rotor cavity is expressed as follows: , The expression for the rotor axial force is: , Among them, AS X Let F be the cavity area of ​​the Xth cavity. 容腔 F is the total axial force in the rotor cavity. 流道 denoted as axial force in the rotor flow channel, and F is the rotor axial force.

[0017] Beneficial effects: The rotor axial force calculation method based on the actual state of an aero-engine in this embodiment fully utilizes the similarity relationship between the boundary disk pressure of the air system and the associated disks. Through sensitivity analysis, it obtains the characteristic relationship between each grate clearance and the cavity pressure, reflecting the change of cavity pressure with the grate clearance. This method offers high calculation accuracy, and the obtained rotor axial force more closely matches the axial force of the engine during actual operation. Furthermore, this method establishes the characteristic relationship between the grate clearance and the cavity pressure, allowing for rapid assessment of the impact of the current grate clearance on the axial force during each assembly / disassembly process, facilitating adjustments to the axial force. This method eliminates the need for monitoring and measuring the pressure of each disk, reducing the number of pressure measurement points and significantly lowering the difficulty of bench testing. Therefore, this invention can be widely applied to the calculation of rotor axial force during the research and testing phase of aero-engines and gas turbines, quickly and accurately evaluating the rotor axial force under the actual grate clearance value without increasing the difficulty of bench testing. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of a rotor axial force calculation method based on the physical state of an aero-engine according to an embodiment of the present invention; Figure 2This is a partial view of the air system flow path according to an embodiment of the present invention; Figure 3 This is another flowchart of a method for calculating rotor axial force based on the physical condition of an aero-engine according to an embodiment of the present invention. Detailed Implementation

[0020] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0021] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0023] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0024] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0025] This application provides a method for calculating the rotor axial force based on the physical condition of an aero-engine, which will be described in detail below with reference to the figures.

[0026] This application provides a method for calculating the rotor axial force based on the physical condition of an aero-engine, including: Step S101: Based on the design network diagram of the aero-engine air system, obtain the boundary disks of each flow path in the air system and the corresponding associated boundaries of each disk. Step S102: Calculate the similarity coefficient between the design pressure of each disk cavity and the design pressure of the corresponding associated boundary of the disk cavity under different conversion speeds; Step S103: For each disc cavity, calculate the theoretical test pressure of the disc cavity based on the similarity coefficient; Step S104: Based on air system engineering analysis software, conduct sensitivity analysis on the flow rate and chamber pressure changes of the corresponding flow path when the gap of each grate tooth changes, and obtain the relationship between the chamber pressure correction coefficient and the grate tooth gap deviation value corresponding to each grate tooth in each disc cavity. Step S105: According to the above formula, calculate the average change of pressure in each chamber relative to its own design value under the preset gap change of the sieve teeth; Step S106: Based on the average change, determine whether there is a correlation between the disk cavity pressure and the tooth gap; Step S107: Based on the correlation judgment results, the theoretical pressure of the disc cavity test, and the aforementioned relationship, calculate the actual pressure of each disc cavity; Step S108: Calculate the rotor axial force of the engine under the current tooth gap based on the actual pressure of each disc cavity.

[0027] In this embodiment, by introducing a similarity coefficient and a cavity pressure correction coefficient, pressure conversion from the design state to the actual state is achieved. This effectively reflects the impact of changes in the grate tooth clearance on the cavity pressure, thereby improving the accuracy of rotor axial force calculation. Simultaneously, sensitivity analysis based on aero-systems engineering analysis software provides reliable data support for obtaining the correction coefficient, making the calculation process more closely reflect the actual operating conditions of the engine. This provides important theoretical basis for the structural design optimization and fault diagnosis of aero-engines.

[0028] Furthermore, depending on the throttling position of the flow path, each rotor disk cavity can be associated with a corresponding boundary. The associated boundary is the boundary with the weakest throttling effect between the disk cavity and the boundary. The boundary disk cavity is located at the intake boundary or the exhaust boundary.

[0029] Furthermore, at a certain converted speed, under the designed grate working clearance, there is a certain similarity between the pressure in the rotor disk cavity and the bleed (or exhaust) boundary. Based on the air system design parameters, i.e., under different speed conditions... , Given that the calculation is performed at different conversion speeds... A similarity relationship lookup table is established. The expression for the similarity coefficient is: , in, Design pressure for cavity A, Design pressure for the boundary of cavity A. The similarity coefficients are calculated for different rotational speeds.

[0030] Furthermore, the main difference between the theoretical and design values ​​of the disk cavity pressure lies in the deviation caused by the difference in intake / exhaust boundary conditions. This difference may be due to factors such as intake conditions, compression component efficiency, and turbine throat area matching. These boundary pressures can be easily obtained from the experimental database. The experimental theoretical value of the disk cavity pressure can then be obtained using the following formula: , in, The theoretical pressure for cavity A is given. The actual pressure at the associated boundary (obtained from experimental data) is the theoretical pressure of cavity A determined in this step. The effect of the gap between the tooth ridges has not yet been considered.

[0031] Furthermore, step S104 is independent of steps S102 and S103 and can be performed simultaneously. Based on the main design parameters of the air system grate elements, the upstream and downstream pressures of each grate element, the mass flow rate through the grate element, and the pressure of each chamber at the design point, the air system engineering analysis software is used to conduct sensitivity analysis on the flow rate of the corresponding flow path and the pressure change of the chamber when the gap of each grate element changes. The range of grate gap analysis variation is not less than twice the drawing tolerance range, and the change amount is taken as 0.02mm each time (the value can be reasonably taken according to different engines). When the grate gap changes, the pressure of the relevant chamber will also change.

[0032] Specifically, obtaining the relationship between the cavity pressure correction coefficient and the tooth gap deviation value corresponding to each tooth in each cavity includes: Set the preset gap variation of the comb teeth; For each tooth in each disc cavity, calculate the cavity pressure correction coefficient and tooth gap deviation value of each tooth gap when the tooth gap changes under the preset gap change amount. A polynomial fitting function is constructed, and the polynomial fitting function is solved based on the cavity pressure correction coefficients and the deviation values ​​of the tooth gaps under multiple sets of tooth gaps to obtain the relationship.

[0033] In practice, when the gap between the grates changes, the pressure in the relevant chambers will also change. For example, if the gap between a certain grating tooth S... X Gap variation At that time, the correction factor for the pressure change in chamber A is Then we have: , The expression for the cavity pressure correction coefficient is: , The expression for the deviation value of the tooth gap is: , The expression for the polynomial fitting function is: , in, P is the cavity pressure correction coefficient corresponding to the i-th tooth of cavity A. A The pressure in the lower cavity of the tooth gap is output by the air system engineering analysis software. This represents the clearance deviation of the i-th tooth, in mm, applicable within twice the tolerance range. Let be the actual clearance of the i-th tooth. The design clearance for the i-th tooth is given by 'a', where 'a' is the first coefficient and 'b' is the second coefficient.

[0034] For the polynomial fitting function, according to The calculation formula can be used to obtain the cavity pressure correction coefficient under different tooth gaps. , Given the given information, by fitting a polynomial, the values ​​of the sensitivity coefficients a and b in the polynomial fitting function can be obtained. Based on the polynomial fitting function, different cavity numbers A and tooth S are established. X The coefficient matrices a and b.

[0035] Given a and b, substitute the actual clearance deviation value of the tooth Si. The actual cavity pressure correction coefficient of the tooth gap can be obtained. .

[0036] Furthermore, step S105 is independent of steps S102 and S103. Based on a 0.02mm change in the grate tooth gap, the average change in pressure in each cavity relative to its design value is: / Gap variation setting for the number of groups.

[0037] Furthermore, determining whether there is a correlation between the disc cavity pressure and the tooth clearance based on the average change includes: The expression for the average change is: , Wherein, β is the average change; When the gap between the teeth changes by a preset amount, if the average change is no greater than 0.01%, it is determined that there is no correlation between the pressure in the cavity and the gap between the teeth; if the average change is greater than 0.01%, it is determined that there is a correlation between the pressure in the cavity and the gap between the teeth.

[0038] In practice, the correlation can be further divided into positive and negative correlations based on whether the trend of cavity pressure change is the same as the trend of gap increase, and a correlation table between cavity pressure and tooth gap can be established.

[0039] Furthermore, for step S107, based on the established correlation table, a coupling influence analysis is performed on the grate tooth clearance of single-branch flow paths and multi-branch flow paths to obtain an approximate representation of the relationship between a certain cavity pressure and the clearance of each grate tooth. The expression for the actual pressure of each cavity is as follows: , in, The actual pressure in cavity A is expressed in Pa, and k represents the number of grates that are correlated with the cavity pressure. This is the correction factor for the actual cavity pressure.

[0040] Furthermore, the calculation of the rotor axial force of the engine under the current grate tooth clearance based on the actual pressure of each disc cavity includes: For each disc cavity, the total axial force of the rotor cavity is calculated based on the actual pressure of the disc cavity and the cavity area. The rotor axial force is obtained from the total axial force in the rotor cavity and the axial force in the rotor flow channel.

[0041] Furthermore, the total axial force in the rotor cavity is expressed as follows: , The expression for the rotor axial force is: , Among them, AS X Let F be the cavity area of ​​the Xth cavity. 容腔 F is the total axial force in the rotor cavity. 流道 denoted as axial force in the rotor flow channel, and F is the rotor axial force.

[0042] The method of this application is described in detail below with a specific example, see below. Figure 3 Specifically, it includes: Step 1: Based on the aero-engine air system design network diagram, obtain the boundary disks and branch flow paths of each flow path in the air system, specifically including: according to Figure 2 The air system design network diagram lists the flow paths within the rotor disk cavity: a) Air is drawn from the outer duct (boundary 17) and the back of the fan (boundary 27), passes through the fan disc cavities 278, 279, 281 and 216, and is finally discharged into the front of the fan (boundary 28). b) Air is drawn from the third-stage compressor, passes through bearing chambers 136, 137, 206, and 239, and is finally discharged into the flow channel (boundary 1). c) The bleed air from the outer bypass outlet (boundary 20) flows into the low-pressure turbine rotor outlet (boundary 26) through chambers 264 and 266, and a small portion flows into chamber 268 through chambers 264 and 287.

[0043] Step 2: Calculate θ at different equivalent speeds based on the air system design parameters, specifically including: At a certain converted speed, under the designed grate working clearance, there is a certain similarity between the pressure in the rotor disk cavity and the induced draft (or exhaust) boundary, namely: (1) in, Design pressure for cavity A, in Pa; Design pressure for the intake / exhaust boundary associated with cavity A, in Pa; For different conversion speeds , The similarity coefficient; Based on the air system design parameters, at different converted speeds , Given the information, the corresponding value can be calculated. The similarity relationship between cavity pressure and associated boundary under different conversion speeds is detailed in Table 1 below.

[0044] Table 1. Similarity between cavity pressure and associated boundary at different converted rotational speeds.

[0045] Step 3: Determine the theoretical value of the chamber pressure using the similarity relationship between the design value and the boundary conditions. Specifically: The engine's intake / exhaust boundary pressures are monitored by corresponding measuring points and are relatively easy to obtain. After the test, the intake / exhaust boundary pressures can be obtained based on the test data, and then the theoretical test value of the disc cavity pressure can be calculated using equation (2): (2), in, The theoretical pressure for chamber A is expressed in Pa. The actual pressure at the vent / exhaust boundary (obtained from test data) is in Pa.

[0046] Assuming the boundary chamber 28 pressure was measured to be 92 Pa at 73% of the equivalent rotational speed during the experiment, the pressure corresponding to chamber 216 at 73% of the equivalent rotational speed can be found in Table 1. The value is 1.0017, and 216 cavities are calculated according to formula (2). =92.16Pa. Similarly, the theoretical pressure of the other disk cavities at the corresponding calculated speed can be obtained, as shown in Table 2.

[0047] Table 2. Actual boundary pressure and corresponding disk cavity pressure at different converted rotational speeds.

[0048] Step 4: Based on the air system design parameters, conduct a sensitivity analysis of the flow rate and chamber pressure changes in the corresponding flow paths when the gaps of each grate element change. Specifically: The main design parameters of the air system tooth elements are shown in Table 3 (the cold and hot gaps in the table are nominal design values). The upstream and downstream pressures of each tooth element and the mass flow rate through the tooth element are shown in Table 4. The design pressures of the air system chambers that affect the axial force are shown in Table 5. All the above data are air system design parameters and are known values.

[0049] Table 3. Main design parameters of the apex and corresponding upstream and downstream cavity numbers.

[0050] Table 4 shows the upstream and downstream pressures and flow rates of the design point toothed element.

[0051] Table 5. Pressure values ​​of each cavity at the design point.

[0052] Using air system engineering analysis software, the flow rate and pressure change trends of the corresponding flow paths and chambers are analyzed when the gap of each grate element changes. The range of grate gap analysis is no less than twice the tolerance range of the drawing.

[0053] Taking the gap of the grating S1 as an example, the design gap changes by 0.02 mm each time. The pressure value of each cavity under this gap is calculated, as shown in Table 6. Similarly, the sensitivity analysis table of the other gratings S1 to S16 can be obtained.

[0054] Table 6. Sensitivity analysis of the ferrule S1 (sorted by the degree of impact on cavity pressure)

[0055] When the gap between the fang teeth changes, the pressure in the related chambers also changes. Suppose that when the gap of a certain fang tooth Si changes... At that time, the relative percentage change in pressure in chamber A was: ,have: (3), (4), (5), in, The clearance deviation of the Si tooth is expressed in mm and is applicable within twice the tolerance. This represents the actual clearance between the comb teeth. The gap is designed for the teeth.

[0056] According to formulas (3) and (4), the cavity pressure correction coefficient for different tooth gaps can be obtained. ,exist , Given the information, by fitting the polynomial, the values ​​of the sensitivity coefficients a and b in formula (6) can be obtained.

[0057] (6) Based on the fitting formula (6), the coefficient matrices a and b for different cavity numbers A and sieve SX are established, as shown in Tables 7 and 8.

[0058] Table 7. Coefficient 'a' Matrix

[0059] Table 8. Coefficient b matrix

[0060] Step 5: Establish a correlation table between chamber pressure and tooth clearance, specifically: Based on a 0.02mm change in the gap between the teeth, the average change in pressure in each chamber relative to its design value ( (See Table 9 for the number of groups for setting the gap variation), the correlation between chamber pressure and tooth gap is divided into the following correlation levels: Unrelated: For every 0.02 mm change in the gap between the tooth ferrules, the change in chamber pressure is no greater than 0.01%; Related: For every 0.02 mm change in the gap between the tooth ferrules, the chamber pressure changes by more than 0.01%; Based on whether the trend of cavity pressure change is the same as the trend of gap increase, the correlation can be divided into positive correlation and negative correlation. The correlation between cavity pressure and tooth gap is shown in Table 10.

[0061] Table 9. Average relative change in pressure in different chambers when the gap between the ferrules changes by 0.02 mm.

[0062] Table 10 Correlation between chamber pressure and tooth clearance

[0063] Step 6: Perform a coupled influence analysis on the grate tooth clearance in single-branch and multi-branch flow paths to obtain the fitting relationship between a certain cavity pressure and the clearance of each grate tooth. Specifically: Based on the correlation analysis in step 5, in practical engineering, the relationship between the actual pressure of a certain cavity and the gaps between each tooth can be approximated by the following formula: (7) in, The actual pressure in cavity A is expressed in Pa, and k represents the number of grates that are related to the pressure in cavity A.

[0064] The actual value of the tooth clearance can be measured during the engine assembly / disassembly process, as shown in Table 11. It can be calculated using formulas (2) and (6). , Substituting the value into formula (7) yields the actual pressure in the disk cavity.

[0065] Table 11. Flanged tooth design parameters and measured values

[0066] Step 7: Calculate the rotor axial force of the engine under the current tooth clearance by actual cavity pressure calculation.

[0067] Calculate the axial force F in the rotor cavity 容腔 (As shown in Table 12), axial force F in the flow channel 流道 The rotor axial force is: (8) Table 12 Rotor cavity pressure

[0068] The embodiments provided by this invention and the method of this application have the following advantages: a) This calculation method makes full use of the similarity relationship between the boundary disk pressure of the air system and the associated disk. Through sensitivity analysis, it obtains the characteristic relationship between the gap of each grate and the cavity pressure, which can reflect the change of cavity pressure with the gap of the grate. The calculation accuracy is high, and the obtained rotor axial force is more in line with the axial force of the engine in actual operation. b) This calculation method establishes a characteristic relationship table between the tooth clearance and the cavity pressure, which can quickly assess the influence of the current tooth clearance on the axial force during each assembly / disassembly operation, making it easier to adjust the axial force; c) This calculation method does not require monitoring and measuring the pressure of each cavity, reducing the number of cavity pressure measurement points and greatly reducing the difficulty of bench testing.

[0069] Based on the above advantages, the method of the present invention can be widely used in the calculation of rotor axial force during the scientific research and testing phase of aero-engines and gas turbines, and can quickly and accurately evaluate the rotor axial force under the actual tooth gap value without increasing the difficulty of bench testing.

[0070] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for calculating rotor axial force based on the physical condition of an aero-engine, characterized in that, include: Based on the design network diagram of the aero-engine air system, obtain the boundary disks of each flow path in the air system and the corresponding associated boundaries of each disk. Calculate the similarity coefficient between the design pressure of each disk cavity and the design pressure of the corresponding associated boundary of the disk cavity under different conversion speeds; For each disc cavity, the theoretical test pressure of the disc cavity is calculated based on the similarity coefficient; Based on air system engineering analysis software, sensitivity analysis was conducted on the flow rate and chamber pressure changes of the corresponding flow path when the gap of each grate tooth changed, and the relationship between the chamber pressure correction coefficient and the grate tooth gap deviation value of each grate tooth in each disc cavity was obtained. Based on the aforementioned formula, calculate the average change in pressure in each chamber relative to its own design value under a preset gap change in the sieve teeth; Based on the average change, determine whether there is a correlation between the cavity pressure and the tooth clearance; Based on the correlation judgment results, the theoretical pressure of the disc cavity test, and the aforementioned relationship, the actual pressure of each disc cavity is calculated. The rotor axial force of the engine under the current tooth clearance is calculated based on the actual pressure of each cavity.

2. The method for calculating rotor axial force based on the physical condition of an aero-engine according to claim 1, characterized in that, The boundary cavity is located at the intake boundary or the exhaust boundary, and the associated boundary is the boundary with the weakest throttling effect between the cavity and the boundary.

3. The method for calculating rotor axial force based on the physical condition of an aero-engine according to claim 1, characterized in that, The expression for the similarity coefficient is: ， in, Design pressure for cavity A, Design pressure for the boundary of cavity A. The similarity coefficients are calculated for different rotational speeds.

4. The method for calculating rotor axial force based on the physical condition of an aero-engine according to claim 3, characterized in that, The expression for the theoretical pressure of the disc cavity test is: ， in, The theoretical pressure for cavity A is given. This represents the actual pressure at the associated boundary.

5. The method for calculating rotor axial force based on the physical condition of an aero-engine according to claim 4, characterized in that, The formula for obtaining the relationship between the cavity pressure correction coefficient and the tooth gap deviation value corresponding to each tooth in each disk cavity includes: Set the preset gap variation of the comb teeth; For each tooth in each disc cavity, calculate the cavity pressure correction coefficient and tooth gap deviation value of each tooth gap when the tooth gap changes under the preset gap change amount. A polynomial fitting function is constructed, and the polynomial fitting function is solved based on the cavity pressure correction coefficients and the deviation values ​​of the tooth gaps under multiple sets of tooth gaps to obtain the relationship.

6. The method for calculating rotor axial force based on the physical condition of an aero-engine according to claim 5, characterized in that, The expression for the cavity pressure correction coefficient is: ， The expression for the deviation value of the tooth gap is: ， The expression for the polynomial fitting function is: ， in, P is the cavity pressure correction coefficient corresponding to the i-th tooth of cavity A. A The pressure in the lower cavity of the tooth gap is output by the air system engineering analysis software. Let be the deviation value of the gap between the i-th tooth ferrules. Let be the actual clearance of the i-th tooth. The design clearance for the i-th tooth is given by 'a', where 'a' is the first coefficient and 'b' is the second coefficient.

7. The method for calculating rotor axial force based on the physical condition of an aero-engine according to claim 6, characterized in that, The step of determining whether there is a correlation between the cavity pressure and the tooth clearance based on the average change includes: The expression for the average change is: ， Wherein, β is the average change; When the gap between the teeth changes by a preset amount, if the average change is no greater than 0.01%, it is determined that there is no correlation between the pressure in the cavity and the gap between the teeth; if the average change is greater than 0.01%, it is determined that there is a correlation between the pressure in the cavity and the gap between the teeth.

8. The method for calculating rotor axial force based on the physical condition of an aero-engine according to claim 4, characterized in that, The expression for the actual pressure in each chamber is: ， in, Let A be the actual pressure, and k be the number of grates that are correlated with the pressure in the disk cavity. This is the correction factor for the actual cavity pressure.

9. The method for calculating rotor axial force based on the physical condition of an aero-engine according to claim 8, characterized in that, The calculation of the rotor axial force of the engine under the current tooth clearance based on the actual pressure of each disc cavity includes: For each disc cavity, the total axial force of the rotor cavity is calculated based on the actual pressure of the disc cavity and the cavity area. The rotor axial force is obtained from the total axial force in the rotor cavity and the axial force in the rotor flow channel.

10. The method for calculating rotor axial force based on the physical condition of an aero-engine according to claim 9, characterized in that, The total axial force in the rotor cavity is expressed as follows: ， The expression for the rotor axial force is: ， Among them, AS X Let F be the cavity area of ​​the Xth cavity. 容腔 F is the total axial force in the rotor cavity. 流道 denoted as axial force in the rotor flow channel, and F is the rotor axial force.

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