A fast prediction method for the flutter of an aeroengine compression system

Abstract

The present invention discloses a rapid prediction method for flutter of an aero-engine compression system. By inputting the overall performance parameters and structural parameters of the compression system, a preliminary assessment and iteration of flutter are realized before the three-dimensional design of the aero-engine compression system. It mainly locates the flutter risk range based on the acoustic propagation characteristics in the upstream and downstream pipelines of the compression system blades, and iteratively avoids the flutter risk area at the operating point to complete the flutter-free design within the flight envelope. Compared with the conventional prediction method, since the three-dimensional design of the compression system blades is not required, the prediction time is shortened, and large-scale three-dimensional computational fluid dynamics and structural dynamics calculations are not needed, reducing the time required for iterative design and saving computational resources. Moreover, this method can integrate blade evaluation into the overall design of the compression system and realize flutter evaluation at the stage of designing the overall performance and structural parameters of the compression system.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engine, and particularly relates to a method for quickly predicting the flutter of an aero-engine compression system, which can realize the quick prediction and evaluation of flutter in the initial stage of the design of the aero-engine compression system. Background Art

[0002] Flutter is an aeroelastic instability phenomenon that threatens the safe and stable operation of the aero-engine compression system, which will cause high-cycle fatigue of the blades and even break the blades in a short time. Therefore, it is necessary to predict the flutter of the compression system in advance to evaluate the risk, so as to take corresponding rectification measures or suppression means. At present, the prediction of flutter usually requires full-scale fluid-structure interaction numerical simulation. This method highly depends on the geometric modeling of the blade / disk, and the flutter evaluation can only be carried out after the three-dimensional design of the blade, and large-scale computing clusters are required for simulation. Its main process is to establish a three-dimensional model of the engine compression system, and then carry out gas dynamics and structural dynamics calculations. This method is time-consuming and expensive, and it is difficult to carry out the flutter prediction of multiple working conditions in the early stage of the design of the engine compression system, which makes the flutter iterative design of the engine compression system take a long time to complete, increasing the complexity and design cycle of the engine compression system design. Therefore, it is necessary to develop a method that can realize the prediction of flutter in the initial stage of the design of the engine compression system. Summary of the Invention

[0003] (I) Object of the Invention

[0004] In view of the above-mentioned defects and deficiencies of the prior art, the present invention provides a method for quickly predicting the flutter of an aero-engine compression system, aiming to solve the problems of long time consumption, high dependence on computing resources, and large flutter design iteration cycle in the prediction of the flutter of the existing aero-engine compression system, and to realize the preliminary evaluation of the flutter risk before the three-dimensional design stage of the engine compression system.

[0005] (II) Technical Solution

[0006] In order to carry out flutter evaluation and iterative design in the early stage of the design of the aero-engine compression system, the present invention provides a method for quickly predicting the flutter of the aero-engine compression system. By inputting the overall performance parameters and structural parameters of the compression system, the preliminary evaluation and iteration of the flutter are realized before the three-dimensional design of the aero-engine compression system. It mainly locates the flutter risk range based on the acoustic propagation characteristics in the upstream and downstream pipelines of the compression system blades, and iteratively avoids the flutter risk area at the working point to complete the flutter-free design within the flight envelope.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0008] A fast prediction method for flutter of an aeroengine compression system, where the engine compression system at least includes a plurality of bladed disks arranged axially and a row of fan blades or a row of compressor blades arranged on the bladed disks, and is characterized in that the fast prediction method at least includes the following steps:

[0009] SS1. Calculate the overall performance parameters of the engine compression system

[0010] According to the environmental variables and flight requirement parameters of the aeroengine, obtain the overall performance parameters of the engine compression system, where the overall performance parameters at least include the flow rate, pressure ratio, loading coefficient, and compression efficiency of the compression system;

[0011] SS2. Calculate the overall structural parameters of the engine compression system

[0012] According to the overall performance parameters of the engine compression system obtained in step SS1, calculate the overall structural parameters of the engine compression system;

[0013] SS3. Calculate the aerodynamic performance parameters of the engine compression system under different working conditions

[0014] Calculate the aerodynamic performance parameters of the engine compression system under different working conditions, where the different working conditions at least include off-design conditions at off-design speeds. According to the aerodynamic performance parameters of the engine compression system under different working conditions, organize and obtain the aerodynamic performance map of the engine compression system under different working conditions;

[0015] SS4. Calculate the cut-on frequencies of each meridional section of the engine compression system

[0016] According to the mass flow rate, Mach number, hub size of the casing, and gas swirl angle of the engine compression system, calculate the cut-on frequencies of each meridional section of the engine compression system in different acoustic modes, where the different acoustic modes are the acoustic modes of the engine compression system at different circumferential orders and different radial orders;

[0017] SS5. Evaluate the risk blade rows of flutter of the engine compression system

[0018] Select a pitch diameter in the engine compression system, and judge whether there is a blade row in the case where the acoustic mode at the same circumferential order as the pitch diameter number is cut-on upstream and cut-off downstream of the blade. If this situation occurs, it can be considered that this blade row is a flutter risk blade row. If there is no blade row that satisfies the upstream acoustic mode cut-on and downstream acoustic mode cut-off, it is considered that there is no blade row with flutter risk under this working condition; then change the pitch diameter and re-evaluate until the flutter risk blade rows corresponding to all risk pitch diameters are obtained;

[0019] SS6. Determine the risk conditions of blade flutter in the engine compression system

[0020] Change the operating conditions of the engine compression system, repeat the above step SS5, obtain the positions of the flutter-risk blade rows and the corresponding pitch diameters under different conditions, and then determine the conditions with flutter risk. If there is no flutter risk in all conditions, the prediction ends;

[0021] SS7. Evaluate the comprehensive impact of flutter on the operation of the engine compression system

[0022] Mark all the conditions with possible flutter risk on the aerodynamic performance diagram of the engine compression system. By comparing with the key conditions, if the area with possible flutter risk is far from the area of the key conditions, the impact of flutter on the performance of the engine compression system can be ignored. If the risk conditions are close to the key conditions, the impact of flutter on the performance of the engine compression system needs to be considered, and the next step SS8 is carried out;

[0023] SS8. Iterative design

[0024] Change the overall structural parameters of the engine compression system, repeat steps SS2~SS7, and carry out iterative design until there is no flutter risk condition within the envelope or the flutter risk condition is far from the common working line and the key flight condition points.

[0025] Preferably, in the above step SS1, the environmental variables and flight requirement parameters at least include flight altitude, Mach number, and specific fuel consumption parameter.

[0026] Preferably, in the above step SS2, the overall structural parameters at least include the meridional flow path size of the compression system, the leading edge and trailing edge position distributions of each row of blades.

[0027] Preferably, in the above step SS3, the aerodynamic performance information included in the aerodynamic performance diagram of the engine compression system at least includes the pressure ratio, flow rate, efficiency, rotational speed, and common working line of the compression system.

[0028] Preferably, in the above step SS7, the key conditions at least include the common working line condition, takeoff point condition, and cruise point condition.

[0029] Preferably, in the above step SS8, changing the overall structural parameters of the engine compression system is to change the meridional flow path size of the compression system or the position distribution of the blade rows.

[0030] (III) Technical effects

[0031] Compared with the prior art, the rapid prediction method for the flutter of the aero-engine compression system of the present invention has significant technical advantages: The present invention enables the rapid prediction of the flutter of the engine compression system before the three-dimensional design of the blades and realizes iterative design. Compared with the conventional prediction method, since the three-dimensional design of the compression system blades is not required, the prediction time is shortened, and large-scale three-dimensional computational fluid dynamics and structural dynamics calculations are not required, reducing the time required for iterative design and saving computational resources. And this method can integrate blade evaluation into the overall design of the compression system to achieve flutter evaluation in the stage of the overall performance and structural parameter design of the compression system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a flow chart of the rapid prediction method for the flutter of the aero-engine compression system of the present invention.

[0033] Figure 2 It is a schematic diagram of the flow path size and blade position of the aero-engine compression system. Only one row of rotor blades and one row of stator blades are shown in the figure, and the meridian section position is used to calculate the acoustic propagation characteristics.

[0034] Figure 3 It is the aerodynamic performance diagram of the aero-engine compression system, which includes the flow rate-pressure ratio curves at different speeds of N1-N4, as well as the positions of the common working line, cruise point, and takeoff point in the performance diagram. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, so that the advantages and features of the present invention can be more easily understood by those skilled in the art. It should be noted that the following are only the preferred embodiments of the present invention, but the content of the present invention is not limited to the following embodiments. In fact, various modifications and changes can be made to the present invention without departing from the scope or spirit of the present invention, which will be obvious to those skilled in the art. For example, features shown or described as part of one embodiment can be used with another embodiment to produce yet another embodiment. Therefore, it is intended that the present invention include such modifications and changes within the scope of the appended claims and their equivalents.

[0036] Figure 1 It is a flow chart of the rapid prediction method for the flutter of the aero-engine compression system of the present invention. According to the Figure 1 flow shown, the implementation process of the rapid prediction method for the flutter of the aero-engine compression system of the present invention is illustrated by the following examples.

[0037] First, the engine compression system generally includes multiple stages of blisks arranged axially and fan blade rows or compressor blade rows provided on the blisks. The rapid prediction method for flutter of the aeroengine compression system of the present invention at least includes the following steps when implemented:

[0038] SS1. Calculate the overall performance parameters of the engine compression system

[0039] According to the environmental variables and flight requirement parameters of the aeroengine, such as flight altitude, air temperature, density, flight Mach number, fuel consumption rate, etc., calculate the overall performance parameters of the engine compression system to obtain overall performance parameters such as the flow rate, pressure ratio, efficiency, and load coefficient of the compression system.

[0040] SS2. Calculate the overall structural parameters of the engine compression system

[0041] According to the overall performance parameters of the engine compression system such as the flow rate, pressure ratio, and load coefficient obtained in step SS1, calculate and obtain overall structural parameters such as the meridional flow path size of the compression system and the position distribution of each row of blades, as Figure 2 shown.

[0042] SS3. Calculate the aerodynamic performance parameters of the engine compression system under different working conditions

[0043] Calculate the aerodynamic performance parameters of the engine compression system at off-design speeds and off-design conditions to obtain the aerodynamic performance map of the compression system. The aerodynamic performance map of the compression system includes information such as pressure ratio, flow rate, efficiency, rotational speed, and common operating line, as Figure 3 shown.

[0044] SS4. Calculate the conduction frequencies of each meridional section of the engine compression system

[0045] According to the mass flow rate, Mach number, casing hub size, and gas swirl angle of the engine compression system, calculate the conduction frequencies of each meridional section of the engine compression system in different acoustic modes. The schematic diagrams of each meridional section are as shown in the positions of mid-section 1 and section 2 in Figure 2 where different acoustic modes refer to acoustic modes with different circumferential orders and different radial orders.

[0046] SS5. Evaluate the risk blade rows of flutter of the engine compression system

[0047] Due to the significant characteristics of blade flutter in the engine compression system, when flutter occurs, the blades / blisks of the compression system exhibit positive nodal diameters and the number of nodal diameters is relatively low. Therefore, it is usually not necessary to evaluate each possible nodal diameter. Select a nodal diameter and determine whether there is a blade row in which the acoustic mode with the same circumferential order as the number of nodal diameters is cut-on upstream of the blade and cut-off downstream. If this situation occurs, the blade row can be considered a risk blade row. Change the nodal diameter and re-evaluate until the risk blade rows corresponding to all risk nodal diameters are obtained.

[0048] If there are no blades that meet the conditions of upstream acoustic mode cut-on and downstream acoustic mode cut-off, it is considered that there is no flutter risk for the blade rows under this operating condition.

[0049] SS6. Determine the risk operating conditions of blade flutter in the engine compression system

[0050] Change the operating conditions of the engine compression system and repeat step SS5 to obtain the positions of the flutter risk blade rows and the corresponding nodal diameters under different operating conditions, and then determine which operating conditions have flutter risks.

[0051] If there is no flutter risk in all operating conditions, the prediction ends.

[0052] SS7. Evaluate the comprehensive impact of flutter on the operation of the compression system

[0053] Mark all possible operating conditions with flutter on the characteristic diagram of the compression system. The positions of the common working line, take-off point, and cruise point are Figure 3 marked in. When the flutter risk area is far from these areas, it can be not considered, and it is considered that the "flutter-free" design requirement is met, and the prediction ends.

[0054] SS8. Iterative design

[0055] If the risk operating conditions are close to key operating conditions such as cruise and take-off, it is necessary to re-perform the structural design in step 2, change the flow path or blade position, and perform iterative design to eliminate the impact of flutter on the key operating points.

[0056] Through the above embodiments, the object of the present invention is fully and effectively achieved. Any equivalent or simple changes made according to the structure, characteristics, and principles described in the inventive concept of the present invention are included in the protection scope of the present invention. Those skilled in the art of the present invention can make various modifications, supplements, or use similar methods to replace the specific embodiments described, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should fall within the protection scope of the present invention.

[0057] The parts not elaborated in detail in the present invention belong to the well-known technologies in the art.

Claims

1. A rapid prediction method for flutter of an aero-engine compression system, wherein the engine compression system at least includes a plurality of bladed disks arranged axially and a fan blade row or a compressor blade row arranged on the bladed disks, characterized in that, The rapid prediction method at least includes the following steps: SS1. Calculate the overall performance parameters of the engine compression system According to the environmental variables and flight requirement parameters of the aeroengine, obtain the overall performance parameters of the engine compression system, where the overall performance parameters at least include the flow rate, pressure ratio, load coefficient, and compression efficiency of the compression system; SS2. Calculate the overall structural parameters of the engine compression system According to the overall performance parameters of the engine compression system obtained in step SS1, calculate the overall structural parameters of the engine compression system; SS3. Calculate the aerodynamic performance parameters of the engine compression system under different working conditions Calculate the aerodynamic performance parameters of the engine compression system under different working conditions, where the different working conditions at least include off-design conditions at off-design speeds. According to the aerodynamic performance parameters of the engine compression system under different working conditions, organize and obtain the aerodynamic performance diagram of the engine compression system under different working conditions; SS4. Calculate the conduction frequencies of each meridional section of the engine compression system According to the mass flow rate, Mach number, casing hub size, and gas swirl angle of the engine compression system, calculate the conduction frequencies of each meridional section of the engine compression system under different acoustic modes, where the different acoustic modes are the acoustic modes of the engine compression system under different circumferential orders and different radial orders; SS5. Evaluate the blade rows at risk of flutter in the engine compression system Select a pitch diameter in the engine compression system and determine whether there is a blade row in which the acoustic mode with the same circumferential order as the pitch diameter number is conductive upstream and truncated downstream of the blade; If this situation occurs, it can be considered that this blade row is a blade row at risk of flutter; If there is no blade row that satisfies the upstream acoustic mode conduction and downstream acoustic mode truncation, it is considered that there is no blade row at risk of flutter under this working condition; After that, change the pitch diameter and re-evaluate until the blade rows at risk of flutter corresponding to all risk pitch diameters are obtained; SS6. Determine the risk working conditions of blade flutter in the engine compression system Change the operating conditions of the engine compression system, repeat the above step SS5, obtain the positions of the blade rows at risk of flutter and the corresponding pitch diameters under different working conditions, and then determine the working conditions with flutter risk. If there is no flutter risk in all working conditions, the prediction ends; SS7. Evaluate the comprehensive impact of flutter on the operation of the engine compression system Mark all the working conditions that may have flutter risk on the aerodynamic performance diagram of the engine compression system. By comparing with the key working conditions, if the area where flutter risk may occur is far from the area of the key working conditions, the impact of flutter on the performance of the engine compression system can be ignored. If the risk working conditions are close to the key working conditions, the impact of flutter on the performance of the engine compression system needs to be considered, and the next step SS8 is carried out; SS8. Iterative design Change the overall structural parameters of the engine compression system, repeat steps SS2~SS7, and carry out iterative design until there is no flutter risk working condition within the envelope or the flutter risk working condition is far from the common working line and the key flight working condition points.

2. The rapid prediction method for flutter of an aeroengine compression system according to claim 1, characterized in that In the above step SS1, the environmental variables and flight requirement parameters at least include flight altitude, Mach number, and fuel consumption rate parameters.

3. The rapid prediction method for the flutter of an aeroengine compression system according to claim 1, wherein In the above step SS2, the overall structural parameters at least include the meridional flow path dimensions of the compression system and the position distributions of the leading edges and trailing edges of each row of blades.

4. The rapid prediction method for the flutter of an aero-engine compression system according to claim 1, wherein, In the above step SS3, the aerodynamic performance information included in the aerodynamic performance map of the engine compression system at least includes the pressure ratio, flow rate, efficiency, rotational speed, and common operating line of the compression system.

5. The rapid prediction method for the flutter of an aeroengine compression system according to claim 1, characterized in that In the above step SS7, the key operating conditions at least include the common operating line condition, take-off point condition, and cruise point condition.

6. The rapid prediction method for the flutter of an aeroengine compression system according to claim 1, characterized in that In the above step SS8, changing the overall structural parameters of the engine compression system is to change the meridional flow path dimensions of the compression system or change the position distribution of the blade rows.

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