CN115600344A - Rapid prediction method for flutter of compression system of aircraft engine - Google Patents

Rapid prediction method for flutter of compression system of aircraft engine Download PDF

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Publication number
CN115600344A
CN115600344A CN202211518104.2A CN202211518104A CN115600344A CN 115600344 A CN115600344 A CN 115600344A CN 202211518104 A CN202211518104 A CN 202211518104A CN 115600344 A CN115600344 A CN 115600344A
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China
Prior art keywords
compression system
flutter
engine compression
blade
engine
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CN202211518104.2A
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Chinese (zh)
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董旭
张燕峰
卢新根
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Institute of Engineering Thermophysics of CAS
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Institute of Engineering Thermophysics of CAS
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/17—Mechanical parametric or variational design
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2111/00—Details relating to CAD techniques
    • G06F2111/10—Numerical modelling
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

Abstract

The invention discloses a method for quickly predicting flutter of an aircraft engine compression system under working conditions, which realizes preliminary evaluation and iteration of flutter before three-dimensional design of the aircraft engine compression system through inputting overall performance parameters and structural parameters of the compression system. The method is mainly based on the sound propagation characteristics in the upstream and downstream pipelines of the compression system blade, the flutter risk range is positioned, and the working point is iteratively realized to avoid the flutter risk area so as to complete the flutter-free design in the flight envelope. Compared with the conventional prediction method, the three-dimensional design of the compression system blade is not required, so that the prediction time is shortened, large-scale three-dimensional computational fluid mechanics and structural dynamics computation is not required, the time required by iterative design is reduced, and the computational resources are saved. And the method can integrate the blade evaluation into the overall design of the compression system, and realize flutter evaluation in the overall performance and structural parameter design stage of the compression system.

Description

Rapid prediction method for flutter of compression system of aero-engine
Technical Field
The invention relates to the technical field of aero-engines, in particular to a method for quickly predicting flutter of an aero-engine compression system, which can be used for quickly predicting and evaluating the flutter at the initial design stage of the aero-engine compression system.
Background
Flutter is an aeroelastic instability phenomenon threatening the safe and stable operation of an aeroengine compression system, can cause high-cycle fatigue of blades, even breaks the blades in a short time, and therefore, the flutter evaluation risk of the compression system needs to be predicted in advance so as to take corresponding rectification measures or inhibition measures. At present, full-scale fluid-solid coupling numerical simulation is generally required for flutter prediction, the method is highly dependent on blade/blade disc geometric modeling, flutter evaluation can be performed after three-dimensional design of blades, and simulation is performed through a large-scale computing cluster. The main process is to establish a three-dimensional model of an engine compression system and then to perform gas dynamics and structural dynamics calculations. The method is time-consuming and expensive, and is difficult to carry out multi-working-condition flutter prediction in the early stage of design of the engine compression system, so that the engine compression system can complete flutter iterative design in a longer period, and the complexity and the design period of the engine compression system are increased, therefore, a method for realizing flutter prediction in the initial stage of design of the engine compression system is necessary to be developed.
Disclosure of Invention
Objects of the invention
Aiming at the defects and shortcomings in the prior art, the invention provides a rapid prediction method for flutter of an aircraft engine compression system, which aims to solve the problems of long time consumption, high dependence degree of computing resources and large flutter design iteration period of the existing aircraft engine compression system, and realize preliminary flutter risk evaluation of the engine compression system before a three-dimensional design stage.
(II) technical scheme
In order to carry out flutter evaluation and iterative design in the early design stage of an aircraft engine compression system, the invention provides a rapid prediction method for flutter of the aircraft engine compression system. The method mainly comprises the steps of positioning a flutter risk range based on sound propagation characteristics in upstream and downstream pipelines of a compression system blade, and iteratively realizing that a working point avoids a flutter risk area to complete a non-flutter design in a flight envelope.
In order to solve the technical problem, the invention adopts the technical scheme that:
a method for rapidly predicting flutter of an aircraft engine compression system, wherein the engine compression system at least comprises a plurality of blade discs arranged along an axial direction and fan blade rows or compressor blade rows arranged on the blade discs, and the method for rapidly predicting flutter of the aircraft engine compression system at least comprises the following steps:
SS1. Calculating overall performance parameters of engine compression system
Obtaining the overall performance parameters of an engine compression system according to the environment variables and flight requirement parameters of the aircraft engine, wherein the overall performance parameters at least comprise the flow, the pressure ratio, the load coefficient and the compression efficiency of the compression system;
SS2, calculating general structure parameter of engine compression system
Calculating the overall structural parameters of the engine compression system according to the overall performance parameters of the engine compression system obtained in the step SS 1;
SS3, calculating the pneumatic performance parameters of the engine compression system under different working conditions
Calculating to obtain the pneumatic performance parameters of the engine compression system under different working conditions, wherein the different working conditions at least comprise non-design working conditions under non-design rotating speed, and arranging to obtain the pneumatic performance diagrams of the engine compression system under different working conditions according to the pneumatic performance parameters of the engine compression system under different working conditions;
SS4, calculating the conduction frequency of each meridian section of the engine compression system
According to the mass flow, the Mach number, the size of a hub of a casing and a gas rotational flow angle of an engine compression system, calculating the conduction frequency of each meridian section of the engine compression system under different acoustic modes, wherein the different acoustic modes are the acoustic modes of the engine compression system under different circumferential orders and different radial orders;
SS5. Evaluation of risk blade row of engine compression system flutter
Selecting a pitch diameter in an engine compression system, judging whether a blade row is in a condition that an acoustic mode with the same circumferential order as the pitch diameter is on (cut-on) at the upstream of the blade and off (cut-off) at the downstream of the blade under the pitch diameter, if so, considering the blade row as a flutter risk blade row, and if no blade row meeting the conditions of upstream acoustic mode on and downstream acoustic mode off exists, considering that no blade row has a flutter risk under the working condition; then changing pitch diameters, and evaluating again until flutter risk blade rows corresponding to all risk pitch diameters are obtained;
SS6, judging the risk working condition of flutter of the blades of the compression system of the engine
Changing the operation condition of the engine compression system, repeating the step SS5 to obtain the flutter risk blade row position and the corresponding pitch diameter under different conditions, further judging the conditions with flutter risks, and if all the conditions have no flutter risks, ending the prediction;
SS7. Evaluation of the comprehensive impact of flutter on the operation of the compression System of an Engine
Marking all working conditions which are possible to generate flutter risks on a pneumatic performance diagram of the engine compression system, comparing the working conditions with the key working conditions, if the area which is possible to generate flutter risks is far away from the area of the key working conditions, not considering the influence of flutter on the performance of the engine compression system, if the risk working conditions are close to the key working conditions, considering the influence of flutter on the performance of the engine compression system, and carrying out the next step SS8;
SS8. Iterative design
And changing the overall structural parameters of the engine compression system, repeating the steps SS 2-SS 7, and carrying out iterative design until no flutter risk working condition or the flutter risk working condition is far away from the common working line and the key flight working condition point in the envelope range.
Preferably, in step SS1, the environment variables and flight request parameters at least include flight altitude, mach number and fuel consumption rate parameters.
Preferably, in the step SS2, the overall structural parameters at least include the meridional flow path size of the compression system and the position distribution of the leading edge and the trailing edge of each row of blades.
Preferably, in step SS3, the aerodynamic performance information included in the aerodynamic performance map of the engine compression system at least includes a pressure ratio, a flow rate, an efficiency, a rotation speed, and a common working line of the compression system.
Preferably, in step SS7, the key operating conditions at least include a common operating line operating condition, a takeoff point operating condition, and a cruise point operating condition.
Preferably, in the above step SS8, the overall structural parameters of the engine compression system are changed to change the meridian flow path size of the compression system or to change the position distribution of the blade rows.
(III) technical effects
Compared with the prior art, the rapid prediction method for the flutter of the compression system of the aircraft engine has the remarkable technical advantages that: the invention can quickly predict the flutter of the engine compression system before the three-dimensional design of the blade and realize the iterative design, compared with the conventional prediction method, the prediction time is shortened because the three-dimensional design of the compression system blade is not needed, and the large-scale three-dimensional computational fluid mechanics and structural dynamics calculation is not needed, thereby reducing the time required by the iterative design and saving the computational resources. And the method can integrate the blade evaluation into the overall design of the compression system, and realize flutter evaluation in the overall performance and structural parameter design stage of the compression system.
Drawings
FIG. 1 is a flow chart of a method for rapidly predicting flutter of an aircraft engine compression system according to the present invention.
FIG. 2 is a schematic representation of aircraft engine compression system flow path dimensions and blade positions showing only one row of rotor blades and one row of stator blades, with meridional section positions used to calculate sound propagation characteristics.
FIG. 3 is a aerodynamic performance diagram of an aircraft engine compression system, including flow-to-pressure ratio curves for different speeds N1-N4, and the locations of the common working line, the cruise point, and the takeoff point in the performance diagram.
Detailed Description
In order that the invention may be better understood, the following further description is provided, taken in conjunction with the accompanying examples, so that the advantages and features of the invention will be more readily understood by those skilled in the art. It should be noted that the following description is only a preferred embodiment of the present invention, but the present invention is not limited to the following embodiment. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. Therefore, it is intended that the present invention encompass such modifications and variations within the scope of the appended claims and their equivalents.
Fig. 1 is a flowchart of a method for rapidly predicting flutter of an aircraft engine compression system according to the present invention, and an implementation process of the method for rapidly predicting flutter of an aircraft engine compression system according to the flowchart shown in fig. 1 is illustrated below.
Firstly, an engine compression system usually comprises a plurality of stages of blade discs arranged along the axial direction and fan blade rows or compressor blade rows arranged on the blade discs, and the method for rapidly predicting the flutter of the aero-engine compression system at least comprises the following steps:
SS1, calculating overall performance parameters of engine compression system
According to the environmental variables and flight requirement parameters of the aircraft engine, such as flight altitude, air temperature, density, flight Mach number, oil consumption and other requirements, the overall performance parameters of the engine compression system are calculated, and the overall performance parameters of the compression system, such as flow, pressure ratio, efficiency, load coefficient and the like, are obtained.
SS2, calculating overall structural parameters of engine compression system
And calculating overall structure parameters such as the meridian flow path size and the position distribution of each row of blades of the compression system according to the overall performance parameters such as the flow rate, the pressure ratio and the load coefficient of the engine compression system obtained in the step SS1, as shown in FIG. 2.
SS3, calculating the pneumatic performance parameters of the engine compression system under different working conditions
And calculating to obtain the non-design rotating speed and the non-design working condition pneumatic performance parameters of the engine compression system, and obtaining a compression system pneumatic performance diagram, wherein the compression system pneumatic performance diagram comprises information such as pressure ratio, flow, efficiency, rotating speed, common working line and the like, as shown in fig. 3.
SS4, calculating the conduction frequency of each meridian section of the engine compression system
According to the mass flow, the Mach number, the size of a hub of a casing and the gas swirl angle of the engine compression system, the conduction frequency of each meridional section of the engine compression system in different acoustic modes is calculated, and each meridional section is schematically shown in the positions of the section 1 and the section 2 in the figure 2. Wherein different acoustic modes refer to acoustic modes of different circumferential orders and different radial orders.
SS5, risk blade row for evaluating flutter of engine compression system
Because of the significant nature of blade flutter in an engine compression system, the blades/discs of the compression system exhibit a positive pitch diameter when flutter occurs, and the pitch diameter is low, and therefore, it is generally not necessary to evaluate each possible pitch diameter. And selecting one pitch diameter, and judging whether the sound mode with the same number of circumferential orders as the pitch diameter of the blade row is conducted (cut-on) at the upstream of the blade and cut-off (cut-off) at the downstream of the blade. If this occurs, the row of blades may be considered a risky row of blades. And changing the pitch diameter, and re-evaluating until the risk blade rows corresponding to all risk pitch diameters are obtained.
And if no blade meeting the requirements of upstream acoustic mode conduction (cut-on) and downstream acoustic mode truncation (cut-off), determining that no blade row has flutter risk under the working condition.
SS6, and determining risk working condition of flutter of engine compression system blade
And changing the operation working condition of the engine compression system, repeating the step SS5, obtaining the flutter risk blade row position and the corresponding pitch diameter under different working conditions, and further judging which working conditions have flutter risks.
And if all the working conditions have no flutter risk, the prediction is finished.
SS7, evaluation of the comprehensive impact of flutter on the operation of the compression System
All working conditions which are possible to generate flutter are marked on a characteristic diagram of the compression system, the positions of a common working line, a flying point and a cruise point are marked in the diagram 3, when flutter risk areas are far away from the areas, the flutter risk areas can not be considered, the design requirement of no flutter is considered to be met, and the prediction is finished.
SS8, iterative design
And (3) if the risk working condition is close to the key working conditions of cruising, takeoff and the like, re-designing the structure in the step (2), changing the position of the flow path or the blade, and performing iterative design, thereby eliminating the influence of flutter on the key working point.
The object of the present invention is fully effectively achieved by the above embodiments. All equivalent or simple changes in the structure, characteristics and principles of the invention which are described in the patent conception are included in the protection scope of the invention. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.
The invention has not been described in detail and is part of the common general knowledge of a person skilled in the art.

Claims (6)

1. A method for rapidly predicting flutter of an aircraft engine compression system, wherein the engine compression system at least comprises a plurality of blade discs which are arranged along an axial direction and fan blade rows or compressor blade rows which are arranged on the blade discs, is characterized by at least comprising the following steps:
SS1. Calculating the overall performance parameters of the compression system of the engine
Obtaining the overall performance parameters of an engine compression system according to the environment variables and flight requirement parameters of the aircraft engine, wherein the overall performance parameters at least comprise the flow, the pressure ratio, the load coefficient and the compression efficiency of the compression system;
SS2, calculating general structure parameter of engine compression system
Calculating the overall structural parameters of the engine compression system according to the overall performance parameters of the engine compression system obtained in the step SS 1;
SS3, calculating the pneumatic performance parameters of the engine compression system under different working conditions
Calculating to obtain the pneumatic performance parameters of the engine compression system under different working conditions, wherein the different working conditions at least comprise non-design working conditions under non-design rotating speed, and obtaining the pneumatic performance diagrams of the engine compression system under different working conditions by sorting according to the pneumatic performance parameters of the engine compression system under different working conditions;
SS4, calculating the conduction frequency of each meridian section of the engine compression system
According to the mass flow, the Mach number, the size of a hub of a casing and a gas rotational flow angle of an engine compression system, calculating the conduction frequency of each meridian section of the engine compression system in different acoustic modes, wherein the different acoustic modes are the acoustic modes of the engine compression system in different circumferential orders and different radial orders;
SS5. Risk blade row for evaluating flutter of engine compression system
Selecting a pitch diameter in an engine compression system, judging whether a blade row under the pitch diameter is in the condition that the sound mode with the same circumferential order as the pitch diameter is conducted at the upstream of the blade and is intercepted at the downstream of the blade,
if this occurs, the row of blades may be considered a row of at-risk blades for flutter,
if the blade row which meets the upstream acoustic mode conduction and the downstream acoustic mode truncation does not exist, the blade row is considered to have no flutter risk under the working condition,
then changing pitch diameters, and evaluating again until flutter risk blade rows corresponding to all risk pitch diameters are obtained;
SS6, judging the risk working condition of flutter of the blades of the compression system of the engine
Changing the operation condition of the engine compression system, repeating the step SS5 to obtain the flutter risk blade row position and the corresponding pitch diameter under different conditions, further judging the conditions with flutter risks, and if all the conditions have no flutter risks, ending the prediction;
SS7. Evaluation of the comprehensive impact of flutter on the operation of the compression System of an Engine
Marking all working conditions which are possible to generate flutter risks on a pneumatic performance diagram of the engine compression system, comparing the working conditions with the key working conditions, if the area which is possible to generate flutter risks is far away from the area of the key working conditions, not considering the influence of flutter on the performance of the engine compression system, if the risk working conditions are close to the key working conditions, considering the influence of flutter on the performance of the engine compression system, and carrying out the next step SS8;
SS8. Iterative design
And changing the overall structural parameters of the engine compression system, repeating the steps SS 2-SS 7, and carrying out iterative design until no flutter risk working condition or flutter risk working condition is far away from the common working line and the key flight working condition point in the envelope range.
2. The method of claim 1, wherein in step SS1, the environmental variables and the flight request parameters comprise at least altitude, mach number, and fuel consumption parameters.
3. The method for the rapid prediction of flutter in an aircraft engine compression system of claim 1 wherein in step SS2 said overall configuration parameters comprise at least meridional flowpath size, leading edge and trailing edge position distribution for each row of blades.
4. The method for rapidly predicting flutter of an aircraft engine compression system according to claim 1, wherein in the step SS3, the aerodynamic performance information included in the aerodynamic performance map of the engine compression system at least comprises a pressure ratio, a flow rate, an efficiency, a rotation speed and a common working line of the compression system.
5. The method of claim 1, wherein in step SS7, said key operating conditions comprise at least a common operating line operating condition, a takeoff point operating condition, and a cruise point operating condition.
6. The method for the rapid prediction of flutter for an aircraft engine compression system according to claim 1 wherein in step SS8 the overall configuration parameters of the engine compression system are changed by changing the meridian flow path dimensions of the compression system or by changing the position distribution of the blade rows.
CN202211518104.2A 2022-11-30 2022-11-30 Rapid prediction method for flutter of compression system of aircraft engine Pending CN115600344A (en)

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Application Number Priority Date Filing Date Title
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