Helicopter engine working mode decision-making method based on flight subject

Abstract

The invention belongs to the technical field of aircraft control, and discloses a helicopter engine working mode decision-making method based on flight subjects, and the method comprises the following steps: S1, determining common typical flight subjects of a helicopter according to typical task scenes, flight subject characteristics and flight quality requirements of the helicopter; s2, based on the flight parameter characteristics of each flight subject, forming a flight subject characteristic parameter set, and determining flight subject fuzzy representation and division; s3, taking engine control requirements under each flight subject into consideration, and forming an engine working mode library; s4, establishing an engine working mode decision rule, and forming a mode decision expert database; s5, according to helicopter flight parameters and power demand change conditions, identifying a flight subject, and utilizing a mode decision expert database to obtain an engine working mode; and S6, taking the obtained engine working modes under different flight subjects as engine control input, and carrying out engine control.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft control, and in particular relates to a helicopter engine operating mode decision method based on flight subjects. Background Art

[0002] Traditional helicopter flight control and engine control adopt independent design methods. Helicopter flight control is designed based on constant rotor speed, and engine control is based on constant speed output as the benchmark target. On the one hand, when designing each subsystem, a certain amount of performance adjustment space needs to be reserved to ensure flight safety; on the other hand, due to the use of a constant rotor speed control method, the flight control system regards rotor speed changes as interference, and the engine control system regards load torque changes as interference. In all flight states, the engine adopts a constant output speed and control mode. From different perspectives such as maneuverability and economy, the helicopter has different requirements for the working characteristics of the engine in low-speed maneuvering flight and cruising flight. For example, the low-speed maneuvering flight of the helicopter requires the engine to have better acceleration and deceleration characteristics; while in the cruising state, lower fuel consumption can bring a better helicopter range. However, the fixed control mode cannot take into account the optimal global performance of the helicopter in different flight states. Summary of the invention

[0003] Purpose of the invention: The new generation of helicopters has put forward higher requirements for the power system, especially the future use requirements of helicopters in multiple scenarios, high maneuverability, high speed, and long range. Starting from the flight state of the helicopter, the optimal control mode of the engine is determined according to different flight states and subjects, which can further tap the performance of the turboshaft engine, improve the flight performance and flight quality, and achieve the best performance within the full flight envelope of the helicopter as much as possible. The decision of the helicopter engine working mode based on the flight subject is also an important link in the comprehensive realization of the comprehensive control of the helicopter / engine.

[0004] The present invention provides a helicopter engine working mode decision method based on flight subjects, which identifies the flight subject according to the helicopter flight state, matches different engine control modes according to the flight subject, and obtains the best performance requirements that meet the helicopter under different flight states. The engine control modes include enhanced maneuvering mode, minimum fuel consumption mode, minimum turbine temperature mode, and different output speed modes.

[0005] Technical Solution

[0006] A method for determining a helicopter engine operating mode based on flight subjects comprises the following steps:

[0007] S1: Determine the commonly used typical flight subjects of helicopters according to the typical mission scenarios, flight subject characteristics and flight quality requirements of helicopters;

[0008] S2: Based on the flight parameter characteristics of each flight subject, a flight subject characteristic parameter set is formed to determine the fuzzy representation and division of the flight subject;

[0009] S3: Consider the engine control requirements under each flight subject and form an engine operating mode library;

[0010] S4: Establish engine working mode decision rules and form a mode decision expert database;

[0011] S5: Identify the flight subject according to the change of helicopter flight parameters and power demand, and obtain the engine working mode by using the mode decision expert library;

[0012] S6: The engine operating modes under different flight subjects are obtained as engine control input to carry out engine control.

[0013] Furthermore, in S1, typical flight subjects include: hovering, transient turns, dive pull-ups, acceleration sprints, and stable level flight at different speed points.

[0014] Further, in S2, the flight subject characteristic parameter set includes the following parameters: power demand Pre, flight speed v, flight altitude hp, heading angle Φ, flight weight W, rotor speed Nr, rotor pitch clp and tail rotor pitch cla.

[0015] Further, in S3, three typical control modes are determined according to the working scenario of the engine: mode 1, enhanced maneuvering mode, mode 2, minimum fuel consumption mode, mode 3, minimum turbine temperature mode;

[0016] Three speed output modes are determined according to the engine speed: mode four, 105% output speed mode, mode five, 100% output speed mode, mode six, 95% output speed mode.

[0017] Further, in S4, the process of establishing the engine operating mode decision rule is as follows:

[0018] When performing transient turns, dive pull-ups, decelerated approaches, and accelerated sprint flight subjects, the engine uses the enhanced maneuvering mode; when performing stable level flight subjects, the engine uses the minimum fuel consumption mode; when performing hovering subjects, the engine uses the minimum turbine temperature mode;

[0019] When performing light-weight, high-speed, low-altitude cruising flight subjects, the engine uses the 95% output speed mode; when performing medium-weight, medium-speed, medium-altitude cruising flight subjects, the engine uses the 100% output speed mode; when performing heavy-weight, low-speed, high-altitude cruising flight subjects, the engine uses the 105% speed mode.

[0020] Furthermore, the flight subject characteristic parameter set

[0021] M={M k |ψ k} m k＝1

[0022] Among them, m represents the number of subdivided flight subjects, M k and ψ k They represent the flight subject model and characteristic parameter set of the kth segment respectively.

[0023] Furthermore, in S4, the model decision expert library is as follows:

[0024]

[0025] Further, in S5, the flight subject identification process is as follows:

[0026] Let M represent the model of the current flight action, ψ={θ1,θ2,···,θ n} is the characteristic parameter set of M;

[0027] M vs M k There are n similar elements between them, and the weight A={a1,a2,···,a n}, M and M k The similarity is Q = (A, M, M k );

[0028] The membership function of the current flight action with respect to the flight subject is defined as follows:

[0029]

[0030] Then, in the full flight envelope, the estimated value of M is

[0031]

[0032] Use intelligent optimization algorithm to divide M, select ψ and design A to meet the consistency inspection requirements of flight envelope division

[0033]

[0034] In the formula, ε is a small amount set;

[0035] The subject corresponding to the feature parameter set with the largest membership degree is the identified flight subject.

[0036] In summary, the beneficial effects of the present invention are as follows:

[0037] The present invention provides a method for deciding the working mode of a helicopter engine based on flight subjects. The method starts from the flight state of the helicopter and decides the optimal control mode of the engine according to different flight states and subjects, which can further explore the performance of the turboshaft engine, improve the flight performance and flight quality, and achieve the best performance within the full flight envelope of the helicopter as much as possible. It is particularly related to the future use requirements of helicopters in multiple scenarios, high maneuverability, high speed, and long range, which can further improve the maneuverability of the helicopter, reduce cruising fuel consumption, and increase the range of the helicopter.

[0038] Based on the needs of helicopters and starting from the integrated control of flight / engine integration, the present invention proposes a helicopter engine working mode decision method based on flight subjects. Through this method, intelligent decision-making can be made on the engine working mode. This method can be used as a manifestation and content of helicopter flight / engine integrated control. From the comprehensive simulation evaluation, it can be seen that the engine working mode decision method proposed by this method can effectively tap the potential performance of the engine and improve the comprehensive performance of the helicopter in the full flight envelope and various flight states. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a flow chart of a helicopter engine operating mode decision method based on flight subjects;

[0040] Figure 2 Decision process for engine operating mode. DETAILED DESCRIPTION

[0041] A method for determining the control mode of a helicopter turboshaft engine identifies flight subjects according to the flight state of the helicopter, matches different engine control modes according to the flight subjects, and obtains the best performance matching requirements under different flight states of the helicopter. The engine control modes include enhanced maneuvering mode, minimum fuel consumption mode, minimum turbine temperature mode, and different output speed modes.

[0042] The specific method is as follows:

[0043] S1: Determine the commonly used typical flight subjects of helicopters according to the typical mission scenarios, flight subject characteristics and flight quality requirements of helicopters;

[0044] S2: Based on the flight parameter characteristics of each flight subject, a flight subject characteristic parameter set is formed to determine the fuzzy representation and division of the flight subject;

[0045] S3: Consider the engine control requirements under each flight subject and form an engine operating mode library;

[0046] S4: Establish engine working mode decision rules and form a mode decision expert database;

[0047] S5: Identify the flight subject according to the change of helicopter flight parameters and power demand, and obtain the engine working mode by using the information of the expert database;

[0048] S6: The engine operating modes under different flight subjects are obtained as engine control input to carry out engine control.

[0049] Specifically, the commonly used flight subjects for helicopters can be given according to the mission requirements and flight quality requirements of the helicopter, such as: hovering near the ground, transient turning, diving and pulling up, accelerating and sprinting, and stable level flight at different speed points.

[0050] Specifically, the flight characteristic parameter set is determined by the helicopter comprehensive model, test flight data and experience, by analyzing and extracting the flight characteristics of typical flight subjects and the change of required power. Generally, the flight characteristic parameters are composed of power demand Pre, flight speed v, flight altitude hp, heading angle Φ, flight weight W, rotor speed Nr, rotor pitch clp and tail rotor pitch cla.

[0051] In particular, taking the hovering subject as an example, its characteristic parameter ψ1 can be defined as:

[0052] ψ1: v=0∩ΔΦ=0∩Δhp=0∩ΔPre=0∩Δclp=0Δcla=0.

[0053] That is, the flight characteristic parameters of the hovering subject can be described as a flight speed v of 0 km / h, and there is no obvious change in the heading angle Φ, flight altitude hp, power demand Pre, rotor pitch clp and tail rotor pitch cla.

[0054] In particular, taking the transient turning subject as an example, its characteristic parameter ψ2 can be defined as:

[0055] ψ2: ΔΦ=25∩Δhp=0∩Δclp=0Δcla=10∩ΔPre=300.

[0056] That is, the flight characteristic parameters of the transient turning subject can be described as large changes in the heading angle Φ and the tail rotor pitch. However, the flight altitude hp and the rotor pitch clp have no obvious changes, and the power demand Pre changes slightly.

[0057] In particular, taking the subduction pull-up subject as an example, its characteristic parameter ψ3 can be defined as:

[0058] ψ3: v=200∩ΔΦ=0∩Δhp=5∩ΔPre=500.

[0059] That is, the flight characteristic parameters of the transient turning subject can be described as the flight speed v remains unchanged at a certain fixed value, the heading angle Φ remains basically unchanged, the flight altitude hp changes rapidly, and the power demand increases rapidly to reach a maximum value.

[0060] In particular, taking the acceleration sprint subject as an example, its characteristic parameter ψ4 can be defined as:

[0061] ψ4: Δv=10∩ΔΦ=0∩Δhp=0∩ΔPre=400.

[0062] That is, the flight characteristic parameters of the acceleration sprint subject can be described as a rapid increase in flight speed v, no significant changes in heading angle Φ and flight altitude hp, and a rapid change in power demand. In particular, taking the 250km / h cruising flight state as an example, its characteristic parameter ψ5 can be defined as:

[0063] ψ5: v=250∩Δv=0∩ΔΦ=0∩Δhp=0∩ΔPre=0.

[0064] That is, the flight characteristic parameters of the 250km / h cruise flight subject can be described as the flight speed v remaining basically unchanged at 250km / h, and there is no obvious change in the heading angle Φ, flight altitude, and power demand hp.

[0065] In particular, in addition to the flight action (subject) directly affecting the required power of the helicopter, the atmospheric environment and flight weight also affect the flight performance of the helicopter and the power output and performance of the engine. Therefore, from the perspective of comprehensive control optimization, the broad classification of flight subjects should include the subdivision of different atmospheric environments and flight weights, and the atmospheric environment mainly includes flight altitude, etc. Specifically, it can be further subdivided according to the flight altitude of low altitude (1000 meters), medium altitude (3000 meters) and high altitude (5000 meters), as well as small weight (minimum flight weight), medium weight and large weight (maximum flight weight).

[0066] Furthermore, all typical flight subjects and their corresponding characteristic parameters are combined to form a flight subject characteristic parameter set M = {M k |ψ k} m k＝1 Among them, m represents the number of subdivided flight subjects, M k and ψ k They represent the flight subject model and characteristic parameter set of the kth segment respectively.

[0067] Specifically, the engine working mode library is determined based on the actual engine conditions and helicopter mission requirements. Generally, three typical control modes proposed to meet the engine control optimization requirements are considered: enhanced maneuvering mode, minimum fuel consumption mode, and minimum turbine temperature mode.

[0068] Generally, considering the aerodynamic efficiency of helicopter rotors in different flight actions and flight environments, the engine can be set to multiple output speed modes, such as 100% output speed, 90% output speed, etc. For example, a simple engine operating mode library is shown in the following table.

[0069] Table 1 Turboshaft engine operating modes

[0070]

[0071] Specifically, for the determination of the engine working mode decision rules, we can find the best engine working mode that meets the current flight subject by comprehensively considering the helicopter power requirements and changes in each flight subject, as well as the main performance indicators of each flight subject, and form a mapping rule between the flight subject and the engine working mode. These rules combine the changes in the helicopter power requirements, the engine working environment and the working mode elements to ensure the helicopter's maneuverable flight and engine operation safety. These rules are not static and can be continuously improved and optimized with use. For example, a typical engine working mode decision expert library is shown in the following table:

[0072] Table 2 Expert knowledge base

[0073]

[0074] Specifically, for the identification of flight subjects, the current flight parameters of the helicopter can be compared with the established flight subject characteristic parameter set M, and the subject identification problem can be transformed into a problem of solving the membership function of the characteristic parameters. For example, a solution is given as follows:

[0075] Let M represent the model of the current flight action, ψ={θ1,θ2,···,θ n} is the characteristic parameter set of M.

[0076] M vs M k There are n similar elements between them. According to the test flight experience, the weight A={a1,a2,···,a n}, M and M k The similarity is Q = (A, M, M k ), then the membership function of the current flight action with respect to the flight subject can be defined as follows

[0077]

[0078] Then on the full flight envelope, the estimate of M is

[0079]

[0080] Use intelligent optimization algorithm to divide M, select ψ and design A to meet the consistency inspection requirements of flight envelope division

[0081]

[0082] In the formula, ε is a small value that is set.

[0083] Furthermore, the above method is used to judge the similarity between the current flight parameter information and the flight subject model, and to find expert knowledge that is most similar to the current engine working environment, helicopter power requirement changes and power requirement upper limit, so as to determine the engine working mode.

Claims

1. A helicopter engine operating mode decision method based on flight subjects, characterized in that: The following steps are involved: S1: Determine the commonly used typical flight subjects of helicopters according to the typical mission scenarios, flight subject characteristics and flight quality requirements of helicopters; S2: Based on the flight parameter characteristics of each flight subject, a flight subject characteristic parameter set is formed to determine the fuzzy representation and division of the flight subject; S3: Consider the engine control requirements under each flight subject and form an engine operating mode library; S4: Establish engine working mode decision rules and form a mode decision expert database; S5: Identify the flight subject according to the change of helicopter flight parameters and power demand, and obtain the engine working mode by using the mode decision expert library; S6: The engine operating modes under different flight subjects are obtained as engine control input to carry out engine control.

2. The method according to claim 1, characterized in that: In S1, typical flight subjects include: hovering, transient turns, dive pull-ups, acceleration sprints, and stable level flight at different weights, speeds and altitudes.

3. The method according to claim 2, characterized in that: In S2, the flight subject characteristic parameter set includes the following parameters: power demand Pre, flight speed v, flight altitude hp, heading angle Φ, flight weight W, rotor speed Nr, rotor pitch clp and tail rotor pitch cla.

4. The method according to claim 3, characterized in that: In S3, three typical control modes are determined according to the working scenarios of the engine: Mode 1, enhanced maneuvering mode, Mode 2, minimum fuel consumption mode, and Mode 3, minimum turbine temperature mode; Three speed output modes are determined according to the engine speed: mode four, 105% output speed mode, mode five, 100% output speed mode, mode six, 95% output speed mode.

5. The method according to claim 4, characterized in that: In S4, the process of establishing the engine working mode decision rule is as follows: When performing transient turns, dive pull-ups, decelerated approaches, and accelerated sprint flight subjects, the engine uses the enhanced maneuvering mode; when performing stable level flight subjects, the engine uses the minimum fuel consumption mode; when performing hovering subjects, the engine uses the minimum turbine temperature mode; When performing light-weight, high-speed, low-altitude cruising flight subjects, the engine uses the 95% output speed mode; when performing medium-weight, medium-speed, medium-altitude cruising flight subjects, the engine uses the 100% output speed mode; when performing heavy-weight, low-speed, high-altitude cruising flight subjects, the engine uses the 105% speed mode.

6. The method according to claim 5, characterized in that: Flight subject characteristic parameter set M={M k |ψ k } m k＝1 Among them, m represents the number of subdivided flight subjects, M k and ψ k They represent the flight subject model and characteristic parameter set of the kth segment respectively.

7. The method according to claim 6, characterized in that: In S4, the model decision expert database is as follows:

8. The method according to claim 7, characterized in that: In S5, the flight subject identification process is as follows: Let M represent the model of the current flight action, ψ={θ1,θ2,···,θ n } is the characteristic parameter set of M; M vs M k There are n similar elements between them, and the weight A={a1,a2,···,a n }, M and M k The similarity is Q = (A, M, M k ); The membership function of the current flight action with respect to the flight subject is defined as follows: Then, in the full flight envelope, the estimated value of M is Use intelligent optimization algorithm to divide M, select ψ and design A to meet the consistency inspection requirements of flight envelope division In the formula, ε is a small amount set; The subject corresponding to the feature parameter set with the largest membership degree is the identified flight subject.

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