Method for evaluating flight engine performance during combined power mode conversion

Abstract

The present invention discloses a method for evaluating flight and engine performance during a combined dynamic mode transition process, which belongs to the field of integrated flight / engine performance calculation and at least partially addresses the low accuracy of existing methods. The method sets a time range for the mode transition process, acquires the aircraft's dynamic characteristic parameters in real time, and calculates the flight and engine performance parameters if the assessment conditions are met. The dynamic characteristic parameters include at least fuel consumption rate and thrust value; the current acceleration in the flight and engine performance parameters can be determined based on flight dynamics equations. The core logic of this method is to calculate flight and engine performance with equal time step integration within the mode transition time range, using flight acceleration and the engine operating envelope as evaluation criteria.

Description

Technical Field

[0001] The present invention belongs to the field of flight / engine integrated performance calculation, and in particular relates to a method for flight and engine performance evaluation in a combined power mode conversion process. Background Art

[0002] The rapid flight and engine performance evaluation method based on mission analysis is an evaluation method that solves specific flight profiles based on flight dynamics equations. Its advantage is that it can quickly evaluate the matching of engine performance with aircraft mission requirements, thereby deriving the optimization direction and goals of the performance scheme, improving the iteration efficiency and design accuracy in the flight / engine scheme demonstration and preliminary design stages, while taking into account the aircraft mission requirements, and avoiding disruptive problems in the subsequent detailed design of the flight / engine scheme to the greatest extent.

[0003] In this method, engine performance parameters at a given moment are determined by interpolating the engine's altitude-speed characteristic data based on the current flight altitude and Mach number. However, when dealing with combined-propulsion aircraft undergoing modal transitions, the thrust at a given moment during the transition is typically calculated by taking the difference between the thrust before and after the transition in the engine's altitude-speed characteristic data. However, this calculation method deviates from the actual thrust changes during the transition, resulting in low accuracy.

[0004] During the actual mode transition, most of the flow is transferred from the turbine to the ramjet. This shift in the primary thrust source causes the thrust to vary during the mode transition according to different control laws. During this transition, the vehicle's acceleration may become negative, causing the flight Mach number to drop. If the flight Mach number drops beyond the ramjet's stable operating limit before the mode transition is complete, the vehicle will be unable to continue climbing and completing its mission. Existing methods are unable to assess this impact. Therefore, it is necessary to develop a flight / engine performance evaluation and optimization method for combined-propulsion vehicles that considers the mode transition process. Summary of the Invention

[0005] In view of this, the present invention provides a method for evaluating engine performance during a combined power mode conversion process, which at least partially solves the technical problem of low accuracy of the methods in the prior art.

[0006] A method for evaluating flight performance during a combined power mode conversion process is provided, which is applicable to the design and optimization of a modal conversion scheme for an aircraft, wherein the aircraft includes a TBCC engine composed of a turbine engine and a ramjet engine. The method comprises:

[0007] Setting aircraft parameters within a time range (0-a) of the modal transition process, obtaining aircraft dynamic characteristic parameters in real time, and calculating flight engine performance parameters if assessment conditions are met, wherein the dynamic characteristic parameters include at least fuel consumption rate and thrust value; and the aircraft parameters include at least aircraft lift-to-drag ratio and modal transition point;

[0008] The aircraft acceleration in the flight performance parameters is determined according to the flight dynamics equation;

[0009] Obtaining a first acceleration at the current moment, determining whether the first acceleration is greater than zero, and if so, integrating and solving the flight dynamics equation to determine the displacement of the aircraft in the current time period and the speed or Mach number at the next moment, and determining whether the Mach number is within the standard allowable range. If so, determining that the aircraft is operating normally, and determining whether the current moment has reached the upper limit of the set time range. If so, determining whether the aircraft can accelerate flight. If so, determining that the design solution is qualified. If not, determining that the ramjet engine does not have climbing capability, adjusting the flight attitude, reducing the track angle, and obtaining the adjusted track angle. Determining whether the adjusted track angle is less than zero. If so, determining that acceleration is impossible in level flight and the test has failed. If not, re-determining whether the adjusted aircraft can accelerate flight.

[0010] If not, the current moment does not reach the upper limit of the set time range, that is, the current moment is within the set mode conversion time range, enters the next moment, and re-acquires the acceleration for judgment;

[0011] If not, the Mach number is less than the standard value, that is, the design parameters are unreasonable, and the parameters should be adjusted and recalculated;

[0012] If not, and the first acceleration is less than or equal to zero, the flight attitude is adjusted to reduce the track angle, and it is determined whether the current track angle is less than zero. If so, the aircraft track angle is forcibly controlled to zero, and the aircraft decelerates in level flight. If not, and the first acceleration is not less than zero, the second acceleration of the airborne flight is obtained again, and the determination is repeated to determine whether the second acceleration is greater than zero.

[0013] The technical beneficial effects of the present invention are:

[0014] The method of the present invention is primarily used in the performance calculation of flight-engine mission analysis during the program demonstration phase. It can evaluate the impact of the modal conversion process on flight-engine performance and provide design constraints for the modal conversion process of the power system. By introducing the time dimension to calculate the dynamic characteristics and the corresponding flight-engine integrated performance matching calculation method during the modal conversion process, the problem of how to evaluate the impact of the modal conversion process on flight-engine integrated performance during flight-engine mission analysis is solved. The modal conversion process design can be constrained from the perspective of flight mission requirements during the program demonstration phase, accelerating the efficiency of flight-engine iteration during the design phase and avoiding disruptive problems during the program demonstration phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1 This is the overall steps of the method for rapid evaluation and optimization of engine performance during combined power mode conversion;

[0017] Figure 2 This is a matching calculation logic diagram of the method of the present invention. DETAILED DESCRIPTION

[0018] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0019] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. 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 the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0020] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this disclosure, it should be understood by those skilled in the art that an 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 described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0021] This study provides a new evaluation method for integrated flight and engine mission analysis and performance calculations during the design demonstration phase. This method provides design constraints and optimization targets for the power system modal transition process, improving the efficiency of flight and engine iteration during the design demonstration phase. Generally, turbine engines operate in the Mach number range of 0-3, while ramjets operate in the Mach number range of 3-5. Modal transition involves switching between turbine and ramjets. If the flight Mach number is 2.6 during the modal transition, the ramjet will not operate.

[0022] like Figure 1 The method for evaluating the performance of a combined power mode conversion process is applicable to the design and optimization of a mode conversion scheme for an aircraft, wherein the aircraft includes a TBCC engine composed of a turbine engine and a ramjet engine, such as Figure 2 As shown, the method includes:

[0023] S101: Set the time range of the mode conversion process (0-a), obtain the dynamic characteristic parameters of the aircraft in real time, and integrate and calculate the flight performance parameters when the evaluation conditions are met. The flight performance parameters include parameters such as fuel consumption rate or thrust value. Specifically:

[0024] The time range for the modal conversion process can be set based on the aircraft's mission profile or the overall performance design requirements of the power system. For example, the modal conversion of the turbine and ramjet engines can be completed within 30 seconds. The time interval can also be set, for example, to 1 second.

[0025] S103: The flight acceleration in the flight engine performance parameters is determined according to the flight dynamics equation. The flight dynamics equation is a known function, and the acceleration is determined by using the power characteristic parameters and the aircraft performance parameters acquired in real time.

[0026] S103: Obtain the first acceleration at the current moment, determine whether the first acceleration is greater than zero, and if so, integrate the first acceleration using a calculus equation to determine the displacement of the aircraft in the current time period and the speed or Mach number at the next moment, and determine whether the Mach number is greater than or equal to a standard value. If so, determine that the aircraft is operating normally (indicating that the ramjet engine can operate normally after the mode conversion, and the ramjet engine can take over when the turbine engine stops working), and determine whether the current moment reaches the upper limit of the set mode conversion time range (for example, the current moment exceeds the set time range). If the upper limit is reached, the modal conversion process is determined to be complete). If so, determine whether the aircraft can accelerate flight (the ramjet engine can drive the entire aircraft to climb, which means determining whether the aircraft can continue to climb according to the predetermined flight profile under this condition after the modal conversion process). If so, determine that the design solution is qualified. If not, determine that the ramjet engine does not have the ability to climb. Adjust the flight attitude and reduce the track angle. Obtain the adjusted track angle and determine whether the adjusted track angle is less than zero. If so, determine that it cannot accelerate in level flight and the test fails. If not, re-determine whether the adjusted aircraft can accelerate flight.

[0027] If not, the current moment is within the set time range, that is, the modal conversion process at the current moment has not been completed, and the next moment is entered to re-acquire the acceleration for judgment;

[0028] If not, the Mach number is less than the standard value, that is, the design parameters are unreasonable, and the parameters should be adjusted and re-evaluated;

[0029] If not, and the first acceleration is less than or equal to zero, the flight attitude is adjusted, the track angle is reduced, and a determination is made as to whether the current track angle is less than zero. If so, the track angle is forcibly controlled to zero, and the aircraft decelerates for level flight. If not, and the first acceleration is not less than zero, the second acceleration of the onboard flight is obtained again, and the determination is repeated to determine whether the second acceleration is greater than zero.

[0030] As a specific implementation method provided in this case, a time range is set to obtain the first acceleration or the second acceleration at each moment according to a preset time interval. The preset time interval is no more than 1 second. For example, within the set 30 seconds, the time interval is greater than 1 second. Data is collected or acquired according to this rule.

[0031] Secondly, the thrust and fuel consumption throttling characteristics of the turbine engine from maximum to shutdown and the ramjet engine from ignition to maximum are calculated. A three-dimensional database of the dynamic characteristics of the modal transition process is constructed, using time, altitude, and Mach number as independent variables. Subsequently, based on the power system's modal transition control laws, the thrust and fuel consumption performance of the turbine engine and ramjet are superimposed and used as the performance change during the engine modal transition to calculate the aircraft and engine performance. Finally, an integrated aircraft and engine performance matching calculation is performed to evaluate the performance changes during the modal transition.

[0032] The final flight-engine integrated matching calculation logic in the above process is as follows: First, the flight dynamics equations are solved using the current differential power characteristics and thrust characteristics as inputs. Secondly, the current along-course acceleration is determined to be greater than 0. If it is less than 0, the flight attitude is adjusted to ensure that the along-course acceleration is greater than 0, and the flight-engine performance is then solved by integrating the equations of motion. If the along-course acceleration is still not greater than 0 after the aircraft attitude is adjusted to level flight, the aircraft will inevitably decelerate. In this case, the flight-engine performance is solved using level flight as the attitude constraint. Subsequently, the calculation results determine whether the current flight altitude and flight Mach number exceed the boundaries of the power system's stable operating envelope. If so, the calculation process exits and the modal transition fails. If the power system is operating normally, the current moment is determined to have reached the modal completion moment. If not, the calculation proceeds to the next moment and iterates again according to the above logic. If so, the flight attitude is adjusted based on the flight-engine performance to determine whether the current state allows for accelerated flight. If so, the modal transition is successful; if not, the modal transition fails.

[0033] As a specific implementation method provided in this case, the data obtained each time is recorded and a database is constructed to reduce the cost of the test flight.

[0034] The above are only specific embodiments of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A method for evaluating flight performance during a combined power mode conversion process, suitable for designing and optimizing a modal conversion scheme for an aircraft, wherein the aircraft includes a TBCC engine consisting of a turbine engine and a ramjet engine, the method comprising: Setting a modal transition process time range and aircraft parameters, obtaining aircraft dynamic characteristic parameters in real time, and calculating engine performance parameters if assessment conditions are met. The dynamic characteristic parameters include at least fuel consumption rate and thrust value; the aircraft parameters include at least lift-to-drag ratio and modal transition point. The aircraft acceleration in the flight performance parameters is determined according to the flight dynamics equation; Obtaining a first acceleration at the current moment, determining whether the first acceleration is greater than zero, and if so, integrating and solving the flight dynamics equation to determine the displacement of the aircraft in the current time period and the Mach number at the next moment, and determining whether the Mach number is within the standard allowable range; if so, determining that the aircraft is operating normally, and determining whether the current moment has reached the upper limit of the set time range; if so, determining whether the aircraft can accelerate to flight; if so, determining that the design solution is qualified; if not, determining that the ramjet engine does not have climbing capability, adjusting the flight attitude, reducing the track angle, and obtaining the adjusted track angle; determining whether the adjusted track angle is less than zero; if so, determining that acceleration is impossible in level flight and the test has failed; if not, re-determining whether the adjusted aircraft can accelerate to flight; If not, the current moment does not reach the upper limit of the set time range, that is, the current moment is within the set mode conversion process time range, enters the next moment, and re-acquires the acceleration for judgment; If not, the Mach number is less than the standard value, that is, the design parameters are unreasonable, and the parameters should be adjusted and recalculated; If not, and the first acceleration is less than or equal to zero, the flight attitude is adjusted to reduce the track angle, and it is determined whether the current track angle is less than zero. If so, the aircraft track angle is forcibly controlled to zero, and level flight deceleration is performed. If not, and the first acceleration is not less than zero, the second acceleration of the airborne flight is obtained again, the determination is repeated, and it is determined whether the second acceleration is greater than zero.

2. The method according to claim 1, characterized in that The set time range is the total duration from the start to the end of the modal conversion.

3. The method according to claim 1, characterized in that The dynamic characteristic parameters are the thrust and fuel consumption rate throttling characteristics of a turbine engine changing from a maximum state to a parking state and a ramjet engine changing from an ignition state to a maximum state, and the dynamic characteristic parameters use time, altitude, and Mach number as independent variables to create a three-dimensional database of dynamic characteristics of the modal conversion process.

4. The method according to claim 2, characterized in that Within the set time range, the first acceleration or the second acceleration is acquired at each moment at a preset time interval.

5. The method according to claim 4, characterized in that The time intervals between the preset moments are the same and no greater than 1s.

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