A method for determining the mode conversion law of the air intake

Abstract

The present invention discloses a method for determining an inlet duct modal conversion law, comprising: step 1, dividing the inlet duct modal conversion process into a plurality of intermediate modes, and ensuring a linear transition of the flow rates entering the turbine channel and the ramjet channel under different modes; step 2, obtaining the back pressure characteristics of the turbine engine channel and the ramjet engine channel of the inlet duct under different diversion modes using a wind tunnel test or a numerical simulation method; step 3, determining a control law that meets the smooth modal conversion requirements based on the changes in the turbine / ramjet engine flow requirements during the modal conversion process and the stable operating conditions of the inlet duct; this determination method can ensure that the turbine / ramjet channel flow rate continuously transitions and meets the engine requirements, and can also ensure the stable and normal operation of the inlet duct.

Description

Technical Field

[0001] The present invention relates to the field of aircraft, and in particular to a method for determining an air inlet modal conversion law. Background Art

[0002] The TBCC propulsion system, a combination of a turbine engine and a ramjet, is one of the ideal propulsion systems for achieving hypersonic flight. A smooth mode transition process is crucial for this combined propulsion system, ensuring a continuous transition of flow and thrust during the transition, enabling a smooth transition from turbine mode to ramjet mode, thereby further accelerating the vehicle to hypersonic speeds. During the mode transition, the turbine engine gradually exits the cycle, reducing the flow required as its speed decreases. The ramjet combustion chamber begins ignition, increasing its required flow. Methods for determining the mode transition pattern must consider the stable and normal operation of the inlet and engine.

[0003] The combined propulsion system accelerates the vehicle from ground takeoff to hypersonic speeds through a combination of turbine and ramjet engines. The turbine engine accelerates the vehicle from a stationary state on the ground to approximately Ma 2.5. Afterward, the turbine engine exits the cycle, reducing the engine's required flow rate. Simultaneously, the ramjet ignites, increasing its required flow rate to continue accelerating the vehicle to hypersonic speeds. During the mode transition, the turbine and ramjet operate simultaneously, necessitating the inlet to provide the required airflow to both engines. To ensure smooth vehicle operation, the combined thrust generated by the turbine and ramjet must vary continuously during the mode transition. Therefore, the control laws for the mode transition must be carefully designed, and the inlet must ensure a smooth flow transition. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a solution that can ensure the stable and normal operation of the intake duct and effectively obtain the intake duct modal conversion control law.

[0005] To achieve the above-mentioned object, the present invention provides a technical solution: a method for determining an intake duct modal conversion law, comprising:

[0006] Step 1: Divide the inlet duct modal conversion process into several intermediate modes and ensure linear transition of the flow rates entering the turbine channel and ramjet channel under different modes;

[0007] Step 2: Using wind tunnel tests or numerical simulation methods to obtain backpressure characteristics of the inlet turbine engine channel and the ramjet engine channel under different diversion modes;

[0008] Step 3: According to the flow demand changes of the turbine / ramjet engine during the modal conversion process and the stable working conditions of the inlet, determine the control law that meets the smooth modal conversion requirements.

[0009] As a preferred technical solution, the intermediate mode includes one or more of a turbine mode, a 1 / 4 split mode, a 2 / 4 split mode, a 3 / 4 split mode and a ram mode.

[0010] As a preferred technical solution, in step 2: under different diversion modes, the back pressure characteristics of the turbine engine channel and the ramjet engine channel are obtained by changing the back pressure at the outlet of the turbine engine channel and the ramjet engine channel.

[0011] As a preferred technical solution, in the step 2: under different diversion modes, the back pressure characteristics of the turbine engine channel and the ramjet engine channel are obtained by changing the blockage degree of the cone at the outlet of the turbine engine and the ramjet engine channel.

[0012] As a preferred technical solution, in the process of changing the blockage degree of the turbine engine outlet cone, the turbine engine passage outlet pressure gradually decreases and the outlet Mach number is maintained at a constant.

[0013] As a preferred technical solution, the air intake duct is an inner parallel combined power air intake duct.

[0014] As a preferred technical solution, the internal parallel combined power intake duct includes a first-stage compression surface and a second-stage compression surface, and the air flows through the first-stage compression surface and the second-stage compression surface to reach the throat. A modal conversion device is provided at the throat, and behind the modal conversion device are the parallel turbine engine channel and the ramjet engine channel.

[0015] The beneficial effects of the present invention compared to the prior art are: by first obtaining the back pressure characteristics of different diversion modes during the modal conversion process of the internal parallel combined power inlet, and then according to the flow requirements of the turbine / ramjet engine and the stable working conditions of the inlet during the modal conversion process, the modal conversion law of the combined power inlet is obtained, which can not only ensure the continuous transition of the turbine / ramjet channel flow and meet the engine requirements, but also ensure the stable and normal operation of the inlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a model diagram of the internal parallel combined power intake duct;

[0017] Figure 2 It is a model diagram of different diversion modes in the modal conversion process;

[0018] Figure 3 The modal conversion law diagram of the turbine channel is obtained by numerical simulation;

[0019] Figure 4 The modal conversion law diagram of the stamping channel obtained by numerical simulation;

[0020] Figure 5 The flow-total pressure recovery law diagram of turbine channel mode conversion obtained from wind tunnel test;

[0021] Figure 6 The pressure ratio-Mach number law diagram of turbine channel mode conversion obtained from wind tunnel test;

[0022] The meanings of the horizontal and vertical coordinates and icons in the figure are:

[0023] σ: total pressure recovery;

[0024] φ: flow coefficient;

[0025] Ma:Mach number;

[0026] P / P0: pressure ratio;

[0027] Numbers in the figure: 1-first stage compression surface, 2-second stage compression surface, 3-throat, 4-modal conversion device, 5-ramjet engine channel, 6-turbine engine channel. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] This embodiment provides a method for determining an intake duct modal conversion law, which can obtain a control law that meets the requirement of smooth modal conversion. The method specifically includes the following steps:

[0030] First, the modal conversion process of the internal parallel combined power inlet is divided into several intermediate modes, and the flow rates entering the turbine channel and ramjet channel in different modes are guaranteed to be different; second, wind tunnel tests or numerical simulation methods are used to obtain the back-pressure characteristics of the turbine channel and ramjet channel of the combined power inlet under different diversion modes; finally, based on the changes in the flow demand of the turbine / ramjet engine during the modal conversion process and the stable working conditions of the inlet, the modal conversion law of the combined power inlet is obtained.

[0031] Combine Figure 1 and Figure 2The working principle of the present invention is as follows: after the supersonic incoming flow is compressed by the first-stage compression surface 1 and the second-stage compression surface 2, it enters the contraction section in the inlet duct, and the airflow is continuously decelerated and pressurized by the contraction of the area until the cross-section with the smallest area, that is, the throat 3, is reached. After the airflow passes through the throat, a terminal positive shock wave reduces the airflow to subsonic speed. Thereafter, the subsonic airflow passes through the mode conversion device 4 and enters the turbine engine channel 6 and the ramjet engine channel 5, and continues to decelerate and pressurize in the turbine engine channel 6 and the ramjet engine channel 5 until the required outlet airflow meets the engine requirements. Therefore, by controlling the outlet conditions of the turbine engine channel 6 and the ramjet engine channel 5, different inlet characteristics can be obtained. During the mode conversion process, the mode conversion device 4 gradually closes the turbine engine channel 6 and opens the ramjet engine channel 5. Therefore, several different diversion positions are set during the mode conversion process, such as the turbine mode (such as Figure 1 ), 1 / 4 split mode, 2 / 4 split mode, 3 / 4 split mode and stamping mode (as shown in Figure 2 shown).

[0032] In the numerical simulation, the back pressure characteristics of the intake duct under different diversion modes are analyzed to obtain the stable working boundary of the intake duct and the outlet parameters that meet the engine requirements under different diversion modes, and the corresponding state points are connected in sequence, such as Figure 3-4 As shown by the dotted line, the modal conversion law that meets the engine flow requirements and the stable operation of the intake duct is obtained.

[0033] In the wind tunnel test, the blockage degree of the downstream throttle cone was changed under different diversion modes to obtain the back pressure characteristics of different diversion modes. Then, according to the engine flow demand and the stable working boundary of the inlet duct, the modal conversion law was sorted out as follows: Figure 5-6 As shown in the figure, two different modal conversion laws are given according to the engine reduced flow requirements. The reduced flow and inlet surge margin required by modal conversion law 1 are both smaller than those of modal conversion law 2. In general, as the modal conversion proceeds, the turbine engine channel outlet pressure gradually decreases, and the outlet Mach number remains at around 0.3.

[0034] It can be seen from the above results that the present invention first obtains the back-pressure characteristics of different diversion modes during the modal conversion process of the internal parallel combined power inlet, and then obtains the modal conversion law of the combined power inlet according to the flow requirements of the turbine / ramjet engine and the stable working conditions of the inlet during the modal conversion process. This can not only ensure that the flow of the turbine / ramjet channel transitions continuously and meets the engine requirements, but also ensure the stable and normal operation of the inlet.

[0035] In addition, an embodiment of the present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium may store a program, which, when executed, includes part or all of the steps of any method for determining the inlet duct modal conversion law recorded in the above method embodiments.

[0036] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0037] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a memory and includes several instructions for enabling a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned memory includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk, and other media that can store program code.

[0038] Those skilled in the art will appreciate that all or part of the steps in the various methods of the above embodiments can be completed by instructing related hardware through a program. The program can be stored in a computer-readable memory, and the memory can include: a flash drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0039] It should be noted that the numerous details included in the above description are merely illustrative of the present invention and are not intended to limit the present invention. In other embodiments of the present invention, the method may have more, fewer, or different steps, and the order, inclusion, functionality, and other relationships between the steps may differ from those described and illustrated.

Claims

1. A method for determining an intake duct modal conversion law, characterized in that: include: Step 1: Divide the inlet duct modal conversion process into several intermediate modes, and ensure the linear transition of the flow entering the turbine duct and ramjet duct under different modes; Step 2: Use wind tunnel tests or numerical simulation methods to obtain the backpressure characteristics of the inlet turbine engine channel and ramjet engine channel under different diversion modes; Step 3: According to the changes in the turbine / ramjet engine flow demand during the modal conversion process and the stable working conditions of the inlet duct, determine the inlet duct modal conversion law that meets the smooth modal conversion requirements.

2. The determination method according to claim 1, characterized in that The intermediate mode includes one or more of a turbine mode, a 1 / 4 split mode, a 2 / 4 split mode, a 3 / 4 split mode and a ram mode.

3. The determination method according to claim 1, characterized in that In step 2: under different flow diversion modes, the back pressure characteristics of the turbine engine channel and the ramjet engine channel are obtained by changing the back pressure at the outlet of the turbine engine channel and the ramjet engine channel.

4. The determination method according to claim 1, characterized in that In the step 2, under different flow diversion modes, the back pressure characteristics of the turbine engine channel and the ramjet channel are obtained by changing the blockage degree of the outlet cones of the turbine engine channel and the ramjet channel.

5. The determination method according to claim 4, characterized in that: In the process of changing the blockage degree of the turbine engine outlet cone, the turbine engine passage outlet pressure gradually decreases and the outlet Mach number is maintained at a constant.

6. The determination method according to any one of claims 1 to 5, characterized in that: The air intake duct is an inner parallel combined power air intake duct.

7. The determination method according to claim 6, characterized in that: The inner parallel combined power intake duct includes a first-stage compression surface and a second-stage compression surface. After flowing through the first-stage compression surface and the second-stage compression surface, the air reaches the throat. A mode conversion device is provided at the throat. Behind the mode conversion device are the parallel turbine engine channel and the ramjet engine channel.

8. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for determining the mode conversion law of the intake duct are implemented.

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