Design method of variable-area rear duct ejector

Abstract

The invention discloses a design method of a variable-area rear duct ejector, which comprises the following steps of: synchronously optimizing airflow ejection pressure or geometric parameters in CFD (computational fluid dynamics) simulation to determine a design process that the geometric parameters of a pneumatic blockage adjusting piece and the airflow ejection pressure reach an optimal matching state. And the UG designs the geometric dimension and circumferential layout of the pneumatic blocking adjusting piece, CFD simulation is carried out on the UG model based on the pneumatic blocking adjusting piece, and according to a CFD simulation result, the airflow ejection pressure or the geometric parameters of the pneumatic blocking adjusting piece are synchronously optimized until the pneumatic blocking adjusting piece and the airflow ejection pressure reach the optimal matching state, so that the pneumatic blocking adjusting piece is obtained. The problem that the geometric dimension of an existing component cannot be optimally matched with the working condition is solved.

Description

Technical Field

[0001] The invention relates to a design method for a variable-area rear duct ejector, belonging to the technical field of aeroengines. Background Art

[0002] The variable cycle engine used in the aircraft meets the performance requirements of low fuel consumption and high power output during flight. The variable area rear duct ejector is a key component for adjusting the internal and external duct flow in the variable cycle engine. The rear duct ejector adjusts the aerodynamic area of ​​the mixed outlet cross section of the internal and external duct flow, and after matching with the whole machine, the engine's bypass ratio is adjusted to achieve the purpose of adjustable engine bypass ratio.

[0003] When designing components for adjusting the outlet areas of inner and outer culverts and the balanced static pressure values, the existing component design process (see Chinese Patent Publication No. CN116595682A) is: designing component geometry based on normal working conditions, performing simulation optimization based on normal working conditions and finally determining the components. There is a situation where the component geometry and working conditions cannot achieve optimal matching. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a design method for a variable area rear duct ejector.

[0005] The present invention is achieved through the following technical solutions.

[0006] The present invention provides a design method for a variable area rear duct ejector, comprising:

[0007] The design process of optimizing the airflow ejection pressure or geometric parameters in CFD simulation to determine the optimal matching state between the geometric parameters of the pneumatic choke adjustment part and the airflow ejection pressure.

[0008] The design process specifically includes four steps.

[0009] The step 1 is: knowing the overall performance at the inner duct outlet and the outer duct outlet at different operating points, that is, the aerodynamic area at the mixing section and the static pressure value at aerodynamic balance, designing a pneumatic blocking adjustment component at the mixer outlet through UG modeling.

[0010] The second step is: the design of the pneumatic blocking adjustment component includes parameters such as circumferential layout, geometric parameters, and airflow pressure P.

[0011] The step three is: based on the UG model, the aerodynamic blocking characteristics of the inner and outer flow at the mixer outlet under different circumferential layouts, different jet pressures, and different geometric parameter combinations are calculated through three-dimensional CFD simulation.

[0012] The step four is: judging whether the pneumatic blocking characteristics meet the requirements of the aerodynamic areas of the inner and outer ducts of the mixer outlet and the aerodynamic balance static pressure value after the airflow is mixed according to the three-dimensional CFD simulation results. If the requirements are met, the design is completed; if not, the design returns to the pneumatic blocking adjustment part design link to further optimize the airflow ejection pressure of the pneumatic blocking adjustment part or the geometric parameters of the pneumatic blocking adjustment part until the requirements are met.

[0013] The beneficial effects of the present invention are as follows: UG designs the geometric dimensions and circumferential layout of the pneumatic blocking adjustment part, and based on the UG model of the pneumatic blocking adjustment part, CFD simulation is performed. According to the CFD simulation results, the airflow ejection pressure or the geometric parameters of the pneumatic blocking adjustment part are simultaneously optimized until the pneumatic blocking adjustment part and the airflow ejection pressure reach the optimal matching state, thereby solving the problem that the geometric dimensions of the existing components and the working conditions cannot achieve the optimal matching state. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the design process of the present invention;

[0015] Figure 2 It is a schematic diagram of the distribution structure of the present invention;

[0016] Figure 3 yes Figure 2 Sectional view along the midline BB;

[0017] Figure 4 It is a schematic diagram of the pneumatic blockage distribution corresponding to the inner channel of the present invention;

[0018] Figure 5 Schematic diagram of aerodynamic blockage distribution corresponding to the outer duct of the present invention;

[0019] In the figure: 1-inner channel; 2-outer channel; 3-pneumatic blocking adjustment member; 31-channel; 32-injection structure. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0021] like Figures 1 to 5 shown.

[0022] A design method of a variable area rear duct ejector of the present application comprises the following steps:

[0023] Step 1: Given the overall performance at different operating points, including the outlet of inner duct 1 and the outlet of outer duct 2, that is, the aerodynamic area at the mixing section and the static pressure value at aerodynamic balance, a pneumatic blocking adjustment member 3 is designed at the mixer outlet through UG modeling.

[0024] Step 2: Design of the pneumatic blocking adjustment member 3 includes circumferential layout, geometric parameters (such as the attached Figure 3The middle BB view shows the geometric dimensions L, injection angle θ), airflow pressure P and other parameters of the high-pressure airflow jet outlet.

[0025] Step 3: Based on the UG model, the aerodynamic blocking characteristics of the inner and outer flow at the mixer outlet are calculated through three-dimensional CFD simulation under different circumferential layouts, different jet pressures, and different geometric parameter combinations.

[0026] Step 4: According to the three-dimensional CFD simulation results, determine whether the pneumatic blocking characteristics meet the requirements of the aerodynamic area of ​​the inner and outer ducts of the mixer outlet and the aerodynamic balance static pressure value after the airflow is mixed. If the requirements are met, the design is completed. If not, return to the pneumatic blocking adjustment part design link to further optimize the airflow ejection pressure of the pneumatic blocking adjustment part 3 or the geometric parameters of the pneumatic blocking adjustment part 3 until the requirements are met.

[0027] This application uses UG to design the geometric dimensions and circumferential layout of the pneumatic blocking adjustment member 3 based on the working condition data of the inner duct 1 outlet and the outer duct 2 outlet. Based on the UG model of the pneumatic blocking adjustment member 3, CFD simulation is performed. According to the CFD simulation results, the airflow ejection pressure or the geometric parameters of the pneumatic blocking adjustment member 3 are simultaneously optimized until the pneumatic blocking adjustment member 3 and the airflow ejection pressure reach the optimal matching state, which solves the problem that the geometric dimensions of the existing components and the working conditions cannot achieve the optimal matching. The pneumatic blocking adjustment member 3 can adjust the outlet area of ​​the inner and outer ducts and the balanced static pressure value during installation and use.

[0028] In actual work, the pneumatic blockage at the outlet of the mixer can be adjusted by adjusting the flow rate and pressure of the high-pressure airflow introduced into the pneumatic blockage adjustment member, so as to achieve the purpose of adjusting the outlet area and balancing the static pressure value.

[0029] A variable area rear duct ejector structure of the present application comprises:

[0030] The pneumatic blocking adjustment member 3 is installed at the mixing section of the inner channel 1 outlet and the outer channel 2 outlet. The pneumatic blocking adjustment member 3 introduces high-pressure airflow to adjust the inner channel 1 outlet and the outer channel 2 outlet area and the balance static pressure value. The pneumatic blocking adjustment member 3 is distributed in four circumferential arrays at intervals.

[0031] The pneumatic blocking adjusting member 3 is provided with a channel 31 for introducing high-pressure airflow inside. The channel 31 can introduce high-pressure airflow from the high-pressure compressor. The pressure of the high-pressure airflow is 1.5 times the pressure of the airflow in the inner duct 1 and the outer duct 2.

[0032] The pneumatic blocking adjustment member 3 at the outlet of the outer duct 2 and the outlet of the inner duct 1 has a jet structure 32 for jetting high-pressure airflow at the upper and lower parts. The jet structures 32 are symmetrically distributed in the same cross section. The jet structures 32 are holes or slits. The size L of the jet structures 32 is 1 to 2 mm. The jet angle θ of the jet structure 32 toward the outlet of the outer duct 2 and the outlet of the inner duct 1 is greater than or equal to 90°, so that when the jet structure 32 jets high-pressure airflow, it is jetted to the mixing cross section of the outlet of the outer duct 2 and the outlet of the inner duct 1 to form a pneumatic blockage. Figure 3 , 4 The circular arrow shown in 5 is a pneumatic blockage.

[0033] The pneumatic blocking adjustment part 3 is installed at the mixed section of the inner duct 1 outlet and the outer duct 2 outlet to spray high-pressure airflow to form pneumatic blocking, and the pressure and flow of the high-pressure airflow entering the channel 31 in the pneumatic blocking adjustment part 3 are adjusted, and the spray structure 32 in the pneumatic blocking adjustment part 3 is adjusted. The present application realizes the control of the pressure, flow and spray position of the high-pressure airflow, and can flexibly adjust the pneumatic blocking according to the actual working conditions, thereby adjusting the outlet area of ​​the inner and outer ducts and the balanced static pressure value, and realizing the adaptive adjustment of the duct ratio of the whole machine. Compared with the conventional rear duct ejector, the actuating mechanism is reduced, and the sealing problem caused by the installation of the actuating mechanism with a driving operation is solved.

Claims

1. A design method for a variable area rear duct ejector, characterized in that: include: The airflow ejection pressure or geometric parameters are optimized synchronously in CFD simulation to determine the design process in which the geometric parameters of the pneumatic blocking adjustment member (3) and the airflow ejection pressure are optimally matched.

2. The variable area rear duct ejector design method according to claim 1, characterized in that: The design process specifically includes four steps.

3. The design method of a variable area rear duct ejector according to claim 2, characterized in that: The first step is: given the overall performance at different operating points, including the outlet of the inner duct (1) and the outlet of the outer duct (2), that is, the aerodynamic area at the mixing cross section and the static pressure value at aerodynamic balance, a pneumatic blocking adjustment component (3) is designed at the outlet of the mixer through UG modeling.

4. The design method of a variable area rear duct ejector according to claim 2, characterized in that: The second step is: the design of the pneumatic blocking adjustment member (3) includes parameters such as circumferential layout, geometric parameters, and airflow pressure P.

5. The design method of a variable area rear duct ejector according to claim 2, characterized in that: The step three is: based on the UG model, the aerodynamic blocking characteristics of the inner and outer flow at the mixer outlet under different circumferential layouts, different jet pressures, and different geometric parameter combinations are calculated through three-dimensional CFD simulation.

6. The design method of a variable area rear duct ejector according to claim 2, characterized in that: The fourth step is to determine whether the pneumatic blocking characteristics meet the requirements of the pneumatic areas of the inner and outer ducts of the mixer outlet and the pneumatic balance static pressure value after the airflow is mixed based on the three-dimensional CFD simulation results. If the requirements are met, the design is completed; if not, the design returns to the pneumatic blocking adjustment part design link to further optimize the airflow ejection pressure of the pneumatic blocking adjustment part (3) or the geometric parameters of the pneumatic blocking adjustment part (3) until the requirements are met.

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