A method for designing a mixed flow nozzle

Abstract

The application discloses a mixed exhaust nozzle design method, and belongs to the technical field of mixed exhaust nozzle design. The method comprises the following steps: acquiring the total temperature, total pressure and flow rate of the outer and inner inlets, and calculating the total pressure of the lobe mixer outlet according to the total pressure recovery coefficient; presetting the Mach number of the inner outlet and calculating the inner outlet area; solving the outer outlet area through static pressure equal coupling; obtaining the mixed total temperature by solving the energy conservation equation through an iterative method; solving the mixed velocity coefficient and total pressure through a nested iterative method; determining the nozzle choke state according to the critical pressure ratio and calculating the nozzle outlet area; and calculating the conceptual thrust of the separate exhaust nozzle and the mixed exhaust nozzle and evaluating the thrust gain. The application can quickly determine the outer and inner lobe mixer areas and the nozzle outlet area, significantly reduce the design iteration number, and shorten the mixed exhaust nozzle design cycle.

Description

Technical Field

[0001] This invention belongs to the field of mixed exhaust nozzle design technology, specifically relating to a mixed exhaust nozzle design method for a gas turbine engine exhaust system. Background Technology

[0002] Modern turbofan engines widely employ mixed exhaust configurations. Lobed mixers, relying on large-scale flow vortices to enhance the mixing of inner and outer bypass airflow, effectively improve thrust gain, reduce heat radiation and exhaust noise, and are core components determining engine propulsion efficiency and stealth performance. The matching design of the outer and inner bypass area and the nozzle exit area, as well as the precise balance between the outer and inner bypass flow rates and the total flow rate, directly affect mixing uniformity, total pressure recovery coefficient, and thrust output, and are key technical aspects of mixed exhaust nozzle aerodynamic design.

[0003] Currently, the design of lobe mixers and nozzles largely relies on empirical formulas, iterative simulations, or experimental calibration. Existing design methods suffer from the following main shortcomings: First, it is difficult to quantify the synergistic constraint relationship between the outer and inner flow exit areas and the nozzle exit area. The area matching of the two airflows, the outer and inner flow, involves complex flow coupling. Traditional methods lack effective analytical solutions, which can easily lead to problems such as flow rate mismatch, incomplete mixing, thrust loss, and nozzle blockage.

[0004] Second, the thrust gain calculation did not form a closed-loop iteration with parameters such as area and flow rate. In the traditional design process, area design, performance evaluation, and scheme optimization are usually carried out sequentially, resulting in long design cycles and low optimization accuracy.

[0005] Third, although there are existing technologies that use computational fluid dynamics (CFD) numerical simulation for the design of mixed-discharge nozzles, the CFD method is costly and time-consuming, making it difficult to quickly obtain key parameters during the design phase and hindering rapid comparison of multiple options.

[0006] Therefore, there is an urgent need in this field for a technical solution that can quickly design parameters such as nozzle area, flow rate, and thrust gain. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hybrid nozzle design method for quickly determining important parameters such as the outer bypass area, inner bypass area, nozzle exit area, thrust gain, and exit Mach number of the beam mixer, which can significantly reduce the number of iterations in the design process.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for designing a mixed-displacement nozzle includes the following steps: Step 1: Design input and total pressure calculation.

[0009] Obtain design input parameters, including the total temperature at the bypass inlet. Total pressure of the outer duct inlet , outflow And the total temperature of imported goods Total Import Pressure Internal flow Based on design experience, the total pressure recovery coefficient of the bypass duct of the beam mixer... and total internal pressure recovery coefficient Typically, a value of 0.98 to 0.99 is used. This yields the total bypass pressure at location A0 of the beam mixer outlet section. and the total pressure of connotation .

[0010] In this invention, the mixing nozzle includes a bevel mixer, a mixing section, and a nozzle exit section arranged sequentially along the flow direction. The bevel mixer exit section A0 divides the flow channel into an outer bypass outlet (A1) and an inner bypass outlet (A2).

[0011] The design input parameters in step 1 ( , , , , , All of these are inlet cross-sectional parameters before entering the beam mixer, which correspond to the airflow parameters of the outer bypass and inner bypass at the inlet of the beam mixer, respectively.

[0012] Step 2: Determine the total length of the nozzle.

[0013] The total length d0 of the nozzle is determined based on the overall scheme dimensional constraints.

[0014] Step 3: Determine the location of the beam mixer outlet section.

[0015] The position A0 of the outlet section of the beam mixer is determined based on the relative length L0 / D0 of the mixing section, where D0 is the nozzle diameter at the outlet section of the beam mixer and L0 is the length of the mixing section.

[0016] The mixing section is the flow channel region from the outlet section position A0 of the lobe mixer to the inlet of the nozzle convergence section, and its length is L0.

[0017] Step 4: Determine the central cone surface.

[0018] The nozzle center cone profile is determined, with key parameters including the center cone convergence angle α2 and the radius R0 of the beam mixer outlet position.

[0019] Step 5: Preset the intrinsic exit Mach number.

[0020] Preset lobe mixer intrinsic exit Mach number Preferably, The value range is 0.3 to 0.5.

[0021] Step 6: Calculate the internal outlet area.

[0022] Calculate the outlet area of ​​the lobe mixer using the following gas dynamics formula. : ..........................(1) .............................(2) .............................(3) ................................(4) in, For intrinsic traffic, For specific heat ratio, The intrinsic export speed coefficient, It is a constant. Internal total temperature, For the overall internal pressure, For the internal export area, The Mach number for the export of internal components.

[0023] Step 7: Determine the geometric parameters of the beam mixer.

[0024] Based on the central cone-shaped surface and the internal outlet area Adjust the geometric parameters of the beam mixer to make the inner outlet area of ​​the beam mixer reach The geometric parameters of the beam mixer include the mixer angle α1, beam width d, inner beam radius R1, outer beam radius R2, beam radius R3, and number of beams. Preferably, the beam width d and the mixer angle α1 are adjusted first to quickly achieve a given... .

[0025] Step 8: Solve for the outer bypass area using static pressure balance coupling.

[0026] Calculate the static pressure at position A0 using the following formula. : ................................(5) in This refers to the intrinsic export speed coefficient.

[0027] This invention assumes that the static pressure of the bypass airflow and the internal airflow are equal in the mixing section, therefore the static pressure of the bypass at position A0 is also equal to... The outlet velocity coefficient of the culvert can be calculated by back-calculating from formula (5). Then, calculate the outlet area of ​​the outer duct of the beam mixer according to formulas (1) to (4). and the Mach number of the outer permeable port .get Then, adjust the outer duct nozzle profile so that the outer duct outlet area of ​​the beam mixer reaches the desired level. .

[0028] Step 9: Solve for the total mixed temperature by energy conservation iteration.

[0029] Calculate the total temperature after complete mixing of the outer and inner components based on the energy conservation equation. : ...........................................(6) in For gas enthalpy, For specific heat capacity and This means that the specific heat capacity has a non-linear relationship with temperature; it is understandable that... This represents the enthalpy of the mixed gases. The enthalpy of the outer gas is represented by the outer gas. Indicates the enthalpy of a gas.

[0030] because The solution varies nonlinearly with temperature and cannot be solved directly. Therefore, an iterative method is used to solve the problem, as follows: Sub-step 9.1: Estimate the total temperature after mixing ; Sub-step 9.2: [The sentence is incomplete and requires more context to be translated accurately.] Substitution get Substituting into formula (6) and solving, we get... ; Sub-step 9.3: Determine and Is the error less than the preset threshold for total temperature (preferably 10)? - ³), if less than then If it is greater than, then take... The steps of the iterative method are repeated until the error between two adjacent iterations is less than the preset threshold for total temperature.

[0031] Step 10: Solve the mixing velocity coefficient and total pressure using nested iterations.

[0032] Neglecting friction, the inlet and outlet momentum are equal, and the flow rate is conserved. Solve the following equations to find the velocity coefficient after mixing. and the total pressure after mixing : ................(7) .....................(8) .............................................(9) ..................................................(10) .....................................................(11) in, The momentum function Both are flow functions, expressed as velocity coefficients. The independent variable is different, but the expression is different. It is understandable that the parameters without subscripts in the above formulas (such as...) , , When substituting a specific cross section, the corresponding subscripts (1, 2, m) can be added. Subscript 1 represents the external parameter, subscript 2 represents the internal parameter, and subscript m represents the corresponding parameter after mixing. When different subscripts are used, the corresponding physical quantities of the cross section are obtained. , , When taking the corresponding subscript, it corresponds to the static pressure, total pressure, and total temperature.

[0033] The solution process for equations (7) to (11) above adopts a nested iterative method, as follows: Sub-step 10.1: Estimate the velocity coefficient after mixing ; Sub-step 10.2: [The text appears to be incomplete and contains several grammatical errors. A more accurate translation would require the full context.] Substituting into formulas (7) and (8), we obtain the total pressure after mixing. Then, the mixed function value is calculated according to formulas (9) and (10). =Q; Sub-step 10.3: Iteratively solve based on Q and formula (2) ; Sub-step 10.4: and Is the error less than the preset threshold of the speed coefficient (preferably 10)? - ³), if less than then = If it is greater than, then take... The nested iteration method is repeated until the error between two adjacent iterations is less than the preset threshold of the speed coefficient. Sub-step 10.5: [The sentence is incomplete and requires more context to be translated accurately.] Substituting into formulas (7) and (8), we obtain the total pressure after mixing. .

[0034] In sub-step 10.3, the solution is obtained iteratively based on Q and formula (2). The specific method is as follows: Sub-step 10.3.1: Rewrite formula (2) as about The equation: ..............................(12) Sub-step 10.3.2: Predict the velocity coefficient ,Will And Q is substituted into formula (12) to calculate the result. ; Sub-step 10.3.3: Determine and Is the error less than the preset threshold for the speed coefficient (preferably 10)? - ³), if less than then = If it is greater than, then As the new predicted velocity coefficient, the process of substituting the predicted velocity coefficient and Q into the rewritten formula to calculate the new predicted velocity coefficient is repeated until the error between two adjacent iterations is less than the preset threshold for the velocity coefficient, ultimately yielding the result. .

[0035] Step 11: Determine the critical pressure ratio and calculate the nozzle exit area.

[0036] judge / Is it greater than the critical pressure ratio of 0.528, where P0 is the ambient pressure? like / If the value is ≥0.528, the nozzle is in a clogging state, and the nozzle exit velocity coefficient is... =1, will =1 and total flow Substitute into formulas (1) to (4) to calculate the nozzle exit area. (i.e., the cross-section at the end of the nozzle exit section), at this time =1; like / If the value is less than 0.528, the nozzle is in an unblocked state. The nozzle exit velocity coefficient can be calculated using the following formula. : ..............................(13) Will and total flow Substitute the gas dynamics formulas (1) to (4) to calculate the nozzle exit area. .

[0037] Step 12: Thrust gain assessment.

[0038] The ideal thrust F1 of the outer bypass and the ideal thrust F2 of the inner bypass of the split nozzle are calculated based on the ideal thrust formula, thus obtaining the total ideal thrust F of the split nozzle. f =F1+F2. Preferably, the ideal thrust formula (14) is: .............................(14) Based on the total mixed temperature obtained in step 9 The total mixed pressure obtained in step 10 Total flow Substituting into the ideal thrust formula, calculate the ideal total thrust F of the mixed exhaust injection system. h .

[0039] Calculate the thrust gain of the mixed-row nozzle relative to the split-row nozzle: η=(F h -F f ) / F f ...................................................(15) The thrust gain η can be used to quantitatively evaluate the performance improvement of the mixed-displacement nozzle scheme compared to the separate-displacement nozzle scheme, providing a basis for judging the feasibility of the scheme.

[0040] Preferably, in the above design method, the Mach number at the exit of the bypass duct of the lobe mixer can also be preset first. Instead of pre-setting the intrinsic exit Mach number in steps 5 to 8 above, The design sequence is as follows: first calculate the outlet area of ​​the outer culvert. Then calculate the internal export area The remaining steps remain unchanged, and the technical effects of the present invention can be achieved in the same way.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects: 1. Based on the inlet parameters of the outer and inner bypasses, this invention can quickly assess the outlet areas of the inner bypass, outer bypass, and nozzle of the beam mixer during the design phase. It can quickly obtain the Mach number at the exit of the inner bypass, the exit of the outer bypass, and the exit of the nozzle, and evaluate the thrust gain of the mixed-flow nozzle relative to the separate-flow nozzle with the same inlet parameters, thereby assessing the feasibility of the mixed-flow nozzle scheme.

[0042] 2. The method of the present invention can greatly shorten the design iteration time of the mixed nozzle flow channel and reduce the number of iterations from design to simulation to optimization.

[0043] 3. The method of the present invention has flexibility in design sequence, which can design the inner area first and then the outer area, or design the outer area first and then the inner area.

[0044] 4. This invention uses an iterative algorithm to solve the momentum equation, continuity equation, and energy equation, ensuring that each parameter converges quickly to obtain accurate values. Attached Figure Description

[0045] Figure 1 This is a flowchart of the mixed-discharge nozzle design method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the mixing nozzle in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the beam mixer in an embodiment of the present invention. Detailed Implementation

[0046] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0047] To better understand this invention, the spatial positions and airflow logic of the components of the mixing nozzle will be explained below: See Figure 2 and Figure 3 The outer bypass airflow and the inner bypass airflow flow into the beam mixer from the outer ring channel and inner ring channel, respectively. The two airflows form the outer bypass outlet area (A0) at the beam mixer outlet cross-section (A0). ) and intrinsic export area ( The fuel then enters a mixing section of length L0 for further mixing, and finally expands and exits through the nozzle exit section. The cross-sectional area at the end of the nozzle exit section is... This invention uses an area / flow rate matching design method to sequentially determine... , and This enables the integrated and rapid design of mixed-discharge nozzles.

[0048] Example 1 This embodiment provides a mixed-displacement nozzle design method, such as Figure 1 As shown, the method includes the following steps: Step 1: Design input and total pressure calculation.

[0049] Obtain design input parameters: total temperature at the bypass inlet Total pressure of the outer duct inlet , outflow And the total temperature of imported goods Total Import Pressure Internal flow Based on design experience, the total pressure recovery coefficient of the bypass duct of the beam mixer... and total internal pressure recovery coefficient All values ​​are taken as 0.98. This yields the total bypass pressure at location A0 of the beam mixer outlet section. and the total pressure of connotation .

[0050] Step 2: Determine the total length of the nozzle.

[0051] like Figure 2 As shown, the total length d0 of the nozzle is determined based on the overall scheme size constraints.

[0052] Step 3: Determine the location of the beam mixer outlet section.

[0053] like Figure 2 As shown, the outlet section position A0 of the beam mixer is determined according to the relative length L0 / D0 of the mixing section, where D0 is the nozzle diameter at the outlet section position of the beam mixer and L0 is the length of the mixing section.

[0054] Step 4: Determine the central cone surface.

[0055] Determine the central cone shape of the nozzle, such as Figure 2 As shown, the main parameters include the central cone convergence angle α2 and the radius R0 of the beam mixer outlet position.

[0056] Step 5: Preset the intrinsic exit Mach number.

[0057] Preset lobe mixer intrinsic exit Mach number =0.4.

[0058] Step 6: Calculate the internal outlet area.

[0059] The outlet area of ​​the lobe mixer is calculated according to the gas dynamics formulas (1) to (4). .

[0060] ..........................(1) .............................(2) .............................(3) ................................(4) middle, For intrinsic traffic, For specific heat ratio, The intrinsic export speed coefficient, It is a constant. Internal total temperature, For the overall internal pressure, For the internal export area, The Mach number for the export of internal components.

[0061] Specifically, according to the preset The velocity coefficient was obtained by conversion. ,Will Substituting into formula (1), we get q( ), will include intrinsic parameters ( , , Substituting into formula (1), the solution can be obtained. .

[0062] Step 7: Determine the geometric parameters of the beam mixer.

[0063] Based on the central cone-shaped surface and the internal outlet area Adjust the geometric parameters of the beam mixer, such as Figure 2 , Figure 3 As shown, the geometric parameters of the beam mixer include the mixer angle α1, beam width d, inner ring radius R1, outer ring radius R2, beam radius R3, and number of beams. Prioritize adjusting the beam width d and the mixer angle α1 to achieve the desired inner outlet area of ​​the beam mixer. .

[0064] Step 8: Solve for the outer bypass area using static pressure balance coupling.

[0065] Calculate the static pressure at position A0 according to formula (5). .

[0066] ................................(5) This embodiment assumes that the static pressure of the bypass airflow and the internal airflow are equal in the mixing section, so the static pressure of the bypass at position A0 is also P. According to formula (5), the total internal pressure is... Replace with total bypass pressure And will include the export speed coefficient. Replace with the outer bypass exit velocity coefficient From this, the static pressure of the duct can be obtained, and from this, the velocity coefficient at the duct outlet can be deduced. .

[0067] get Then, the outlet area of ​​the beam mixer is calculated according to formulas (1) to (4). and the Mach number of the outer permeable port .get Then, adjust the outer duct nozzle profile so that the outer duct outlet area of ​​the beam mixer reaches the desired level. .

[0068] The core of this step lies in using the physical constraint of "equal static pressure" to strongly couple the area design of the outer and inner ducts, thereby achieving a precise match between the outlet areas of the outer and inner ducts.

[0069] Step 9: Solve for the total mixed temperature by energy conservation iteration.

[0070] The total temperature after complete mixing of the outer and inner layers is calculated based on the energy conservation equations (6) for import and export. .

[0071] ...........................................(6) in For gas enthalpy, For specific heat capacity and This means that the specific heat capacity has a non-linear relationship with temperature.

[0072] because Since the relationship is nonlinear, an iterative method is used to solve it, as follows: First, estimate the total temperature after mixing. ; Will Substitution get Substituting into formula (6) and solving, we get... ; judge and Is the error less than 10? - ³, if less than 3 If it is greater than, then take... The steps of the iterative method are repeated until the error between two adjacent iterations is less than 10. - ³.

[0073] Step 10: Solve the mixing velocity coefficient and total pressure using nested iterations.

[0074] Neglecting friction, solve equations (7) to (11) to find the velocity coefficient after mixing. and the total pressure after mixing .

[0075] ................(7) .....................(8) .....................................................(9) ..................................................(10) ....................................................(11) Using a nested iteration method: First, estimate the velocity coefficient after mixing. ; Will Substituting into formulas (7) and (8), we obtain the total pressure after mixing. Then, the mixed function value is calculated according to formulas (9) and (10). =Q; Iterative solution based on Q and formula (2) ,include: Rewrite formula (2) as formula (12): ..............................(12) Predicted speed coefficient ,Will And Q is substituted into formula (12) to calculate the result. ,judge and Is the error less than 10? - ³, if less than 3 = If it is greater than, then As the new estimated velocity coefficient, the steps of substituting the estimated velocity coefficient and Q into the rewritten formula (12) to back-calculate the new estimated velocity coefficient are repeated until convergence (i.e., the error between two adjacent iterations is less than the preset threshold of the velocity coefficient). judge and Is the error less than 10? - ³, if less than 3 = If it is greater than, then take... The nested iteration method is repeated until the error between two adjacent iterations is less than 10. - ³; Will Substituting into formulas (7) and (8), we obtain the total pressure after mixing. .

[0076] Step 11: Determine the critical pressure ratio and calculate the nozzle exit area.

[0077] judge / Is it greater than the critical pressure ratio of 0.528, where P0 is the ambient pressure?

[0078] like / If the value is ≥0.528, the nozzle is in a clogging state, and the nozzle exit velocity coefficient is... =1, will =1 and total flow Substitute into formulas (1) to (4) to calculate the nozzle exit area. ,at this time =1.

[0079] like / If the value is less than 0.528, the nozzle is in an unblocked state. The nozzle exit velocity coefficient can be calculated according to formula (13). : ..............................(13) Will and total flow Substitute the gas dynamics formulas (1) to (4) to calculate the nozzle exit area. .

[0080] Step 12: Thrust gain assessment.

[0081] The ideal thrust F1 of the outer circumferential nozzle and the ideal thrust F2 of the inner circumferential nozzle are calculated according to the ideal thrust formula (14) to obtain the total ideal thrust F of the nozzle.f =F1+F2. Wherein, the ideal thrust formula (14) is: .............................(14) Based on the total mixed temperature obtained in step 9 The total mixed pressure obtained in step 10 Total flow Substitute into the ideal thrust formula (14) to calculate the ideal total thrust F of the mixed-emission jet system. h .

[0082] The thrust gain of the mixed-row nozzle relative to the split-row nozzle is calculated according to formula (15): η=(F h -F f ) / F f ...................................................(15) The thrust gain η can be used to determine whether the mixed-row nozzle scheme is superior to the separate-row nozzle scheme, providing a quantitative basis for scheme decision-making.

[0083] Example 2 The difference between this embodiment and Embodiment 1 lies in the adjustment of the design order.

[0084] In this embodiment, the Mach number at the exit of the beam mixer is preset first. In alternative embodiment 1, steps 5 to 8 pre-set the intrinsic exit Mach number. The design sequence. Specifically: Step 5': Preset the Mach number at the exit of the beam mixer outer bypass. ; Step 6': Calculate the outlet area of ​​the outer bypass of the lobe mixer according to gas dynamics formulas (1) to (4). ; Step 7': Based on the central cone surface and the outer culvert outlet area Adjusting the geometric parameters of the beam mixer to achieve the desired outer bypass exit area ; Step 8': Calculate the static pressure of the duct at position A0 according to formula (5). Assuming the static pressure of the inner and outer bypass airflows is equal in the mixing section, the velocity coefficient at the inner exit can be calculated. Then, calculate the inner outlet area of ​​the beam mixer according to formulas (1) to (4). and the Mach number of exports .

[0085] The remaining steps (steps 9 to 12) are the same as in Example 1.

[0086] This embodiment illustrates that the design method of the present invention has flexibility in design sequence. It can design the inner area first and then the outer area, or design the outer area first and then the inner area, and both can achieve the technical effect of the present invention.

[0087] Example 3 Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium, and when executed, the program performs the steps of the above method embodiments.

[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations of the embodiments of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for designing a mixed-discharge nozzle, characterized in that, Includes the following steps: Step 1: Obtain design input parameters, including the total temperature at the bypass inlet. Total pressure of the outer duct inlet , outflow , total temperature of imported Total Import Pressure and intrinsic traffic And based on the total pressure recovery coefficient of the outer bypass of the beam mixer and total internal pressure recovery coefficient The total pressure of the bypass duct at position A0 of the outlet section of the beam mixer is obtained. and the total pressure of connotation ; Step 2: Determine the total length d0 of the nozzle based on the overall scheme dimensional constraints; Step 3: Determine the outlet section position A0 of the beam mixer based on the relative length L0 / D0 of the mixing section, where D0 is the nozzle diameter at the outlet section position of the beam mixer and L0 is the length of the mixing section; Step 4: Determine the central cone shape of the nozzle. The parameters of the central cone shape include the central cone convergence angle α2 and the radius R0 of the outlet position of the beam mixer. Step 5: Preset the exit Mach number of the beam mixer. ; Step 6: Calculate the outlet area of ​​the lobe mixer using the following gas dynamics formula. : ， ， ， in, For intrinsic traffic, For specific heat ratio, The intrinsic export speed coefficient, It is a constant. Internal total temperature, For the overall internal pressure, For the internal export area, The Mach number for the internal export; Step 7: Based on the central conical surface and the inner outlet area Adjust the geometric parameters of the beam mixer to make the inner outlet area of ​​the beam mixer reach The geometric parameters of the beam mixer include the mixer angle α1, beam width d, inner ring radius R1, outer ring radius R2, beam radius R3, and number of beams; Step 8: Calculate the static pressure at position A0 using the following formula. : Assuming the external and internal airflows have equal static pressures in the mixing section, then the static pressure of the external airflow at position A0 is also equal to... The outlet velocity coefficient of the culvert is derived by back-calculating the static pressure formula. Then, the outlet area of ​​the outer bypass of the beam mixer is calculated according to the gas dynamics formula. and the Mach number of the outer permeable port Adjust the outer duct nozzle profile to make the outer duct outlet area of ​​the beam mixer reach the desired level. ; Step 9: Calculate the total temperature after complete mixing of the external and internal components using the energy conservation equation. : in For gas enthalpy, For specific heat capacity and , This represents the enthalpy of the mixed gases. The enthalpy of the outer gas is represented by the outer gas. The gas enthalpy is represented by the intrinsic gas content; an iterative method is used to solve for it. Specifically, it includes: Predicted total temperature after mixing ; Will Substitution get Substituting into the energy conservation equation and solving, we obtain... judge and Is the error less than the preset threshold for total temperature? If it is less, then... If it is greater than, then take... The steps of the iterative method are repeated until the error between two adjacent iterations is less than the total temperature preset threshold. Step 10: Solve for the velocity coefficients after mixing and the total pressure after mixing : The solution is obtained using a nested iterative method, specifically including: Predict the velocity coefficient after mixing ; Will Substituting into the following formula, we obtain the total pressure after mixing. : ， Then, calculate the mixed function value according to the following formula. =Q; ， Iterative solution based on Q and gas dynamics formulas ; judge and Is the error less than the preset threshold for the speed coefficient? If it is less, then... = If it is greater than, then take... The nested iteration method is repeated until the error between two adjacent iterations is less than the preset threshold of the speed coefficient. Finally, based on Obtain the total pressure after mixing ; Step 11: Determine / Is it greater than the critical pressure ratio of 0.528, where... Due to environmental pressures, if / If the value is ≥0.528, then the nozzle exit velocity coefficient is... =1, will =1 and total flow Substitute the gas dynamics formula to calculate the nozzle exit area. ;like / If the value is less than 0.528, the nozzle exit velocity coefficient can be calculated using the following formula. : Will and total flow Substitute the gas dynamics formula to calculate the nozzle exit area. ; Step 12: Calculate the ideal thrust F1 of the outer bypass and the ideal thrust F2 of the inner bypass of the nozzle according to the ideal thrust formula, and obtain the total ideal thrust F of the nozzle. f =F1+F2; Based on the total mixed temperature obtained in step 9 The total mixed pressure obtained in step 10 Total flow Substituting into the ideal thrust formula, calculate the ideal total thrust F of the mixed exhaust injection system. h ; Calculate the thrust gain η = (F) of the mixed-row nozzle relative to the split-row nozzle. h -F f ) / F f .

2. The mixed-displacement nozzle design method according to claim 1, characterized in that, The preset lobe mixer in step 5 includes the exit Mach number. The value range is 0.3 to 0.

5.

3. The mixed-displacement nozzle design method according to claim 1, characterized in that, The total pressure recovery coefficient of the beam mixer in step 1 and total internal pressure recovery coefficient The values ​​range from 0.98 to 0.

99.

4. The mixed-displacement nozzle design method according to claim 1, characterized in that, The total temperature preset threshold in step 9 is 10. - ³.

5. The mixed-displacement nozzle design method according to claim 1, characterized in that, The preset threshold for the velocity coefficient in step 10 is 10. - ³.

6. The mixed-displacement nozzle design method according to claim 1, characterized in that, In step 7, the beamwidth d and the mixer angle α1 are adjusted first to make the inner outlet area of ​​the beam mixer reach the desired value. .

7. The mixed-displacement nozzle design method according to claim 1, characterized in that, In step 11 when / When ≥0.528, q( =1.

8. The mixed-displacement nozzle design method according to claim 1, characterized in that, The ideal thrust formula is: 。 9. The mixed-displacement nozzle design method according to claim 1, characterized in that, In step 10, the solution is obtained iteratively based on Q and the gas dynamics formula. The specific method is as follows: In the gas dynamics formula, q( Rewrite as Q about The equation: Predicted speed coefficient ,Will And Q is substituted into the rewritten formula to calculate the result. ; judge and If the error is less than the preset threshold for the speed coefficient, then... = If it is greater than, then As the new estimated velocity coefficient, the process of substituting the estimated velocity coefficient and Q into the rewritten formula to back-calculate the new estimated velocity coefficient is repeated until the error between two adjacent iterations is less than the preset threshold of the velocity coefficient.

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