Performance matching design method of air-air integrated heat exchanger

Abstract

The present application belongs to the field of aircraft fuel inerting system thermal management, and particularly relates to a performance matching design method of an air-air integrated heat exchange device. At present, there is a lack of positive design and verification capability for the function and reliability design and implementation of the air-air integrated heat exchange device. The present application determines the working condition points of the integrated heat exchange device under the entire flight envelope through demand analysis on the flight envelope and system working conditions matched with the integrated heat exchange device, determines the most severe heat exchange point, and performs performance matching design on the heat exchanger and bypass valve for each working condition point to obtain a performance structure scheme meeting the demand, thereby solving the single-point and repetitive problems of traditional design. Through determination of the bypass flow ratio, precise control of the outlet temperature can be realized, the heat exchange performance of the heat exchange device is improved, thermal fatigue life analysis is performed, and the optimal structure and high reliability of the heat exchange device are ensured.

Description

Technical Field

[0001] This invention belongs to the field of thermal management of aircraft fuel inerting systems, and specifically relates to a performance matching design method for an air-to-air integrated heat exchange device. Background Technology

[0002] The inerting system processes the high-pressure gas from the engine compressor into a nitrogen-rich gas with a low oxygen concentration suitable for fuel tank inerting, and then introduces it into the fuel tank to ensure that the fuel tank is in an inerted safe state. The air-to-air heat exchanger, as an essential accessory in the heat exchange system of the aero-engine inerting system, generally consists of a radiator 1 and a temperature control valve 2, such as... Figure 1 As shown, high-temperature air exchanges heat with cold-side air through heat exchanger 1, controlling the hot-side air outlet temperature within the required range. A temperature-controlled valve 2 is installed in the hot-side air flow channel of the heat exchanger; by adjusting the valve opening, the bypass flow rate is adjusted to control the hot-side air outlet temperature.

[0003] The hot-side outlet temperature of the heat exchanger is a crucial indicator for the entire system and must be maintained within a certain tolerance range. Currently, there is a lack of functional forward design and verification capabilities for the functional and reliability design and implementation of air-to-air integrated heat exchangers. This leads to a failure to consider the internal and external environments of the entire flight envelope, resulting in frequent ultra-low temperature issues after the heat exchanger is installed. Furthermore, unreasonable reliability design and allocation, inadequate identification and control, insufficient reliability verification methods and acceptance criteria, and frequent leaks and spills occur. Summary of the Invention

[0004] In view of the above-mentioned situation of the prior art, the present invention provides a performance matching design method for a high-reliability air-to-air integrated heat exchanger. By conducting a requirements analysis on the flight envelope and system operating conditions of the integrated heat exchanger, the operating points of the integrated heat exchanger within the entire flight envelope are determined, identifying the most severe heat exchange point. Performance matching design of the heat exchanger and temperature control valve is then performed for each operating point to obtain a performance-oriented structural solution that meets the requirements, solving the problems of single-point and iterative design in traditional methods. By determining the bypass flow ratio, precise control of the outlet temperature can be achieved, improving the heat exchange performance of the heat exchanger. Thermal fatigue life analysis ensures the optimal structural design and high reliability of the heat exchanger.

[0005] This invention provides a performance matching design method for an air-to-air integrated heat exchanger. The integrated heat exchanger includes a heat exchanger and a temperature control valve. The method is implemented by setting a guide vane at the intersection of the hot-side inlet pipe of the heat exchanger and the bypass pipe inlet of the temperature control valve, and specifically includes the following steps:

[0006] S1. Demand Determination

[0007] Determine the inlet temperature, flow rate, and pressure of the heat exchanger at the hot and cold sides, as well as the required outlet temperature at the hot side, flow resistance, and lifespan of the heat exchanger.

[0008] S2, Operating Condition Determination

[0009] Based on the parameters obtained in step S1, determine the operating point of the integrated heat exchanger under the flight envelope.

[0010] S3, performance matching analysis of heat exchanger and temperature control valve

[0011] The design of the heat exchange device structure includes: the structure and dimensions of the heat exchanger, the structure and dimensions of the temperature control valve, and the shape, position, angle, and dimensions of the guide vanes. The heat exchange performance of the heat exchange device is calculated based on each operating point, including the bypass flow rate and flow resistance of the temperature control valve, the hot-side outlet temperature of the heat exchanger, and the flow resistance. The bypass flow rate and dimensionless flow resistance curves of the temperature control valve and the flow rate and dimensionless flow resistance curves of the heat exchanger are plotted at each operating point. The flow resistance value at which the sum of the flow rates of the heat exchanger and the temperature control valve equals the total inlet flow rate of the heat exchange device is found.

[0012] S4. Determine whether the result of step S3 meets the requirements of step S1. If it does, proceed to step S5. If it does not, return to step S3.

[0013] S5, High Reliability Design

[0014] Thermal fatigue analysis was performed to obtain the fatigue life of each component in the heat exchanger.

[0015] S6. Determine whether the fatigue life in step S5 meets the requirements in step S1. If it does, complete the design. If it does not, return to step S3.

[0016] Advantageously, in step S1, the inlet temperature, flow rate, and pressure of the hot and cold sides of the heat exchanger, as well as the outlet temperature requirement of the hot side, are determined based on the ambient temperature, flight speed, flight altitude, and aircraft inerting requirements of the aircraft fuel inerting system under the flight envelope.

[0017] Advantageously, in step S3, when designing the structure of the heat exchange device, the size of the heat exchanger core fins, the number of hot and cold edge layers, and the length of the hot and cold edge flow channels are first adjusted. If the heat exchange performance still does not meet the requirements, the angle of the guide vanes is further adjusted or the bypass flow size of the temperature control valve is reduced.

[0018] Advantageously, in step S3,

[0019] The specific steps for calculating the hot-side outlet temperature and flow resistance of a heat exchanger are as follows:

[0020] ① Given the core structure dimensions of the heat exchanger, calculate the heat transfer performance at each operating point, and obtain the hot-side air outlet temperature and flow resistance ΔP1 of the heat exchanger at each operating point;

[0021] ② Convert the flow resistance ΔP1 to the dimensionless parameter sigmaΔP, and plot the curves of sigmaΔP1 versus different airflow rates, where...

[0022]

[0023] The specific steps for calculating the bypass flow rate and flow resistance of a temperature-controlled valve are as follows:

[0024] ① Given the structure and diameter of the bypass pipe, select the control method of the temperature control valve;

[0025] ② Calculate the bypass flow rate and flow resistance of the temperature control valve under each operating condition, and obtain the bypass flow rate and flow resistance ΔP2 under different operating conditions with the same valve opening, as well as the bypass flow rate and flow resistance ΔP under different valve openings.

[0026] ③ Convert the flow resistance ΔP2 to the dimensionless parameter sigmaΔP, and plot the sigmaΔP2 vs. bypass flow rate curves for the bypass.

[0027]

[0028] Advantageously, the temperature-controlled valve control forms include butterfly valves, valve plates, or other forms.

[0029] Advantageously, in step S5, the high-reliability design includes the following steps:

[0030] ① Determine the operating point for thermal fatigue analysis;

[0031] ② Boundary parameters are determined;

[0032] ③ Fatigue life calculation;

[0033] ④ Thermal fatigue stress analysis.

[0034] Advantageously, the structure, position, and form of the guide vanes need to be determined based on the simulation results of the pressure flow field distribution of the heat exchanger and the temperature control valve bypass.

[0035] Advantageously, based on the results of thermal fatigue stress analysis in high-reliability design, the structure of each component of the heat exchanger is optimized and improved.

[0036] Advantageously, the temperature control valve (2) adjusts the valve opening through a stepper motor and a variable speed gear mechanism. The stepper motor has a step length of 60° and a shaft step length of 1.3°, and it has a power-on reset function.

[0037] This invention provides a high-reliability air-to-air integrated heat exchanger performance matching design method and apparatus, which solves the problem of forward design and verification of the function and reliability of integrated heat exchangers. The matching design calculation method for the performance flow resistance and flow rate of the heat exchanger and temperature control valve in the heat exchanger can accurately determine the flow ratio distribution between the two. It can also calculate the thermal fatigue stress and life of each component in the heat exchanger when the temperature field is non-uniform, and optimize the structural design based on the analysis, which greatly improves the life and reliability of the heat exchanger.

[0038] The performance matching design method for the air-to-air integrated heat exchanger of the present invention mainly includes the following beneficial effects:

[0039] 1) Integrated design of the overall structure of the heat exchanger

[0040] The heat exchange device integrates a heat exchanger and a temperature control valve, with a compact structure that achieves miniaturization and weight reduction;

[0041] 2) Dimensionless conversion of parameters under different operating conditions

[0042] Taking into account the heat exchange performance of the entire flight package of the heat exchange device, the air parameters under different temperatures and pressures are converted into parameters under standard conditions for design. This method is highly feasible, convenient and efficient, and avoids the insufficiency and one-sidedness of single-operating-point design.

[0043] 3) High reliability design of heat exchange device.

[0044] Thermal fatigue life analysis of each component of the heat exchanger can complete the structural optimization and performance iteration process of the parts during the design phase, shorten the development cycle, improve the life reliability of the entire device, and significantly enhance safety.

[0045] 4) Design of the flow ratio between the heat exchanger and the temperature control valve.

[0046] By determining the bypass flow ratio, precise control of the hot-side outlet temperature can be achieved, thereby improving the heat exchange performance of the heat exchange device and ensuring the optimization of the heat exchanger and bypass structure. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the operation and bypass structure of the heat exchanger.

[0048] Figure 2 This is a flowchart illustrating the performance matching design method for the high-reliability air-to-air integrated heat exchanger of the present invention.

[0049] Figure 3 This is a flowchart of the heat exchange performance calculation;

[0050] Figure 4 It shows the flow resistance-flow rate curve and matching diagram.

[0051] 1-Heat exchanger, 2-Temperature control valve Detailed Implementation

[0052] To better understand the purpose, technical solution, and advantages of this invention, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0053] Figure 1 The diagram shows a flow chart of the performance matching design method for the air-to-air integrated heat exchanger of the present invention. The specific execution steps are as follows:

[0054] (1) Demand determination

[0055] The heat exchanger is functionally required based on the ambient temperature, flight speed, flight altitude, and aircraft inerting requirements under the full flight envelope of the aircraft fuel inerting system. This analysis determines the inlet temperature, flow rate, and pressure of the hot and cold sides of the heat exchanger, as well as the hot side outlet temperature requirements, flow resistance requirements, and lifespan requirements of the heat exchanger.

[0056] (2) Determination of operating conditions of heat exchanger

[0057] Using step (1), a demand analysis is performed to determine the operating points of the heat exchanger across the entire flight envelope.

[0058] (3) Performance matching design of heat exchangers and temperature control valves in heat exchange devices

[0059] Based on the operating point in step (2), the heat exchange performance of the heat exchanger is calculated, the bypass flow and flow resistance of the heat exchanger and the temperature control valve are analyzed, and the matching design of the flow and flow resistance of the heat exchanger and the temperature control valve is carried out to obtain a performance structure scheme that meets the requirements of step (1).

[0060] The specific steps include:

[0061] 1) Preliminary calculation of the heat exchanger's heat exchange performance. The specific steps are as follows:

[0062] ① Given the core structure dimensions of the heat exchanger, calculate the heat transfer performance at each operating point, and obtain the hot-side air outlet temperature and flow resistance ΔP1 of the heat exchanger at different operating points.

[0063] ② Convert the airflow resistance at all operating points in step ① into the dimensionless parameter sigmaΔP, and plot the curves of sigmaΔP1 versus different airflow rates.

[0064] 2) Calculation of flow rate and flow resistance of the temperature-controlled valve bypass. The specific steps are as follows:

[0065] ① Given the diameter of the bypass channel where the temperature control valve is placed, select the control method of the temperature control valve, and the structure and size of the connection channel with the heat exchanger.

[0066] ② Calculate the bypass flow rate and flow resistance of the temperature control valve under non-operating conditions. Obtain the bypass flow rate and flow resistance ΔP2 at different operating points when the valve opening is the same. The bypass flow rate and flow resistance ΔP are different when the valve opening is different. The design can be carried out iteratively according to the method.

[0067] ③ Convert the bypass flow rate and flow resistance ΔP2 at all operating points in step ② into the dimensionless parameter sigmaΔP, and plot the bypass sigmaΔP2 and bypass flow rate curves.

[0068] 3) Performance matching design of heat exchangers and temperature control valves in heat exchange devices.

[0069] ① Match the curves of the air flow resistance sigmaΔP1 on the hot and cold sides of the heat exchanger at all operating points with the curves of the bypass flow rate and flow resistance sigmaΔP2 of the temperature control valve at all operating points, and plot the overall curves. See Figure 4 .

[0070] ② Based on the total inlet flow rate Q of the heat exchanger (Q = Q1 + Q2), the x-coordinate value (X-coordinate values ​​Q1 and Q2 corresponding to the intersection of the horizontal dashed line and the flow resistance curve under the same flow resistance design can be obtained. This is the bypass flow rate through the radiator and the temperature control valve, and its ratio is the flow rate ratio = Q1:Q2. See Figure 4 .

[0071] ③ If the flow ratio does not meet the requirements, it is necessary to iteratively design and calculate according to steps 1), 2), and 3).

[0072] (4) High reliability design of heat exchange device

[0073] Thermal fatigue analysis was performed using the structural scheme in step (3). Based on the results, the structural form of the components in the heat exchanger was optimized. Step (3) was repeated, and a high-reliability, optimal performance structural scheme that meets the requirements of step (1) was obtained.

[0074] The specific steps for the reliability design of the heat exchanger include:

[0075] 1) Determine the operating point for thermal fatigue analysis;

[0076] 2) Boundary parameters are determined;

[0077] The heat exchanger core and other components of the integrated heat exchange device are analyzed separately. Given the inlet temperatures and flow rates of the hot and cold sides of the heat exchanger core and other components of the integrated heat exchange device, input the thermodynamic and mechanical properties of the materials.

[0078] 3) Fatigue life calculation

[0079] The SN method is used to calculate the fatigue life of the heat exchanger core and other components of the integrated heat exchanger. During operation, the temperature distribution of the heat exchanger core and other components of the integrated heat exchanger is uneven. When performing fatigue analysis in MSC Fatigue considering the temperature effect, the SN data for a certain material needs to take into account the temperature effect to obtain the temperature field and determine the thermal deformation and thermal stress caused by the uneven temperature of the heat exchanger core and other components of the integrated heat exchanger during operation.

[0080] 4) Thermal fatigue stress analysis.

[0081] Calculate the stress of the heat exchanger core and other components of the heat exchange device under thermal load and internal air pressure. The thermal load is the temperature field in the fatigue life calculation, and the air pressure at the hot and cold sides is given.

[0082] 5) Calculate the fatigue life of each component. Based on the fatigue life analysis results, the structure of the heat exchanger core and other components of the integrated heat exchange device can be optimized.

Claims

1. A performance matching design method for an air-to-air integrated heat exchanger, the integrated heat exchanger comprising a heat exchanger (1) and a temperature control valve (2), characterized in that: This method is implemented by setting a guide vane at the intersection of the hot-side inlet pipe of the heat exchanger (1) and the bypass pipe inlet where the temperature control valve (2) is located, and specifically includes the following steps: S1. Demand Determination Determine the inlet temperature, flow rate, and pressure of the heat exchanger at the hot and cold sides, as well as the required outlet temperature at the hot side, flow resistance, and lifespan of the heat exchanger. S2, Operating Condition Determination Based on the parameters obtained in step S1, determine the operating point of the integrated heat exchanger under the flight envelope. S3, performance matching analysis of heat exchanger and temperature control valve The design of the heat exchange device structure includes: the structure and dimensions of the heat exchanger, the structure and dimensions of the temperature control valve, and the shape, position, angle, and dimensions of the guide vanes. The heat exchange performance of the heat exchange device is calculated based on each operating point, including the bypass flow rate and flow resistance of the temperature control valve, the hot-side outlet temperature of the heat exchanger, and the flow resistance. The bypass flow rate and dimensionless flow resistance curves of the temperature control valve and the flow rate and dimensionless flow resistance curves of the heat exchanger are plotted at each operating point. The flow resistance value at which the sum of the flow rates of the heat exchanger and the temperature control valve equals the total inlet flow rate of the heat exchange device is found. S4. Determine whether the result of step S3 meets the requirements of step S1. If it does, proceed to step S5. If it does not, return to step S3. S5, High Reliability Design Thermal fatigue analysis was performed to obtain the fatigue life of each component in the heat exchanger. S6. Determine whether the fatigue life in step S5 meets the requirements in step S1. If it does, complete the design. If it does not, return to step S3.

2. The performance matching design method for the air-to-air integrated heat exchanger according to claim 1, characterized in that: In step S1, the inlet temperature, flow rate, and pressure of the hot and cold sides of the heat exchange device, as well as the outlet temperature requirements of the hot side, are determined based on the ambient temperature, flight speed, flight altitude, and aircraft inerting requirements under the flight envelope of the aircraft fuel inerting system.

3. The performance matching design method for the air-to-air integrated heat exchanger according to claim 1, characterized in that: In step S3, when designing the structure of the heat exchange device, first adjust the size of the heat exchanger core fins, the number of hot and cold edge layers, and the length of the hot and cold edge flow channels. If the heat exchange performance still does not meet the requirements, further adjust the angle of the guide vanes or reduce the bypass flow size of the temperature control valve.

4. The performance matching design method for the air-to-air integrated heat exchanger according to claim 1, characterized in that: In step S3, The specific steps for calculating the hot-side outlet temperature and flow resistance of a heat exchanger are as follows: ① Given the core structure dimensions of the heat exchanger, calculate the heat transfer performance at each operating point, and obtain the hot-side air outlet temperature and flow resistance ΔP1 of the heat exchanger at each operating point; ② Convert the flow resistance ΔP1 to the dimensionless parameter sigmaΔP1, and plot the curves of sigmaΔP1 versus different airflow rates, where... ； The specific steps for calculating the bypass flow rate and flow resistance of a temperature-controlled valve are as follows: ① Given the structure and diameter of the bypass pipe, select the control method of the temperature control valve; ② Calculate the bypass flow rate and flow resistance of the temperature control valve under each operating condition, and obtain the bypass flow rate and flow resistance ΔP2 under different operating conditions with the same valve opening, as well as the bypass flow rate and flow resistance ΔP2 under different valve openings. ③ Convert the flow resistance ΔP2 to the dimensionless parameter sigmaΔP2, and plot the sigmaΔP2 vs. bypass flow rate curves for the bypass. 。 5. The performance matching design method for the air-to-air integrated heat exchanger according to claim 4, characterized in that: Temperature-controlled valves can be controlled in various forms, including butterfly valves, valve plates, or other types.

6. The performance matching design method for the air-to-air integrated heat exchanger according to claim 1, characterized in that: In step S5, the high-reliability design includes the following steps: ① Determine the operating point for thermal fatigue analysis; ② Boundary parameters are determined; ③ Fatigue life calculation; ④ Thermal fatigue stress analysis.

7. The performance matching design method for the air-to-air integrated heat exchanger according to claim 1, characterized in that: The structure, position, and form of the guide vanes need to be determined based on the simulation results of the pressure flow field distribution of the heat exchanger and the temperature control valve bypass.

8. The performance matching design method for the air-to-air integrated heat exchanger according to claim 1, characterized in that: Based on the results of thermal fatigue stress analysis in high-reliability design, the structure of each component of the heat exchanger is optimized and improved.

9. The performance matching design method for the air-to-air integrated heat exchanger according to claim 1, characterized in that: The temperature control valve (2) adjusts the valve opening through a stepper motor and a speed-changing gear mechanism. The stepper motor has a step length of 60° and a shaft step length of 1.3°, and it has a power-on reset function.

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