Air system thermal inertia calculation and regulation method and system

Abstract

The application discloses an air system thermal inertia calculation and regulation method and system, and belongs to the technical field of aero-engines. The core of the application is to define an air system flow path thermal inertia equivalent time constant, which is jointly determined by the volume of the flow path, air thermal properties, heat exchange conditions, and volume change rate and wind resistance power change rate in the transition process; and a compliance criterion is defined as a quantitative criterion for starting regulation. When regulation is needed, measures such as reducing wind resistance power are taken for disc cavity type regions, and / or measures such as controlling thermal deformation to reduce volume change are taken for gap type regions, so as to realize directional regulation of the flow path thermal inertia. The application provides a quantitative evaluation method for air system thermal response and a quantitative criterion for starting regulation, and can effectively guide design and improve the dynamic working reliability of the engine.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine technology, and relates to the design of aero-engine air systems, and particularly to a method and system for calculating and controlling the thermal inertia of an air system. Background Technology

[0002] Aircraft engine air systems typically draw air from appropriate locations within the compression system. Various flow units are designed to force the gas to flow in the intended direction and according to specified parameters, fulfilling its designated functions. Finally, the gas is discharged from designated locations, either merging with the main flow or leaking directly to the outside of the engine. Closely related to the working environment and overall performance of engine components, it is one of the most critical systems in an engine. With the continuous improvement of aircraft engine performance, the gas temperature and its rate of change have increased significantly. In such extreme, harsh, and rapidly changing dynamic operating environments, engine erosion due to cooling lag frequently occurs, severely restricting engine performance.

[0003] The time-delay effect in air systems is the primary cause of ablation problems. This effect has long been a research hotspot in the field of heat transfer, both domestically and internationally. Current technologies primarily utilize the lumped heat capacity method to simulate the unsteady-state heat transfer process of solid systems, such as wheel cooling, motor heat dissipation, and temperature measurement. However, a method specifically describing the heat transfer process and thermal inertia of gas systems has been lacking, hindering engine design and impacting engine reliability.

[0004] Currently, publicly available solutions for thermal inertia in aero-engines mainly include: a method for predicting dynamic process performance parameters of turboshaft engines considering thermal inertia, which proposes a method for calculating the performance of aero-engine components considering thermal inertia, based on real experimental data, and using machine learning methods to correct the impact of thermal inertia on component performance; however, this method is only applicable to component performance calculations and does not provide methods for calculating and controlling the thermal inertia of gases. Another method is a transient liquid crystal test convective heat transfer coefficient based on thermal inertia correction, which proposes a method for correcting the impact of thermal inertia on temperature measurements, but it still pertains to solid systems and does not provide methods for calculating and controlling the thermal inertia of gases.

[0005] Therefore, in the existing technology, the design of advanced aero-engine air systems suffers from a lack of methods for calculating and controlling thermal inertia. Summary of the Invention

[0006] The purpose of this invention is to address the lack of methods for describing and controlling the thermal inertia of the heat transfer process in gas systems in existing technologies. By defining the equivalent time constant of the thermal inertia of the air system flow path, a quantitative evaluation of the flow path thermal response is achieved. Furthermore, compliance judgment criteria and specific control measures to reduce thermal inertia are proposed, thereby improving the thermal response speed of the air system under strong dynamic engine operating conditions (such as rapid acceleration and deceleration) and avoiding component burn-out failures caused by cooling lag.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for calculating the thermal inertia of an air system, comprising the following steps: Step S100: Select the target air system functional flow path and divide the functional flow path into multiple regions according to the flow element type; the flow element type includes at least disk cavity type and gap type.

[0009] Furthermore, the disc cavity type is mainly divided into rotating disc cavity, rotating stationary disc cavity, and stationary disc cavity; the gap type is mainly divided into comb tooth type, rotating stationary gap type, and rotating-rotating gap type.

[0010] Step S200: Calculate the equivalent time constant for each of the regions. Then, the equivalent time constants of each region are summed to obtain the thermal inertia equivalent time constant of the entire functional flow path. .

[0011] Among them, the equivalent time constant of each region The expression is:

[0012] In the formula, The average equivalent time constant of the transition process in the selected region is expressed as follows: ,in, The average volume of the transition process in the selected region. The average air density during the transition process in the selected area. The average isobaric specific heat capacity of air during the transition process in the selected region. The average heat transfer coefficient of the transition process in the selected region. The average heat transfer area for the transition process in the selected region.

[0013] The time constant of the transient process in the selected region is corrected for the derivative, and its exponential term is... For dynamically adjusted parameters, the expression is: ,in, The rate of volume change during the transition process in the selected region. The initial volume of the selected region, The volume increment of the transition process in the selected region; The rate of change of wind resistance power during the transition process in the selected area. The initial wind resistance power for the selected area, The wind resistance power increment during the transition process in the selected area.

[0014] Preferably, when calculating the equivalent time constant of a region belonging to the disk cavity type, its dynamic correction parameter Transition process volume change rate The value is 0; when calculating the equivalent time constant of regions belonging to the gap class, its dynamic correction parameter is... Transient process wind resistance power change rate The value is 0; when calculating the equivalent time constant of regions belonging to other types, its dynamic correction parameter is... Transition process volume change rate and the rate of change of wind resistance power during the transition process All values ​​can be 0.

[0015] The thermal inertia equivalent time constant of the entire functional flow path The expression is:

[0016] In the formula, To assign numbers to the regions, This represents the total number of regions.

[0017] Secondly, the present invention provides a method for controlling the thermal inertia of an air system, comprising the following steps: First, using the air system thermal inertia calculation method described in the first aspect above, the equivalent time constant of the thermal inertia of the target flow path before regulation is calculated. .

[0018] Step S300: Compliance Judgment. Define the equivalent time constant compliance criterion:

[0019] In the formula, This refers to the acceleration time at maximum engine speed. At that time, it was determined that it was necessary to carry out the adjustment and optimization of the equivalent time constant.

[0020] When it is determined that regulation is needed, perform at least one of the following regulation steps: Step S410: Adjusting wind resistance power. Using empirical formulas and numerical simulations, the factors affecting wind resistance power variation in the disc-shaped region are analyzed to determine methods to reduce wind resistance power, namely, reducing the wind resistance power increment during the transient process. To reduce dynamic correction parameters Furthermore, the wind resistance power of disk-type components is controlled by employing flow field reconstruction methods to increase the airflow velocity on the rotor surface, covering the bolt surface to reduce the windward area, and adjusting the bolt connection position to change the source of wind resistance power.

[0021] Step S420: Controlling gap deformation. Using deformation analysis and fluid-thermal-structure interaction simulation, the volume change factors in the gap region are analyzed to determine methods to reduce volume change, namely, reducing the volume increment during the transition process. To reduce dynamic correction parameters Furthermore, by matching the thermal deformation of the comb-shaped honeycomb assembly and reducing the thermal deformation of the rotor structure, the volume increment of the gap-type components can be controlled.

[0022] Step S500: Recalculate the equivalent time constant of the flow path Based on the control results of steps S410 and S420, an air system flow path adjustment scheme is determined. Based on the control results, the equivalent time constant of the flow path's thermal inertia after control is recalculated using the air system thermal inertia calculation method described in the first aspect. And recalculate the compliance criteria. To quantitatively assess the effectiveness of regulation.

[0023] Thirdly, the present invention provides an air system thermal inertia control system, comprising: The calculation module is used to execute the air system thermal inertia calculation method described in the first aspect above, so as to obtain the thermal inertia equivalent time constant of the target flow path. ; The compliance judgment module is used to determine whether control and optimization work needs to be carried out based on the equivalent time constant compliance criterion. The acceleration time at maximum engine speed, when It is determined at this time that adjustment is needed; The control implementation module is used to reduce the increase in wind resistance power during the transition process in areas belonging to the disk cavity type when it is determined that control is needed. Operations, and / or operations to reduce the volume increment of the transition process for regions belonging to the gap category. The operation.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects: 1. A method for quantifying the thermal inertia of an air system is proposed: This invention defines for the first time the equivalent time constant of the thermal inertia of the air system flow path. Its calculation method provides theoretical support for the transient design of air systems.

[0025] 2. Provides quantitative criteria for whether to initiate regulation: This invention defines compliance criteria. This provides a clear quantitative threshold for initiating control in engineering design, avoiding blind control and improving design efficiency.

[0026] 3. Clear and efficient hierarchical and classified control strategies: This invention proposes special control measures for the physical nature of the large thermal inertia of the cavities and gaps. The cavities are controlled to control wind resistance power, and the gaps are controlled to control volume changes. The strategies are clear and the measures are precise.

[0027] 4. Strong engineering applicability: All parameters involved in this invention can be obtained through CFD simulation, experimental measurement or engineering experience, making it easy to integrate into existing engine design processes and thus having strong engineering applicability.

[0028] 5. Significant Results: Examples demonstrate that the method of this invention can reduce the equivalent time constant of thermal inertia. The time decreased from 35.3s to 19.7s, a reduction of 44%. The value decreased from 8.825 to 4.925, meeting compliance requirements and significantly improving the dynamic reliability of the air system. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart illustrating the method for calculating and controlling the thermal inertia of an air system according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the engine transition state process according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the airflow path partitioning before regulation in an embodiment of the present invention; Figure 4 This is a schematic diagram of the regulated airflow path structure in an embodiment of the present invention; In the diagram: 1-Cavity I, 2-Gap I, 3-Cavity II, 4-Gap II, 5-Cavity III, 6-Change in the installation method of the honeycomb (independent installation), 7-Stator bolt outer cover, 8-Change in the rotor bolt connection position (position adjusted downward). Detailed Implementation

[0031] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] This invention provides a method for calculating and controlling the thermal inertia of an air system. For example... Figure 1 As shown, the method for calculating and controlling the thermal inertia of the air system includes the following steps: Step S100: Select flow path and classify type.

[0034] In the airflow network of an engine air system, the functional flow path for which thermal inertia needs to be calculated is selected, and the flow path is divided into multiple different regions. Based on the type of flow elements in the flow path, they are generally classified into: disc-cavity type, gap type, and other types. Among them, the disc-cavity type is mainly divided into rotating disc cavities, rotating-stationary disc cavities, and stator disc cavities; the gap type is mainly divided into toothed type, rotating-stationary slot type, and rotating-rotating slot type.

[0035] In this embodiment of the invention, the high-pressure turbine drum cooling flow path of a certain type of engine is selected as the target functional flow path, such as... Figure 3 As shown, the flow path is divided into 5 regions: region I (disc cavity), region I (gap), region II (disc cavity), region II (gap), and region III (disc cavity). Regions 1, 3, and 5 belong to the disc cavity type; regions 2 and 4 belong to the gap type.

[0036] Step S200: Calculate the equivalent time constant of the flow path.

[0037] Based on the flow path division in step S100, calculate the equivalent time constant for each region. The calculation formula is:

[0038] In the formula, The average equivalent time constant of the transition process in the selected region. ,in, The average volume of the transition process in the selected region. The average air density during the transition process in the selected area. The average isobaric specific heat capacity of air during the transition process in the selected region. The average heat transfer coefficient of the transition process in the selected region. The average heat transfer area for the transition process in the selected region; The time constant of the transient process in the selected region is corrected for the derivative, and its exponential term is... For dynamically adjusted parameters, the expression is: ,in, The rate of volume change during the transition process in the selected region. The initial volume of the selected region, The volume increment of the transition process in the selected region; The rate of change of wind resistance power during the transition process in the selected area. The initial wind resistance power for the selected area, The wind resistance power increment during the transition process in the selected area.

[0039] As a preferred simplified processing method, the volume of the disc cavity region remains relatively stable during the transition process, and its volume change rate during the transition process is relatively stable. The value is 0; the wind resistance power change in the gap region is not significant, and the wind resistance power change rate during the transition process is... The value is 0; the volume change rate of the transition process in other types of regions. and the rate of change of wind resistance power during the transition process All values ​​can be 0.

[0040] Obtain the data for each region using computational fluid dynamics simulation or engineering experience. , , , , and dynamic parameters , , , Substituting into the formula, the results for each region are obtained. Then, the summation of each region yields the equivalent time constant for the entire flow path. :

[0041] In the formula, To assign numbers to the regions, This represents the total number of regions.

[0042] The transition process in the embodiments of the present invention is as follows: Figure 2 The acceleration process of "ab" in the middle. The equivalent time constant of the flow path is calculated. .

[0043] Step S300: Compliance judgment.

[0044] Define the equivalent time constant compliance criterion:

[0045] In the formula, This refers to the acceleration time at maximum engine speed. This indicates that the thermal response speed of the air system is severely insufficient relative to the acceleration requirements of the engine, necessitating the optimization of the equivalent time constant.

[0046] In this embodiment of the invention, ,but Since 8.825 > 6, the compliance criterion is not met, and it is determined that the flow path needs to be adjusted and optimized.

[0047] Steps S410 and S420: Implement targeted regulation.

[0048] Based on the calculation and analysis in step S200 and the compliance judgment in step S300, it was found that the volume change in the transition process of gap I zone 2 and the wind resistance power change in disk cavity II zone 3 are the main reasons for the high overall thermal inertia and failure to meet the compliance requirements. Therefore, the following targeted control measures were implemented: Adjusting gap deformation (step S420): For gap I region 2, a matching honeycomb deformation method is adopted. For example... Figure 4 As shown in reference numeral 6, the honeycomb assembly is installed independently, decoupling its thermal deformation from the deformation of the entire casing. This allows for better matching of the honeycomb deformation and effectively reduces the volume increase of gap I region 2 during the transition process. .

[0049] Adjusting wind resistance power (step S410): For cavity II zone 3, the following two methods are used in combination for adjustment: like Figure 4 As shown in reference numeral 7, an outer cover is added to the surface of the stator bolt to reduce the bolt's windward area, thereby reducing the increase in wind resistance power during the transition process. ; like Figure 4 As shown in reference numeral 8, by lowering the position of the turbine disk rotor bolt connection, the source of wind resistance power is changed, eliminating the main wind resistance effect generated by this bolt in disk cavity II zone 3, and further reducing... .

[0050] Step S500: Recalculate and verify the control effect.

[0051] according to Figure 4 The new air system scheme after regulation is shown. Steps S100 and S200 are repeated to reacquire and calculate the parameters to obtain the equivalent time constant of the flow path after regulation. Recalculate compliance criteria. .

[0052] The results before and after the adjustment are compared as follows:

[0053] As can be seen, after targeted regulation, the equivalent time constant of the flow path thermal inertia was reduced by approximately 44%, meeting the compliance criterion. The value decreased from 8.825 to 4.925, which meets the requirements. The design requirements are met. This embodiment verifies that the method of the present invention can effectively quantify and directionally control the thermal inertia of the air system, significantly improving the cooling response speed under strong dynamic conditions.

[0054] This invention also provides an air system thermal inertia control system, which is used to execute the above-described air system thermal inertia calculation method and control method. The system includes a calculation module, a compliance judgment module, and a control implementation module.

[0055] The calculation module is used to execute the above-described air system thermal inertia calculation method (steps S100 and S200) to obtain the thermal inertia equivalent time constant of the target flow path. Specifically, the calculation module receives the input target functional flow path partitioning information and the geometric parameters (volume) of each region. Heat exchange area etc.), air thermophysical parameters (density) Specific heat capacity at constant pressure ), heat transfer characteristic parameters (heat transfer coefficient) ) and dynamic parameters (volume change rate) Wind resistance power change rate According to the formula Calculate the equivalent time constant for each partitioned region separately, and then apply the formula. Calculate the equivalent time constant of thermal inertia for the entire flow path.

[0056] The compliance judgment module, connected to the calculation module, is used to determine compliance based on the equivalent time constant criterion. To determine whether regulation and optimization work is needed, among other things... This refers to the acceleration time at maximum engine speed, a parameter determined by the overall engine performance requirements. When the compliance judgment module outputs a "requires adjustment" judgment result, it triggers the adjustment implementation module to start working; when When the condition is met, output the result "Requirements met" and the process ends.

[0057] The control implementation module, connected to the compliance judgment module, is used to reduce the wind resistance power increment during the transition process in areas belonging to the disk cavity type after receiving a "control required" signal. Operations, and / or operations to reduce the volume increment of the transition process for regions belonging to the gap category. The operation is as follows. Specifically, the control implementation module can output control suggestions for disk cavity areas, including but not limited to: using flow field reconstruction methods to increase the airflow velocity on the rotor surface, adding a cover to the bolt surface to reduce the windward area, and adjusting the bolt connection position to change the source of wind resistance power, etc.; and output control suggestions for gap areas, including but not limited to: using matching toothed honeycomb components to reduce thermal deformation (such as installing the toothed honeycomb independently to decouple it from the casing deformation), and reducing the thermal deformation of the rotor structure, etc.

[0058] After the adjustment is performed, the calculation module and the compliance judgment module can be called again to recalculate the equivalent time constant of thermal inertia after the adjustment. and compliance criteria The control effect is quantitatively evaluated. Each module can run iteratively until the compliance judgment module outputs a "meets requirements" judgment result.

[0059] 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 can be made to the embodiments of the present invention. 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 calculating the thermal inertia of an air system, characterized in that, Includes the following steps: Select the target air system functional flow path and divide the functional flow path into multiple regions according to the type of flow element; the flow element type includes at least disk cavity type and gap type. Calculate the equivalent time constant for each of the regions. Then, the equivalent time constants of each region are summed to obtain the thermal inertia equivalent time constant of the entire functional flow path. ; Among them, the equivalent time constant of each region The expression is: In the formula, The average equivalent time constant of the transition process in the selected region is expressed as follows: ,in, The average volume of the transition process in the selected region. The average air density during the transition process in the selected area. The average isobaric specific heat capacity of air during the transition process in the selected region. The average heat transfer coefficient of the transition process in the selected region. The average heat transfer area for the transition process in the selected region; The time constant of the transient process in the selected region is corrected for the derivative, and its exponential term is... For dynamically adjusted parameters, the expression is: ,in, The rate of volume change during the transition process in the selected region. The initial volume of the selected region, The volume increment of the transition process in the selected region; The rate of change of wind resistance power during the transition process in the selected area. The initial wind resistance power for the selected area, The wind resistance power increment during the transition process in the selected area.

2. The method for calculating the thermal inertia of an air system according to claim 1, characterized in that, The thermal inertia equivalent time constant of the entire functional flow path The expression is: In the formula, To assign numbers to the regions, This represents the total number of regions.

3. The method for calculating the thermal inertia of an air system according to claim 1, characterized in that, When calculating the equivalent time constant of regions belonging to the disk cavity type, its dynamic correction parameter Transition process volume change rate The value is 0.

4. The method for calculating the thermal inertia of an air system according to claim 1, characterized in that, When calculating the equivalent time constant of regions belonging to the gap category, its dynamic correction parameter Transient process wind resistance power change rate The value is 0.

5. The method for calculating the thermal inertia of an air system according to claim 1, characterized in that, The disc cavity type is divided into rotating disc cavity, rotating stationary disc cavity, and stationary disc cavity; the gap type is divided into tooth type, rotating stationary gap type, and rotating-rotating gap type.

6. A method for controlling the thermal inertia of an air system, characterized in that, Includes the following steps: Using the air system thermal inertia calculation method as described in any one of claims 1 to 5, calculate the equivalent time constant of the thermal inertia of the target flow path before regulation. ; Define the equivalent time constant compliance criterion: In the formula, This refers to the acceleration time at maximum engine speed. when When it is determined that equivalent time constant adjustment and optimization work needs to be carried out, at least one of the following adjustment steps shall be performed: For disc-shaped areas, the increase in wind resistance power during the transition process can be reduced. To reduce dynamic correction parameters value; For interstitial regions, this can be achieved by reducing the volume increment during the transition process. To reduce dynamic correction parameters value.

7. The method for controlling the thermal inertia of an air system according to claim 6, characterized in that, Reduce the increase in wind resistance power during the transition process The methods include at least one of the following: using flow field reconstruction to increase the airflow velocity on the rotor surface, adding a cover to the bolt surface to reduce the windward area, or adjusting the bolt connection position to change the source of wind resistance power.

8. The method for controlling the thermal inertia of an air system according to claim 6, characterized in that, Reduce the volume increment of the transition process The methods include at least one of: using matching pylon honeycomb components to reduce thermal deformation, or reducing the thermal deformation of the rotor structure.

9. The method for controlling the thermal inertia of an air system according to claim 6, characterized in that, Also includes: Based on the control results, the equivalent time constant of the flow path after control is recalculated using the air system thermal inertia calculation method as described in any one of claims 1 to 5. And recalculate the compliance criteria. To quantitatively assess the effectiveness of regulation.

10. An air system thermal inertial control system, characterized in that, include: The calculation module is used to execute the air system thermal inertia calculation method as described in any one of claims 1 to 5, so as to obtain the thermal inertia equivalent time constant of the target flow path. ; The compliance judgment module is used to determine compliance based on the equivalent time constant criterion. To determine whether regulation and optimization work is needed, among other things... The acceleration time at maximum engine speed, when It is determined at this time that adjustment is needed; The control implementation module is used to reduce the increase in wind resistance power during the transition process in areas belonging to the disk cavity type when it is determined that control is needed. Operations, and / or operations to reduce the volume increment of the transition process for regions belonging to the gap category. The operation.

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