A calculation method of bearing cavity temperature field based on similarity criterion

Abstract

The present application belongs to the field of aircraft engine temperature field calculation, and particularly relates to a bearing cavity temperature field calculation method based on similarity criteria. The method comprises the following steps: Step 1: determining the basic parameters that affect the bearing cavity temperature of the lubricating oil system, wherein the basic parameters include the temperature of the heat source outside the bearing cavity, the temperature of the cooling source inside the bearing cavity, and the surface temperature of the parts inside the bearing cavity; Step 2: establishing a similarity criterion based on the basic parameters to obtain a dimensionless θ parameter calculation formula for the similarity criterion; Step 3: obtaining the temperature of the heat source outside the bearing cavity, the temperature of the cooling source inside the bearing cavity, and the surface temperature of the parts inside the bearing cavity at multiple ground state points of the lubricating oil system bearing cavity through ground lubricating oil system testing, and calculating a dimensionless θ value. Based on the principle that the dimensionless θ values ​​of all working states of the same lubricating oil system are the same, the surface temperature of the parts inside the bearing cavity at each aerial state point of the lubricating oil system bearing cavity is deduced using the dimensionless θ value.

Description

Technical Field

[0001] The present application relates to the field of aero-engine temperature field calculation, and in particular to a bearing cavity temperature field calculation method based on similarity criteria. Background Art

[0002] During the design of aircraft engine lubricating oil systems, it is necessary to determine the temperature levels of components in the bearing cavity at high altitude. Currently, the temperature calculation and analysis of components in the bearing cavity is mainly based on the simulation model of the bearing cavity and the boundary parameters of a single operating point. There are often many factors that affect the boundary parameters. When calculating a single point step by step, a relatively realistic temperature field in the bearing cavity can be theoretically obtained, but the calculation speed is slow, which is only suitable for designs with fewer state points in the early stages of engine development.

[0003] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned deficiencies of the prior art. Summary of the Invention

[0004] The purpose of this application is to provide a bearing cavity temperature field calculation method based on similarity criteria to solve at least one problem existing in the prior art.

[0005] The technical solution of this application is:

[0006] A similarity criterion-based calculation method for bearing cavity temperature field includes:

[0007] Step 1: determining basic parameters that affect the bearing cavity temperature of the lubricating oil system, wherein the basic parameters include the temperature of the heating source outside the bearing cavity, the temperature of the cooling source inside the bearing cavity, and the surface temperature of the parts inside the bearing cavity;

[0008] Step 2: Establish a similarity criterion based on the basic parameters and obtain the dimensionless θ parameter calculation formula of the similarity criterion:

[0009]

[0010] Among them, T r is the temperature of the heating source outside the bearing cavity, T A is the surface temperature of the parts in the bearing cavity, T oxЛ is the temperature of the cooling source in the bearing cavity;

[0011] Step 3: Through ground lubricating oil system testing, the temperature of the heating source outside the bearing cavity, the temperature of the cooling source inside the bearing cavity, and the surface temperature of the parts inside the bearing cavity at multiple ground state points of the lubricating oil system bearing cavity are obtained, and the dimensionless θ value is calculated. According to the principle that the dimensionless θ value of all working states of the same lubricating oil system is the same, the surface temperature of the parts inside the bearing cavity at each aerial state point of the lubricating oil system bearing cavity is deduced by the dimensionless θ value.

[0012] In at least one embodiment of the present application, the temperature of the heating source outside the bearing cavity is the temperature of the sealed bleed air of the air system.

[0013] In at least one embodiment of the present application, the temperature of the cooling source in the bearing cavity is the lubricating oil supply temperature.

[0014] In at least one embodiment of the present application, in step three, corresponding dimensionless θ values ​​are calculated based on the temperature of the heating source outside the bearing cavity, the temperature of the cooling source inside the bearing cavity, and the surface temperature of the parts inside the bearing cavity at multiple state points of the bearing cavity of the lubricating oil system, and the multiple dimensionless θ values ​​are averaged to obtain the final dimensionless θ value.

[0015] In at least one embodiment of the present application, step four is further included, which is to calculate the bearing cavity temperature field based on the surface temperature of the parts in the bearing cavity at each air state point of the bearing cavity of the lubricating oil system.

[0016] The invention has at least the following beneficial technical effects:

[0017] The bearing cavity temperature field calculation method based on the similarity criterion of this application evaluates the calculation results of the bearing cavity temperature field in the high-altitude state according to the temperature results of existing components that have been measured on the ground of the engine. When the engine structure is relatively stable and subsequent derivative models are developed, this method can easily and quickly obtain the temperature distribution of each point in the bearing cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of a method for calculating the bearing cavity temperature field based on similarity criteria in one embodiment of the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be understood as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0020] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as limiting the scope of protection of this application.

[0021] The following is combined with Figure 1 This application is described in further detail.

[0022] This application provides a method for calculating the bearing cavity temperature field based on a similarity criterion, comprising the following steps:

[0023] Step 1: Determine the basic parameters that affect the bearing cavity temperature of the lubricating oil system, including the temperature of the heating source outside the bearing cavity, the temperature of the cooling source inside the bearing cavity, and the surface temperature of the parts inside the bearing cavity;

[0024] Step 2: Establish a similarity criterion based on the basic parameters and obtain the dimensionless θ parameter calculation formula of the similarity criterion:

[0025]

[0026] Among them, T r is the temperature of the heating source outside the bearing cavity, T A is the surface temperature of the parts in the bearing cavity, T oxл is the temperature of the cooling source in the bearing cavity;

[0027] Step 3: Through ground lubricating oil system testing, the temperature of the external heating source of the bearing cavity, the temperature of the cooling source in the bearing cavity, and the surface temperature of the parts in the bearing cavity at multiple ground state points of the lubricating oil system bearing cavity are obtained, and a dimensionless θ value is calculated. Based on the principle that the dimensionless θ value of all working states of the same lubricating oil system is the same, the dimensionless θ value is used to deduce the surface temperature of the parts in the bearing cavity at each aerial state point of the lubricating oil system bearing cavity;

[0028] Step 4: Calculate the bearing cavity temperature field based on the surface temperature of the parts in the bearing cavity at each air state point of the lubricating oil system bearing cavity.

[0029] The dimensionless θ value is calculated based on the temperature of the external heating source, the internal cooling source, and the surface temperature of the components within the lubricating oil system bearing cavity at multiple ground-based points. The final dimensionless θ value is then averaged. The temperature of the external heating source and the temperature of the internal cooling source at each airborne point are measured.

[0030] The present application's similarity-based bearing cavity temperature field calculation method utilizes a thermal analysis similarity approach. The calculation model for the lubricating oil system's bearing cavity thermal characteristics is linked to the engine's mainstream temperature parameters, ensuring superior independent operation, versatility, and accuracy. Based on the similarity relationship established between the engine's mainstream temperature parameters and the lubricating oil system's thermal characteristics, basic parameters are determined, and a temperature similarity criterion, the θ method, is established. Specifically, the basic parameters influencing the temperature at various locations within the lubricating oil system's bearing cavity are determined based on the engine's mainstream temperature parameters, including the temperature of the external heating source, the temperature of the internal cooling source, and the surface temperature of components within the bearing cavity. Based on these basic parameters, a similarity criterion is established, and a dimensionless θ parameter is calculated based on the similarity criterion. The temperature of the external heating source is the temperature of the air system's seal bleed air, while the temperature of the internal cooling source is the lubricating oil supply temperature. For engines with identical air and oil systems, the dimensionless θ value is assumed to be the same for all operating points. However, changes to the engine's air and oil systems will cause the dimensionless θ value to change.

[0031] The present application's similarity-based bearing cavity temperature field calculation method implements the similarity-criteria θ method. Based on ground-based lubricating oil system testing, the temperatures of key lubricating oil system nodes and bearing cavity component temperatures are obtained, and dimensionless θ values ​​for the bearing cavity are calculated. For the same lubricating oil system, the dimensionless θ values ​​are then used to deduce the temperature values ​​for each location in the air. The similarity-criteria θ method primarily derives and calculates based on ground-based temperature measurement results for the entire engine, using the temperature similarity criterion to determine the dimensionless θ values ​​for ground-based points. Based on the principle that dimensionless θ values ​​for all operating states of the same system are the same, various airborne points are derived from ground-based points. Because airborne points cannot be tested and verified, the errors in boundary condition calculations are greater than those for ground-based points. The similarity-criteria θ method provides a similar thermal analysis method that approximates actual engine operating conditions, providing a beneficial and necessary supplement to finite element methodologies. The similarity-criteria θ method is suitable for engines with a finalized design or relatively stable structure, allowing for a simple and rapid determination of the temperature distribution at each point in the bearing cavity when developing subsequent derivative models.

[0032] This application's similarity-based bearing cavity temperature field calculation method, based on temperature measurement results from crystals within the bearing cavity during a dedicated temperature test of the entire engine, analyzes and establishes a similarity relationship between the engine's mainstream temperature parameters and the thermal characteristics of the lubricating oil system. This method then develops the similarity-based θ method for lubricating oil system thermal analysis. Comparison of the calculated results demonstrates the feasibility of the similarity-based θ method for calculating the bearing cavity temperature field, demonstrating low error and high accuracy.

[0033] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for calculating the bearing cavity temperature field based on similarity criterion, characterized in that: include: Step 1: determining basic parameters that affect the bearing cavity temperature of the lubricating oil system, wherein the basic parameters include the temperature of the heating source outside the bearing cavity, the temperature of the cooling source inside the bearing cavity, and the surface temperature of the parts inside the bearing cavity; Step 2: Establish a similarity criterion based on the basic parameters and obtain the dimensionless θ parameter calculation formula of the similarity criterion: Among them, T r is the temperature of the heating source outside the bearing cavity, T Д is the surface temperature of the parts in the bearing cavity, T охл is the temperature of the cooling source in the bearing cavity; Step 3: Through ground lubricating oil system testing, the temperature of the heat source outside the bearing cavity, the temperature of the cooling source inside the bearing cavity, and the surface temperature of the parts inside the bearing cavity at multiple ground state points of the lubricating oil system bearing cavity are obtained, and a dimensionless θ value is calculated. Based on the principle that the dimensionless θ value is the same for all working states of the same lubricating oil system, the surface temperature of the parts inside the bearing cavity at each aerial state point of the lubricating oil system bearing cavity is deduced from the dimensionless θ value; The temperature of the heating source outside the bearing cavity is the temperature of the air system seal air; The temperature of the cooling source in the bearing cavity is the lubricating oil supply temperature.

2. The method for calculating the bearing cavity temperature field based on similarity criterion according to claim 1 is characterized in that: In step three, the corresponding dimensionless θ values ​​are calculated based on the temperature of the heating source outside the bearing cavity, the temperature of the cooling source inside the bearing cavity, and the surface temperature of the parts inside the bearing cavity at multiple ground state points of the lubricating oil system bearing cavity. The multiple dimensionless θ values ​​are averaged to obtain the final dimensionless θ value.

3. The method for calculating the bearing cavity temperature field based on similarity criterion according to claim 2 is characterized in that: The method also includes step 4, which is to calculate the bearing cavity temperature field based on the surface temperature of the parts in the bearing cavity at each air state point of the lubricating oil system bearing cavity.

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