A time-domain-based hydraulic thermal load spectrum determination method

Abstract

The application provides a time-domain-based hydraulic thermal load spectrum determination method, which comprises the following steps: performing hydraulic system flow demand analysis under a typical mission profile, determining a hydraulic system thermal power, an actuating system thermal power and an environmental heat dissipation power; determining a heat capacity heat storage power of hydraulic oil in the hydraulic system, determining a peak thermal power according to the hydraulic system thermal power, the actuating system thermal power and the environmental heat dissipation power, and removing the heat capacity heat storage power of the hydraulic oil from the peak thermal power to obtain a hydraulic thermal load spectrum. The time-domain-based hydraulic thermal load spectrum determination method provided by the application can reduce the peak heat dissipation demand of the hydraulic system by removing a part of the heat capacity heat storage power of the hydraulic oil in the peak heat dissipation demand, reduce the structure weight of the heat dissipation accessory, and make the hydraulic system heat dissipation accessory have a certain weight reduction benefit.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aircraft hydraulic pipeline, and particularly relates to a hydraulic thermal load spectrum determination method based on a time domain. BACKGROUND

[0002] According to the corresponding requirements of an aircraft hydraulic system, the temperature of hydraulic oil needs to be controlled within a certain range to avoid the decline of oil quality and the accelerated aging of system seals due to the excessively high temperature of the hydraulic oil. Therefore, in the design of the hydraulic system, the heat dissipation design is often based on the maximum thermal power of the hydraulic system, but the heat dissipation design leads to high redundancy of the heat dissipation design and heavy structure. SUMMARY

[0003] The application aims to provide a hydraulic thermal load spectrum determination method based on a time domain to solve or alleviate at least one problem in the background art.

[0004] The technical solution of the application is: a hydraulic thermal load spectrum determination method based on a time domain, which comprises the following steps:

[0005] Performing hydraulic system flow demand analysis under a typical mission profile to determine the thermal power of the hydraulic system, the thermal power of the actuating system, and the environmental heat dissipation power;

[0006] Determining the heat capacity and heat storage power of the hydraulic oil in the hydraulic system, determining the peak thermal power according to the thermal power of the hydraulic system, the thermal power of the actuating system, and the environmental heat dissipation power, and removing the heat capacity and heat storage power of the hydraulic oil from the peak thermal power to obtain the hydraulic thermal load spectrum.

[0007] Further, the determination process of the thermal power of the hydraulic system comprises the following steps:

[0008] Determining the thermal power under zero flow and maximum flow of the hydraulic system at different rotational speeds of the hydraulic pump;

[0009] Obtaining the thermal power of the hydraulic system under the actual output flow of the hydraulic pump by an interpolation method according to the thermal power under zero flow and maximum flow of the hydraulic system, wherein the calculation formula of the thermal power of the hydraulic system is:

[0010] W 泵最大流量 =(P-P0)·Q 液压泵 ·η 液压泵

[0011] In the formula, P is the full-flow supply pressure;

[0012] P0 is the inlet pressure of the hydraulic pump;

[0013] Q 液压泵 is the maximum output flow of the hydraulic pump at different rotational speeds;

[0014] η 液压泵The ratio of the thermal power to the output power of the hydraulic pump at the maximum output flow rate.

[0015] Further, the determination process of the thermal power of the actuating system comprises:

[0016] determining the actuating efficiency of the actuating system;

[0017] calculating the thermal power of the actuating system according to the actuating efficiency, wherein the calculation formula of the thermal power of the actuating system is:

[0018] W 通用动作 = P·Q 通用动作 ·(1-η 通用动作 )

[0019] wherein P is the pressure supplied to the full flow rate;

[0020] Q 通用动作 is the actual output flow rate;

[0021] η 通用动作 is the general actuating working efficiency.

[0022] Further, the determination process of the environmental heat dissipation power comprises:

[0023] calculating the environmental heat dissipation power according to the solid heat conduction and the natural convection heat exchange with the surrounding air, wherein the calculation formula of the environmental heat dissipation power is:

[0024] W = K·A·ΔT

[0025] wherein K is the heat exchange coefficient;

[0026] A is the heat exchange area;

[0027] △T is the temperature difference between the hydraulic oil and the environment.

[0028] Further, the peak thermal power is equal to the sum of the thermal power of the hydraulic system, the thermal power of the actuating system and the environmental heat dissipation power.

[0029] The hydraulic thermal load spectrum determination method based on the time domain provided in the application can reduce the peak heat dissipation requirement of the hydraulic system by removing a part of the heat storage power of the hydraulic oil thermal capacity in the peak heat dissipation requirement, reduce the structure weight of the heat dissipation accessory, and make the hydraulic system heat dissipation accessory have a certain weight reduction benefit. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions provided in the application, the following will briefly introduce the drawings. Obviously, the drawings described below are only some embodiments of the application.

[0031] Figure 1 is the flow chart of the hydraulic load spectrum determination method of the application.

[0032] Figure 2 is a schematic diagram of heat dissipation requirement in an embodiment of the present application.

[0033] Figure 3 is a schematic diagram of temperature control in an embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present application more clear, the technical scheme in the embodiments of the present application will be described in more detail below with reference to the drawings in the embodiments of the present application.

[0035] In order to solve the problems proposed in the background art, the present application comprehensively considers the hydraulic pump heat power spectrum, hydraulic system internal leakage, actuation system efficiency and other factors, fully utilizes the environmental heat dissipation and hydraulic oil heat capacity heat storage, realizes the hydraulic heat load spectrum calculation method for reducing the peak heat dissipation requirement of the hydraulic system, and finally realizes the weight reduction of the heat dissipation accessories of the hydraulic system.

[0036] As shown in Figure 1 , the present application proposes a hydraulic heat load spectrum calculation method, which comprises:

[0037] S1, based on the time domain task requirement, the hydraulic system flow requirement analysis is carried out under the typical profile, the hydraulic system heat power calculation, the actuation system heat power calculation and the environmental heat dissipation calculation are carried out, and the specific process comprises:

[0038] 1) based on the hydraulic pump at different speeds, the heat power of the hydraulic system at zero flow and maximum flow is determined, the heat power of the hydraulic system is obtained by interpolation calculation according to the actual output flow of the hydraulic pump, wherein the calculation formula of the heat power of the hydraulic system is:

[0039] W 泵最大流量 =(P-P0)·Q 液压泵 ·η 液压泵

[0040] In the formula, P is the full flow supply pressure;

[0041] P0 is the inlet pressure of the hydraulic pump;

[0042] Q 液压泵 is the maximum output flow of the hydraulic pump at different speeds;

[0043] η 液压泵 is the ratio of the heat power to the output power when the hydraulic pump has maximum output flow.

[0044] 2) based on the actuation efficiency, the actuation system heat power is calculated, and the influence of the internal leakage of the actuation system is fully considered, wherein the calculation formula of the actuation system heat power is:

[0045] W 通用动作 =P·Q通用动作 ·(1-η 通用动作 )

[0046] Where: P is the full-flow supply pressure;

[0047] Q 通用动作 This refers to the actual output flow rate;

[0048] η 通用动作 To improve general working efficiency.

[0049] 3) Calculate environmental heat dissipation based on solid heat conduction and natural convection heat transfer with surrounding air. The ambient temperature is analyzed iteratively based on actual conditions. The formula for calculating heat transfer power is:

[0050] W = K·A·ΔT

[0051] Where: K is the heat transfer coefficient;

[0052] A represents the heat exchange area;

[0053] △T represents the temperature difference between the hydraulic oil and the ambient temperature.

[0054] S2. Determine the heat capacity and heat storage power of the hydraulic oil in the hydraulic system. Calculate the peak heat power of the hydraulic system at its maximum stage based on the heat power of the hydraulic system, the heat power of the actuation system, and the heat dissipation power of the environment. Obtain the hydraulic thermal load spectrum from the heat capacity and heat storage power of the hydraulic oil in this peak heat power. Calculate the temperature change of the hydraulic system using this hydraulic thermal load spectrum, thereby reducing the peak heat dissipation demand of the hydraulic system.

[0055] like Figure 2 The bar chart showing the heat dissipation demand of an embodiment of this application has tasks 1 to 18 on the horizontal axis representing tasks under different speed conditions, and the vertical axis representing the heat dissipation demand power (kW). As can be seen from the bar chart, the peak stage of heat dissipation demand is in the stages of tasks 8 to 9.

[0056] like Figure 3 The figure shows a temperature control curve diagram of an embodiment of this application. The horizontal axis corresponds to different speed working conditions, and the vertical axis is the hydraulic oil temperature (°C). It can be seen from the figure that the hydraulic oil temperature is also at its peak around task 8-9.

[0057] The hydraulic thermal load spectrum determination method provided in this application reduces the peak heat dissipation demand of the hydraulic system by removing a portion of the hydraulic oil heat capacity storage power from the peak heat dissipation demand, thereby reducing the structural weight of the heat dissipation accessories and enabling the hydraulic system heat dissipation accessories to achieve certain weight reduction benefits.

[0058] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for determining the hydraulic thermal load spectrum based on the time domain, characterized in that, The method includes: A flow demand analysis of the hydraulic system is performed under a typical task profile to determine the thermal power of the hydraulic system, the thermal power of the actuation system, and the environmental heat dissipation power, among which: The process of determining the thermal power of the hydraulic system includes: Determine the thermal power of the hydraulic system at zero flow and maximum flow at different speeds of the hydraulic pump; The thermal power of the hydraulic system at the actual output flow rate of the hydraulic pump is obtained by interpolation based on the thermal power at zero flow and maximum flow rates. The formula for calculating the thermal power of the hydraulic system is as follows: W 泵最大流量 =(P-P0)·Q 液压泵 ·η 液压泵 In the formula, P is the full-flow supply pressure; P0 is the inlet pressure of the hydraulic pump; Q 液压泵 This represents the maximum output flow rate of the hydraulic pump at different speeds. η 液压泵 This is the ratio of thermal power to output power when the hydraulic pump is at its maximum output flow rate. The process of determining the thermal power of the actuation system includes: Determine the actuation efficiency of the actuation system; The thermal power of the actuation system is calculated based on the actuation efficiency, wherein the formula for calculating the thermal power of the actuation system is: W 通用动作 =P·Q 通用动作 ·(1-η 通用动作 ) Where: P is the full-flow supply pressure; Q 通用动作 This refers to the actual output flow rate; η 通用动作 To improve general working efficiency; The process of determining the environmental heat dissipation power includes: The environmental heat dissipation power is calculated based on solid heat conduction and natural convection heat transfer with the surrounding air. The formula for calculating the environmental heat dissipation power is as follows: W = K·A·ΔT Where: K is the heat transfer coefficient; A represents the heat exchange area; △T represents the temperature difference between the hydraulic oil and the ambient temperature; The thermal capacity and heat storage power of the hydraulic oil in the hydraulic system are determined. The peak thermal power is determined based on the thermal power of the hydraulic system, the thermal power of the actuation system, and the heat dissipation power of the environment. The hydraulic thermal load spectrum is obtained by removing the thermal capacity and heat storage power of the hydraulic oil from the peak thermal power.

2. The method for calculating the hydraulic thermal load spectrum based on the time domain as described in claim 1, characterized in that, The peak thermal power is equal to the sum of the thermal power of the hydraulic system, the thermal power of the actuation system, and the heat dissipation power of the environment.

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