Asymmetric heat exchange turntable surface heat transfer coefficient measuring method
By establishing a one-dimensional transient thermal conductivity model of the turntable under asymmetric thermal boundary conditions, using iterative calculation of optimization theory, the problem of difficulty in measuring the heat transfer coefficients on both sides of the rotating disk cavity in the prior art is solved, and a simplified experiment is achieved Steps and cost-reducing effects.
Patent Information
- Application Number
- CN202411404057.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-09
- Publication Date
- 2025-01-03
AI Technical Summary
In the prior art, when measuring the heat transfer coefficient of the rotary disk surface in the rotary disk cavity, it is difficult to obtain data on both sides in one experiment at the same time. Especially when the thermal boundary conditions are asymmetric, multiple experiments are required, resulting in cumbersome experimental steps. and high cost.
Establish a one-dimensional transient thermal conductivity model of the turntable under asymmetric thermal boundary conditions. By measuring the instantaneous temperature data of the walls on both sides of the turntable, iterative calculations are used to predict the surface heat transfer coefficients on both sides, and simplify the Experimental steps and reduce costs.
The surface heat transfer coefficients on both sides of the turntable are achieved simultaneously in an experiment, which simplifies the experimental steps, reduces the difficulty and cost of the experiment, and breaks through the limitations of conventional transient calculation methods.
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Figure CN119246607A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of aviation engine air systems, and in particular relates to a method for measuring the heat transfer coefficient of a turntable surface with asymmetric heat exchange. Background Art
[0002] Aircraft engine air system is an important part of aircraft engine, and the thermal management technology in aircraft engine air system is related to the reliability and life of the engine. Therefore, the measurement technology of the surface heat transfer coefficient of the rotating disk in the rotating disk cavity of the air system is particularly critical.
[0003] Conventional transient measurement methods are used under ideal conditions. It is necessary to ensure that heat cannot penetrate solids during the measurement process, or only the surface heat transfer coefficient on one side of the turntable can be measured in one experiment. When the thermal boundary conditions and heat transfer intensity on both sides of the turntable are asymmetric, in order to obtain the surface heat transfer coefficient on the other side, another experiment is required under the same working conditions. For the measurement of heat transfer coefficient in axial flow rotating disk cavity or multi-stage rotating disk cavity experiments, it is more cumbersome to use conventional measurement methods to conduct experiments, and multiple experiments are required to obtain.
[0004] Therefore, the present invention proposes a method for measuring the surface heat transfer coefficient of a rotating disk cavity under complex thermal boundary conditions. Summary of the invention
[0005] Technical issues to be solved:
[0006] In order to avoid the shortcomings of the prior art, the present invention provides a method for measuring the surface heat transfer coefficient of a turntable with asymmetric heat exchange, and establishes a one-dimensional transient heat conduction model of the turntable under asymmetric thermal boundary conditions, that is, a reasonable modeling is performed based on the transient heat conduction differential equation, the flow field characteristics in the disk cavity, and the thermal boundary conditions, and the instantaneous wall temperature data of the turntable and the instantaneous heat exchange temperature data measured in the experiment are used as boundary conditions to import the model to predict the surface heat transfer coefficient of both sides of the turntable in the experiment. The method of the present invention can simultaneously obtain the surface heat transfer coefficient of both sides of the turntable in one experiment, reducing the experimental difficulty and experimental cost; breaking through the limitations of the existing conventional transient calculation method, and greatly simplifying the experimental steps.
[0007] The technical solution of the present invention is: a method for measuring the heat transfer coefficient of a turntable surface with asymmetric heat exchange, and the specific steps are as follows:
[0008] Obtain the instantaneous temperature data of the wall surface at the corresponding radial position on both sides of the turntable, and the heat exchange temperature data on both sides of the turntable;
[0009] The instantaneous wall temperature data and the heat transfer temperature data are respectively fitted with time as the independent variable to obtain an experimental wall temperature function and an experimental heat transfer temperature function;
[0010] Establish a transient heat conduction model of a turntable under asymmetric thermal boundary conditions;
[0011] The experimental heat transfer temperature function on one side of the turntable and the experimental wall temperature function on the other side of the turntable are loaded into the transient heat conduction model of the turntable, and the surface heat transfer coefficient on one side of the turntable is obtained through iterative calculation of the optimization theory;
[0012] The experimental wall temperature function on one side of the turntable and the experimental heat transfer temperature function on the other side of the turntable are loaded into the transient heat conduction model of the turntable, and the surface heat transfer coefficient on the other side of the turntable is obtained through iterative calculation of the optimization theory.
[0013] A further technical solution of the present invention is that the instantaneous temperature data of the wall surface is obtained by measuring it through a thermocouple temperature measuring element in a rotating disk cavity heat exchange experiment.
[0014] A further technical solution of the present invention is: the heat exchange temperature data is obtained through a thermocouple temperature measuring element and an airflow pressure measuring element.
[0015] A further technical solution of the present invention is: the calculation formula of the heat exchange temperature data is as follows:
[0016]
[0017] Among them, T f,x (τ) is the static temperature of the airflow at the temperature measurement point in the experiment, measured by a thermocouple; R is the coefficient of recovery; w is the angular velocity of the turntable, r is the local radius position, c p is the specific heat capacity of the air flow, is the circumferential velocity of the airflow, obtained by the airflow pressure measuring element.
[0018] A further technical solution of the present invention is that: the wall instantaneous temperature data is fitted to obtain the wall temperature function on the left and right sides of the turntable as T w,x＝0 (τ),T w,x＝δ (τ).
[0019] A further technical solution of the present invention is that: the heat exchange temperature function obtained by fitting the heat exchange temperature data on the left and right sides of the turntable is T aw,x＝0 (τ),T aw,x＝δ (τ).
[0020] A further technical solution of the present invention is: the expression of the transient heat conduction model of the turntable is as follows:
[0021] Differential equation for heat conduction:
[0022]
[0023] Initial conditions:
[0024] T(x,t=0)=F(x)
[0025] Boundary Condition 1:
[0026]
[0027] T(x=δ)=T w,x＝0 (τ)
[0028] Boundary Condition 2:
[0029]
[0030] T(x=δ)=T w,x＝δ (τ).
[0031] Where T represents the instantaneous temperature of the rotating disk, x represents the internal coordinate of the solid domain, τ represents time, a represents thermal diffusivity, F(x) represents the initial temperature field function of the rotating disk, t represents time, and h 1 、h 2 represents the heat transfer coefficient of the surfaces on both sides of the turntable, λ represents the thermal conductivity; δ represents the thickness of the turntable, T w,x＝0 (τ),T w,x＝δ (τ) represents the function of fitting the wall temperature data on the left and right sides of the turntable in the experiment, T aw,x＝0 (τ),T aw,x＝δ (τ) represents the function of fitting the heat exchange temperature data on the left and right sides of the turntable in the experiment.
[0032] A further technical solution of the present invention is: when the transient heat conduction model of the turntable solves the surface heat transfer coefficient on the left side of the turntable, boundary condition 1 is used; when solving the surface heat transfer coefficient on the right side of the turntable, boundary condition 2 is used.
[0033] A further technical solution of the present invention is: the method for calculating the surface heat transfer coefficient through optimization theory is to use the heat conduction differential equation under asymmetric thermal boundary conditions and the corresponding boundary conditions to set the surface heat transfer coefficient interval, and use the local optimization method to find the surface heat transfer coefficient corresponding to the minimum deviation between the calculated wall temperature result within the interval and the experimentally measured wall temperature result.
[0034] Beneficial Effects
[0035] The beneficial effect of the present invention is that the present invention proposes a method for measuring the heat transfer coefficient of the rotating disk surface under the asymmetric heat exchange boundary conditions of the rotating disk cavity in the field of aircraft engine air system, and the surface heat transfer coefficients on both sides of the rotating disk are obtained simultaneously by the local optimization method through the wall temperature data and heat exchange temperature data measured in the experiment. The advantage of this measurement method is that compared with the conventional surface heat transfer coefficient transient measurement method, the surface heat transfer coefficients on both sides of the rotating disk can be obtained at one time, which simplifies the experimental steps and reduces the experimental difficulty. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] Figure 1 This is a flow chart of a method for measuring the heat transfer coefficient on both sides of the rotating disk in an experiment under specific asymmetric boundary conditions of the present invention;
[0037] Figure 2 Schematic diagram of the rotating disk heat exchange model under asymmetric thermal boundary conditions. DETAILED DESCRIPTION
[0038] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.
[0039] Based on the existing conventional transient measurement method, only the surface heat transfer coefficient of one side of the turntable can be measured in one experiment. When the thermal boundary conditions and heat exchange intensity on both sides of the turntable are asymmetric, in order to obtain the surface heat transfer coefficient of the other side, it is necessary to conduct another experiment under the same working conditions, which leads to the problem of cumbersome experiments. The present invention provides a method for measuring the surface heat transfer coefficient of both sides of the turntable in an experiment under asymmetric thermal boundary conditions of an aircraft engine. Figure 1 As shown, the specific steps are as follows:
[0040] S1. In the rotating disk cavity heat transfer experiment, the instantaneous temperature data of the wall on both sides of the corresponding radial position of the rotating disk and the heat transfer temperature data on both sides are obtained.
[0041] In this embodiment, the wall temperature data can be obtained by a thermocouple temperature measuring element, and the heat exchange temperature can be obtained by a thermocouple temperature measuring element and an airflow pressure measuring element. The airflow pressure measuring element is a total pressure probe and a static pressure probe.
[0042] Specifically, the method for obtaining the heat exchange temperature is:
[0043]
[0044] Where, T f,x (τ) is the static temperature of the airflow at the corresponding position in the experiment, obtained from the thermocouple measurement data; R is the recovery coefficient, usually taken as R = Pr 1 / 3 , where R is 0.89; w is the turntable angular velocity, r is the local radius position, c p is the specific heat capacity of the air flow, is the circumferential velocity of the airflow, obtained through the measurement data of the airflow pressure.
[0045] S2, the turntable wall temperature data and heat transfer temperature data obtained in the experiment are fitted with time as the independent variable;
[0046] Specifically, the function after fitting the wall temperature data on the left and right sides of the turntable is T w,x＝0 (τ),T w,x＝δ (τ), function T after fitting the heat exchange temperature data on the left and right sides of the turntableaw,x＝0 (τ),T aw,x＝δ (τ).
[0047] The fitted functions include but are not limited to polynomial functions, exponential functions, etc. In this case, a polynomial function is used as an example: T w,x＝0 (τ) = a 1 +a 2 τ+a 3 τ 2 +a 4 τ 3 +a 5 τ 4 …, where a1, a2, a3....are the polynomial coefficients.
[0048] S3. Establish a transient heat conduction model of the turntable under asymmetric thermal boundary conditions.
[0049] Reference Figure 2 As shown, in this example, the transient heat conduction model of the turntable under the asymmetric thermal boundary conditions includes: obtaining the specific model parameters of the turntable in the actual experiment; establishing the corresponding one-dimensional transient heat conduction differential equation, and solving it according to the heat conduction differential equation and the corresponding boundary conditions. Please refer to Figure 2 , the one-dimensional transient heat conduction differential equation is shown below.
[0050] Differential equation for heat conduction:
[0051]
[0052] Initial conditions:
[0053] T(x,t=0)=F(x) (2)
[0054] Boundary Condition 1:
[0055]
[0056] T(x=δ)=T w,x＝0 (τ) (4)
[0057] Boundary Condition 2:
[0058]
[0059] T(x=δ)=T w,x＝δ (τ) (6)
[0060] Where T represents the instantaneous temperature of the rotating disk, x represents the internal coordinate of the solid domain, τ represents time, a represents thermal diffusivity, F(x) represents the initial temperature field function of the rotating disk, t represents time, and h 1 、h 2represents the heat transfer coefficient of the surfaces on both sides of the turntable, λ represents the thermal conductivity, δ represents the thickness of the turntable, T w,x＝0 (τ),T w,x＝δ (τ) represents the function of fitting the wall temperature data on the left and right sides of the turntable in the experiment, T aw,x＝0 (τ),T aw,x＝δ (τ) represents the function of fitting the heat exchange temperature data on the left and right sides of the turntable in the experiment.
[0061] S4. Load the experimental heat transfer temperature function on one side of the turntable and the experimental wall temperature function on the other side of the turntable into the transient heat conduction model of the turntable, and obtain the surface heat transfer coefficient on one side of the turntable through iterative calculation of the optimization theory;
[0062] The experimental wall temperature function on one side of the turntable and the experimental heat transfer temperature function on the other side of the turntable are loaded into the transient heat conduction model of the turntable, and the surface heat transfer coefficient on the other side of the turntable is obtained through iterative calculation of the optimization theory.
[0063] The application steps of the turntable transient heat conduction model under the asymmetric thermal boundary conditions described in this embodiment in the experiment are as follows: when it is necessary to solve the surface heat transfer coefficient on the left side of the turntable, the boundary condition adopted by the model is boundary condition 1; when it is necessary to solve the surface heat transfer coefficient on the right side, the boundary condition adopted by the model is boundary condition 2.
[0064] Specifically, the experimental data is imported into the model as boundary conditions. When the heat transfer coefficient of the rotating disk surface at x = 0 is required, T w,x＝δ (τ) is introduced into the transient heat conduction model as the first type of boundary condition, and T aw,x＝0 (τ) and the surface heat transfer coefficient h assumed in the subsequent optimization theory 1 The transient heat conduction model is imported as a third type of boundary condition.
[0065] The optimization theory described in the present invention needs to use the one-dimensional heat conduction equation under asymmetric thermal boundary conditions and the corresponding boundary conditions. First, the surface heat transfer coefficient size range is set, and the local optimization method is used to find the surface heat transfer coefficient size corresponding to the minimum deviation between the calculated wall temperature result and the experimental wall temperature measurement result within the range. The calculated surface heat transfer coefficient result is the required surface heat transfer coefficient.
[0066] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.
Claims
1. A method for measuring the heat transfer coefficient of a turntable surface for asymmetric heat exchange, characterized in that The specific steps are as follows: Obtain the instantaneous temperature data of the wall surface at the corresponding radial position on both sides of the turntable, and the heat exchange temperature data on both sides of the turntable; The instantaneous wall temperature data and the heat transfer temperature data are respectively fitted with time as the independent variable to obtain an experimental wall temperature function and an experimental heat transfer temperature function; Establish a transient heat conduction model of a turntable under asymmetric thermal boundary conditions; The experimental heat transfer temperature function on one side of the turntable and the experimental wall temperature function on the other side of the turntable are loaded into the transient heat conduction model of the turntable, and the surface heat transfer coefficient on one side of the turntable is obtained through iterative calculation of the optimization theory; The experimental wall temperature function on one side of the turntable and the experimental heat transfer temperature function on the other side of the turntable are loaded into the transient heat conduction model of the turntable, and the surface heat transfer coefficient on the other side of the turntable is obtained through iterative calculation of the optimization theory.
2. According to claim 1, a method for measuring the heat transfer coefficient of a turntable surface for asymmetric heat exchange, characterized in that: The instantaneous wall temperature data is obtained by measuring it with a thermocouple temperature measuring element in a rotating disk cavity heat exchange experiment.
3. The method for measuring the heat transfer coefficient of a turntable surface for asymmetric heat exchange according to claim 1, characterized in that: The heat exchange temperature data is obtained through a thermocouple temperature measuring element and an airflow pressure measuring element.
4. The method for measuring the heat transfer coefficient of a turntable surface for asymmetric heat exchange according to claim 3, characterized in that: The calculation formula of the heat exchange temperature data is as follows: Among them, T f,x (τ) is the static temperature of the airflow at the temperature measurement point in the experiment, measured by a thermocouple; R is the coefficient of recovery; w is the angular velocity of the turntable, r is the local radius position, c p is the specific heat capacity of the air flow, is the circumferential velocity of the airflow, obtained by the airflow pressure measuring element.
5. A method for measuring heat transfer coefficient of a turntable surface for asymmetric heat exchange according to any one of claims 1 to 4, characterized in that: The wall instantaneous temperature data is fitted to obtain the wall temperature function on the left and right sides of the turntable as T w,x＝0 (τ),T w,x＝δ (τ).
6. The method for measuring the heat transfer coefficient of a turntable surface for asymmetric heat exchange according to claim 5, characterized in that: The heat exchange temperature data is fitted to obtain the heat exchange temperature function of the left and right sides of the turntable as T aw,x＝0 (τ),T aw,x＝δ (τ).
7. The method for measuring the heat transfer coefficient of a turntable surface for asymmetric heat exchange according to claim 6, characterized in that: The expression of the turntable transient heat conduction model is as follows: Differential equation for heat conduction: Initial conditions: T(x,t=0)=F(x) Boundary Condition 1: T(x=δ)=T w,x＝0 (t) Boundary Condition 2: T(x=δ)=T w,x＝δ (t)。 Where, T represents the instantaneous temperature of the turntable, x represents the internal coordinate of the solid domain, τ represents time, a represents thermal diffusivity, F(x) represents the initial temperature field function of the turntable, t represents time, h1 and h2 represent the heat transfer coefficients on both sides of the turntable, λ represents thermal conductivity; δ represents the thickness of the turntable, T w,x＝0 (τ),T w,x＝δ (τ) represents the function of fitting the wall temperature data on the left and right sides of the turntable in the experiment, T aw,x＝0 (τ),T aw,x＝δ (τ) represents the function of fitting the heat exchange temperature data on the left and right sides of the turntable in the experiment.
8. The method for measuring the heat transfer coefficient of a turntable surface for asymmetric heat exchange according to claim 7, characterized in that: When the transient heat conduction model of the turntable is used to solve the surface heat transfer coefficient on the left side of the turntable, boundary condition 1 is used; when the surface heat transfer coefficient on the right side of the turntable is solved, boundary condition 2 is used.
9. The method for measuring the heat transfer coefficient of a turntable surface for asymmetric heat exchange according to claim 8, characterized in that: The method for calculating the surface heat transfer coefficient by optimization theory is to use the heat conduction differential equation under asymmetric thermal boundary conditions and the corresponding boundary conditions to set the surface heat transfer coefficient interval, and use the local optimization method to find the surface heat transfer coefficient corresponding to the minimum deviation between the calculated wall temperature result and the experimentally measured wall temperature result within the interval.