Temperature sensor time constant selection method for measuring aero-engine inlet total temperature distortion

Abstract

The invention discloses a temperature sensor time constant selection method used for measuring aero-engine inlet total temperature distortion. The method comprises the steps that an air inlet total temperature distortion flow field temperature change curve is obtained through a numerical simulation method; establishing a theoretical mathematical model for measuring the dynamic temperature by the temperature sensor; a mathematical model is adopted to determine a response curve and a measurement error when the dynamic flow field temperature is obtained through temperature sensor measurement numerical simulation of different time constants; and determining a sensor time constant to be selected according to the measurement error and the intake total temperature distortion evaluation precision requirement. According to the method, four works are carried out in sequence, the selected temperature sensor time constant is determined according to the intake total temperature distortion evaluation precision requirement, the problem of low sensor reliability caused by excessively pursuing a small time constant is avoided, and the accuracy and reliability of intake temperature distortion measurement are ensured.

Description

Technical Field

[0001] The present invention relates to, but is not limited to, the technical field of flight test measurement, and particularly refers to a method for selecting the time constant of a temperature sensor for measuring the total temperature distortion at the inlet of an aeroengine. Background Art

[0002] When an aircraft is in formation flight, vertical takeoff and landing, vector nozzle operation, reverse thrust device operation, takeoff in front of a deflector, flying over a smoke area or a fire area, and launching airborne weapons, it may inhale the high-temperature exhaust gas of other aircraft, its own aircraft, the environment, and the weapon system, forming total temperature distortion at the engine inlet. In severe cases, it may cause engine surge, affecting the use and flight safety.

[0003] High response and high reliability are the contradictions in the research and development of current temperature sensors or probes for flight tests. Taking the commonly used small-inertia temperature sensor as an example, nickel-chromium-nickel-silicon thermocouple wires are usually used. The characteristic is that the smaller the diameter, the shorter the time response and the more accurate the measurement result. However, the smaller the diameter, the worse the reliability, and it is easy to have fracture phenomena and more bad points, resulting in inaccurate calculation of the total temperature distortion intensity and distorted temperature maps. How to balance high response and high reliability has always been a difficult point in the total temperature distortion flow field measurement scheme. In flight tests, high response is often emphasized, resulting in an increase in the damage rate of temperature sensors or probes as the flight test progresses. Summary of the Invention

[0004] Object of the present invention: To solve the above technical problems, an embodiment of the present invention provides a method for selecting the time constant of a temperature sensor for measuring the total temperature distortion at the inlet of an aeroengine, so as to solve the problem that in the existing measurement methods for the total temperature distortion at the engine inlet, due to the difficulty in balancing the high response and high reliability of the temperature sensor, excessive pursuit of a smaller time constant leads to low reliability of the sensor, resulting in a high failure rate of measurement points.

[0005] Technical solution of the present invention: An embodiment of the present invention provides a method for selecting the time constant of a temperature sensor for measuring the total temperature distortion at the inlet of an aeroengine, including:

[0006] Step 1, obtaining the total temperature distortion flow field and the flow field temperature change curve by means of numerical simulation;

[0007] Step 2, establishing a theoretical mathematical model in the process of the temperature sensor measuring the dynamic temperature;

[0008] Step 3, using the theoretical mathematical model established in Step 2 to determine the response curve obtained by measuring the dynamic flow field temperature with the temperature sensor at different time constants, and obtaining the flow field characteristic index and the flow field measurement error at different time constants according to the response curve and the flow field temperature change curve;

[0009] Step 4: Determine the sensor time constant to be selected according to the flow field measurement error and the intake total temperature distortion evaluation error requirements under different time constants.

[0010] Optionally, in the method for selecting the temperature sensor time constant for measuring the intake total temperature distortion of an aeroengine as described above, the numerical simulation method in step 1 includes:

[0011] Establish a geometric model of the aircraft and the intake duct, perform mesh division on the geometric model to form a mesh model, establish a flow field calculation model by splicing the mesh model with a pre-established far-field mesh model, set flow field simulation boundary conditions for the flow field calculation model, and use the flow field calculation model to carry out transient flow field numerical simulation to obtain the intake total temperature distortion flow field and the flow field temperature change curve of the engine.

[0012] Optionally, in the method for selecting the temperature sensor time constant for measuring the intake total temperature distortion of an aeroengine as described above, step 1 includes:

[0013] Step 11: Establish a geometric model of the aircraft and the intake duct, simplify the landing gear structure during the establishment of the geometric model, and retain the auxiliary intake doors on the aircraft; for the working conditions with splitter plates, the geometric model also includes splitter plates.

[0014] Step 12: Perform mesh division on the geometric model, locally refine the meshes at the positions of the intake duct, auxiliary intake doors, and under the fuselage to form a mesh model of the aircraft and the intake duct.

[0015] Step 13: Establish a far-field mesh model with the length and width of the computational domain being 20 times the wingspan and fuselage length of the aircraft respectively, and the height being 10 times the height of the aircraft.

[0016] Step 14: Splice the mesh model of the aircraft and the splitter plate with the far-field mesh model to establish a flow field calculation model.

[0017] Step 15: Set flow field simulation boundary conditions for the flow field calculation model, that is, set the computational domain of the flow field calculation model.

[0018] Step 16: Taking the afterburner fuel supply timing and fuel supply distribution from the intermediate state to the maximum state of the engine as a reference, obtain the total temperature change curve at the nozzle inlet during the engine afterburner ignition process by fitting. Based on the computational domain set in step 15, use the total temperature change curve at the nozzle inlet as the nozzle inlet boundary condition inside the computational domain, and use the flow field calculation model to carry out transient flow field numerical simulation to obtain the intake total temperature distortion flow field and the flow field temperature change curve of the engine.

[0019] Optionally, in the method for selecting the time constant of the temperature sensor for measuring the total temperature distortion at the inlet of an aeroengine as described above, in step 15, setting the computational domain of the flow field calculation model includes:

[0020] The setting of the external boundary of the computational domain includes: setting the bottom surface of the computational domain as a no-slip wall boundary condition, and setting the remaining surfaces as pressure far-field boundary conditions;

[0021] The setting inside the computational domain includes: setting the outlet of the inlet duct as a pressure outlet boundary condition so that the target flow rate is consistent with the flow rate in the true engine takeoff state; setting the inlet of the nozzle as a pressure inlet boundary condition, and using the total temperature change curve at the inlet of the nozzle during the engine afterburner engagement process as the boundary condition at the inlet of the nozzle inside the computational domain.

[0022] Optionally, in the method for selecting the time constant of the temperature sensor for measuring the total temperature distortion at the inlet of an aeroengine as described above, if the temperature sensor in step 2 is a thermocouple, then step 2 includes:

[0023] The dynamic characteristics during the temperature measurement process of the thermocouple are described by a differential equation, and the theoretical solution of the differential equation is the theoretical mathematical model of the dynamic response of the thermocouple, specifically:

[0024] T - T 0 =(T e - T 0 )(1 - e -t / τ );

[0025] Wherein, T is the instantaneous measured intake air temperature of the sensor, T 0 is the initial temperature, T e is the true intake air temperature, the above temperature units are all Kelvin (K), e is the natural constant, t is the temperature step time, and τ is the time constant of the sensor.

[0026] Optionally, in the method for selecting the time constant of the temperature sensor for measuring the total temperature distortion at the inlet of an aeroengine as described above, step 3 includes:

[0027] Step 31, taking the flow field temperature change curve obtained by numerical simulation in step 1 as the ideal temperature change, and using the theoretical mathematical model established in step 2 to calculate the response curves of the dynamic flow field temperature measurement using the temperature sensor at different time constants;

[0028] Step 32, by comparing the response curve and the flow field temperature change curve, obtaining the temperature changes at different time constants; according to the temperature changes at different time constants, calculating the total temperature distortion index and the flow field measurement error; wherein, the total temperature distortion index includes the temperature distortion intensity and the circumferential distortion non-uniformity.

[0029] Optionally, in the method for selecting the time constant of the temperature sensor for measuring the total temperature distortion at the inlet of an aero-engine as described above, when obtaining the flow field temperature change curve through numerical simulation in step 31,

[0030] At the engine inlet position, the "water" or "rice" measurement point distribution scheme is adopted, and the required measurement point distribution scheme for numerical simulation is consistent with the measurement point arrangement scheme during measurement by the temperature sensor.

[0031] Optionally, in the method for selecting the time constant of the temperature sensor for measuring the total temperature distortion at the inlet of an aero-engine as described above, the criterion for selecting the sensor time constant in step 4 is:

[0032] Select the time constant with a flow field measurement error less than the requirement of the intake total temperature distortion evaluation error as the minimum requirement for the dynamic response characteristic index of the temperature sensor for measuring the engine intake total temperature distortion.

[0033] Optionally, in the method for selecting the time constant of the temperature sensor for measuring the total temperature distortion at the inlet of an aero-engine as described above, the total temperature distortion index in step 3 further includes: the temperature rise rate and the circumferential range of the high-temperature area;

[0034] The requirements for the intake total temperature distortion evaluation error in step 4 include: temperature distortion intensity < 10%, temperature rise rate < 10%, circumferential range of high-temperature area < 5%; then in step 4, it is determined that:

[0035] When the time constant ≤ 0.1 s, the relative error of the temperature distortion intensity between the numerical simulation flow field and the sensor measurement < 10%, the relative error of the temperature rise rate < 10%, and the circumferential range of the high-temperature area < 5%, within the acceptable error range of the yaw plate test.

[0036] Advantages of the present invention: The embodiment of the present invention provides a method for selecting the time constant of a temperature sensor for measuring the total temperature distortion at the inlet of an aero-engine. Aiming at the situation where the time constant and reliability of the commonly used temperature sensors in current flight tests cannot be both achieved, a guiding method for determining the time constant of the temperature sensor according to the characteristics of the dynamic temperature field change and the evaluation accuracy requirements of the total temperature distortion at the inlet is given. In this method, a numerical simulation method is used to obtain the temperature change curve of the total temperature distortion flow field at the inlet; a theoretical mathematical model for the temperature sensor to measure the dynamic temperature is established; the response curve and measurement error of the temperature sensor with different time constants when measuring the dynamic flow field temperature obtained by numerical simulation are determined by using the mathematical model; the time constant of the sensor to be selected is determined according to the measurement error and the evaluation accuracy requirements of the total temperature distortion at the inlet. The method for selecting the time constant of the temperature sensor provided by the present invention carries out four tasks in sequence, determines the time constant of the selected temperature sensor according to the evaluation accuracy requirements of the total temperature distortion at the inlet, avoids the problem of low reliability of the sensor caused by excessive pursuit of a smaller time constant, and ensures the accuracy and reliability of the measurement of the intake temperature distortion; thus solving the problems of poor reliability of the sensor and high failure rate of the measurement point caused by excessive pursuit of a smaller time constant. Description of the Drawings

[0037] The drawings are used to provide a further understanding of the technical solutions of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present application to explain the technical solutions of the present invention, and do not constitute a limitation to the technical solutions of the present invention.

[0038] Figure 1 It is a schematic flow chart of a method for selecting the time constant of a temperature sensor for measuring the total temperature distortion at the inlet of an aero-engine provided by an embodiment of the present invention;

[0039] Figure 2 It is a schematic diagram of the geometric model and the auxiliary intake valve in an embodiment of the present invention;

[0040] Figure 3 It is a schematic diagram of the flow field calculation model in front of the yaw plate in an embodiment of the present invention. Detailed Embodiments

[0041] To make the purpose, technical solutions and advantages of the present invention clearer and more understandable, the embodiments of the present invention will be described in detail below with reference to the drawings. It should be noted that, without conflict, the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily.

[0042] As described in the above background art, when the total temperature distortion at the inlet of an aero-engine is severe, it will cause the engine to surge, affecting the use and flight safety. In the existing measurement methods for the total temperature distortion at the inlet of the engine, under the condition that it is difficult to balance the high response and high reliability of the temperature sensor, due to excessive pursuit of a smaller time constant, the reliability of the sensor is low, resulting in a high failure rate of the measurement point.

[0043] For the above problems, it is necessary to reasonably select the sensor time constant according to the temperature change rate at the engine inlet. Based on this need, the embodiments of the present invention provide a method for selecting the temperature sensor time constant for measuring the total temperature distortion at the inlet of an aeroengine. By using this method, a temperature sensor that can take into account the reliability requirements while ensuring that the measurement accuracy meets the requirements can be selected to reduce the failure rate of temperature measurement points. Generally, a temperature sensor with a relatively thick diameter and high strength is preferably selected.

[0044] To make the technical solutions and advantages of the present invention clearer, the following takes the method for selecting the temperature sensor time constant for measuring the transient flow field in front of the deflector of a carrier-based aircraft as an example to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0045] The present invention provides the following specific embodiments that can be combined with each other. For the same or similar concepts or processes, they may not be repeated in some embodiments.

[0046] Figure 1 It is a schematic flowchart of a method for selecting the temperature sensor time constant for measuring the total temperature distortion at the inlet of an aeroengine provided by the embodiments of the present invention. The method for selecting the temperature sensor time constant for measuring the total temperature distortion at the inlet of an aeroengine provided by the embodiments of the present invention includes the following steps:

[0047] Step 1, obtaining the total temperature distortion flow field and the flow field temperature change curve by means of numerical simulation;

[0048] The implementation manner of this step can be: establishing the geometric model of the aircraft and the inlet duct, dividing the geometric model into a mesh model, splicing the mesh model with the pre-established far-field mesh model to establish a flow field calculation model, setting the flow field simulation boundary conditions for the flow field calculation model, and using the flow field calculation model to carry out transient flow field numerical simulation to obtain the total temperature distortion flow field and the flow field temperature change curve at the engine inlet.

[0049] Step 2, establishing a theoretical mathematical model during the process of the temperature sensor measuring the dynamic temperature;

[0050] In this step, a theoretical mathematical model during the process of the temperature sensor measuring the dynamic temperature is established based on the heat transfer theory.

[0051] Step 3: Use the theoretical mathematical model established in Step 2 to determine the response curves obtained by measuring the dynamic flow field temperature with a temperature sensor at different time constants. Based on the response curves and the flow field temperature change curves, obtain the flow field characteristic indexes and flow field measurement errors at different time constants.

[0052] In this step, take the temperature change obtained by numerical simulation as the ideal temperature change, use the theoretical mathematical model of the temperature sensor to calculate the temperatures measured by temperature sensors with different time constants, and calculate the total temperature distortion index of the engine intake air flow field and the relative error with the numerical simulation flow field, etc.

[0053] Step 4: Determine the time constant of the sensor to be selected according to the flow field measurement errors at different time constants and the intake total temperature distortion evaluation error requirements.

[0054] In this step, select the time constant with a flow field measurement error less than the intake total temperature distortion evaluation error requirement as the minimum requirement for the dynamic response characteristic index of the temperature sensor used to measure the intake total temperature distortion of the engine.

[0055] In an implementation manner of the embodiment of the present invention, the number of simulation steps per unit time in the transient flow field numerical simulation in Step 1 should not be less than the sampling rate of the temperature measurement system to be adopted; wherein, the number of simulation steps refers to the change frequency of the input parameters of the theoretical calculation model.

[0056] In an implementation manner of the embodiment of the present invention, the commonly used thermocouples and thermal resistors of the temperature sensor in Step 2 both have first-order dynamic response characteristics and are first-order sensors, and their dynamic response theoretical mathematical models can be described by first-order differential equations.

[0057] In an implementation manner of the embodiment of the present invention, in Step 3, when obtaining the dynamic flow field temperature (i.e., the flow field temperature change curve) through the numerical simulation flow field, the "water" - shaped measurement point or "rice" - shaped measurement point distribution scheme is adopted, which is consistent with the measurement point arrangement scheme of the temperature sensor.

[0058] In an implementation manner of the embodiment of the present invention, calculating the intake total temperature distortion index in Step 3 further includes: the temperature rise rate and the circumferential range of the high - temperature area. Among them, the temperature rise rate can be obtained by taking the first derivative of the temperature time - history curve; the circumferential range of the high - temperature area is the circumferential range higher than the surface average temperature in the circumferential temperature field linearly interpolated from the radial average temperature of the intake air flow field.

[0059] In an implementation manner of the embodiment of the present invention, when the intake total temperature distortion evaluation error requirements in Step 4 include: temperature distortion intensity < 10%, temperature rise rate < 10%, circumferential range of high - temperature area < 5%; correspondingly, in Step 4, it is determined that:

[0060] When the time constant ≤ 0.1 s, the relative error of the numerical simulation flow field and the temperature distortion intensity measured by the sensor < 10%, the relative error of the temperature rise rate < 10%, and the circumferential range of the high-temperature area < 5%, which are within the acceptable error range of the deflector test.

[0061] The method for selecting the time constant of the temperature sensor for measuring the total inlet temperature distortion of an aeroengine provided by the embodiment of the present invention aims at the situation that the time constant and reliability of the commonly used temperature sensors in current flight tests cannot be both obtained, and gives a guiding method for determining the time constant of the temperature sensor according to the dynamic temperature field change characteristics and the evaluation accuracy requirements of the total inlet temperature distortion. In this method, a numerical simulation method is used to obtain the temperature change curve of the intake total temperature distortion flow field; a theoretical mathematical model for the temperature sensor to measure the dynamic temperature is established; the response curve and measurement error of the temperature sensor with different time constants when measuring the dynamic flow field temperature obtained by numerical simulation are determined by using the mathematical model; the time constant of the sensor to be selected is determined according to the measurement error and the evaluation accuracy requirements of the intake total temperature distortion. The method for selecting the time constant of the temperature sensor provided by the present invention carries out four tasks in sequence, determines the time constant of the selected temperature sensor according to the evaluation accuracy requirements of the intake total temperature distortion, avoids the problem of low reliability of the sensor caused by excessive pursuit of a smaller time constant, and ensures the accuracy and reliability of the intake temperature distortion measurement; thus solving the problems of poor reliability of the sensor and high failure rate of the measuring point caused by excessive pursuit of a smaller time constant.

[0062] The following takes the method for selecting the time constant of the temperature sensor for measuring the transient flow field in front of the deflector of a carrier-based aircraft as an example to provide a specific implementation example to illustrate the specific implementation manners of the steps of the method for selecting the time constant of the temperature sensor provided by the embodiment of the present invention:

[0063] Implementation example

[0064] See Figure 1 As shown, the method for selecting the time constant of the temperature sensor for measuring the total inlet temperature distortion of an aeroengine provided by this implementation example is implemented by the following steps:

[0065] Step 1, taking the method for selecting the time constant of the temperature sensor for measuring the transient flow field in front of the deflector of a carrier-based aircraft as an example, a numerical simulation method is used to obtain the intake total temperature distortion flow field and the flow field temperature change curve;

[0066] 1) Establish a geometric model of the aircraft and the intake duct. For the working condition with a deflector, the geometric model also has a deflector. When establishing the geometric model, structures such as the landing gear are simplified, and the auxiliary intake door on the aircraft is retained, and this auxiliary intake door has a greater influence on the intake flow field; as Figure 2 shown, it is a schematic diagram of the geometric model and the auxiliary intake door in the embodiment of the present invention;

[0067] 2) Mesh the geometric model, locally refine the meshes at the inlet duct, the position of the auxiliary inlet valve, and under the fuselage to establish the mesh model of the aircraft and the inlet duct;

[0068] 3) Establish the far-field mesh model with the length and width of the computational domain being 20 times the wingspan and the fuselage length of the aircraft respectively, and the height being 10 times the height of the aircraft;

[0069] 4) Stitch together the mesh models of the aircraft and the deflector plate and the far-field mesh model to establish the computational model of the flow field in front of the deflector plate; as Figure 3 shown, it is a schematic diagram of the computational model of the flow field in front of the deflector plate in the embodiment of the present invention;

[0070] 5) Set the boundary conditions of the flow field simulation, that is, set the computational domain of the computational model of the flow field in front of the deflector plate. Among them, the setting of the external boundary of the computational domain includes: setting the bottom surface of the computational domain as the no-slip wall boundary condition, and setting the other surfaces as the pressure far-field boundary condition; the setting of the internal part of the computational domain includes: setting the outlet of the inlet duct as the pressure outlet boundary condition so that the target flow rate is consistent with the flow rate in the real engine take-off state; by setting the inlet of the nozzle as the pressure inlet boundary condition, the total temperature change curve at the inlet of the nozzle during the engine afterburner engagement process can be used as the boundary condition of the inlet of the nozzle inside the computational domain; based on the above numerical settings, numerical simulation is carried out;

[0071] 6) Taking the fuel supply timing and fuel supply quantity distribution from the intermediate state to the maximum state of the engine as a reference, obtain the total temperature change curve at the inlet of the nozzle during the engine afterburner engagement process through fitting. Based on the setting of the computational domain of the computational model of the flow field in front of the deflector plate in 5), using the total temperature change curve at the inlet of the nozzle as the boundary condition of the inlet of the nozzle inside the computational domain, carry out transient flow field numerical simulation using the computational model of the flow field in front of the deflector plate to obtain the total temperature distortion flow field at the inlet of the engine and the flow field temperature change curve.

[0072] Step 2, establish the theoretical mathematical model during the process of the temperature sensor measuring the dynamic temperature;

[0073] The dynamic characteristics during the thermocouple temperature measurement are described by a differential equation, and the theoretical solution of the differential equation is the theoretical mathematical model of the dynamic response of the thermocouple, specifically:

[0074] T - T 0 =(T e - T 0 )(1 - e -t / τ ); (1)

[0075] Among them, T is the instantaneous measured intake air temperature of the sensor, T 0 is the initial temperature, T eis the inlet true temperature, and the above temperature units are all in Kelvin (K). e is the natural constant, t is the temperature step time, and τ is the sensor time constant.

[0076] Step 3: Use the theoretical mathematical model to determine the response curves obtained by measuring the dynamic flow field temperature with a temperature sensor at different time constants. According to the response curves and the flow field temperature change curves, obtain the flow field characteristic indexes and flow field measurement errors at different time constants.

[0077] In this step, the flow field temperature change curve of the "cross" measurement point distribution scheme on the equal annulus at the engine inlet obtained by numerical simulation is used as the ideal temperature change. Using the theoretical mathematical model in Equation (1), calculate the response curves obtained by measuring the dynamic flow field temperature with a temperature sensor when the time constants are 0.03 s, 0.05 s, 0.1 s, 0.2 s, 0.5 s, and 1.0 s respectively, and obtain the corresponding temperature changes at different time constants. By comparing the response curves at different time constants with the flow field temperature change curve in Step 1, calculate the temperature distortion intensity, circumferential distortion non-uniformity, and flow field measurement error, etc. It should be noted that in the execution of this step, the curves of the above parameters are obtained respectively at each time constant; in addition, the dynamic flow field temperature measured by the temperature sensor in this step is actually the flow field temperature obtained by numerical simulation.

[0078] In this step, the methods for calculating the temperature distortion intensity, circumferential distortion non-uniformity, and flow field measurement error are as follows:

[0079] Temperature distortion intensity: where, δT 2FAV is the temperature distortion intensity, T 0 is the total free stream temperature, and T 2FAV is the average temperature of the engine inlet cross-section.

[0080] Circumferential distortion non-uniformity: where, is the circumferential distortion non-uniformity, and T HAV is the average temperature of the air flow in the high-temperature area, and the high-temperature area is defined as the circumferential area where the temperature is higher than the surface average temperature.

[0081] Flow field measurement error: ε is the measurement error, S τ is the measured value of the flow field distortion index at different time constants, and S CFD is the value of the flow field distortion index obtained by numerical simulation.

[0082] Step 4: Determine the sensor time constant to be selected according to the flow field measurement error at different time constants and the evaluation error requirements of the total inlet air temperature distortion.

[0083] Since the total temperature distortion index in step 3 includes: temperature distortion intensity, circumferential distortion non-uniformity, temperature rise rate, and circumferential range of the high-temperature zone.

[0084] The intake total temperature distortion evaluation error requirements in step 4 include: temperature distortion intensity < 10%, temperature rise rate < 10%, circumferential range of the high-temperature zone < 5%; then it is determined in step 4 that:

[0085] Specifically, when the time constant ≤ 0.1 s, the relative error of the temperature distortion intensity between the numerical simulation flow field and the temperature measured by the sensor < 10%, the relative error of the temperature rise rate < 10%, and the circumferential range of the high-temperature zone < 5%, which is within the acceptable error range of the yaw plate test.

[0086] Although the embodiments disclosed in the present invention are as above, the content is only the embodiments adopted for the convenience of understanding the present invention and is not used to limit the present invention. Any person skilled in the art within the scope of the present invention can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention. However, the scope of patent protection of the present invention shall still be subject to the scope defined by the appended claims.

Claims

1. A method for selecting a time constant of a temperature sensor for measuring total temperature distortion at an aircraft engine inlet, characterized in that: include: Step 1, using numerical simulation to obtain the intake total temperature distortion flow field and flow field temperature change curve; Step 2, establishing a theoretical mathematical model of the temperature sensor in the process of measuring dynamic temperature; Step 3, using the theoretical mathematical model established in step 2 to determine the response curve obtained by measuring the temperature of the dynamic flow field using a temperature sensor at different time constants, and obtaining the flow field characteristic index and flow field measurement error at different time constants according to the response curve and the flow field temperature change curve; Step 4: Determine the sensor time constant to be selected according to the flow field measurement error and intake total temperature distortion evaluation error requirements under different time constants.

2. The method for selecting a time constant of a temperature sensor for measuring total temperature distortion of an aircraft engine inlet according to claim 1, characterized in that: The numerical simulation method of step 1 includes: A geometric model of the aircraft and the air inlet is established, and the geometric model is meshed to form a grid model. A flow field calculation model is established by splicing the grid model with the pre-established far-field grid model. Flow field simulation boundary conditions are set for the flow field calculation model, and the flow field calculation model is used to carry out transient flow field numerical simulation to obtain the engine inlet total temperature distortion flow field and flow field temperature change curve.

3. The method for selecting a time constant of a temperature sensor for measuring total temperature distortion of an aircraft engine inlet according to claim 2, characterized in that: The step 1 comprises: Step 11, establishing a geometric model of the aircraft and the air inlet duct. In the process of establishing the geometric model, the landing gear structure is simplified and the auxiliary air inlet valve on the aircraft is retained; for the working condition with a deflector plate, the geometric model also has a deflector plate; Step 12, meshing the geometric model, locally encrypting the meshes at the air inlet, the auxiliary air inlet valve position and the bottom of the fuselage, to form a mesh model of the aircraft and the air inlet; Step 13, establish a far-field grid model with a calculation domain length and domain width of 20 times the aircraft wingspan and fuselage length, and a height of 10 times the aircraft height; Step 14, splicing the grid model of the aircraft and the deflector with the far-field grid model to establish a flow field calculation model; Step 15, setting flow field simulation boundary conditions for the flow field calculation model, that is, setting the calculation domain of the flow field calculation model; Step 16, taking the afterburner fuel supply timing and fuel supply distribution from the intermediate state to the maximum state of the engine as a reference, the nozzle inlet total temperature change curve during the engine afterburner process is obtained by fitting, based on the calculation domain set in step 15, the nozzle inlet total temperature change curve is used as the nozzle inlet boundary condition inside the calculation domain, and the flow field calculation model is used to carry out transient flow field numerical simulation to obtain the engine inlet total temperature distortion flow field and flow field temperature change curve.

4. The method for selecting a time constant of a temperature sensor for measuring total temperature distortion of an aircraft engine inlet according to claim 3, characterized in that: The calculation domain of the flow field calculation model is set in step 15, including: The external boundary settings of the computational domain include: the bottom surface of the computational domain is set to the no-slip wall boundary condition, and the other surfaces are set to the pressure far-field boundary condition; The internal settings of the calculation domain include: setting the inlet outlet as the pressure outlet boundary condition so that the target flow rate is consistent with the flow rate of the actual engine takeoff state; setting the nozzle inlet as the pressure inlet boundary condition so that the total temperature change curve of the nozzle inlet during the engine afterburner process is used as the nozzle inlet boundary condition inside the calculation domain.

5. The method for selecting a time constant of a temperature sensor for measuring total temperature distortion of an aircraft engine inlet according to claim 1, characterized in that: If the temperature sensor in step 2 is a thermocouple, step 2 includes: The dynamic characteristics of the thermocouple temperature measurement process are described by differential equations. The theoretical solution of the differential equation is the theoretical mathematical model of the dynamic response of the thermocouple, which is: T-T0=(T e -T0)(1-e -t / τ ); Where T is the instantaneous intake temperature measured by the sensor, T0 is the initial temperature, and T e is the actual intake air temperature, the temperature unit is Kelvin (K), e is a natural constant, t is the temperature step time, and τ is the sensor time constant.

6. The method for selecting a time constant of a temperature sensor for measuring total temperature distortion of an aircraft engine inlet according to claim 1, characterized in that: The step 3 comprises: Step 31, using the flow field temperature change curve obtained by numerical simulation in step 1 as the ideal temperature change, and using the theoretical mathematical model established in step 2 to calculate the response curve obtained by measuring the dynamic flow field temperature using a temperature sensor at different time constants; Step 32, by comparing the response curve and the flow field temperature change curve, the temperature change under different time constants is obtained; according to the temperature change under different time constants, the total temperature distortion index and the flow field measurement error are calculated; wherein the total temperature distortion index includes the temperature distortion intensity and the circumferential distortion non-uniformity.

7. The method for selecting a time constant of a temperature sensor for measuring total temperature distortion of an aircraft engine inlet according to claim 6, characterized in that: When the numerical simulation in step 31 obtains the flow field temperature variation curve, The engine inlet position adopts a "water"-shaped measuring point or a "meter"-shaped measuring point distribution scheme, and the measuring point distribution scheme required for numerical simulation is consistent with the measuring point arrangement scheme when measuring with a temperature sensor.

8. The method for selecting a time constant of a temperature sensor for measuring total temperature distortion at an aircraft engine inlet according to any one of claims 1 to 7, characterized in that: The criteria for selecting the sensor time constant in step 4 are: The time constant in which the flow field measurement error is smaller than the intake total temperature distortion evaluation error is selected as the minimum requirement for the dynamic response characteristic index of the temperature sensor used to measure the engine intake total temperature distortion.

9. The method for selecting a time constant of a temperature sensor for measuring total temperature distortion of an aircraft engine inlet according to claim 8, characterized in that: The total temperature distortion index in step 3 also includes: temperature rise rate and circumferential range of high temperature zone; The requirements for the evaluation error of the total temperature distortion of the intake air in step 4 include: temperature distortion intensity <10%, temperature rise rate <10%, and circumferential range of the high temperature zone <5%; then, in step 4, it is determined that: When the time constant is ≤0.1s, the relative error of the temperature distortion intensity between the numerical simulation flow field and the sensor measurement is <10%, the relative error of the temperature rise rate is <10%, and the circumferential range of the high temperature zone is <5%, which are within the acceptable error range of the deflector plate test.

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