A gust flow field calibration method based on a dynamic pressure sensor probe

Abstract

This invention provides a method for calibrating gust flow fields based on a dynamic pressure sensor probe. Using the dynamic pressure sensor probe, the pressure data under no-wind conditions is averaged and then subtracted from the incoming static pressure to obtain the zero-point pressure. Then, the wind speed control system is activated, and after the wind speed stabilizes, the collected pressure is subtracted from the zero-point pressure to obtain the gust field pressure value. The gust field pressure is then averaged to obtain the gust field atmospheric pressure value at each point. The gust direction angle is obtained by substituting the measured pressure data into the calibration fitting formula, based on the incoming wind speed. Finally, the gust amplitude is obtained by combining the wind direction angle and the incoming wind speed. This method uses simple probe equipment, has low requirements for the measurement environment, is not easily damaged, and can obtain the incoming velocity and gust amplitude in real time. It can also provide the direction angle of the velocity after disturbance by the gust generator.

Description

Technical Field

[0001] This invention relates to the field of flow field measurement technology, specifically a method for calibrating gust flow fields based on a dynamic pressure sensor probe. Background Technology

[0002] Gusts are a type of deterministic wind disturbance with significant intensity in the atmosphere. When an aircraft encounters a gust, the airframe generates additional unsteady aerodynamic forces and moments, which adversely affect the aircraft's flight performance. Modern civil aircraft, such as large passenger aircraft, emphasize economy, comfort, safety, and reliability, requiring high aerodynamic efficiency and low structural weight. They typically employ high aspect ratio wings and extensively use composite materials in their structural materials. Aircraft wings have considerable flexibility, making them more sensitive to gusts. Gust loads, especially vertical discrete gust loads, often become the most severe flight loads. When an aircraft encounters unsteady aerodynamic loads from low- to moderate-intensity gusts, it causes turbulence, leading to passenger anxiety, reduced comfort, and even injury. When an aircraft encounters high-intensity unsteady aerodynamic loads, localized overloads can exceed 2.5g, causing structural damage or fatigue cracks, impacting its lifespan, and significantly affecting its safety and reliability. Civil aircraft are extremely sensitive to fatigue damage caused by gust loads, and the gust load spectrum is a crucial scientific basis for aircraft structural lifespan reliability design. Due to gust load issues, strengthening the aircraft structure is necessary to maintain strength, increasing weight and consequently affecting economic efficiency.

[0003] Both domestic and international civil aircraft airworthiness regulations have made clear provisions regarding gust loads. China's transport category aircraft airworthiness standard (CCAR-25-R4) and the US aviation regulations (FAR-25) both provide corresponding provisions for gust load design guidelines. Accurately predicting gust loads is an important task that must be carried out during the aircraft design phase.

[0004] Experimental studies on mitigation of gust loads are mainly conducted in wind tunnels, which requires calibration of the gust flow field formed in the wind tunnel in order to understand the amplitude and frequency characteristics of the gust flow field.

[0005] Currently, due to the increasing aspect ratio of aircraft and the extensive use of composite materials, aircraft wings are becoming increasingly flexible. This necessitates measuring high-frequency and high-velocity gust winds. To improve experimental efficiency, a single gust wind field calibration test requires measuring the amplitude, frequency, and swerve angle of the gust wind. This not only provides gust wind field parameters but also verifies the parameters of the gust wind generator. Previously, wind tunnels commonly used instruments such as hot-wire probes, laser Doppler velocimeters, and particle imaging velocimetry to calibrate gust wind fields. However, hot-wire probes are easily contaminated by oil in the air, affecting accuracy, and are also easily broken by dust and particles, making them unsuitable for use in wind tunnel environments. Laser Doppler velocimeters and particle imaging velocimetry require high precision in terms of tracer particle size, tracking ability, and uniform distribution. While these methods can provide the gust amplitude, they cannot provide the wind direction angle. Furthermore, these measurement devices are generally complex and inconvenient to use, and their measurement range is fixed and limited. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a method for calibrating gust flow fields based on a dynamic pressure sensor probe. The probe equipment used is simple, has low requirements for the measurement environment, is not easily damaged, and can obtain the incoming flow velocity and gust amplitude in real time. It can also provide the direction angle of the velocity after the gust generator disturbance. The equipment is inexpensive, has no moving mechanical parts, and responds quickly to airflow deflection angles. Furthermore, the sensor range can be selected according to the measured wind speed range. For example, a sensor with a large range can be selected for high-speed wind tunnels, while a sensor with a small range can be used for low-speed wind tunnels, which can further improve measurement accuracy.

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

[0008] A method for calibrating gust flow field based on a dynamic pressure sensor probe includes the following steps:

[0009] Step 1: Install the probe on the bracket and make fine adjustments to ensure that the dynamic pressure sensor is facing the direction of the incoming flow and the installation angle is zero, and that the probe does not wobble during the test;

[0010] Step 2: Connect the dynamic pressure sensor cable to the data acquisition system and set the data sampling rate and acquisition time;

[0011] Step 3: Under windless conditions, collect the initial pressure, and obtain the zero-point pressure based on the collected initial pressure and the incoming static pressure;

[0012] Step 4: Set the test wind speed in the wind tunnel and collect the pressure after the wind speed stabilizes. Based on the collected pressure and the zero-point pressure, obtain the gust pressure value.

[0013] Step 5: Based on the obtained gust pressure values, obtain the atmospheric pressure values ​​of the gust fields at each calibration point in sequence;

[0014] Step 6: Calculate the dimensionless constant that is only related to the gust direction angle using the measured pressure data, and substitute the dimensionless constant into the calibrated gust direction angle fitting formula to obtain the gust direction angle;

[0015] Step 7: Calculate the nominal pressure value of the calibration point based on the data from each dynamic pressure sensor of the probe, convert the obtained nominal pressure value into the actual pressure value, obtain the incoming wind speed based on the actual pressure value, and obtain the gust amplitude based on the obtained incoming wind speed and gust direction angle.

[0016] Preferably, the specific steps of step two are as follows:

[0017] The five pressure measurement holes on the probe head are numbered, with the center hole designated as hole 1, and the four holes around the center hole numbered 2, 3, 4, and 5 clockwise, with hole 2 located above hole 1. The power supply and signal cables for the five dynamic pressure sensors are led out from the tail of the probe and numbered to correspond to the numbers of the five pressure measurement holes. The five signal cables are then connected to the data acquisition system, and the data sampling rate and acquisition time are set.

[0018] Preferably, the specific steps of step three are as follows:

[0019] Under no-wind conditions, a set of initial pressure data was collected. Take the average value and then subtract the static pressure of the incoming flow. , recorded as zero-point pressure ;

[0020]

[0021] Preferably, the specific steps of step four are as follows:

[0022] The wind tunnel is given a test wind speed. After the wind speed stabilizes, the pressure is collected. The collected pressure is then... Zero point pressure Then, the units of the values ​​collected by the dynamic pressure sensor are converted from Psi to Pa to obtain the gust field pressure value. ;

[0023]

[0024] in, These are pressure data collected after the wind picked up. This refers to the sensitivity coefficient of the dynamic pressure sensor.

[0025] Preferably, the specific steps of step five are as follows:

[0026] The obtained gust pressure value Take the average value, and obtain the results sequentially. Atmospheric pressure values ​​of gust winds at individual school monitoring points ;

[0027]

[0028] Preferably, the specific steps of step six are as follows:

[0029] Based on the measurement principle of differential pressure sensors, the pressure data obtained from the measurement is used to calculate... ;

[0030]

[0031] in, Only with respect to the direction angle of the gust The relevant dimensionless parameters, The pressure difference between probe hole 4 and hole 2. The pressure difference between the pressure at probe hole 1 and the average pressure at probe holes 2 and 4;

[0032] The result Substituting the fitted formula into the calibration, we obtain the gust direction angle. ;

[0033]

[0034] in, , , , The constants obtained for calibration;

[0035] Preferably, the specific steps of step seven are as follows:

[0036] The nominal pressure value at the calibration point is calculated based on the data from each dynamic pressure sensor of the probe:

[0037]

[0038] in, , , , and The pressure values ​​measured at probe holes 1, 2, 3, 4, and 5 are respectively.

[0039] The fitting formula for the actual pressure and nominal pressure obtained during the calibration process is as follows:

[0040]

[0041] in, , The constants obtained for calibration;

[0042] According to the formula Find the air velocity. ;

[0043]

[0044] According to the formula Calculate the gust amplitude; among which, To obtain the incoming air velocity , To obtain the gust direction angle , This represents the amplitude of gusts.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] The present invention provides a method for calibrating gust flow field based on a dynamic pressure sensor probe. The probe equipment used is simple, has low requirements for the measurement environment, is not easily damaged, and can obtain the incoming flow velocity and gust amplitude in real time. It can also provide the direction angle of the velocity after the gust generator disturbance. The equipment is inexpensive, has no mechanical moving parts, and has a fast response speed to the airflow deflection angle. The sensor range can also be selected according to the measurement wind speed range. For example, a sensor with a large range can be selected for high-speed wind tunnels, while a sensor with a small range can be used for low-speed wind tunnels, which can further improve the measurement accuracy. Attached Figure Description

[0047] Figure 1 This is a schematic diagram showing the hole positions and numbering on the probe head;

[0048] Figure 2 This is a schematic diagram showing the location of the probe's marked points;

[0049] Figure 3 This is a schematic diagram of a dynamic pressure sensor.

[0050] Figure 4 This is a flowchart of the method of the present invention;

[0051] Figure 5 This is a graph showing the change in gust amplitude with generator oscillation frequency under different gust direction angles.

[0052] Explanation of reference numerals in the attached figures

[0053] 6 - Marker point, 7 - Pressure sampling hole. Detailed Implementation

[0054] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0055] See Figures 1 to 4 This embodiment provides a method for calibrating gust flow field based on a dynamic pressure sensor probe, which includes the following steps:

[0056] Step 1: Install the probe on the bracket and make fine adjustments to ensure that the dynamic pressure sensor is facing the direction of the incoming flow and that the installation angle is zero, and that the probe does not wobble during the test.

[0057] Step 2: Connect the dynamic pressure sensor cable to the data acquisition system and set the data sampling rate and acquisition time.

[0058] Specifically, the five pressure measurement holes on the probe head are numbered, with the central hole being hole 1, and the four holes around the central hole numbered 2, 3, 4, and 5 in clockwise order, with hole 2 located above hole 1. The power supply and signal cables of the five dynamic pressure sensors are led out from the tail of the probe and numbered to correspond to the numbers of the five pressure measurement holes. The five signal cables are then connected to the data acquisition system, and the data sampling rate and acquisition time are set.

[0059] In this embodiment, the probe head has a marker point 6. Five pressure measuring holes on the probe head are led to the probe tail via five steel pipes, where they connect to dynamic pressure sensors. The pressure measuring hole corresponding to marker point 6 is hole number 2. After the probe is fixed, hole number 2 is positioned above hole number 1. The five dynamic pressure sensors are powered by a DC regulated power supply. The dynamic pressure sensors are cylindrical, and their signals are differential signals. The sensor range can be selected according to the actual wind speed range.

[0060] Step 3: Under windless conditions, collect the initial pressure, and obtain the zero-point pressure based on the collected initial pressure and the incoming static pressure.

[0061] Specifically, under no-wind conditions, a set of initial pressure data was collected. Take the average value and then subtract the static pressure of the incoming flow. , recorded as zero-point pressure ;

[0062]

[0063] Step 4: Set the test wind speed in the wind tunnel and collect the pressure after the wind speed stabilizes. Based on the collected pressure and the zero-point pressure, obtain the gust pressure value.

[0064] Specifically, the wind tunnel is given a test wind speed, and after the wind speed stabilizes, the pressure is collected. The collected pressure is then... Zero point pressure Then, the units of the values ​​collected by the dynamic pressure sensor are converted from Psi to Pa to obtain the gust field pressure value. ;

[0065]

[0066] in, These are pressure data collected after the wind picked up. This represents the sensitivity coefficient of the dynamic pressure sensor.

[0067] Step 5: Based on the obtained gust pressure values, obtain the gust atmospheric pressure values ​​at each calibration point in sequence.

[0068] Specifically, the obtained gust pressure values Take the average value, and obtain the results sequentially. Atmospheric pressure values ​​of gust winds at individual school monitoring points ;

[0069]

[0070] Step 6: Calculate the dimensionless constant that is only related to the gust direction angle using the measured pressure data, and substitute the dimensionless constant into the calibrated gust direction angle fitting formula to obtain the gust direction angle.

[0071] Specifically, based on the measurement principle of the differential pressure sensor, the pressure data obtained from the measurement is used to calculate... ;

[0072]

[0073] in, Only with respect to the direction angle of the gust The relevant dimensionless parameters, The pressure difference between probe hole 4 and hole 2. The pressure difference between the pressure at probe hole 1 and the average pressure at probe holes 2 and 4;

[0074] The result Substituting the fitted formula into the calibration, we obtain the gust direction angle. ;

[0075]

[0076] in, , , , The constants obtained for calibration;

[0077] Step 7: Calculate the nominal pressure value of the calibration point based on the data from each dynamic pressure sensor of the probe, convert the obtained nominal pressure value into the actual pressure value, obtain the incoming wind speed based on the actual pressure value, and obtain the gust amplitude based on the obtained incoming wind speed and gust direction angle.

[0078] Specifically, the nominal pressure value at the calibration point is calculated based on the data from each dynamic pressure sensor of the probe:

[0079]

[0080] in, , , , and The pressure values ​​measured at probe holes 1, 2, 3, 4, and 5 are respectively.

[0081] The fitting formula for the actual pressure and nominal pressure obtained during the calibration process is as follows:

[0082]

[0083] in, , The constants obtained for calibration;

[0084] According to the formula Find the air velocity. ;

[0085]

[0086] According to the formula Calculate the gust amplitude; among which, To obtain the incoming air velocity , To obtain the gust direction angle , This represents the amplitude of gusts.

[0087] Obtain gust amplitude Then, different gust direction angles can be plotted. Below, gust amplitude Oscillation frequency of the generator Changing curves, for example Figure 5 .

[0088] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A dynamic pressure sensor probe based method of gust flow field calibration, characterized in that, It comprises the following steps: Step one, install the probe on the support and fine-tune it to ensure that the dynamic pressure sensor faces the flow direction and the installation angle is zero, and the probe does not shake during the test; Step two, connect the dynamic pressure sensor cable to the acquisition system and set the data sampling rate and acquisition time; Step three, collect the initial pressure in the absence of wind, and obtain the zero-point pressure according to the collected initial pressure and the static pressure of the incoming flow; Step four, set the test wind speed in the wind tunnel, collect the pressure after the wind speed stabilizes, and obtain the gust field pressure value according to the collected pressure and the zero-point pressure; Step five, obtain the gust field pressure value of each calibration point in turn according to the obtained gust field pressure value; Step six, calculate the dimensionless constant related only to the gust direction angle using the measured pressure data, and obtain the gust direction angle by bringing the dimensionless constant into the calibrated gust direction angle fitting formula; Step seven, calculate the nominal pressure value of the calibration point according to the data of each dynamic pressure sensor of the probe, convert the obtained nominal pressure value into actual pressure value, obtain the incoming flow wind speed according to the actual pressure value, and obtain the gust amplitude according to the obtained incoming flow wind speed and gust direction angle.

2. The method of claim 1, wherein, The specific steps of step two are: Number the five pressure measuring holes on the probe head, with the center hole being No. 1 hole, the four holes around the center hole being No. 2 hole, No. 3 hole, No. 4 hole and No. 5 hole in clockwise order, and No. 2 hole being above No. 1 hole; the power cables and signal cables of the five dynamic pressure sensors are led out from the probe tail and numbered, corresponding to the numbering of the five pressure measuring holes, the five signal cables are connected to the data acquisition system respectively, and the data sampling rate and acquisition time are set.

3. The method of claim 2, wherein, The specific steps of step three are: In the absence of wind load, a set of initial pressure data is collected , averaged and subtracted from the free-stream static pressure , denoted as zero-point pressure ; 。 4. The method of claim 3, wherein, The specific steps of step four are: The wind tunnel is given a test wind speed, and the pressure is collected after the wind speed is stable Subtracting the zero pressure The unit of the value collected by the dynamic pressure sensor is converted from Psi to Pa to obtain the gust field pressure value ; ； wherein is the pressure data collected after the wind-up, is the dynamic pressure sensor sensitivity coefficient.

5. The dynamic pressure sensor probe based wind blast flow field calibration method of claim 4, wherein, The specific steps of step five are: The obtained gust field pressure values The average value is obtained in sequence The normal pressure value of the gust field of the measured point ; 。 6. The dynamic pressure sensor probe based wind blast flow field calibration method of claim 5, wherein, The specific steps of step six are: According to the measurement principle of the differential pressure pressure sensor, the pressure data obtained by measurement is used to calculate ; ； wherein, is a dimensionless parameter related only to the gust direction angle , is the pressure difference between the probe 4th hole and the 2nd hole, is the pressure difference between the probe 1st hole pressure and the average pressure of the 2nd and 4th holes; The resulting The calibrated fit formula is entered to obtain the gust direction angle ; ； wherein , , , is a constant obtained from calibration.

7. The dynamic pressure sensor probe based wind blast flow field calibration method of claim 6, wherein, The specific steps of step seven are: The nominal pressure value of the calibration point calculated according to the data of each dynamic pressure sensor of the probe is: ； wherein, , , , and are the pressure values measured by the probe 1st hole, 2nd hole, 3rd hole, 4th hole and 5th hole, respectively. The fitting formula of actual pressure and nominal pressure obtained in the calibration process is: ； wherein , is a constant obtained from calibration; According to the formula Find the air velocity. ; ； The gust amplitude is found according to the formula wherein is the obtained incoming flow wind speed , is the obtained gust direction angle , is the gust amplitude.

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