CN116992576A - Open wind tunnel unmanned aerial vehicle wing profile aerodynamic test data processing method - Google Patents
Open wind tunnel unmanned aerial vehicle wing profile aerodynamic test data processing method Download PDFInfo
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Abstract
The invention discloses a data processing method for aerodynamic force test of an airfoil of an unmanned aerial vehicle in an open wind tunnel, and belongs to the technical field of aerodynamic force measurement of unmanned aerial vehicles. The method comprises the steps of obtaining an initial load quantity of the aerodynamic balance; acquiring aerodynamic load of the airfoil model under an aerodynamic balance shafting; acquiring an attitude angle of an airfoil model; shaft system conversion; carrying out initial load deduction and airflow deflection correction on aerodynamic load under the airflow shafting of the wind tunnel; and carrying out dimensionless treatment on the corrected aerodynamic load. The test data processing step provided by the invention considers the influence of the turntable in the calculation and subtraction processes of the initial quantity of the aerodynamic balance, carries out airflow deflection correction, obtains unmanned wing type aerodynamic wind tunnel test data with higher precision through the steps, does not need to carry out tunnel wall interference correction and bracket interference correction like a closed wind tunnel, and can obtain aerodynamic measurement results with higher precision.
Description
Technical Field
The invention belongs to the technical field of aerodynamic force measurement of unmanned aerial vehicles, and particularly relates to a data processing method for aerodynamic force test of an airfoil of an unmanned aerial vehicle in an open wind tunnel.
Background
Along with artificial intelligence and information technology energization, unmanned plane technology development is gradually changed. Unmanned aerial vehicles are widely applied to the fields of national economy and national defense construction in China. The aerodynamic properties of an unmanned airfoil have an important impact on its flight performance. The aerodynamic characteristics of the unmanned aerial vehicle wing profile are obtained through wind tunnel test measurement, so that references can be provided for optimization designs of the unmanned aerial vehicle wing, such as lift augmentation, drag reduction, noise reduction and the like, and further the flight performance of the unmanned aerial vehicle is improved.
In general, after the test is finished, the corresponding aerodynamic force and moment coefficient need to be calculated, and most of current wind tunnel test data processing methods are used for processing test data obtained by wind tunnel tests in wind tunnels or processing test data obtained by wind tunnel tests for supporting a model through a rod type strain balance.
For example, chinese patent application publication No. CN114912301a discloses a system for processing and correcting test data of a low-speed wind tunnel full-machine model, which introduces test data, converts the test data into dimensionless data under an airflow shafting, corrects bracket interference, airflow deflection angle deviation and tunnel wall interference, and finally derives all the data. However, this approach is directed to data from full-aircraft model wind tunnel experiments in closed-mouth wind tunnels, and only wall hole disturbances and bracket disturbance corrections, airflow bias angle corrections are considered.
For another example, the Chinese patent with the publication number of CN114608794B discloses a model wind tunnel virtual flight test aerodynamic coefficient measurement method, which acquires the zero reading of a balance in a windless and model-less state and the balance data of the model in different attitude angles (respectively in different pitch angles, yaw angles and roll angles) so as to acquire model mass and mass center parameters according to the two data, namely, the influence of the gravity center offset of the model on the aerodynamic force of the balance; then, the model attitude angles are respectively acquired under the windless and model states: and the balance readings when the pitch angle, the yaw angle and the roll angle are zero, and the balance readings under different attitude angles of the model under the action of wind and in the windy and model states, deducting the balance zero readings (the pitch angle, the yaw angle and the roll angle are all 0) under the windy and model states by using the balance readings under the windy and model states, and correcting after balance iteration and shafting conversion are completed.
However, the method is still aimed at test data obtained by testing in a closed wind tunnel, and is test data in a simulated flight state, namely test data under the condition that multiple degrees of freedom (pitch angle, yaw angle and roll angle) are changed simultaneously or are mutually influenced under the action of wind, and is not applicable to single degree of freedom obtained by aerodynamics wind tunnel test of an open wind tunnel unmanned aerial vehicle airfoil, namely test data under different attitude angles. In addition, due to the arrangement of the multi-degree-of-freedom motion mechanism, the problems of bracket interference and airflow deflection angle interference still exist in practice, and due to the flight test in the closed wind tunnel, hole wall interference still exists, so that the accuracy of the obtained test data is still lower.
For another example, publication number CN108332937a discloses a method for correcting the data of a continuous variable attack angle force measurement test of a wind tunnel, which is to collect initial self-weight readings (i.e. balance readings when the attack angle is zero) and self-weight data (i.e. balance readings when the attack angle is zero) of a model under the condition of no wind and model, so as to correct the delay of balance signals; then, the model dead weight, the inertia force and the centrifugal force influence in the running process of the model are deducted by collecting initial test readings (namely balance readings when the attack angle is zero) and test data (namely balance readings when the attack angle is different) of the model in the windy and model state and deducting dead weight data in the windy and model state by utilizing the test data in the windy and model state.
However, this approach is still actually directed to the test data obtained by performing the complete machine test in the closed wind tunnel, and the use of a lever type strain balance to carry the model is not applicable to the test data obtained by the open wind tunnel unmanned aerial vehicle aerodynamics wind tunnel test. In addition, the whole test data processing method only considers the influence of the dead weight of the model, the inertia force and the centrifugal force in the running process of the model, does not consider the problems of strut interference and hole wall interference, and does not consider the influence of a rotating structure for driving the model to rotate.
Therefore, the influence of the turntable in the process of driving the model to rotate is not found in the existing test data processing method.
Disclosure of Invention
The invention aims to provide a method for processing aerodynamic test data of an airfoil of an unmanned aerial vehicle in an open wind tunnel, which aims at processing test data obtained by aerodynamic measurement of the airfoil of the unmanned aerial vehicle in the open wind tunnel, and provides for the first time to eliminate the influence of a turntable on test results so as to improve the accuracy of the test data.
In order to solve the technical problems, the invention adopts the following technical scheme: a method for processing aerodynamic test data of an airfoil of an unmanned aerial vehicle in an open wind tunnel comprises the following steps:
obtaining an initial load of the aerodynamic balance, wherein the initial load comprises an initial load in a windless and aerofoil-less model stateInitial quantity in aerofoil model state with or without windInitial quantity in windless aerofoil model stateThe method comprises the steps of carrying out a first treatment on the surface of the The initial load amount includes an initial lift amount and an initial drag amount;
wind tunnel test is carried out according to preset test parameters, and aerodynamic load of the airfoil model under an aerodynamic balance shafting is obtained, wherein the aerodynamic load comprises aerodynamic lift force and aerodynamic resistance;
acquiring a posture angle of the airfoil model, wherein the posture angle comprises a geometric attack angle;
converting the aerodynamic load under the aerodynamic balance shafting from the aerodynamic balance shafting to the model shafting based on the aerodynamic balance installation angle to obtain the aerodynamic load under the model shafting, and converting the aerodynamic load under the model shafting to the wind tunnel airflow shafting based on the geometric attack angle to obtain the aerodynamic load under the wind tunnel airflow shafting;
carrying out initial load deduction and airflow deflection correction on aerodynamic load under the airflow shafting of the wind tunnel; the load initial amount subtraction includes:
initial quantity in the state of aerofoil model with or without windInitial quantity in a windless and aerofoil-less model stateAs the initial amount of pneumatic load of the turntable; subtracting initial quantity in a windless wing model state by using aerodynamic load under wind tunnel airflow shaftingThe initial amount of the pneumatic load of the turntable obtains the corrected pneumatic load;
and carrying out dimensionless treatment on the corrected aerodynamic load to obtain an aerodynamic load coefficient.
As an improvement, the formula is utilizedConverting the initial load and aerodynamic load under the aerodynamic balance shafting from voltage data to aerodynamic data, whereinFor aerodynamic data of 6 rows and 1 column,for a calibration coefficient matrix of 6 rows and 6 columns,is 6 rows and 1 column of voltage data.
As an improvement, the method for acquiring the attitude angle of the airfoil model includes:
when the unmanned aerial vehicle wing is installed on the turntable, the 0-degree attack angle of the unmanned aerial vehicle wing is overlapped with the central line of the wind tunnel;
the rotating angle of the mechanical turntable driving the turntable to rotate is the geometrical attack angle of the wing profile.
As an improvement, the step of converting the aerodynamic load under the aerodynamic balance shafting from the aerodynamic balance shafting to the model shafting includes:
using the formula，Performing shaft system conversion;
wherein, is the aerodynamic lift force under the shafting of the model,is the aerodynamic resistance under the shafting of the model,is the aerodynamic resistance under the aerodynamic balance shafting,is pneumatic lifting under the pneumatic balance shaftingThe force with which the force is applied,is the balance mounting angle.
As an improvement, the step of converting aerodynamic load under the model shafting to the wind tunnel airflow shafting comprises:
using the formulaThe shaft system is converted to be a shaft system,
wherein, is the aerodynamic lift under the airflow shafting of the wind tunnel,is the aerodynamic resistance under the airflow shafting of the wind tunnel,is the aerodynamic lift force under the shafting of the model,is the aerodynamic resistance under the shafting of the model,is the geometric angle of attack of the airfoil.
As an improvement, the step of correcting the deflection of the air flow includes:
using the formula:
，
，
，
and performing air flow deflection correction, wherein,in order to be an equivalent angle of attack,in order to be a geometric angle of attack,for the chord length of the airfoil shape,is the height of the wind tunnel nozzle.
The step for obtaining the initial quantity of the aerofoil model state with or without wind as an improvement specifically comprises the following steps: presetting a target wind speed in the test parametersIn the wing-free model state, acquiring a second aerodynamic load initial quantity when the turntable rotates by a corresponding angle;
aiming at each preset target attitude angle in the test parameters, acquiring a third aerodynamic load initial quantity when the turntable rotates to a corresponding angle under the conditions of different preset wind speeds and model without wing profiles;
calculating an aerodynamic load initial quantity average value corresponding to each preset target attitude angle according to the second aerodynamic load initial quantity and the third aerodynamic load initial quantity so as to enable the aerodynamic load initial quantity average value to be equal to the initial quantity in a windless and aerofoil-less model stateThe difference is used as the initial pneumatic load of the turntable to carry out aerodynamic force correction.
As an improvement, the step of dimensionless shaping the modified aerodynamic load comprises:
using the formula:
，
，
non-dimensionalization is performed, wherein,is the coefficient of aerodynamic lift and is used for the control of the air lift,is the coefficient of aerodynamic resistance and is used for the air-actuated resistance,is the aerodynamic lift force of the device,the air-operated resistance is the air-operated resistance,in order to achieve an air density of the air,for the incoming wind speed,the lift coefficient reference area (namely the product of the chord length and the span length of the unmanned wing);is the reference area of the drag coefficient (i.e., the product of unmanned airfoil thickness and span).
As an improvement, after the modified aerodynamic load is dimensionless, the aerodynamic test data is stored as a binary file in the following storage format: the file header of the binary file records test numbers, test dates, names of test persons in charge, atmospheric temperature/humidity/pressure parameters, and wind speed and wing section geometric attack angle information in aerodynamic test data; the aerodynamic test data also comprise aerodynamic data and corresponding moment data, wherein the aerodynamic data comprise aerodynamic resistance, aerodynamic lift and aerodynamic side force; the aerodynamic force data and the moment data are stored in rows, the first row is aerodynamic force to the third row, and the fourth row is aerodynamic moment to the sixth row.
The invention has the advantages that: according to the test data processing method provided by the invention, the influence of the turntable is considered in the calculation and subtraction processes of the initial quantity of the aerodynamic balance, the air flow deflection correction is carried out, the unmanned wing type aerodynamic wind tunnel test data obtained through the steps is high in precision, and the tunnel wall interference correction and the bracket interference correction such as a closed wind tunnel are not needed, so that a high-precision aerodynamic measurement result can be obtained.
In practical application, the airfoil model is driven to rotate by the turntable, so that the interference generated by the turntable is different at different wind speeds (for example, under the condition of larger wind speeds, the angle of the turntable can slightly deflect or the turntable can be inclined up and down and left and right, shake and other unstable conditions due to lighter turntable, for example, the surface of the turntable is not smooth due to a mounting structure for mounting the airfoil model on the turntable or is limited by a processing technology, a microstructure and the like are generated, and an airflow field can be influenced), thereby causing the interference. In order to eliminate such interference, it is generally necessary to optimally design the structure of the turntable itself and the mounting structure (for example, in order to avoid the influence of the turntable at a high wind speed, the stability of the turntable is ensured by providing a counterweight or adopting a specific material to make the turntable). However, the optimization of the structure of the turntable itself and the mounting structure increases the cost. In addition, when the model is used for unmanned aerial vehicle wing models of different types or different specifications, the corresponding turntable structure and the corresponding mounting structure are required to be designed in a self-adaptive mode according to the unmanned aerial vehicle wing models of different types or different specifications, and the rotating disc structure and the mounting structure are further optimized, so that the cost is further increased, and the flexibility of the whole measuring device is lower.
According to the invention, by collecting the pneumatic load data of the turntable at different angles under the specific preset wind speed and the non-wing model state and the pneumatic load data of the turntable at the specific angles, different wind speeds and the non-wing model state and carrying out data processing according to the two data, the interference of the turntable under the specific wind speed is eliminated, and the interference generated by the turntable under the different wind speeds is eliminated, so that the high-precision test data can be obtained without optimizing the existing turntable structure and the installation structure, the flexibility is greatly improved, and the turntable structure and the installation structure only need to be simply amplified in size even for the non-wing model with different types or different specifications.
The prior art (CN 114608794B) aims at a closed wind tunnel, although the acquisition of a windless model is disclosed, and the three-degree-of-freedom mechanism angle is zero, namely, the zero readings in the state that the pitch angle, the yaw angle and the roll angle are all zero; then combining the model without wind, and calculating the model mass and the position of the model mass center relative to the model rotation center by the readings of the balance under different pitch angle, yaw angle and roll angle states of the model, namely the model has the functions of: in order to obtain model mass and centroid parameters; in the calculation of model aerodynamic forces, the calculation is performed only by using balance readings in the windless model state and in the windy model state. I.e. the influence of the turntable on the aerodynamic forces is not considered in the prior art. Compared with the prior art CN114608794B, the influence of the turntable is eliminated, and the precision of test data is further improved.
The corresponding technology (CN 108332937A) aims at a closed wind tunnel, and only discloses that the reading of a balance in a windless model state and the reading of the balance in a windless model state are collected, and then the dead weight data in the windless and model states are subtracted by using the test data in the windless and model states, so that the influence of the dead weight of the model, the inertia force and the centrifugal force in the running process of the model is subtracted. That is, in the prior art, only the influence of the aerodynamic load of the model itself is considered, and the influence of the turntable on the aerodynamic load is not considered. In addition to the influence of the model itself, the influence of the turntable is subtracted, so that compared with the prior art, the accuracy of the obtained test data is higher.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Like elements or portions are generally identified by like reference numerals throughout the several figures. In the drawings, elements or portions thereof are not necessarily drawn to scale. It will be apparent to those of ordinary skill in the art that the drawings in the following description are of some embodiments of the invention and that other drawings may be derived from these drawings without inventive faculty.
FIG. 1 is a flow chart of a method of processing aerodynamic test data of an airfoil of an open wind tunnel unmanned aerial vehicle according to an exemplary embodiment of the invention;
fig. 2 is a schematic structural diagram of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In this document, suffixes such as "module", "component", or "unit" used to represent elements are used only for facilitating the description of the present invention, and have no particular meaning in themselves. Thus, "module," "component," or "unit" may be used in combination.
The terms "upper," "lower," "inner," "outer," "front," "rear," "one end," "the other end," and the like herein refer to an orientation or positional relationship based on that shown in the drawings, merely for convenience of description and to simplify the description, and do not denote or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The terms "mounted," "configured to," "connected," and the like, herein, are to be construed broadly as, for example, "connected," whether fixedly, detachably, or integrally connected, unless otherwise specifically defined and limited; the two components can be mechanically connected, can be directly connected or can be indirectly connected through an intermediate medium, and can be communicated with each other. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
Herein, "and/or" includes any and all combinations of one or more of the associated listed items. Herein, "plurality" means two or more, i.e., it includes two, three, four, five, etc.
The deflection angle of the air flow is referred to herein as: the angle between the main axis of the airflow in the open wind tunnel (i.e. the velocity profile axis of the jet in the core jet region of the open wind tunnel) and the main axis of the open wind tunnel. The creation of an airflow down wash due to airfoil changes in angle of attack will create an airflow deflection angle or angle of airflow deflection.
In the aerodynamic test of the unmanned wing model of the open wind tunnel, the turntable is used for bearing the unmanned wing model to rotate, so that when the wind tunnel test is carried out, the turntable can cause certain interference, and the obtained aerodynamic force measurement test data precision is lower. In order to solve the problems, the invention provides a method for processing aerodynamic test data of an airfoil of an unmanned aerial vehicle in an open wind tunnel, which aims to eliminate the influence of a turntable on test results. Referring to fig. 1, the specific steps include:
s1, acquiring initial load quantity of the aerodynamic balance, wherein the initial load quantity comprises initial quantity in a windless and aerofoil-less model stateInitial quantity in aerofoil model state with or without windInitial quantity in windless aerofoil model state。
The load comprises aerodynamic lift and aerodynamic resistance, the initial load quantity in the step also comprises the initial lift quantity and the initial resistance quantity, and the aerodynamic load in the subsequent step also comprises the aerodynamic lift and the aerodynamic resistance.
In the step, the initial load of the aerodynamic balance is divided into three cases, namely, the initial load in the state that an open wind tunnel is windless and an airfoil model is not installed on a turntable(initial amount of resistance)Initial amount of lift) The method comprises the steps of carrying out a first treatment on the surface of the Secondly, initial quantity of open wind tunnel in windy state without wing model installed on turntable(initial amount of resistance)Initial amount of liftThe method comprises the steps of carrying out a first treatment on the surface of the Third, initial quantity of open wind tunnel under no wind but wing model state mounted on turntable(initial amount of resistance)Initial amount of lift）。
The initial amounts in the three states are used for subsequent elimination of the effect of the turntable.
In some embodiments, the initial amount of the windless and aerofoil model state is obtained in the step S1Initial quantity in aerofoil model state with or without windSpecifically comprises the following steps:
under the windless and aerofoil model state, according to each preset target attitude angle in the test parameters, acquiring a first aerodynamic load initial quantity when the turntable rotates to a corresponding angle；
Preset target wind speed in test parametersUnder the non-wing model state, according to each preset attitude angle in preset test parameters, obtaining a second aerodynamic load initial quantity when the turntable rotates by a corresponding angle。
In other embodiments, in order to eliminate the effect of the turntable at different wind speeds, the step of obtaining the initial quantity in the state of the aerofoil model with or without wind further comprises:
for each preset target attitude angle, a target wind speed is preset at a different wind speed (from the preset target wind speed in the test parametersDifferent) and under the non-wing model state, acquiring a third aerodynamic load initial quantity when the turntable rotates to a corresponding angle, thereby preparing for eliminating the influence of the turntable at different wind speeds in the subsequent data processing process.
S2, acquiring aerodynamic load of the airfoil model under an aerodynamic balance shafting, wherein the aerodynamic load comprises aerodynamic lift and aerodynamic resistance.
Aerodynamic loads, i.e. aerodynamic lift and aerodynamic drag, at a certain wind speed and under the geometrical attack angle of the wing profile can be obtained by means of an aerodynamic balance. The aerodynamic balance collects voltage data, so in step S1 and this step, the voltage data also needs to be converted into aerodynamic data. The invention uses the formula。
Initial load quantity and aerodynamic balanceConversion of aerodynamic loads under shafting from voltage data to aerodynamic data, whereinFor aerodynamic data of 6 rows and 1 column,for a calibration coefficient matrix of 6 rows and 6 columns,is 6 rows and 1 column of voltage data.
S3, acquiring an attitude angle of the airfoil model, wherein the attitude angle comprises a geometric attack angle.
The method for obtaining the geometric attack angle in the embodiment is that when the unmanned aerial vehicle wing is installed on the turntable, the 0-degree attack angle of the unmanned aerial vehicle wing is overlapped with the central line of the wind tunnel; the rotating angle of the mechanical turntable driving the turntable to rotate is the geometrical attack angle of the wing profile.
S4, converting the aerodynamic load under the aerodynamic balance shafting from the aerodynamic balance shafting to the model shafting based on the aerodynamic balance installation angle to obtain the aerodynamic load under the model shafting, and converting the aerodynamic load under the model shafting to the wind tunnel airflow shafting based on the geometric attack angle to obtain the aerodynamic load under the wind tunnel airflow shafting.
The purpose of this step is to perform shafting conversion, which requires conversion of aerodynamic load under the aerodynamic balance shafting to under the wind tunnel airflow shafting. However, the two shafting cannot be directly converted, and the transfer is required to be performed through a model shafting.
The step of converting the aerodynamic load under the aerodynamic balance shafting from the aerodynamic balance shafting to the model shafting in S41 includes:
using the formula
，
，
Conversion shafting, itsIn the process, is the aerodynamic lift force under the shafting of the model,is the aerodynamic resistance under the shafting of the model,is the aerodynamic resistance under the aerodynamic balance shafting,is the aerodynamic lift force under the aerodynamic balance shafting,is the balance mounting angle. Wherein the balance mounting angle can be directly read.
S42, converting aerodynamic load under a model shafting into a wind tunnel airflow shafting comprises the following steps of:
using the formula
；
；
The shaft system is converted, wherein,is the aerodynamic lift under the airflow shafting of the wind tunnel,is the aerodynamic resistance under the airflow shafting of the wind tunnel,is the aerodynamic lift force under the shafting of the model,is the aerodynamic resistance under the shafting of the model,is the geometric angle of attack of the airfoil.
S5, carrying out initial load deduction and airflow deflection correction on aerodynamic load under the airflow shafting of the wind tunnel.
In some embodiments, the load initiation amount subtraction specifically includes:
s51 initial amountAnd initial amount ofAs the initial amount of pneumatic load of the turntable; subtracting initial amount by aerodynamic load under wind tunnel airflow shaftingAnd subtracting the initial pneumatic load of the turntable to obtain the corrected pneumatic load.
Specifically, the formula is utilized
;
;
Calculating the initial amount of pneumatic load of the turntable, wherein,for an initial amount of resistance of the turntable,for an initial amount of lift force of the turntable,for the initial amount of resistance in the windy or non-windy airfoil model state,for the initial amount of drag in the windless and airfoil-less model state,for the initial amount of lift in the windy and non-aerofoil model state,the initial lift force is the initial lift force in the windless and wing-less model state.
Using the formula
，
，
The corrected aerodynamic load is calculated, wherein,in order to correct the aerodynamic drag after the correction,is the aerodynamic resistance under the airflow shafting of the wind tunnel,for the initial amount of drag in the windless aerofoil model state,for an initial amount of resistance of the turntable,in order to correct the aerodynamic lift after the correction,is the aerodynamic lift under the airflow shafting of the wind tunnel,for the initial amount of lift in the windless aerofoil model state,is the initial amount of lift for the turntable.
However, for some special cases, for example, the incoming wind speed is unstable due to long-term use loss of the equipment, which may cause the incoming wind speed in the windy or non-windy wing model state to be different from the incoming wind speed in the windy wing model state obtained in the test process, and the influence of the structure of the turntable itself and various mounting structures arranged on the turntable for mounting the wing model can further amplify the interference to reduce the accuracy of test data, so that the influence of the turntable at different wind speeds needs to be eliminated.
Specifically, in other embodiments, as previously described, for each preset target attitude angle, the wind speed is adjusted between a preset different wind speed (from a preset target wind speedDifferent; preferably, the wind tunnel wind speed instability is considered, and the preset target wind speed is adopted when different wind speeds are preset, namely the target wind speed is preset in the test parametersFor setting, as reference, for example, each wind speed and the preset target wind speedThe deviation range between them is-5%, 5%]) Under the non-wing model state, acquiring a third aerodynamic load initial quantity when the turntable rotates to a corresponding angle, and then calculating different wind speeds (including preset target wind speeds) according to each preset target attitude angle) The lower obtained second and third aerodynamic load initial quantity average valueThen use the formula:;and calculating the initial pneumatic load of the turntable.
Furthermore, the third aerodynamic load initial quantity average value is pre-stored in a database in advance for a specific open wind tunnel, and is directly called in the subsequent test process, so that the acquisition process of initial quantity data is performed to a certain extent, and the test period is reduced to a certain extent.
In the embodiment, the aerodynamic load initial quantity corresponding to each attitude angle in the state of the model without the wing type at different wind speeds is obtained, the average value is obtained, and then the difference between the aerodynamic load initial quantity and the aerodynamic load initial quantity in the state of the model without the wing type is calculated and used as the aerodynamic load initial quantity of the turntable to correct the aerodynamic load obtained by actual measurement of the balance, namely, the influence of the turntable at different wind speeds is eliminated, so that the structure and the mounting structure of the turntable are not required to be optimally designed. The measuring system is particularly suitable for a measuring system of a turntable (with a certain gap between the turntable and the hollow) arranged in the hollow of the lower end plate and directly carrying the unmanned aerial vehicle wing model.
In addition, because the influence of the turntable is eliminated, even if aerodynamic forces of unmanned aerial vehicle wing models of different types or different specifications are required to be tested, only the turntable structure and the mounting structure are required to be simply amplified in size, and the turntable structure and the mounting structure are not required to be further optimized, so that the flexibility of the whole measuring device is greatly improved.
The step of S52 airflow deflection correction includes:
using the formulaAnd (5) carrying out airflow deflection correction.
Wherein, ，；in order to be an equivalent angle of attack,in order to be a geometric angle of attack,for the chord length of the airfoil shape,is the height of the wind tunnel nozzle.
S6, carrying out dimensionless treatment on the corrected aerodynamic load to obtain an aerodynamic load coefficient.
In particular using the formula
，
，
Non-dimensionalization is performed, wherein,is the coefficient of aerodynamic lift and is used for the control of the air lift,is the coefficient of aerodynamic resistance and is used for the air-actuated resistance,is the aerodynamic lift force of the device,the air-operated resistance is the air-operated resistance,in order to achieve an air density of the air,for the incoming wind speed,is the lift coefficient reference area;is the reference area for the drag coefficient.
S7, storing the pneumatic test data into a binary file in the following storage format: (1) The file header of the binary file records test numbers, test dates, names of test persons in charge, atmospheric temperature/humidity/pressure parameters and corresponding wind speed and wing section geometric attack angle information in aerodynamic test data; (2) Aerodynamic force data of aerodynamic force test data, such as aerodynamic resistance, aerodynamic lift force, aerodynamic side force, and corresponding moment data thereof are stored in columns, wherein 1-3 columns are aerodynamic force data, and 4-6 columns are moment data.
As shown in fig. 2, the present invention further provides an open wind tunnel unmanned aerial vehicle airfoil aerodynamic test data processing system, including:
a load initial quantity acquisition module for acquiring a load initial quantity of the aerodynamic balance, wherein the load initial quantity comprises an initial quantity in a windless and aerofoil-less model stateInitial quantity in aerofoil model state with or without windInitial quantity in windless aerofoil model stateThe method comprises the steps of carrying out a first treatment on the surface of the The initial load amount includes an initial lift amount and an initial drag amount; the initial load amount includes an initial lift amount and an initial drag amount;
the aerodynamic load acquisition module is used for acquiring aerodynamic load of the airfoil model under an aerodynamic balance shafting, wherein the aerodynamic load comprises aerodynamic lift and aerodynamic resistance;
the attitude angle acquisition module is used for acquiring an attitude angle of the airfoil model, wherein the attitude angle comprises a geometric attack angle;
the system comprises a shafting conversion module, a wind tunnel airflow shafting and a wind tunnel airflow shafting, wherein the shafting conversion module is used for converting aerodynamic load under an aerodynamic balance shafting from the aerodynamic balance shafting to a model shafting based on an aerodynamic balance installation angle to obtain aerodynamic load under the model shafting, and converting the aerodynamic load under the model shafting to the wind tunnel airflow shafting based on the geometric attack angle to obtain aerodynamic load under the wind tunnel airflow shafting;
the correction module is used for carrying out initial load deduction and airflow deflection correction on aerodynamic load under the wind tunnel airflow shafting; the load initial amount subtraction includes:
will be of initial quantityAnd initial amount ofAs the initial amount of pneumatic load of the turntable; subtracting initial amount by aerodynamic load under wind tunnel airflow shaftingSubtracting the initial pneumatic load of the turntable to obtain a corrected pneumatic load;
the dimensionless module is used for dimensionless treatment of the corrected aerodynamic load to obtain an aerodynamic load coefficient;
and the storage module is used for storing the pneumatic test data into a binary file. The storage format is: (1) The file header of the binary file records test numbers, test dates, names of test persons in charge, atmospheric temperature/humidity/pressure parameters and corresponding wind speed and wing section geometric attack angle information in aerodynamic test data; (2) Aerodynamic force data of aerodynamic force test data, such as aerodynamic resistance, aerodynamic lift force, aerodynamic side force, and corresponding moment data thereof are stored in columns, wherein 1-3 columns are aerodynamic force data, and 4-6 columns are moment data.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
From the above description of the embodiments, it will be clear to those skilled in the art that the above-described embodiment method may be implemented by means of software plus a necessary general hardware platform, but of course may also be implemented by means of hardware, but in many cases the former is a preferred embodiment. Based on such understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art in the form of a software product stored in a storage medium (e.g. ROM/RAM, magnetic disk, optical disk) comprising several instructions for causing a computer terminal (which may be a mobile phone, a computer, a server, or a network device, etc.) to perform the method according to the embodiments of the present invention.
The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present invention and the scope of the claims, which are to be protected by the present invention.
Claims (10)
1. The method for processing aerodynamic test data of the open wind tunnel unmanned aerial vehicle wing profile is characterized by comprising the following steps of:
obtaining an initial load of the aerodynamic balance, wherein the initial load comprises an initial load in a windless and aerofoil-less model stateInitial amount in aerofoil model state with wind +.>And initial amount in windless aerofoil model state +.>The method comprises the steps of carrying out a first treatment on the surface of the The initial load amount includes an initial lift amount and an initial drag amount;
wind tunnel test is carried out according to preset test parameters, and aerodynamic load of the airfoil model under an aerodynamic balance shafting is obtained, wherein the aerodynamic load comprises aerodynamic lift force and aerodynamic resistance;
acquiring a posture angle of the airfoil model, wherein the posture angle comprises a geometric attack angle;
converting the aerodynamic load under the aerodynamic balance shafting from the aerodynamic balance shafting to the model shafting based on the aerodynamic balance installation angle to obtain the aerodynamic load under the model shafting, and converting the aerodynamic load under the model shafting to the wind tunnel airflow shafting based on the geometric attack angle to obtain the aerodynamic load under the wind tunnel airflow shafting;
carrying out initial load deduction and airflow deflection correction on aerodynamic load under the airflow shafting of the wind tunnel; the load initial amount subtraction includes:
initial quantity in the state of aerofoil model with or without windInitial quantity +.>As the initial amount of pneumatic load of the turntable; subtracting the initial quantity +.f under the condition of the model without wind wing profile by using the aerodynamic load under the wind tunnel airflow shafting>And obtaining a corrected aerodynamic load by the initial amount of the aerodynamic load of the turntable;
and carrying out dimensionless treatment on the corrected aerodynamic load to obtain an aerodynamic load coefficient.
2. The method for processing aerodynamic test data of an open wind tunnel unmanned aerial vehicle airfoil according to claim 1, wherein the method comprises the following steps:
using the formula:converting the initial load amount and aerodynamic load under the aerodynamic balance shafting from voltage data to aerodynamic data;
wherein the method comprises the steps ofAerodynamic data of 6 rows and 1 column, +.>Calibration coefficient matrix for 6 rows and 6 columns, < >>Is 6 rows and 1 column of voltage data.
3. The method for processing aerodynamic test data of an airfoil of an open wind tunnel unmanned aerial vehicle according to claim 1, wherein the step of obtaining the attitude angle of the airfoil model comprises the steps of:
when the unmanned aerial vehicle wing is installed on the turntable, the 0-degree attack angle of the unmanned aerial vehicle wing is overlapped with the central line of the wind tunnel;
the rotating angle of the mechanical turntable driving the turntable to rotate is the geometrical attack angle of the wing profile.
4. The method for processing aerodynamic test data of an open wind tunnel unmanned aerial vehicle airfoil according to claim 1, wherein the step of converting aerodynamic load under an aerodynamic balance shafting from the aerodynamic balance shafting to a model shafting comprises:
using the formula:
，
，
the shaft system is converted, wherein,is the aerodynamic lift force under the model shafting, +.>For aerodynamic resistance under the model shafting +.>Is pneumatic resistance under the aerodynamic balance shafting, < +.>Is aerodynamic lift force under an aerodynamic balance shafting, < +.>The balance mounting angle is set; and/or the number of the groups of groups,
the step of converting aerodynamic load under the model shafting into the wind tunnel airflow shafting comprises the following steps of:
using the formula:
，
，
the shaft system is converted, wherein,is the aerodynamic lift force under the wind tunnel airflow shafting, +.>Is the aerodynamic resistance under the airflow shafting of the wind tunnel,is the aerodynamic lift force under the model shafting, +.>For aerodynamic resistance under the model shafting +.>Is the geometric angle of attack of the airfoil.
5. The method for processing aerodynamic test data of an open wind tunnel unmanned aerial vehicle airfoil according to claim 1, wherein the step of correcting the deflection of the airflow specifically comprises:
using the formula:carrying out airflow deflection correction;
wherein, ，/>；/>is equivalent to the angle of attack->Is the geometric attack angle->Is airfoil chord length->Is the height of the wind tunnel nozzle.
6. The method for processing aerodynamic test data of an airfoil of an unmanned aerial vehicle with an open wind tunnel according to claim 1, wherein the step of obtaining the initial quantity in the state of the model with or without an airfoil is specifically included:
presetting a target wind speed in the test parametersIn the wing-free model state, acquiring a second aerodynamic load initial quantity when the turntable rotates by a corresponding angle;
aiming at each preset target attitude angle in the test parameters, acquiring a third aerodynamic load initial quantity when the turntable rotates to a corresponding angle under the conditions of different preset wind speeds and model without wing profiles;
calculating an aerodynamic load initial quantity average value corresponding to each preset target attitude angle according to the second aerodynamic load initial quantity and the third aerodynamic load initial quantity so as to enable the aerodynamic load initial quantity average value to be equal to the initial quantity in a windless and aerofoil-less model stateThe difference is used as the initial pneumatic load of the turntable to carry out aerodynamic force correction.
7. The method for processing aerodynamic test data of an open wind tunnel unmanned aerial vehicle airfoil according to claim 1, wherein the step of dimensionless correcting the aerodynamic load is:
using the formula:
，
，
non-dimensionalization is performed, wherein,is aerodynamic lift coefficient>Is pneumatic resistance coefficient->For aerodynamic lift force->For aerodynamic resistance, < ->For air density->For incoming wind speed, < >>Is the lift coefficient reference area; />Is the reference area for the drag coefficient.
8. The method for processing aerodynamic test data of an open wind tunnel unmanned aerial vehicle airfoil according to claim 1, wherein the method comprises the following steps: and storing the pneumatic test data as a binary file after dimensionless treatment on the corrected aerodynamic load.
9. The method for processing aerodynamic test data of an open wind tunnel unmanned aerial vehicle airfoil according to claim 8, wherein the method comprises the following steps: the file header of the binary file records test numbers, test dates, names of test persons in charge, atmospheric temperature/humidity/pressure parameters, and wind speed and wing section geometric attack angle information in aerodynamic test data.
10. The method for processing aerodynamic test data of an open wind tunnel unmanned aerial vehicle airfoil according to claim 9, wherein the method comprises the following steps: the pneumatic test data further includes: aerodynamic force data and corresponding moment data thereof, wherein the aerodynamic force data comprises: aerodynamic drag, aerodynamic lift, aerodynamic side force; the aerodynamic force data and the moment data are stored in columns, wherein the first column to the third column are the aerodynamic force data, and the fourth column to the sixth column are the moment data.
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