CN103471803A - Method for determining aerodynamic parameters of model free flight tests - Google Patents

Abstract

A method for determining aerodynamic parameters of model free flight tests is used in model free flight tests including a wind tunnel free flight test, an atmospheric free flight test and the like. Under the situation that a model used in wind tunnel free flight or atmospheric free flight moves in a plane, the method of polynomial time is adopted to match the linear displacement of the centroid of the model in the horizontal direction and the vertical direction and the shooting recording observing value, changing along with time, of the angle of pitch of the model, then, the time-dependent changing rule of the linear displacement, the linear velocity and the linear acceleration of the centroid of the model and the angle displacement, the angle velocity and the angle acceleration of the angle of pitch is obtained, and accordingly the time-dependent changing rule of the resistance coefficient, the lift coefficient and the pitch moment coefficient in the process of model flying is obtained. The application conditions and the range of a data processing method of the model free flight tests are expanded, and the test recorded data can be processed in wide application conditions and ranges to obtain the aerodynamic parameters and the movement rule of the model.

Description

A kind of aerodynamic parameter of model free flight test is determined method

Technical field

The aerodynamic parameter that the invention provides a kind of model free flight test is determined method, is applied to determining of plane motion situation drag free flight test aerodynamic parameter, and the scope of application comprises wind-tunnel free flight and atmosphere free flight test etc.

Background technology

In the plane motion situation, the data of model free flight test record are the displacement of model mass center line and angle of pitch displacement-view of time measured value { x _i, t _i} _{i=1,2 ... N}, { y _i, t _i} _{i=1,2 ... N}{ θ _i, t _i} _{i=1,2 ... N}, usually adopt the single-degree-of-freedom form of parametric differentiation or three periodic methods, and the relational expression of liter, resistance coefficient and the angle of attack carries out parameter identification to record data, thereby obtains liter, the aerodynamic parameter such as resistance coefficient and dynamic and static stable derivative.But in the situation that the aerodynamic force rule of aircraft and pattern are not too clear and definite, as engine not yet cut-offs or guided missile breaks away from launcher not yet fully, and other exist in the situation of external energy input, now the aerodynamic force rule of aircraft and pattern are comparatively complicated, and the model free flight test Aerodynamic Parameter Identification method of above-mentioned normal employing can't be suitable for.In this class situation, obtaining of aerodynamic parameter just becomes a difficult problem.In addition, free flight test data identification method in the past normally directly obtains the numerical value of liter, resistance coefficient and aerodynamic derivative coefficient, or and the angle of attack between relation, can't obtain model mass center line speed, linear acceleration and angular velocity and angular acceleration rule over time, thus can't to model in-flight the time dependent characteristics of motion analyzed.

Summary of the invention

The problem that the technology of the present invention solves is: overcome the deficiencies in the prior art, provide a kind of aerodynamic parameter of model free flight test to determine method, make up the deficiency of existing model free flight test Aerodynamic Parameter Identification technology, solved in the model free flight test in the plane motion situation, aerodynamic force rule and pattern at aircraft are not too clear and definite, make parametric differentiation and three periodic methods of common employing, and rise in the situation that the resistance coefficient discrimination method can't be applicable the problem of how to confirm aerodynamic parameter.

Technical solution of the present invention is:

A kind of aerodynamic parameter of model free flight test is determined method, and described aerodynamic parameter comprises resistance coefficient, lift coefficient and the pitching moment coefficient of model, and step is as follows:

(1) in model free flight test, the model flight path of free flight is carried out to recording image, process and obtain model mass center line Displacement Sequence { x by image afterwards _i, t _i} _{i=1,2 ... N}, { y _i, t _i} _{i=1,2 ... N}with angle of pitch Displacement Sequence { θ _i, t _i} _{i=1,2 ... N}; Wherein, x _ifor model horizontal direction displacement of the lines, y _ifor model vertical direction displacement of the lines, θ _ifor the displacement of the model angle of pitch, t _ifor time point, N is the Displacement Sequence number obtained;

(2) the mass center line Displacement Sequence and the angle of pitch Displacement Sequence that obtain in step (1) are done respectively to the time polynomial matching, obtain the relational expression of mass center line displacement and time

and the relational expression of angle of pitch displacement and time

wherein, BB0, BB1 and BB2 are respectively the high order power of displacement of the lines x, y and angular displacement time polynomial; a _i, b _iand c _ibe fitting coefficient, determined by fitting result respectively;

(3) according to the mass center line displacement obtained in step (2) and the relational expression of time and the relational expression of angle of pitch displacement and time, respectively the time is asked to first order derivative, can obtain the relational expression of mass center line speed and time $\stackrel{\&CenterDot;}{x}=\underset{i=1}{\overset{\mathrm{BB}0}{\mathrm{\&Sigma;}}}{\mathrm{ia}}_i{t}^{i-1},$ $\stackrel{\&CenterDot;}{y}=\underset{i=1}{\overset{\mathrm{BB}1}{\mathrm{\&Sigma;}}}{\mathrm{ib}}_i{t}^{i-1}$ And the relational expression of rate of pitch and time $\stackrel{\&CenterDot;}{\mathrm{\&theta;}}=\underset{i=1}{\overset{\mathrm{<figure-callout\; id="2"\; label="BB"\; filenames="HDA0000386392650000011.png"\; state="\{\{state\}\}">BB</figure-callout>}2}{\mathrm{\&Sigma;}}}{\mathrm{ic}}_i{t}^{i-1};$

(4) according to the mass center line displacement obtained in step (2) and the relational expression of time and the relational expression of angle of pitch displacement and time, respectively the time is asked to second derivative, can obtain the relational expression of mass center line acceleration and time $\stackrel{\&CenterDot;\&CenterDot;}{x}=\underset{i=2}{\overset{\mathrm{BB}0}{\mathrm{\&Sigma;}}}i(i-1)a_i{t}^{i-2},$ $\stackrel{\&CenterDot;\&CenterDot;}{y}=\underset{i=2}{\overset{\mathrm{BB}1}{\mathrm{\&Sigma;}}}i(i-1)b_i{t}^{i-2}$ And the relational expression of angle of pitch acceleration and time $\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&theta;}}=\underset{i=2}{\overset{\mathrm{BB}2}{\mathrm{\&Sigma;}}}i(i-1)c_i{t}^{i-2};$

(5) according to formula $C_D=C_{\mathrm{xx}}\stackrel{\&CenterDot;\&CenterDot;}{x}=C_{\mathrm{xx}}\underset{i=2}{\overset{\mathrm{BB}0}{\mathrm{\&Sigma;}}}i(i-1)a_i{t}^{i-2},$ $C_L=C_{\mathrm{yy}}\stackrel{\&CenterDot;\&CenterDot;}{y}=C_{\mathrm{yy}}\underset{i=2}{\overset{\mathrm{BB}1}{\mathrm{\&Sigma;}}}i(i-1)b_i{t}^{i-2}$ With determine resistance coefficient C _d, lift coefficient C _land pitching moment coefficient C _m; Wherein, coefficient C _xx=C _yy=m/ (q _∞s _r), coefficient C _mm=I _z/ (q _∞s _rl _r), m is model quality, I _zfor model pitch rotation inertia, q _∞for incoming flow dynamic pressure, s _rfor the area of reference of model, l _rreference length for model.

In model mass center line Displacement Sequence, the time interval between adjacent two mass center line displacements is identical, in angle of pitch Displacement Sequence, the time interval between adjacent two angle of pitch displacements is identical, and the time interval between described adjacent two mass center line displacements is identical with the time interval between described adjacent two angle of pitch displacements.

The present invention's beneficial effect compared with prior art is:

1, the present invention is applied in the time polynomial fitting process in the data analysis of model free flight test, has expanded application conditions and the scope of the data processing method of model free flight test.The method not only can be in the parametric differentiation and three periodic methods that usually adopt, and rise in the situation that the resistance coefficient discrimination method can use fully applicable, and in the situation that said method can't applicablely stand good, therefore it can be realizing the processing to the test data sheet data in application conditions and scope more widely, with aerodynamic parameter and the characteristics of motion of obtaining model.

2, carry out differentiate by the time polynomial fitting expression to model line displacement, angular displacement, obtain model line speed, linear acceleration, angular velocity, angular acceleration and the relational expression of time, thereby can obtain the aloft characteristics of motion of model, this is to compare exclusive characteristics with other model free flight data analysing methods.Liter, resistance coefficient and the relational expression of pitching moment coefficient and time also can obtain.

The accompanying drawing explanation

Fig. 1 is process flow diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described.

The present invention can realize in the model free flight situation analysis to the test data sheet data, and obtains the aerodynamic parameters such as model liter, resistance coefficient, pitching moment coefficient.The method can obtain the displacement of model mass center line, linear velocity, linear acceleration and the displacement of the model angle of pitch, angular velocity, angular acceleration and the relational expression of time, thereby realizes the aloft characteristics of motion of model is analyzed.In addition, the method is in the parametric differentiation and three periodic methods that usually adopt, and rises in the situation that the resistance coefficient discrimination method can apply also fully applicablely, so it can be used as a kind of verification method of said method analysis result.

As shown in Figure 1, the aerodynamic parameter of a kind of model free flight test provided by the invention determines that (model free flight test is to make model in tunnel airstream (or in atmosphere) carry out free flight to method, the time history of the movement locus by measurement model, attitude angle etc., inverse goes out to act on the test method of the aerodynamic parameter on model), described aerodynamic parameter comprises resistance coefficient, lift coefficient and the pitching moment coefficient of model, it is characterized in that step is as follows:

(1) in model free flight test, the model flight path of free flight is carried out to recording image, process and obtain model mass center line Displacement Sequence { x by image afterwards _i, t _i} _{i=1,2 ... N}, { y _i, t _i} _{i=1,2 ... N}with angle of pitch Displacement Sequence { θ _i, t _i} _{i=1,2 ... N}; Wherein, x _ifor model horizontal direction displacement of the lines, y _ifor model vertical direction displacement of the lines, θ _ifor the displacement of the model angle of pitch, t _ifor time point, N is the Displacement Sequence number obtained; In model mass center line Displacement Sequence, the time interval between adjacent two mass center line displacements is identical, in angle of pitch Displacement Sequence, the time interval between adjacent two angle of pitch displacements is identical, and the time interval between described adjacent two mass center line displacements is identical with the time interval between described adjacent two angle of pitch displacements.

(2) the mass center line Displacement Sequence and the angle of pitch Displacement Sequence that obtain in step (1) are done respectively to the time polynomial matching, obtain the relational expression of mass center line displacement and time

and the relational expression of angle of pitch displacement and time

wherein, BB0, BB1 and BB2 are respectively the high order power of displacement of the lines x, y and angular displacement time polynomial; Choosing of its value need to be definite with the degree that overlaps of observed reading according to matched curve, i.e. matched curve should be able to give expression to principal character and the variation tendency of observed reading curve, under the prerequisite that can meet this requirement, chooses less numerical value.Coefficient a _i, b _iand c _iby fitting result, determined respectively;

(3) according to the mass center line displacement obtained in step (2) and the relational expression of time and the relational expression of angle of pitch displacement and time, respectively the time is asked to first order derivative, can obtain the relational expression of mass center line speed and time $\stackrel{\&CenterDot;}{x}=\underset{i=1}{\overset{\mathrm{BB}0}{\mathrm{\&Sigma;}}}{\mathrm{ia}}_i{t}^{i-1},$ $\stackrel{\&CenterDot;}{y}=\underset{i=1}{\overset{\mathrm{BB}1}{\mathrm{\&Sigma;}}}{\mathrm{ib}}_i{t}^{i-1}$ And the relational expression of rate of pitch and time $\stackrel{\&CenterDot;}{\mathrm{\&theta;}}=\underset{i=1}{\overset{\mathrm{<figure-callout\; id="2"\; label="BB"\; filenames="HDA0000386392650000011.png"\; state="\{\{state\}\}">BB</figure-callout>}2}{\mathrm{\&Sigma;}}}{\mathrm{ic}}_i{t}^{i-1};$

(4) according to the mass center line displacement obtained in step (2) and the relational expression of time and the relational expression of angle of pitch displacement and time, respectively the time is asked to second derivative, can obtain the relational expression of mass center line acceleration and time $\stackrel{\&CenterDot;\&CenterDot;}{x}=\underset{i=2}{\overset{\mathrm{BB}0}{\mathrm{\&Sigma;}}}i(i-1)a_i{t}^{i-2},$ $\stackrel{\&CenterDot;\&CenterDot;}{y}=\underset{i=2}{\overset{\mathrm{BB}1}{\mathrm{\&Sigma;}}}i(i-1)b_i{t}^{i-2}$ And the relational expression of angle of pitch acceleration and time $\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&theta;}}=\underset{i=2}{\overset{\mathrm{BB}2}{\mathrm{\&Sigma;}}}i(i-1)c_i{t}^{i-2};$

(5) according to formula $C_D=C_{\mathrm{xx}}\stackrel{\&CenterDot;\&CenterDot;}{x}=C_{\mathrm{xx}}\underset{i=2}{\overset{\mathrm{BB}0}{\mathrm{\&Sigma;}}}i(i-1)a_i{t}^{i-2},$ $C_L=C_{\mathrm{yy}}\stackrel{\&CenterDot;\&CenterDot;}{y}=C_{\mathrm{yy}}\underset{i=2}{\overset{\mathrm{BB}1}{\mathrm{\&Sigma;}}}i(i-1)b_i{t}^{i-2}$ With

determine resistance coefficient C _d, lift coefficient C _land pitching moment coefficient C _m; Wherein, coefficient C _xx=C _yy=m/ (q _∞s _r), coefficient C _mm=I _z/ (q _∞s _rl _r), m is model quality, I _zfor model pitch rotation inertia, q _∞for incoming flow dynamic pressure, s _rfor the area of reference of model, l _rreference length for model.

Resistance coefficient C _d, lift coefficient C _land pitching moment coefficient C _mafter determining, will can be the aircraft Design of Aerodynamic Configuration reference will be provided, and be provided as the required aerodynamic parameter support of raising aircraft flight performance.

Claims (2)

1. the aerodynamic parameter of a model free flight test is determined method, and described aerodynamic parameter comprises resistance coefficient, lift coefficient and the pitching moment coefficient of model, it is characterized in that step is as follows:

(1) in model free flight test, the model flight path of free flight is carried out to recording image, process and obtain model mass center line Displacement Sequence { x by image afterwards _i, t _i} _{i=1,2 ... N}, { y _i, t _i} _{i=1,2 ... N}with angle of pitch Displacement Sequence { θ _i, t _i} _{i=1,2 ... N}; Wherein, x _ifor model horizontal direction displacement of the lines, y _ifor model vertical direction displacement of the lines, θ _ifor the displacement of the model angle of pitch, t _ifor time point, N is the Displacement Sequence number obtained;

(2) the mass center line Displacement Sequence and the angle of pitch Displacement Sequence that obtain in step (1) are done respectively to the time polynomial matching, obtain the relational expression of mass center line displacement and time

and the relational expression of angle of pitch displacement and time

wherein, BB0, BB1 and BB2 are respectively the high order power of displacement of the lines x, y and angular displacement time polynomial; a _i, b _iand c _ibe fitting coefficient, determined by fitting result respectively;

(3) according to the mass center line displacement obtained in step (2) and the relational expression of time and the relational expression of angle of pitch displacement and time, respectively the time is asked to first order derivative, can obtain the relational expression of mass center line speed and time $\stackrel{\&CenterDot;}{x}=\underset{i=1}{\overset{\mathrm{BB}0}{\mathrm{\&Sigma;}}}{\mathrm{ia}}_i{t}^{i-1},$ $\stackrel{\&CenterDot;}{y}=\underset{i=1}{\overset{\mathrm{BB}1}{\mathrm{\&Sigma;}}}{\mathrm{ib}}_i{t}^{i-1}$ And the relational expression of rate of pitch and time $\stackrel{\&CenterDot;}{\mathrm{\&theta;}}=\underset{i=1}{\overset{\mathrm{BB}2}{\mathrm{\&Sigma;}}}{\mathrm{ic}}_i{t}^{i-1};$

(4) according to the mass center line displacement obtained in step (2) and the relational expression of time and the relational expression of angle of pitch displacement and time, respectively the time is asked to second derivative, can obtain the relational expression of mass center line acceleration and time $\stackrel{\&CenterDot;\&CenterDot;}{x}=\underset{i=2}{\overset{\mathrm{BB}0}{\mathrm{\&Sigma;}}}i(i-1)a_i{t}^{i-2},$ $\stackrel{\&CenterDot;\&CenterDot;}{y}=\underset{i=2}{\overset{\mathrm{BB}1}{\mathrm{\&Sigma;}}}i(i-1)b_i{t}^{i-2}$ And the relational expression of angle of pitch acceleration and time $\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&theta;}}=\underset{i=2}{\overset{\mathrm{BB}2}{\mathrm{\&Sigma;}}}i(i-1)c_i{t}^{i-2};$

(5) according to formula $C_D=C_{\mathrm{xx}}\stackrel{\&CenterDot;\&CenterDot;}{x}=C_{\mathrm{xx}}\underset{i=2}{\overset{\mathrm{BB}0}{\mathrm{\&Sigma;}}}i(i-1)a_i{t}^{i-2},$ $C_L=C_{\mathrm{yy}}\stackrel{\&CenterDot;\&CenterDot;}{y}=C_{\mathrm{yy}}\underset{i=2}{\overset{\mathrm{BB}1}{\mathrm{\&Sigma;}}}i(i-1)b_i{t}^{i-2}$ With

determine resistance coefficient C _d, lift coefficient C _land pitching moment coefficient C _m; Wherein, coefficient C _xx=C _yy=m/ (q _∞s _r), coefficient C _mm=I _z/ (q _∞s _rl _r), m is model quality, I _zfor model pitch rotation inertia, q _∞for incoming flow dynamic pressure, s _rfor the area of reference of model, l _rreference length for model.

2. the aerodynamic parameter of a kind of model free flight test according to claim 1 is determined method, it is characterized in that: in model mass center line Displacement Sequence, the time interval between adjacent two mass center line displacements is identical, in angle of pitch Displacement Sequence, the time interval between adjacent two angle of pitch displacements is identical, and the time interval between described adjacent two mass center line displacements is identical with the time interval between described adjacent two angle of pitch displacements.

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