CN103940575A - Wind tunnel test balance assessment method based on strain signal energy - Google Patents

Abstract

A wind tunnel test balance assessment method based on strain signal energy mainly includes the steps that a model three-dimensional strain gauge, a framework three-dimensional strain gauge and a balance three-dimensional strain gauge are installed on the inner wall of the top end of an aircraft model, a model framework and a balance respectively; Fourier transformation is carried out on strain signals measured out by the three strain gauges in different directions, then a frequency spectrum signal is obtained, energy normalization characteristic values of six frequency bands within 0-300 Hz are calculated out, the difference value between the energy normalization characteristic values of the strain signals in the same direction of the model and the framework is calculated out, and the difference value between the energy normalization characteristic values of the strain signals in the same direction of the model and the balance is calculated out; when the two difference values between the energy normalization characteristic values in the different directions are within the specialized range, an assessment result determines that test data of the balance are credible, and when the two difference values are not within the specialized range, the assessment result determines that the test data of the balance are not credible. Consequently, model mechanical data measured out through the balance are accurate and reliable in a wind tunnel test, and more accurate and reliable test data are provided for aerospace aircrafts.

Description

A kind of appraisal procedure of the wind tunnel test balance based on strain signal energy

Technical field

The present invention relates to calibration and the appraisal procedure of aerospace flight vehicle wind tunnel test balance, relate in particular to a kind of appraisal procedure of the wind tunnel test balance based on strain signal energy.

Background technology

In the development process of aerospace flight vehicle, in order to understand aircraft performance, to reduce aircraft development the risk and cost, conventionally can carry out wind tunnel model test.The aerodynamic force size, the moment that under various test conditions, aircraft test model are subject to are measured, and are experimental projects the most basic in wind tunnel test.Its test philosophy is, fixes a model bearing in the bottom of wind-tunnel, and the upper end of model bearing penetrates in test model and is threaded with the stiff end of balance, and the measuring junction of balance is threaded with the model framework in test model; Model framework is bolted to connection again test model.When test, pass into the air-flow of certain wind speed toward wind-tunnel, test model is subject to the effect of corresponding flight force and moment, and this flight force and moment passes to the balance of bearing upper end by model framework, is responded to and is measured the flight force and moment on six-freedom degree by balance.The flight force and moment that balance (being subject to) is measured is inferred as the flight force and moment that test model is subject to.

Due to flight force and moment from test model to model framework and balance transmit time, the coupling bolt of test model and model framework, the coupling bolt of model framework and balance, model framework itself all can cause decay and disturb the flight force and moment transmitting, cause in wind tunnel model test, the test error of flight force and moment is large, and precision is low.Therefore, need to proofread and correct or assessment balance.

Existing balance calibration technology mostly is on balance calibration equipment, and balance is applied to normal loading, and gathers balance output signal, calculates the output signal of the each component of balance and the variation relation of normal loading.This calibration steps cycle is long, step is many, and can only calibrate the static characteristics of balance, cannot assess the dynamic perfromance of balance under actual condition, cause accuracy and the reliability of the Mechanical Data of the wind tunnel test under actual condition to be difficult to determine, can not evaluate accurately, reliably the performance of aerospace flight vehicle, can not provide accurately for aerospace flight vehicle, reliable test figure.

Summary of the invention

The object of this invention is to provide a kind of appraisal procedure of the wind tunnel test balance based on strain signal energy, the method can realize the assessment of balance dynamic output characteristic in the aerospace flight vehicle wind tunnel model test under actual condition, make aerospace flight vehicle wind tunnel model test flight force and moment test error in allowed limits, the Mechanical Data that wind tunnel experiment is measured more accurately, reliable; Thereby can evaluate more accurately, reliably the performance of aerospace flight vehicle, also can provide more accurate, reliable test figure for aerospace flight vehicle.

The present invention for the technical scheme that realizes its goal of the invention and adopt is: a kind of appraisal procedure of the wind tunnel test balance based on strain signal energy, and its step is as follows:

Before A, test, model three-dimensional foil gauge, framework three-dimensional foil gauge and balance three-dimensional foil gauge are installed respectively on the top of dummy vehicle inwall, model framework and balance, and the signal output part of model three-dimensional foil gauge, framework three-dimensional foil gauge and balance three-dimensional foil gauge is all connected with signal condition instrument; Signal condition instrument is also connected with computing machine by data acquisition equipment;

B, simulation actual condition, carry out wind tunnel test to dummy vehicle; When test, model three-dimensional foil gauge, framework three-dimensional foil gauge and balance three-dimensional foil gauge are by the strain signal f measuring separately ^pv(t) send into computing machine with sample frequency L by signal condition instrument; Wherein p=1,2,3, represent respectively the strain signal that gathers on model three-dimensional foil gauge, framework three-dimensional foil gauge and balance three-dimensional foil gauge, v=X, Y, Z represents respectively the strain signal that three-dimensional foil gauge collects in X, Y, Z direction, t=1,2,3 ..., N, representation signal f ^pv(t) sequence number of sampled point, N is total sampling number;

C, computing machine are by Fourier transform Jiang Mei road strain signal f ^pv(t) be transformed into spectrum signal φ ^pv(ω); Wherein ω=1,2 ..., L/2 is frequency Bing Jiangmei road spectrum signal φ ^pv(ω) be divided into six frequency bands at 0～300Hz frequency band, extract spectrum signal φ ^pv(ω) in the energy normalized eigenwert of the strain signal of frequency band i i=1,2, L, the sequence number that 6, i is frequency band;

D, energy normalized eigenwert by the strain signal in X, the Y, the Z direction that are obtained by model three-dimensional foil gauge at frequency band i with the energy normalized eigenwert at the strain signal of frequency band i in the X, the Y that are obtained by framework three-dimensional foil gauge, Z direction be calculated as follows respectively the relative difference obtaining in X, Y, Z direction in model strain and the framework strain of frequency band i

$s_i^{(1-2)v}=\frac{|r_i^{1v}-r_i^{2v}|}{r_i^{1v}}\×100\%,$

In formula || represent to ask absolute value,

Energy normalized eigenwert by the strain signal in X, the Y, the Z direction that are obtained by model three-dimensional foil gauge at frequency band i with the energy normalized eigenwert at the strain signal of frequency band i in the X, the Y that are obtained by balance three-dimensional foil gauge, Z direction be calculated as follows respectively the relative difference obtaining in X, Y, Z direction in model strain and the balance strain of frequency band i

$s_i^{(1-3)v}=\frac{|r_i^{1v}-r_i^{3v}|}{r_i^{1v}}\×100\%;$

If E X, on Y, Z direction at the relative difference of model strain and the framework strain of frequency band i in maximal value be less than 5%, and in X, Y, Z direction at the relative difference of model strain and the balance strain of frequency band i in maximal value be less than 10%, judge that error that all flight force and moments are delivered to balance from test model by model framework is in allowed band, the balance test data of wind tunnel test is credible; Otherwise, judge that the error that flight force and moment is delivered to balance from test model by model framework exceeds allowed band, the balance test data of wind tunnel test is insincere.

Compared with prior art, the invention has the beneficial effects as follows:

One, at test model, the linear positive correlation of flight force and moment that the strain signal occurring on model framework and balance is subject to it, the strain value that the three-dimensional foil gauge of installing at three places is measured and the linear positive correlation of power being subject to separately.The difference of the unidirectional strain value that therefore, model foil gauge and framework foil gauge are measured has reflected that flight force and moment is delivered to decay and the interference model framework from test model; The difference of the unidirectional strain value that model foil gauge and balance foil gauge are measured has reflected that flight force and moment is delivered to decay and the interference balance from test model by framework; When these two kinds respectively when strain difference is all in specialized range, show that all flight force and moments are delivered to the decay of balance and are disturbed all in allowed band by model framework from test model, assessment result judges that test data is credible, otherwise assessment judges that test result is insincere, need to the gentle model framework in sky be improved, be calibrated.Thereby the Mechanical Data of the model of measuring by balance while ensureing wind tunnel test accurately, reliably; Make wind tunnel test can evaluate more accurately, reliably the performance of aerospace flight vehicle, also can provide more accurate, reliable test figure for aerospace flight vehicle.

Two, method of the present invention does not need sky flat structure and the factor that affects accuracy of balance to carry out strict analysis modeling, only need to install three three-dimensional foil gauges and subsequent processing device thereof additional, measurement accuracy that just can rapid evaluation balance by test and data processing.Equipment simple installation, can reuse, and has saved experimentation cost, shortens the test period, is easy to be applied to widely the detection test of balance performance, and the development of aerospace flight vehicle is all had great importance.

In above-mentioned step C, extract spectrum signal φ ^pv(ω) in the energy normalized eigenwert of the strain signal of frequency band i specific practice be:

Adopt energy computing formula calculate every road spectrum signal φ ^pv(ω) at the energy of the strain signal of frequency band i in formula, ∫ is integration, || ²for absolute value square; Calculate again every road spectrum signal φ ^pv(ω) in the energy normalized eigenwert of frequency band i

Adopt as above method to quantize and normalized strain energy, its calculating is easy, also can unify the dimension of strain signal simultaneously, is convenient to investigate the capacity volume variance between the signal of each road; Objectively respond decay and the interference of flight force and moment in transmittance process.

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.

Brief description of the drawings

Fig. 1 is the mounting structure schematic diagram of related device when wind tunnel test balance is assessed by the method for the embodiment of the present invention.

In Fig. 1,1b is model bearing, the airflow direction that the direction of arrow is wind-tunnel.

Embodiment

Embodiment

Fig. 1 illustrates, a kind of embodiment of the present invention is, a kind of appraisal procedure of the wind tunnel test balance based on strain signal energy, and its step is as follows:

Before A, test, model three-dimensional foil gauge 1a, framework three-dimensional foil gauge 2a and balance three-dimensional foil gauge 3a are installed respectively on the top of dummy vehicle 1 inwall, model framework 2 and balance 3, and model three-dimensional foil gauge 1a, framework three-dimensional foil gauge 2a are all connected with signal condition instrument with the signal output part of balance three-dimensional foil gauge 3a; Signal condition instrument is also connected with computing machine by data acquisition equipment;

B, simulation actual condition, carry out wind tunnel test to dummy vehicle; When test, model three-dimensional foil gauge 1a, framework three-dimensional foil gauge 2a and balance three-dimensional foil gauge 3a are by the strain signal f measuring separately ^pv(t) send into computing machine with sample frequency L by signal condition instrument; Wherein p=1,2,3, represent respectively the upper strain signal gathering of model three-dimensional foil gauge 1a, framework three-dimensional foil gauge 2a and balance three-dimensional foil gauge 3a, v=X, Y, Z represents respectively the strain signal that three-dimensional foil gauge collects in X, Y, Z direction, t=1,2,3 ..., N, representation signal f ^pv(t) sequence number of sampled point, N is total sampling number;

C, computing machine are by Fourier transform Jiang Mei road strain signal f ^pv(t) be transformed into spectrum signal φ ^pv(ω); Wherein ω=1,2 ..., L/2 is frequency; Bing Jiangmei road spectrum signal φ ^pv(ω) be divided into six frequency bands at 0～300Hz frequency band, extract spectrum signal φ ^pv(ω) in the energy normalized eigenwert of the strain signal of frequency band i i=1,2, L, the sequence number that 6, i is frequency band;

D, energy normalized eigenwert by the strain signal in X, the Y, the Z direction that are obtained by model three-dimensional foil gauge 1a at frequency band i with the energy normalized eigenwert at the strain signal of frequency band i in the X, the Y that are obtained by framework three-dimensional foil gauge 2a, Z direction be calculated as follows respectively the relative difference obtaining in X, Y, Z direction in model strain and the framework strain of frequency band i

$s_i^{(1-2)v}=\frac{|r_i^{1v}-r_i^{2v}|}{r_i^{1v}}\×100\%,$

In formula || represent to ask absolute value;

Energy normalized eigenwert by the strain signal in X, the Y, the Z direction that are obtained by model three-dimensional foil gauge 1a at frequency band i with the energy normalized eigenwert at the strain signal of frequency band i in the X, the Y that are obtained by balance three-dimensional foil gauge 3a, Z direction be calculated as follows respectively the relative difference obtaining in X, Y, Z direction in model strain and the balance strain of frequency band i

$s_i^{(1-3)v}=\frac{|r_i^{1v}-r_i^{3v}|}{r_i^{1v}}\×100\%;$

If E X, on Y, Z direction at the relative difference of model strain and the framework strain of frequency band i in maximal value be less than 10%, and in X, Y, Z direction at the relative difference of model strain and the balance strain of frequency band i in maximal value be less than 10%, judge that error that all flight force and moments are delivered to balance from test model by model framework is in allowed band, the balance test data of wind tunnel test is credible; Otherwise, judge that the error that flight force and moment is delivered to balance from test model by model framework exceeds allowed band, the balance test data of wind tunnel test is insincere.

In this routine step C, extract spectrum signal φ ^pv(ω) in the energy normalized eigenwert of the strain signal of frequency band i specific practice be:

Adopt energy computing formula calculate every road spectrum signal φ ^pv(ω) at the energy of the strain signal of frequency band i in formula, ∫ is integration, || ²for absolute value square; Calculate again every road spectrum signal φ ^pv(ω) in the energy normalized eigenwert of frequency band i

Three-dimensional foil gauge and signal condition instrument that the present invention adopts can be selected various existing foil gauges and regulating instrument, as foil gauge can be selected BE120-2CA (11) the three-dimensional foil gauge of Air China industry Electrical Measuring Instrument incorporated company, strain regulating instrument can be selected Beijing Orient vibration and the portable strain regulating instrument of the INV1861A of noise technique research institute, and data acquisition equipment is selected the INV3020C signal gathering analysis meter of Beijing Orient vibration and noise technique research institute.

Claims (2)

1. An evaluation method of a wind tunnel test balance based on strain signal energy, the steps are as follows: A. Before the test, install the model three-way strain gauge (1a), the frame three-way strain gauge (2a) and the balance three-way strain gauge on the top inner wall of the aircraft model (1), the model frame (2) and the balance (3). The signal output terminals of the three-way strain gauge (3a), the model three-way strain gauge (1a), the frame three-way strain gauge (2a) and the balance three-way strain gauge (3a) are all connected to the signal conditioner; connected to a computer; B. Simulate the actual working conditions and carry out wind tunnel tests on the aircraft model; at the same time as the test, the model three-way strain gauge (1a), the frame three-way strain gauge (2a) and the balance three-way strain gauge (3a) respectively measure the The strain signal f ^pv (t) is sent to the computer through the signal conditioner at the sampling frequency L; where p=1, 2, 3, respectively represent the model three-way strain gauge (1a), the frame three-way strain gauge (2a) and the balance three-way The strain signal collected on the strain gauge (3a), v=X, Y, Z represent the strain signal collected by the three-way strain gauge in the X, Y, and Z directions respectively, t=1,2,3,...,N , represents the sequence number of sampling points of the signal f ^pv (t), and N is the total number of sampling points; C. The computer transforms each strain signal f ^pv (t) into a spectrum signal φ ^pv (ω) through Fourier transform; where ω=1,2,...,L/2 is the frequency; and each spectrum The signal φ ^pv (ω) is divided into six frequency bands in the 0-300Hz frequency range, and the energy normalized eigenvalue of the strain signal of the spectral signal φ ^pv (ω) in the frequency band i is extracted i=1,2,L,6, i is the serial number of the frequency band; D. Normalize the energy eigenvalues of the strain signals in the X, Y, and Z directions in the frequency band i obtained from the model three-way strain gauge (1a) and the energy normalized eigenvalues of the strain signal in the frequency band i in the X, Y, and Z directions obtained from the frame three-way strain gauge (2a) Calculate the relative difference between the model strain and the frame strain in the frequency band i in the X, Y, and Z directions according to the following formula ${\mathrm{the\; s}}_i^{(1-2)v}=\frac{|r_i^{1v}-r_i^{2v}|}{r_i^{1v}}\&times;100\%,$ In the formula |·| means to find the absolute value Normalize the energy-normalized eigenvalues of the strain signals in the X, Y, and Z directions in the frequency band i obtained from the model three-way strain gauge (1a) The energy normalized eigenvalue of the strain signal in the frequency band i in the X, Y, and Z directions obtained from the balance three-way strain gauge (3a) Calculate the relative difference between the model strain and the balance strain in the frequency band i in the X, Y, and Z directions according to the following formula ${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; |</span>}{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; v</span>}}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span><span\; class="notranslate">\; ;</span>$ E. If the relative difference between the model strain and the frame strain in the frequency band i in the X, Y, and Z directions The maximum value in is less than 5%, and the relative difference between the model strain and the balance strain in the frequency band i in the X, Y, and Z directions If the maximum value in is less than 10%, it is judged that the error of all the aerodynamic forces and moments transmitted from the test model to the balance through the model frame is within the allowable range, and the balance test data of the wind tunnel test is credible; otherwise, it is determined that the aerodynamic forces and moments are from The error transmitted from the test model to the balance through the model framework exceeds the allowable range, and the balance test data of the wind tunnel test is not credible. 2. the evaluation method of a kind of wind tunnel test balance based on strain signal energy according to claim 1, it is characterized in that: extract spectrum signal φ ^pv (ω) in the energy of the strain signal of frequency band i in the described step C normalized eigenvalues The specific method is: Using energy calculation formula Calculate the energy of the strain signal of each spectrum signal φ ^pv (ω) in the frequency band i In the formula, ∫ is the integral, |·| ² is the square of the absolute value; then calculate the energy normalized eigenvalue of each spectrum signal φ ^pv (ω) in the frequency band i