CN1912630A - Triplanar visual particle image speed measuring system - Google Patents

Abstract

A speed measuring system of three sections and stereoscopic particle image type consists of three pulse laser set for outputting light beam with different wavelength, three adjacent light shoots formed by said laser set, three stereoscopic cross-frame CCD digital cameras set at output end of said laser set, microprocessor connected with said digital cameras, integrated software for finalizing various calculations and special software for deriving out vorticity vector field and stress vector field.

Description

Triplanar visual particle image speed measuring system

Technical field

The present invention relates to a kind of image speed measurement system, refer in particular to a kind of triplanar visual particle image speed measuring system.

Background technology

" optical technology and image processing in fluid and the solid the diagnosis " (SPIV that published by SPIE in 2003,5058 volumes, the 131-138 page or leaf, 2003) " about the error analysis of stereoscopic particle image velocity-measuring system " (Mindi Zhang* of delivering of collection of thesis, Gongxin Shen, Run jie Wei*, " Error analysis of Stereoscopic Particle Image velocimetry ", Optical technologyand Image processing for Fluids and Solids Diagnostics, SPIE, Vol.5058, p-131-138, .2003) in the literary composition, announced a kind of digital stereoscopic particle image velocity-measuring system (DSPIV) of development, adopt two and stride the hardwood digital camera, similar human eye stereoscopic principle, move stereoscopic layout according to translation or angle, to the mobile tangent plane that includes trace particle by laser pulse sheet optical illumination, take the instantaneous particle picture sequence of record, adopt cross-correlation calculation, stereoscopic calibration function (object space X, Y, Z with about picture plane X r on the two digital cameras records image, Yr, Xl, the mapping relations of Yl), calculate the displacement field of particle, can record the instantaneous three-dimensional (u of a tangent plane in flowing, v, w) time history of velocity vector field (can put points up to ten thousand) from hundreds of.This article has also been announced a kind of key component in the DSPIV system, and regulator is moved at combined translation-angle, ordinary numbers is striden the hardwood camera be adapted as and can be used in the stereoscopic measurement.If without repacking, about two cameras all can't obtain clearly image record of focusing to a common observation area, can't realize the measurement of stereoscopic PIV.This article is also analyzed at last and has been estimated measuring error (range rate error e in the tangent plane under the various conditions _u, e _vWith range rate error e perpendicular to the tangent plane direction _w).

Obviously " digital stereoscopic particle image velocity-measuring system (DSPIV) " is progressive to some extent than " two-dimentional particle image velocity-measuring system (2DPIV) ", and 2DPIV can only record the interior two-dimension speed vector field of face, and (u v), can not record the speed component (w) of the third dimension.But list cover DSPIV system still is confined to speed (u, v, w) measurement of vector field of a mobile tangent plane, still can not realize flow three dimensions (volume, X, Y, Z) three-dimensional (u, v, w) measurement of velocity vector field, so above-mentioned existing whole flow field measuring method (comprises PIV, particle spike velocity-measuring system PTV, and laser-induced fluorescence (LIF) velocity-measuring system LIFV), all be only limited to the velocity vector field of surveying a tangent plane, can't try to achieve instantaneous vorticity, the space vector field of shear stress etc.

In addition, because it is existing three-dimensional (as digital holographic particle image velocity-measuring system DHPIV, polyphaser three dimensions particle spike velocity-measuring system 3DPTV) observation technology, although can record three dimensions velocity vector field u (x, y, z), but its spatial resolution is too low, that is measuring point distance (grid is too thick) far away, can get vorticity, the shear stress error is big.

Than the stereoscopic particle image velocity-measuring system of existing two tangent planes, its existence provides the velocity vector field data imperfect problem, promptly can not accurately try to achieve all orientation (direction) vorticity vector, the stress vector field.

Summary of the invention

In order to overcome the defective of above-mentioned prior art, the object of the present invention is to provide a kind of triplanar visual particle image speed measuring system.

For achieving the above object, the technical solution used in the present invention is as follows:

A kind of triplanar visual particle image speed measuring system, this system comprises:

Three overlap the pulsed laser groups, are used to export the light beam of different optical wavelengths; Form three adjacent sheet light LS by three cover pulsed laser groups; Be arranged on three cover pulsed laser group light beam output terminals, be positioned at the stereoscopic frame CCD digital camera of striding of three covers around the F of mobile observation test block, be used for gathering respectively simultaneously the particle picture of three tangent planes, respectively three sheet light faces are write down the seasonal effect in time series image that particles move, the instantaneous velocity field that can record three sheet light faces respectively; Stride the microprocessor E that frame CCD digital camera links to each other with stereoscopic, be used for the view data of record can directly be transmitted and entered internal memory, integrated software comprises the The whole control software systems in this microprocessor, and possess relevant image and data processing function, finish multiple computing, graphic presentation, image is obtained the velocity field data via the calculating such as cross correlation algorithm of conventional SPIV, and try to achieve relevant vorticity field, stress field by special software.

Described triplanar visual particle image speed measuring system, synchronous in order to guarantee pulsed light beam and the stereoscopic frame CCD digital camera record of striding that laser array is sent, both guaranteed to write down the instantaneity of three tangent plane particle pictures, guarantee the simultaneity of the velocity field that three tangent planes are measured again, control end in this three covers pulsed laser group connects a synchronous chronotron D, this three covers pulsed laser group is carried out synchro control by the synchronizing relay device, and its delay precision is about 0.5ns (nanosecond).

Because adopt different pulsed laser groups, the optical wavelength difference that it sends further, looks a single-pass light filter lens to be set before striding frame CCD digital camera at every stage body, be used to guarantee that the instantaneous of particle picture of obtaining three tangent planes respectively do not disturb mutually.

The led to optical wavelength scope of above-mentioned single-pass light filter lens is: λ=± 2nm.

Three above-mentioned cover pulsed laser groups comprise: the YAG pulsed laser group that a cover adopts for conventional PIV, its wavelength is λ ₀=532nm, and a separate set of is Dyelaser pulsed fuel laser array, its wavelength is respectively ${\mathrm{\λ}}_1\≅580\mathrm{nm},{\mathrm{\λ}}_2\≅482\mathrm{nm}.$

Every suit pulsed laser group comprises two pulsed lasers; Every cover is stereoscopic strides frame CCD digital camera and comprises also that two stage bodies are looked and stride frame CCD digital camera.

This stereoscopic pixel 1k * 2k that strides frame CCD digital camera, frequency 30Hz, model ES-2093.

Use beneficial effect of the present invention to be: the function that native system has is the result that can obtain the quantitative measurment of most complete flow field that can test at present.Provide among the present invention and can ask instantaneous vorticity, the measurement data u (x ± Δ x, y ± Δ y, z ± Δ z) of the space velocity vector field that space vector places such as stress need.The present invention is owing to adopt three optical techs, and the thickness of sheet light can approach (100 μ magnitude), can adjust thickness according to mobile needs again, improves the spatial resolution of velocity field greatly, can obtain quite accurate vorticity thus, the partial data of stress vector field.For turbulent flow, provide a kind of both may observe fluidal texture especially, can obtain speed, vorticity, stress vector field of a whole space tangent plane etc. again, and the quantitative measurment result of spatial evolution.The triplanar visual particle image velocity measuring technique is as up-to-date, state-of-the-art fluid measurement technology in the present age, it has embodied the globality and the instantaneity of FLOW VISUALIZATION technology, can once measure the velocity amplitude of thousands of points in the tested flow field, for the fine structure of studying the flow field provides effective means.

Description of drawings

Fig. 1 is a triplanar visual particle image speed measuring system of the present invention;

Fig. 1 a is the light path enlarged diagram that the light pulse of pulsed laser among Fig. 1 forms sheet light;

Fig. 2 is vorticity of the present invention, stress vector field measurement sequential chart;

Fig. 3 constitutes synoptic diagram for the solid arrangement of three component velocity vector fields of the tight adjacent tangent plane of three of the present invention;

Fig. 4 is the space instantaneous velocity distribution field synoptic diagram of each spatial point of the present invention;

Fig. 5 is a related function field measurement sequential chart of the present invention.

Embodiment

Below by embodiment, accompanying drawing describes the present invention in addition.

The critical flow field characteristic parameter and the quantitative data thereof of non-permanent complex flow (as turbulent flow etc.) are used significant to understanding non-permanent complex flow and engineering thereof.

So-called triplanar visual particle image speed measuring system (Triple planes SPIV system) is a kind of non-permanent velocity vector field, vorticity vector field, stress vector field measurement system.

As shown in Figure 1, be triplanar visual particle image speed measuring system of the present invention; By the stereoscopic particle image velocimetry of three covers system (being called for short SPIV) is basic comprising, form (every cover pulsed laser group is made up of two pulsed lasers) three neighbours' sheet light by three cover pulsed laser groups, as shown in Figure 1a: sheet light 1, sheet light 0, sheet light 2, the stereoscopic frame CCD digital camera group C0 that strides of three covers is set around the F of mobile observation test block, C1, C2, every cover is stereoscopic strides frame CCD digital camera and strides frame CCD digital camera by two and form (wherein, dotted line is represented the pickup light axis of camera among Fig. 1), the seasonal effect in time series image that three sheet light faces record particles are moved is right respectively, via the calculating such as cross correlation algorithm of conventional SPIV, can record the instantaneous velocity field of three sheet light faces respectively.

Wherein three overlap the pulsed laser groups, and output beam has different optical wavelengths, and the first pulsed laser group A is the YAG pulsed laser group that conventional PIV adopts, and wavelength is λ ₀=532nm, the second pulsed laser group B and the 3rd pulsed laser group C are Dyelaser pulsed fuel laser array, and wavelength is respectively ${\mathrm{\λ}}_1\≅580\mathrm{nm},{\mathrm{\λ}}_2\≅482\mathrm{nm}.$ The light pulse of three cover pulsed laser groups simultaneously to (two the time interval can by the laser pulse of the accurate control of chronotron) by synchronizing relay device D (delay precision 0.5ns nanosecond) synchro control, the light pulse of three cover pulsed laser groups forms sheet light (LS) as shown in the figure, and synchronous light-emitting, guarantee the simultaneity of the velocity field that three tangent planes are measured.

Three the cover stereoscopic digital frame straddling cameras group C0-1, C0-2, C1-1, C1-2, C2-1, (1k * 2k pixel, 30Hz ES-2093), gather the particle picture of three tangent planes respectively to C2-2 simultaneously.Because of adopting different laser light wavelength, and by corresponding single-pass light filter lens (F0, F1, F2, can lead to the optical wavelength scope and be: λ=± 2nm), guarantee that the instantaneous of particle picture of obtaining three tangent planes respectively do not disturb mutually.

Synchronizing relay device D guarantees the laser light pulse and to stride frame CCD cameras record synchronous, has both guaranteed to write down the instantaneity of three tangent plane particle pictures, guarantees its same instantaneous (synchronously) property again.Its instantaneity error is in 6-8ns, and its synchronism error is seen the instantaneous vorticity of Fig. 2, stress field measurement sequential chart in 10ns.

Total system is by system controlled by computer E, microcomputer be many CPU (at least 6 CPU), internal memory greater than 12GB, and be connected with digital camera by 64 buses, the view data of record can directly be transmitted and enter internal memory.

The integrated software of system not only comprises the The whole control software systems, and possesses relevant image and data processing function, finishes multiple computing, graphic presentation etc.Image is obtained the velocity field data via the calculating such as cross correlation algorithm of conventional SPIV, and tries to achieve relevant vorticity vector field, stress vector field etc. by special software.

Measuring principle is based on the measuring principle of stereoscopic particle image velocimetry, as shown in Figure 3, be three tight adjacent tangent planes three components (u, v.w) the solid arrangement of velocity vector field constitutes,

Interpretation position: p _Ij(x _Ijk, y _Ijk, z _Ijk), i=1-N, j=1-M, k=1-3;

Interpretation unit size: Δ x Δ y-interpretation window size (16 * 16,32 * 32,64 * 64 picture dots);

Δ z-sheet optical thickness, Δ z=δ;

Δ x Δ y Δ z cube-interpretation unit's size (16 * 16 * δ, 32 * 32 * δ, 64 * 64 * δ picture dot);

Thus, above system can measure three components (u, v.w) the velocity vector field of three tight adjacent tangent planes simultaneously.The three tangent plane velocity fields of t are constantly: u=u (u, v, w, t _l)

$\left\{\begin{array}{c}\stackrel{\‾}{u}=\stackrel{\‾}{u}(x,y,z_{\mathrm{ijk}},t)\\ \stackrel{\‾}{u}=\stackrel{\‾}{u}(x,y,z_{\mathrm{ijk}}+{\mathrm{\Δz}}_{\mathrm{ijk}},t)\\ \stackrel{\‾}{u}=\stackrel{\‾}{u}(x,y,z_{\mathrm{ijk}}-{\mathrm{\Δz}}_{\mathrm{ijk}},t)\end{array}\right.$

Or to each spatial point (z t) can get following 26 adjacent area velocity vectors (instantaneous velocity vector distribution field, space) as shown in Figure 4 for x, y:

u(x，y，z)， u(x，y，z+Δz)， u(x，y，z-Δz)

$\left\{\begin{array}{c}\stackrel{\‾}{u}(x+\mathrm{\Δx},y,z),\stackrel{\‾}{u}(x-\mathrm{\Δx},y,z)\\ \stackrel{\‾}{u}(x,y+\mathrm{\Δy},z),\stackrel{\‾}{u}(x,y-\mathrm{\Δy},z)\\ \stackrel{\‾}{u}(x+\mathrm{\Δx},y+\mathrm{\Δy},z),\stackrel{\‾}{u}(x+\mathrm{\Δx},y-\mathrm{\Δy},z)\\ \stackrel{\‾}{u}(x-\mathrm{\Δx},y+\mathrm{\Δy},z),\stackrel{\‾}{u}(x-\mathrm{\Δx},y-\mathrm{\Δy},z)\end{array}\right.$

$\left\{\begin{array}{c}\stackrel{\‾}{u}(x+\mathrm{\Δx},y,z+\mathrm{\Δz}),\stackrel{\‾}{u}(x-\mathrm{\Δx},y,z+\mathrm{\Δz})\\ \stackrel{\‾}{u}(x,y+\mathrm{\Δy},z+\mathrm{\Δz}),\stackrel{\‾}{u}(x,y-\mathrm{\Δy},z+\mathrm{\Δz})\\ \stackrel{\‾}{u}(x+\mathrm{\Δx},y+\mathrm{\Δy},z+\mathrm{\Δz}),\stackrel{\‾}{u}(x+\mathrm{\Δx},y-\mathrm{\Δy},z+\mathrm{\Δz})\\ \stackrel{\‾}{u}(x-\mathrm{\Δx},y+\mathrm{\Δy},z+\mathrm{\Δz}),\stackrel{\‾}{u}(x-\mathrm{\Δx},y-\mathrm{\Δy},z+\mathrm{\Δz})\end{array}\right.$

$\left\{\begin{array}{c}\stackrel{\‾}{u}(x+\mathrm{\Δx},y,z-\mathrm{\Δz}),\stackrel{\‾}{u}(x-\mathrm{\Δx},y,z-\mathrm{\Δz})\\ \stackrel{\‾}{u}(x,y+\mathrm{\Δy},z-\mathrm{\Δz}),\stackrel{\‾}{u}(x,y-\mathrm{\Δy},z-\mathrm{\Δz})\\ \stackrel{\‾}{u}(x+\mathrm{\Δx},y+\mathrm{\Δy},z-\mathrm{\Δz}),\stackrel{\‾}{u}(x+\mathrm{\Δx},y-\mathrm{\Δy},z-\mathrm{\Δz})\\ \stackrel{\‾}{u}(x-\mathrm{\Δx},y+\mathrm{\Δy},z-\mathrm{\Δz}),\stackrel{\‾}{u}(x-\mathrm{\Δx},y-\mathrm{\Δy},z-\mathrm{\Δz})\end{array}\right.$

(1+26) individual point, available different difference schemes (are minimumly got 6,18, how desirable 27, Fig. 4) can be got following velocity gradient field (t=t constantly) thus

$\frac{\∂{\stackrel{\‾}{u}}_i}{\∂{\stackrel{\‾}{x}}_j}=\left\{\begin{array}{c}\frac{\∂u}{\∂x},\frac{\∂u}{\∂y},\frac{\∂u}{\∂z}\\ \frac{\∂v}{\∂x},\frac{\∂v}{\∂y},\frac{\∂v}{\∂z}\\ \frac{\∂w}{\∂x},\frac{\∂w}{\∂y},\frac{\∂w}{\∂z}\end{array}\right.$

And can get following vorticity vector field thus, and the normal stress vector field, the shear stress vector field:

$\begin{array}{c}{\mathrm{\ω}}_i(x,t)\\ s_{\mathrm{ij}}(x,t)\end{array}\left\{\begin{array}{c}{\mathrm{\ω}}_x=(\frac{\∂w}{\∂y}-\frac{\∂v}{\∂z}),{\mathrm{\ω}}_y=(\frac{\∂u}{\∂z}-\frac{\∂w}{\∂x}),{\mathrm{\ω}}_z=(\frac{\∂v}{\∂x}-\frac{\∂u}{\∂y})\\ s_{\mathrm{xx}}=\frac{\∂u}{\∂x},s_{\mathrm{yy}}=\frac{\∂v}{\∂y},s_{\mathrm{zz}}=\frac{\∂w}{\∂z}\\ s_{\mathrm{xy}}=\frac{1}{2}(\frac{\∂u}{\∂y}+\frac{\∂v}{\∂x}),s_{\mathrm{yz}}=\frac{1}{2}(\frac{\∂v}{\∂z}+\frac{\∂w}{\∂y}),s_{\mathrm{xy}}=\frac{1}{2}(\frac{\∂w}{\∂x}+\frac{\∂u}{\∂z})\end{array}\right.$

Also can get following vector acceleration field thus:

$\frac{d\stackrel{\‾}{u}}{\mathrm{dt}}=\frac{\∂\stackrel{\‾}{u}}{\∂t}+\frac{\∂\stackrel{\‾}{u}}{\∂x}+\frac{\∂\stackrel{\‾}{u}}{\∂y}+\frac{\∂\stackrel{\‾}{u}}{\∂z}$

In addition, these stereoscopic particle image velocity-measuring systems of three tangent planes (3P-SPIV) adopt the sequential control of related function field measurement (to be different from vorticity, stress vector field measurement sequential chart, shown in Figure 2), as shown in Figure 5, can obtain following crucial related physical quantity vector field: intend entropy vector field Q (x, t) ω _Ii, intend entropy long-pending vector field QP (x, t) ω _is _Ijω _jWith energy absorbing device vector field ε=2vs _Ijs _Ij

Claims (9)

1. a triplanar visual particle image speed measuring system is characterized in that, this system comprises:

Three overlap the pulsed laser groups, are used to export the light beam of different optical wavelengths; Form three adjacent sheet light (LS) by three cover pulsed laser groups;

Be arranged on three cover pulsed laser group light beam output terminals, be positioned at mobile observation test block (F) the stereoscopic frame CCD digital camera of striding of three covers on every side, be used for gathering respectively simultaneously the particle picture of three tangent planes, respectively three sheet light faces are write down the seasonal effect in time series image that particles move, can record the instantaneous velocity vector field of three sheet light faces respectively;

Stride the microprocessor (E) that frame CCD digital camera links to each other with stereoscopic, be used for the view data of record can directly be transmitted and entered internal memory, integrated software comprises the The whole control software systems in this microprocessor, and possess relevant image and data processing function, finish multiple computing, graphic presentation, image is obtained the velocity field data via the calculating such as cross correlation algorithm of conventional SPIV, and try to achieve relevant vorticity vector field, stress vector field by special software.

2. triplanar visual particle image speed measuring system according to claim 1, it is characterized in that, synchronous in order to guarantee light beam pulse and the stereoscopic frame CCD digital camera record of striding that laser array is sent, both guaranteed to write down the instantaneity of three tangent plane particle pictures, guarantee the simultaneity of the velocity field that three tangent planes are measured again, control end in this three covers laser array connects a synchronous chronotron (D), this three covers pulsed laser group is carried out synchro control by the synchronizing relay device, and its delay precision is about 0.5 nanosecond.

3. triplanar visual particle image speed measuring system according to claim 1, it is characterized in that, because adopt different pulsed laser groups, the optical wavelength difference that it sends, further, look a single-pass light filter lens to be set before striding frame CCD digital camera at every stage body, be used to guarantee that the instantaneous of particle picture of obtaining three tangent planes respectively do not disturb mutually.

4. triplanar visual particle image speed measuring system according to claim 3 is characterized in that, the led to optical wavelength scope of this single-pass light filter lens is: λ=± 2nm.

5. triplanar visual particle image speed measuring system according to claim 1 is characterized in that, this three covers laser array comprises: the YAG pulsed laser that a cover adopts for conventional PIV, its wavelength is λ ₀=532nm, and a separate set of is the pulsed fuel laser array, its wavelength is respectively ${\mathrm{\λ}}_1\≅580\mathrm{nm},$ ${\mathrm{\λ}}_2\≅482\mathrm{nm}.$

6. according to claim 1 or 4 described triplanar visual particle image speed measuring systems, it is characterized in that, every suit pulsed laser group comprises two pulsed lasers, and the time-delay of two laser pulse devices is by synchronizing relay device (D) control, and laser pulse repetition frequency is 30HZ; Every cover is stereoscopic strides frame CCD digital camera and comprises also that two stage bodies are looked and stride frame CCD digital camera.

7. according to any described triplanar visual particle image speed measuring system in the claim 1 to 5, it is characterized in that this stereoscopic pixel 1k * 2k that strides frame CCD digital camera, frequency 30Hz, model ES-2093.

8. triplanar visual particle image speed measuring system according to claim 6 is characterized in that, this stereoscopic pixel 1k * 2k that strides frame CCD digital camera, frequency 30Hz, model ES-2093.

9. according to each described triplanar visual particle image speed measuring system in the claim 1 to 5, every cover pulsed laser group includes two pulsed lasers, time-delay between two laser pulse is controlled by synchronizing relay device (D), change time delay and can adapt to the measurement friction speed, the repetition frequency of pulsed laser is 30HZ.

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