CN214751259U - Multi-beam PIV lighting system - Google Patents
Multi-beam PIV lighting system Download PDFInfo
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- CN214751259U CN214751259U CN202120812001.1U CN202120812001U CN214751259U CN 214751259 U CN214751259 U CN 214751259U CN 202120812001 U CN202120812001 U CN 202120812001U CN 214751259 U CN214751259 U CN 214751259U
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Abstract
The utility model relates to a many beam PIV lighting system, the main beam of laser 5-0 that possesses the double exposure characteristic is from the emergence in the Nd: YAG dipulse laser 7, adjustment beam splitting unit adjustment seat 1 makes main beam of laser 5-0 through fix on beam splitting unit adjustment seat 1 depolarization beam splitter prism 2 after, the left path outgoing beam 5-1 that is divided into shines perpendicularly on left path piece light modulation device 6-1, the right path outgoing beam 5-2 shines on the single beam reflector 4 that is fixed in on reflector modulation seat 3, adjustment reflector modulation seat 3 makes right path outgoing beam 5-2 after fixing the reflection of single beam reflector 4 on reflector modulation seat 3, shine perpendicularly on right path piece light modulation device 6-2.
Description
Technical Field
The utility model relates to a many light beams PIV lighting system belongs to aerospace experiment technical field.
Background
In the PIV technology, the illumination of a flow field is of great importance, generally, high-energy pulse laser is modulated into a sheet light source to irradiate tracing particles in an experimental area, meanwhile, a camera is used for recording scattering moving images of the particles, and the velocity distribution of the flow field at the position is calculated in an inversion mode through a corresponding iterative reconstruction algorithm. Although a multi-camera three-dimensional velocity field measurement technology is developed in recent years, the technology is limited to basic research, has low measurement precision and high optical complexity, and cannot be widely popularized and applied in aircraft flow field verification application, and the two-dimensional plane PIV technology is still the mainstream technology for velocity field measurement in a period of time in the future.
The technical requirements of new generation aircrafts and refined complex flow field measurement and diagnosis are continuously increased, if the two sides of the model are shielded, the flow field information of the other side cannot be obtained on one side, so that how to obtain the speed information of a plurality of sections as much as possible in a primary wind tunnel test in a large market range is a problem encountered in the practical measurement and development of engineering. YAG resonant cavity, through accurate beam combination and time sequence control, two beams of laser can irradiate at the same position according to the preset time interval, but only can shoot the velocity field information of a section, if supplementary shooting is carried out through a plurality of wind tunnel tests, the measurement cost is improved, and the flow correlation of velocity fields in different measurement environments separated by shielding surfaces cannot be obtained.
SUMMERY OF THE UTILITY MODEL
The utility model provides a technical problem do: the defects of the prior art are overcome, the multi-beam PIV illumination system is provided, the limitation problem that the existing single-station double-exposure laser can only irradiate a single flow field section is solved, and synchronous shooting of more than 2 flow field sections is realized.
The utility model provides a technical scheme do: a multi-beam PIV illumination system, comprising: the device comprises a laser generating unit, a main beam splitting unit, a beam direction adjusting unit, a sheet light modulating unit, an image shooting unit and a simulation shielding surface (8), wherein the simulation shielding surface (8) is used for separating an environment to be measured;
a sheet light modulation unit comprising: a left-path light modulation device (6-1) and a right-path light modulation device (6-2);
an image capturing unit comprising: a left-path shooting cross-frame camera (9-1) and a right-path shooting cross-frame camera (9-2);
the laser generating unit emits a main laser beam (5-0) to the main beam splitting unit;
the main beam splitting unit receives a main laser beam (5-0) and splits the main laser beam (5-0) into two beams, wherein one beam is used as a left emergent beam (5-1), and the other beam is used as a right emergent beam (5-2);
the left emergent light beam (5-1) vertically irradiates on the left path light modulation device (6-1); the left path of emergent light beam (5-1) is modulated by a left path of sheet light modulation device (6-1) to form sheet light (5-1)' modulated by the left path of emergent light beam, the sheet light irradiates one side of a simulated shielding surface (8) in a flow field (10), and a left path shooting frame-crossing camera (9-1) shoots;
the right outgoing beam (5-2) irradiates on the beam direction adjusting unit, so that the right outgoing beam (5-2) is reflected by the beam direction adjusting unit to form a reflected beam 5-2 'of the right outgoing beam, and the reflected beam 5-2' of the right outgoing beam vertically irradiates on the right path light modulation device (6-2), and is modulated by the right path light modulation device (6-2) to become a right outgoing beam modulated sheet (5-2 ");
the left path of emergent light beam (5-1) is modulated by a left path of light modulation device (6-1) to form left path of emergent light beam modulated light beam (5-1)', the left path of emergent light beam irradiates one side, namely the left side, of a simulated shielding surface (8) in a flow field (10), and a left path shooting frame-crossing camera (9-1) shoots;
the right path of emergent light beam (5-2) is reflected by the light beam direction adjusting unit and then becomes a reflected light beam 5-2 'of the right path of emergent light beam, and then becomes a sheet light 5-2' modulated by the right path of emergent light beam, the sheet light irradiates the other side, namely the right side, of the simulated shielding surface (8) in the flow field (10), and the right path of emergent light beam is shot by the right path of shooting frame-crossing camera (9-2).
Preferably, the laser generating unit is an Nd: YAG double pulse laser (7).
Preferably, the outgoing laser main beam (5-0) is a laser main beam having a double exposure characteristic.
Preferably, the main beam splitting unit includes: a light splitting unit adjusting seat (1) and a depolarization light splitting prism (2);
the depolarization beam splitter prism (2) is arranged on the beam splitting unit adjusting seat (1); the light splitting unit adjusting seat (1) can adjust the position of the depolarization light splitting prism (2).
Preferably, after a main laser beam (5-0) passes through a depolarizing beam splitter prism (2) arranged on the beam splitter unit adjusting seat (1) by adjusting the beam splitter unit adjusting seat (1), a left outgoing beam (5-1) is divided to vertically irradiate on a left path light modulation device (6-1), and a right outgoing beam (5-2) irradiates on a single beam reflector 4 arranged on a reflector modulation seat (3).
Preferably, the beam direction adjusting unit includes: a reflector modulation base (3) and a single beam reflector (4);
the single-beam reflector (4) is arranged on the reflector modulation seat (3); the reflector modulation base (3) can adjust the position of the single-beam reflector (4).
Preferably, the right outgoing light beam (5-2) is reflected by a single light beam reflector (4) arranged on the reflector modulation seat (3) through adjusting the reflector modulation seat (3) and then vertically irradiates the right path light modulation device (6-2).
Preferably, the left path light modulation device (6-1) modulates the left path outgoing light beam (5-1) to become the left path outgoing light beam modulated sheet light (5-1'), specifically: the left outgoing light beam (5-1) is modulated into a fan-shaped sheet light source with a certain thickness, namely a sheet light (5-1') modulated by the outgoing light beam after passing through a plano-convex spherical lens and a plano-concave cylindrical lens in the left sheet light modulation device (6-1).
Preferably, the right path sheet light modulation device 6-2 modulates the reflected light beam (5-2') of the right path outgoing light beam to become the sheet light (5-2 ") modulated by the right path outgoing light beam, specifically: the reflected light beam (5-2') of the left path of emergent light beam passes through a plano-convex spherical lens and a plano-concave cylindrical lens in the left path of light modulation device (6-2) and is modulated into a fan-shaped sheet light source with certain thickness, namely, a sheet light (5-2') modulated by the right path of emergent light beam.
Compared with the prior art, the utility model the advantage lie in:
(1) the utility model discloses can realize that large-scale low-speed wind-tunnel and inferior stride supersonic wind-tunnel interior model wind flow field 2 and above the measurement in cross-section speed field.
(2) The utility model discloses a high transmissivity narrowband depolarization beam split design guarantees polarization uniformity and the homogeneity of beam split energy of appointed wave band laser beam at the beam split in-process to reduce the energy loss of laser on the beam split device.
(3) The utility model discloses a secondary reflection of light path in optical element is eliminated to the reflecting element of front surface coating film, combines the depolarization beam split characteristic and the modular optical element integrated design in aforementioned advantage (2), can expand downwards and carry out multistage beam splitting.
Drawings
FIG. 1 is a schematic view of the layout and testing of the multi-beam splitting optical path of the present invention;
fig. 2 is a schematic diagram of the depolarizing beam splitter prism semi-transmitting and semi-reflecting;
in the figure, 1 is a light splitting unit adjusting seat, 2 is a depolarizing light splitting prism, 3 is a reflector adjusting seat, 4 is a single-beam reflector, 5-0 is a main laser beam, 5-1 is a left outgoing beam, 5-1' is a sheet modulated by the left outgoing beam, 5-2 is a right outgoing beam, 5-2' is a reflected beam of the right outgoing beam, 5-2' is a sheet modulated by the right beam, 6-1 is a left sheet light modulating device, 6-2 is a left sheet light modulating device, 7 is an Nd: YAG double-pulse laser, 8 is a simulated blocking surface, 9-1 is a left shooting frame crossing camera, 9-2 is a right shooting frame crossing camera, and 10 is a flow field.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The utility model discloses a many beam PIV lighting system is used for the flow field illumination of Particle Image Velocimetry (PIV) technique.
The PIV is a measuring technology for measuring an instantaneous velocity field in fluid without interference, the measurement of a flow velocity field is one of key problems of fluid mechanics development and practical engineering application, and the PIV not only is directly related to the appearance design and optimization of streamlined power machines such as aircrafts, automobiles, high-speed rails and the like, but also restricts the development of the fluid mechanics. Especially in the development process of an aircraft, quantitative measurement of the flow field velocity is an indispensable content. Accurate velocity measurements are of great importance for understanding the flow mechanism and for analyzing the aerodynamic properties of the aircraft and its components.
At present, wind tunnel tests have more and more requirements on spatial velocity field measurement by using a PIV technology, such as velocity field measurement tests of turbulent flow fields of aircraft models in large low-speed wind tunnels and sub-span supersonic wind tunnels. Because the existence that the model sheltered from, like wing, bellying etc. can separate the flow field, need measure the cross section velocity field in the different flow field regions that have the condition of sheltering from, the utility model discloses a design, utilize single two exposure laser to realize the synchronous illumination of 2 flow field cross sections and above, input two slice light source illuminations through optical window to the flow field and have the different flow field regions that shelter from the condition to adopt the cross-frame camera to shoot the flow field that is shone respectively, acquire corresponding flow field cross section velocity field. The utility model discloses not only can be used for acquireing abundant mobile information in the single wind tunnel test, reduce the measurement cost, more satisfied by the mobile correlation demand of speed field in the different measurement environment of sheltering from face divided.
The utility model discloses a realize through following scheme.
The preferred scheme is as follows: the laser generating unit comprises an Nd-YAG double-pulse laser (7), as shown in figure 1, the specific requirements are as follows: preferably, a double-cavity pulse laser based on Nd-YAG resonant crystal is adopted, the wavelength lambda of the emergent laser main beam (5-0) is 532nm, and the pulse repetition frequency f1Not less than 10 Hz. Preferred Single Cavity Exposure energy E0A double-cavity pulse laser with the pulse width w not more than 15ns and the diameter d not less than 8mm and not more than 300mJ is used as a laser generating unitlLess than or equal to 10mm, the Nd-YAG double-pulse laser (7) strictly combines and outputs through an internal beam combination light path, and the time interval delta t of the double-pulse laser1The control error is less than 1ns through the accurate control of a high-precision time schedule controller.
The preferred scheme is as follows: the light splitting unit comprises a light splitting unit adjusting seat (1) and a depolarizing light splitting prism (2), and is used for splitting a main laser beam (5-0) into a left outgoing beam (5-1) and a right outgoing beam (5-2) as shown in fig. 1. The concrete requirements are as follows: the light splitting unit adjusting seat (1) preferably has an optical support with 3-degree-of-freedom angle adjusting function and 2-degree-of-freedom displacement adjusting function, the unidirectional angle adjusting error is less than 3', the unidirectional displacement adjusting error is less than 0.02mm, and the light splitting unit adjusting seat has a clamping function on the depolarization light splitting prism; the depolarization beam splitter prism (2) has depolarization beam splitting characteristics, two prisms are spliced into the beam splitter prism, as shown in figure 2, K9 or quartz material is preferred, the surface type of the depolarization beam splitter prism is lambda/4, and the clear aperture dx≥2dlThe deflection error of the emergent light beam is less than 3', the temperature application range is-30 to +70 ℃, the reflection surface is plated with a depolarization beam splitting film, and the four outer surfaces are plated with antireflection films.
The preferred scheme is as follows: the beam direction adjusting unit comprises a reflector adjusting base (3) and a single-beam reflector (4), as shown in fig. 1, and is used for adjusting the right outgoing beam (5-2) into a reflected beam (5-2') of the right outgoing beam. The concrete requirements are as follows: the reflector adjusting seat (3) preferably has an optical bracket with 3-degree-of-freedom angle adjusting function and 2-degree-of-freedom displacement adjusting function, the unidirectional angle adjusting error is less than 3', the unidirectional displacement adjusting error is less than 0.02mm, and the reflector has a clamping function on a single beam reflector; the single-beam reflector (4) is preferably K9 or material, the front surface of the reflector is reflective and coated with 532nm laser reflection increasing film, and the clear aperture df≥2dlThe temperature is in the range of-30 to +70 ℃.
The preferred scheme is as follows: the sheet light modulation unit comprises a left sheet light modulation device (6-1) and a left sheet light modulation device (6-2), and is used for emitting a left light beam (5) as shown in figure 1-1) and the reflected beam (5-2') of the right outgoing beam are modulated as a sheet (5-1') modulated for the left outgoing beam and a sheet (5-2 ") modulated for the right outgoing beam, respectively. The specific requirement is that a plane-convex spherical lens and a plane-concave cylindrical lens are combined and pass through an aperture dp≥2dlPreferably K9 or quartz material, and is plated with 532nm laser antireflection film at the temperature of-30 to +70 ℃.
The image shooting unit mainly comprises a left-path shooting cross-frame camera (9-1) and a right-path shooting cross-frame camera (9-2), and as shown in figure 1, the image shooting of the illuminated tracer particles in the areas on two sides of the flow field (10) separated by the simulated shielding surface (8) is realized. The specific requirement is that a cross-frame digital camera is adopted, and the set cross-frame shooting time interval delta t2＝Δt1Repeated shooting frequency f of frame-crossing digital camera2＝f1Preferably, the image resolution is not lower than 1k multiplied by 1k, and the image gray scale bit depth is not lower than 12 bit.
The utility model discloses realize the preferred scheme that spectral energy loss further reduces: let the spectral transmittance of the depolarization beam splitter prism (2) be k1The reflectivity of the single beam mirror (4) is k2The multi-beam PIV lighting system obtains 2 in total through n-level lightnThe energy requirement of each emergent beam is EnThen, the spectral transmittance k1And reflectivity k2Should satisfy (k)1 k2)n≥1.05*En/E0Because the maximum single exposure energy of the existing laser is limited, the number n of the spectral stages is less than or equal to 3. Satisfying the optimal constraint condition can realize further reduction of the light splitting energy loss.
The preferred scheme is as follows: the utility model discloses a many light beams PIV lighting system establishes the back, tests to beam split homogeneity and beam split energy efficiency. The uniformity of the split light beam is tested by using 532nm laser sensitive paper, a left path light modulation device (6-1) and a left path light modulation device (6-2) are removed, the system is opened, aiming at a left path emergent light beam (5-1) and a reflected light beam (5-2') of a right path emergent light beam, the reflected light beams are respectively irradiated on the sensitive paper at the distance of 2m to obtain laser spots, and after the system is closed, a digital camera can be used for shooting the sensitive paper to obtain the laser spotsAnd detecting the roundness and the uniformity of the laser spots on the paper. The utility model discloses well facula circularity shows, the actual measurement through the difference between maximum radius and minimum radius the utility model discloses a many beam PIV lighting system circularity is superior to 0.1 mm. The spectral energy efficiency R is detected by an energy meter, and in the case of only 1-level light path, the energy meter is firstly used for detecting the energy of the main laser beam (5-0) and is recorded as E0Then the energy of the left outgoing beam (5-1) and the energy of the reflected beam (5-2') of the right outgoing beam are detected, denoted as E1lAnd E1rThe energy efficiency of the left outgoing beam is Rl＝E1l/E0100%, energy efficiency of right outgoing beam is Rl＝E1r/E0100%, ideally Rl＝Rl50%, but attenuation must actually occur through beam splitting and reflection, with the preferred measured E for the post-system1l≈43.4％，E1r≈39.8％。
Claims (9)
1. A multi-beam PIV illumination system, comprising: the device comprises a laser generating unit, a main beam splitting unit, a beam direction adjusting unit, a sheet light modulating unit, an image shooting unit and a simulation shielding surface (8), wherein the simulation shielding surface (8) is used for separating an environment to be measured;
a sheet light modulation unit comprising: a left-path light modulation device (6-1) and a right-path light modulation device (6-2);
an image capturing unit comprising: a left-path shooting cross-frame camera (9-1) and a right-path shooting cross-frame camera (9-2);
the laser generating unit emits a main laser beam (5-0) to the main beam splitting unit;
the main beam splitting unit receives a main laser beam (5-0) and splits the main laser beam (5-0) into two beams, wherein one beam is used as a left emergent beam (5-1), and the other beam is used as a right emergent beam (5-2);
the left emergent light beam (5-1) vertically irradiates on the left path light modulation device (6-1); the left path of emergent light beam (5-1) is modulated by a left path of sheet light modulation device (6-1) to form sheet light (5-1') modulated by the left path of emergent light beam, the sheet light irradiates one side of a simulated shielding surface (8) in a flow field (10), and a left path shooting frame-crossing camera (9-1) shoots;
the right outgoing beam (5-2) irradiates on the beam direction adjusting unit, so that the right outgoing beam (5-2) is reflected by the beam direction adjusting unit to form a reflected beam (5-2') of the right outgoing beam, the reflected beam (5-2') vertically irradiates on the right path of light modulating device (6-2), and the reflected beam (5-2') of the right outgoing beam is modulated by the right path of light modulating device (6-2) and then becomes a right path of outgoing beam modulated sheet (5-2 ");
the left path of emergent light beam (5-1) is modulated by a left path of sheet light modulation device (6-1) to form sheet light (5-1') modulated by the left path of emergent light beam, the sheet light irradiates one side, namely the left side, of a simulated shielding surface (8) in a flow field (10), and a left path shooting frame-crossing camera (9-1) shoots;
the right path of emergent light beam (5-2) is reflected by the light beam direction adjusting unit and then becomes a reflected light beam (5-2') of the right path of emergent light beam, and then becomes a sheet light (5-2') modulated by the right path of emergent light beam, the sheet light irradiates the other side, namely the right side, of the simulated shielding surface (8) in the flow field (10), and the right path of shooting is carried out by the right path of shooting frame-crossing camera (9-2).
2. A multi-beam PIV illumination system as recited in claim 1, wherein: the laser generating unit is an Nd-YAG double-pulse laser (7).
3. A multi-beam PIV illumination system as recited in claim 1, wherein: the outgoing laser main beam (5-0) is a laser main beam having a double exposure characteristic.
4. A multi-beam PIV illumination system as recited in claim 1, wherein: a main beam splitting unit comprising: a light splitting unit adjusting seat (1) and a depolarization light splitting prism (2);
the depolarization beam splitter prism (2) is arranged on the beam splitting unit adjusting seat (1); the light splitting unit adjusting seat (1) can adjust the position of the depolarization light splitting prism (2).
5. The multi-beam PIV illumination system of claim 4, wherein: by adjusting the light splitting unit adjusting seat (1), after a main laser beam (5-0) passes through a depolarizing light splitting prism (2) arranged on the light splitting unit adjusting seat (1), a left outgoing light beam (5-1) is divided to vertically irradiate on a left path light modulation device (6-1), and a right outgoing light beam (5-2) irradiates on a single-beam reflector (4) arranged on a reflector modulation seat (3).
6. A multi-beam PIV illumination system as recited in claim 1, wherein: a beam direction adjustment unit comprising: a reflector modulation base (3) and a single beam reflector (4);
the single-beam reflector (4) is arranged on the reflector modulation seat (3); the reflector modulation base (3) can adjust the position of the single-beam reflector (4).
7. The multi-beam PIV illumination system of claim 6, wherein: by adjusting the reflector modulation seat (3), the right path emergent light beam (5-2) is reflected by a single light beam reflector (4) arranged on the reflector modulation seat (3) and then vertically irradiates on the right path light modulation device (6-2).
8. A multi-beam PIV illumination system as recited in claim 1, wherein: the left path light modulation device (6-1) modulates the left path outgoing light beam (5-1) to become a left path outgoing light beam modulated sheet light (5-1'), which specifically comprises the following steps: the left outgoing light beam (5-1) is modulated into a fan-shaped sheet light source with a certain thickness, namely a sheet light (5-1') modulated by the outgoing light beam after passing through a plano-convex spherical lens and a plano-concave cylindrical lens in the left sheet light modulation device (6-1).
9. A multi-beam PIV illumination system as recited in claim 1, wherein: the right path light modulation device (6-2) modulates the reflected light beam (5-2') of the right path emergent light beam to become the right path emergent light beam modulated light sheet (5-2 "), and the method specifically comprises the following steps: the reflected light beam (5-2') of the right path emergent light beam passes through a plano-convex spherical lens and a plano-concave cylindrical lens in the right path light modulation device (6-2) and is modulated into a fan-shaped sheet light source with a certain thickness, namely, a sheet light (5-2') modulated by the right path emergent light beam.
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| CN202120812001.1U CN214751259U (en) | 2021-04-20 | 2021-04-20 | Multi-beam PIV lighting system |
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