Single camera full field Doppler speed measuring device
A Doppler velocity measurement and single-camera technology, which is applied in measuring devices, fluid velocity measurement, velocity/acceleration/impact measurement, etc., can solve problems such as unsatisfactory results and expensive equipment cost, and reduce equipment cost and simplify velocity measurement The effect of the device
Inactive Publication Date: 2009-11-11
CHINA JILIANG UNIV
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Problems solved by technology
In order to eliminate the influence of laser frequency and intensity changes on the measurement results, a reference signal is required for correction. Therefore, two cameras are required for each velocity component in DGV technology, namely, a signal camera and a reference camera, resulting in expensive equipment and Inevitable optical path alignment error
To this end, researchers have proposed a variety of improvement methods, such as dual-frequency lasers, lens partitions, etc., but the effects of these methods are not very satisfactory
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[0029] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0030] The basic method of the present invention to solve its technical problem is to use frequency modulated laser instead of constant frequency laser (during measurement) in conventional DGV, assuming its frequency
[0031] f L (t) = f c + f h cos(2πf m t)
[0032] Among them, f c is the laser center frequency, f h is the frequency modulation amplitude, f m is the modulation frequency.
[0033] Due to the frequency change-light intensity change conversion effect of the molecular filter, after passing through the molecular filter, the camera (or probe) detects a light intensity modulation signal (such as image 3 shown). Since the transmittance curve of the molecular filter is nonlinear, the light intensity signal contains various harmonics. Such as Figure 4 As shown, the typical light intensity modulation signal and its energy spectrum are...
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The invention discloses a single camera full field Doppler speed measuring device. The modulation laser light emitted by an Nd:YAG laser is split by a light splitter; one path forms a surface light illuminating flow field test zone through a column lens and a first spherical lens; the other path is connected with a control computer through a plane mirror, a first iodine filter, a second spherical lens, a photodiode and a computer interface; the three paths of control signals of the computer interface are respectively connected with the Nd:YAG laser through a frequency controller, a temperature controller and a synchronous controller; and the scattered light in the flow field test zone is connected to the control computer through a lens, a second iodine filter and a CCD camera. Compared with the conventional DGV speed measuring device, the single camera full field Doppler speed measuring device only adopts one CCD camera, thus simplifying the speed measuring device and reducing the equipment cost. Compared with the PIV speed measuring device, the single camera full field Doppler speed measuring device can meet the requirements of full field speed measurement of large-scale flow field. Aiming at large-scale flow field, the single camera full field Doppler speed measuring device has measurement accuracy higher than that of the conventional DGV speed measuring device and the PIV speed measuring device.
Description
technical field [0001] The invention relates to a flow velocity measurement device, in particular to a single-camera full-field Doppler velocity measurement device. Background technique [0002] With the development of technologies such as lasers, computers and sensors, new technologies and instruments for flow field measurement are constantly being created, such as laser Doppler anemometer (LDA), particle imaging velocimetry (PIV), planar laser induced Fluorescent technology (PLIF) and so on are widely used. [0003] However, there are still some flow fields that do not have good means for non-contact measurement or there are large errors in the measurement, for example, high Mach number and ultra-high Mach number flow field measurement, large-scale wind tunnel flow field real-time measurement, combustion field with many Parameter real-time measurement, etc. For the measurement device based on PIV technology, due to the high requirements on the scattered light of the part...
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Inventor 赵晓东张洪军彭海波
Owner CHINA JILIANG UNIV