The study developed a triple-exposure color particle image velocimetry(TE-CPIV) technique associated with pressure reconstruction, and validated its feasibility. A light source with the three primary colors of red, gr...The study developed a triple-exposure color particle image velocimetry(TE-CPIV) technique associated with pressure reconstruction, and validated its feasibility. A light source with the three primary colors of red, green, and blue(R, G, and B) is produced in a time sequence by a liquid crystal display(LCD) projector. Particle images at three different instants under the color illuminations are captured in one snapshot using a color digital single-lens reflex(SLR) camera with a complementary metal-oxide semiconductor(CMOS) sensor. A contamination correction algorithm based on a specific calibration is performed on the different color layers(R layer, G layer, and B layer) of the raw color image to reduce the contaminated intensity of each color illumination on the other two color layers. The corrected intensity generates three new color layers, from which a standard cross-correlation process in the classical PIV method is used to obtain two velocity fields. Eventually, an instantaneous pressure field is reconstructed from the two velocity fields. The feasibility of TE-CPIV was tested by two experiments with a solid body rotation flow and a cylinder wake flow. The results show acceptable accuracy and robustness of the new technique. The idea of the TE-CPIV is believed to provide a simple and effective way of estimating a pressure field with low cost and high convenience.展开更多
This study proposes a three-dimensional (3D) particle image velocimetry (PIV) method using W- shaped light sheet and color PIV with a digital SLR camera. The uncertainty of the velocity measurement was also studied an...This study proposes a three-dimensional (3D) particle image velocimetry (PIV) method using W- shaped light sheet and color PIV with a digital SLR camera. The uncertainty of the velocity measurement was also studied and it was acceptable. The spatial resolution of the z-direction has much room for improvement by increasing the number of cameras. When applied to the velocity distribution measurement of a thermal vertical buoyant plume, the proposed 3D PIV method is found to be very effective for studying thermal structures and well suited for measuring the airflow velocity field.展开更多
A novel single color camera trichromatic mask 3D-PIV technique suitable for measurement of complex flow fields in confined spaces is presented in this paper.By using a trichromatic mask to modulate the imaging optical...A novel single color camera trichromatic mask 3D-PIV technique suitable for measurement of complex flow fields in confined spaces is presented in this paper.By using a trichromatic mask to modulate the imaging optical path of a color camera,the RGB(Red,Green,and Blue)channels of the photosensitive chip were used to record full-frame full-resolution images of tracer particles from three viewing angles.The MLOS-SMART particle reconstruction algorithm was used to obtain three-dimensional particle distribution matrix from particle trichromatic mask images.The impact of parameters such as the inter-hole spacing and hole diameter of the trichromatic mask on the quality of particle reconstruction was analyzed.Through numerical simulation experiments on artificially synthesized three-dimensional flow fields of Gaussian vortex rings,the practicality of this technique in measuring three-dimensional transient velocity fields and the accuracy of velocity measurements were examined.The accuracy and feasibility of the technique are illustrated based on experimental measurements of a zero-net-mass-flux jet.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11472030,11327202&11490552)the Fundamental Research Funds for the Central Universities(Grant No.YWF-16-JCTD-A-05)
文摘The study developed a triple-exposure color particle image velocimetry(TE-CPIV) technique associated with pressure reconstruction, and validated its feasibility. A light source with the three primary colors of red, green, and blue(R, G, and B) is produced in a time sequence by a liquid crystal display(LCD) projector. Particle images at three different instants under the color illuminations are captured in one snapshot using a color digital single-lens reflex(SLR) camera with a complementary metal-oxide semiconductor(CMOS) sensor. A contamination correction algorithm based on a specific calibration is performed on the different color layers(R layer, G layer, and B layer) of the raw color image to reduce the contaminated intensity of each color illumination on the other two color layers. The corrected intensity generates three new color layers, from which a standard cross-correlation process in the classical PIV method is used to obtain two velocity fields. Eventually, an instantaneous pressure field is reconstructed from the two velocity fields. The feasibility of TE-CPIV was tested by two experiments with a solid body rotation flow and a cylinder wake flow. The results show acceptable accuracy and robustness of the new technique. The idea of the TE-CPIV is believed to provide a simple and effective way of estimating a pressure field with low cost and high convenience.
文摘This study proposes a three-dimensional (3D) particle image velocimetry (PIV) method using W- shaped light sheet and color PIV with a digital SLR camera. The uncertainty of the velocity measurement was also studied and it was acceptable. The spatial resolution of the z-direction has much room for improvement by increasing the number of cameras. When applied to the velocity distribution measurement of a thermal vertical buoyant plume, the proposed 3D PIV method is found to be very effective for studying thermal structures and well suited for measuring the airflow velocity field.
基金co-supported by the National Natural Science Foundation of China(Nos.12102284,12172242,12332017)the Shanxi Province Science Foundation for Youths,China(No.20210302124262)the Chunhui Project Foundation of the Education Department of China(No.202200257)。
文摘A novel single color camera trichromatic mask 3D-PIV technique suitable for measurement of complex flow fields in confined spaces is presented in this paper.By using a trichromatic mask to modulate the imaging optical path of a color camera,the RGB(Red,Green,and Blue)channels of the photosensitive chip were used to record full-frame full-resolution images of tracer particles from three viewing angles.The MLOS-SMART particle reconstruction algorithm was used to obtain three-dimensional particle distribution matrix from particle trichromatic mask images.The impact of parameters such as the inter-hole spacing and hole diameter of the trichromatic mask on the quality of particle reconstruction was analyzed.Through numerical simulation experiments on artificially synthesized three-dimensional flow fields of Gaussian vortex rings,the practicality of this technique in measuring three-dimensional transient velocity fields and the accuracy of velocity measurements were examined.The accuracy and feasibility of the technique are illustrated based on experimental measurements of a zero-net-mass-flux jet.
