scholarly journals Visualization of a Standing Lattice of Scattered Light on Spherical Water Droplets under an Acoustic Field Using Biogenic Microparticles

2021 ◽  
Author(s):  
Masakazu Iwasaka
Keyword(s):  
Acoustic Field ◽  
Optical Measurement ◽  
Scattered Light ◽  
Measurement Techniques ◽  
Droplet Surface ◽  
Cell Manipulation ◽  
Water Droplets ◽  
Reflected Light ◽  
Lattice Width ◽  
Lattice Pattern

Micromanipulation using acoustic sound is a promising technique for drug delivery, cell manipulation, biosensors, and microfluidic devices. Additionally, the visualization of acoustic fields by advanced optical measurement techniques can be combined with this micromanipulation technique. The present study reveals that a lattice pattern of reflected light appears on the surface of water droplets containing microparticles when the droplets are exposed to audible sound in the range of 1900 to 10000 Hz. A piezoelectric membrane providing an audible acoustic field induced a stream of microparticles on which the lattice pattern overlapped, with the appearance of a standing wave. The effects of microparticles, including BaSO4, TiO2, and guanine platelets derived from fish scales, on the formation of the lattice pattern were investigated. These three types of microparticles in water enabled a visualization of the vortex streams and generated a lattice pattern of reflected light. The guanine platelets exhibited the most precise lattice pattern over the droplet surface, with a lattice width of 100 to 200 μm. This phenomenon may provide a new tool for detecting and manipulating micro vortex flows in the aqueous chamber of a microfluidic device combined with an acoustic transducer.

High Intensity Focused Ultrasound (HIFU) Transducer Characterization Using Acoustic Streaming

2007 ◽  
Author(s):  
Prasanna Hariharan ◽  
Ronald A. Robinson ◽  
Matthew R. Myers ◽  
Rupak K. Banerjee
Keyword(s):  
High Intensity ◽  
Focused Ultrasound ◽  
Optical Measurement ◽  
Measurement Techniques ◽  
Acoustic Streaming ◽  
Acoustic Power ◽  
High Intensity Focused Ultrasound ◽  
Medical Ultrasound ◽  
Intensity Field ◽  
Streaming Velocity

A new, non-perturbing optical measurement technique was developed to characterize medical ultrasound fields generated by High Intensity Focused Ultrasound (HIFU) transducers using a phenomenon called ‘acoustic streaming’. The acoustic streaming velocity generated by HIFU transducers was measured experimentally using Digital Particle Image Velocimetry (DPIV). The streaming velocity was then calculated numerically using the finite-element method. An optimization algorithm was developed to back-calculate acoustic power and intensity field by minimizing the difference between experimental and numerical streaming velocities. The intensity field and acoustic power calculated using this approach was validated with standard measurement techniques. Results showed that the inverse method was able to predict acoustic power and intensity fields within 10% of the actual value measured using standard techniques, at the low powers where standard methods can be safely applied. This technique is also potentially useful for evaluating medical ultrasound transducers at the higher power levels used in clinical practice.

scholarly journals Planar droplet sizing: Application to a spray of Jet A1 kerosene

2017 ◽  
Author(s):  
Pierre Doublet ◽  
Christine Lempereur ◽  
Virginel Bodoc ◽  
Mikael Orain ◽  
Pierre Gajan
Keyword(s):  
Light Intensity ◽  
Scattered Light ◽  
Droplet Surface ◽  
Scattered Light Intensity ◽  
Field Of View ◽  
Fluorescence Signal ◽  
Droplet Volume ◽  
Image Processing Algorithm ◽  
Two Phase ◽  
Scattering Angle

Optical techniques are  widely employed for their non-intrusive behavior and are applied to two-phase flowinvestigations. Until now, the most commonly used technique to determine the droplet size is the Phase Doppler Anemogranulometry, although it is time consuming for an overall injector characterization. An imaging technique called Planar Droplet Sizing has been used to offer an alternative and provide a spatially-resolved 2D map of the Sauter Mean Diameter (SMD). The measurement is based on the ratio between laser-induced fluorescence and scattered light intensities which are assumed to be proportional respectively to the droplet volume and droplet surface area. However, previous studies revealed that the dependence of fluorescence intensity on the droplet volume can be altered by the absorption of light in the liquid. The scattered light intensity depends on the scattering angle and intensity variations within the field of view must be avoided.The aim of this study is to make the PDS technique operational for a Jet A-1 kerosene spray. A strong absorption of liquid kerosene appears under UV excitation at 266 nm making the technique unsuitable. Under visible excitation at 532 nm, a fluorescent tracer (Pyrromethene 597) must be added to the kerosene to enhance the fluorescence signal. To prevent scattered light intensity variations within the field of view, an optimal scattering angle close to 115° is required. An image processing algorithm is proposed in order to reduce the effects ofmultiple scattering.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4698

A Comparative Study on Hydraulic Bulge Testing and Analysis Methods

2008 ◽  
Author(s):  
Eren Billur ◽  
Muammer Koc¸
Keyword(s):  
Flow Stress ◽  
Optical Measurement ◽  
Measurement Techniques ◽  
Material Behavior ◽  
Biaxial Stress ◽  
Dome Height ◽  
Bulge Test ◽  
Analysis Methods ◽  
Bulge Testing ◽  
Hydraulic Bulge

Hydraulic bulge testing is a material characterization method used as an alternative to tensile testing with the premise of accurately representing the material behavior to higher strain levels (∼70% as appeared to ∼30% in tensile test) in a biaxial stress mode. However, there are some major assumptions (such as continuous hemispherical bulge shape, thinnest point at apex) in hydraulic bulge analyses that lead to uncertainties in the resulting flow stress curves. In this paper, the effect of these assumptions on the accuracy and reliability of flow stress curves is investigated. The goal of this study is to determine the most accurate method for analyzing the data obtained from the bulge testing when continuous and in-line thickness measurement techniques are not available. Specifically, in this study the stress-strain relationships of two different materials (SS201 and Al5754) are obtained based on hydraulic bulge test data using various analysis methods for bulge radius and thickness predictions (e.g., Hill’s, Chakrabarty’s, Panknin’s theories, etc.). The flow stress curves are calculated using pressure and dome height measurements and compared to the actual 3-D strain measurement from a stereo optical and non-contact measurement system ARAMIS. In addition, the flow stress curves obtained from stepwise experiments are compared with the ones from above methods. Our findings indicate that Enikeev’s approach for thickness prediction and Panknin’s approach for bulge radius calculation result in the best agreement with both stepwise experiment results and 3D optical measurement results.

Application of Optical Scanning and Photogrammetry for Evaluation of Geometrical Tolerance Values

2013 ◽  
Author(s):  
Andrzej Gessner ◽  
Roman Staniek ◽  
Jakub Michałek
Keyword(s):  
Cross Sections ◽  
Optical Measurement ◽  
Measurement Techniques ◽  
Reference Method ◽  
Test Stand ◽  
Optical Methods ◽  
Test Surface ◽  
Test Plate ◽  
Optical Scanning ◽  
Measurement Area

The hereby presented research, funded by the restricted grant LIDER, NCBiR, deals, in part, with the identification of the full implementation potential of the proposed optical measurement techniques in determination of surface flatness parameters, and their comparative assessment. The test methods included the photogrammetric measurement technique (TRITOP, GOM) and the structural light scanning approach (scanner ATOS, GOM), while the CMM measurement (DEA Global Image Clima) was the reference method. The accordingly designed and assembled experimental test stand comprised 2 steel plates. The test surfaces of the plates were appropriately ground; subsequently, the entire test stand was blackened to ascertain efficient optical scanning. Furthermore, the plates were connected by means of 8 screws, thus introducing considerable distortion. A measurement area of 140 × 240 mm was defined on the plate test surface, as determined by CMM, denoting 15 measurement paths of 240 mm in length, distributed every 10 mm, and characterized by measurement point densities of 1, 5, and 20 pt/mm. The reference CMM measurements were conducted on 3 consecutive days at different times (22 measurements in total) to exclude any possible surface modifications. Subsequently, optical scanning was applied and the measurement points lying at the cross-sections of the CMM measurement paths were isolated from the obtained polygon mesh. To further apply the photogrammetric method, the test surface was labeled with markers distributed every 10 mm and coinciding with the CMM measurement paths. Comparative analysis of the flatness parameter for the selected CMM measurement and the measurement values obtained by means of the tested optical methods included: - the entire measurement area, - the sections comprising 80, 60, 50, 45, 40, 30, 20, 15, and 10 % of the entire measurement area, decreasing centrically, - the measurement sub-areas of 30 × 50 mm allotted in the corners and in the center of the test plate. The photogrammetric error of the tested parameter was established at 1.26–19.82 %, depending on the size of the measurement area. The corresponding error value, as determined by the structural light scanning technique, amounted to 0.03–4.31 %.

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