Density-Based Techniques

Merzkirch, W.; Egami, Yasuhiro

doi:10.1007/978-3-540-30299-5_6

Cited by 6 publications

(6 citation statements)

References 23 publications

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“…The distortion is caused by the bending of the light rays from the straight line propagation due to inhomogeneities in the medium, and it is described by the functional dependence of the refractive index on space, n(r) (Hecht 2002). One can consider BOS as an improvement and/or simplification of defocused grid schlieren (Vasil'ev 1971), white light speckle photography (Giglio et al 1980), moiré deflectometry (Merzkirch 2007), and similar techniques. A large group of researchers refer to BOS as synthetic schlieren, with the main difference between the two being that BOS is more general in terms of the background, while synthetic schlieren employs an optimized synthetically generated pattern as a background (Dalziel et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Measurement sensitivity and resolution for background oriented schlieren during image recording

Gojani

Kamishi

Obayashi

2013

J Vis

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Background oriented schlieren (BOS) visualization technique is examined by means of optical geometry. Two most important results are the calculation of the sensitivity and spatial resolution of a BOS system, which allows for the determination of the experiment design space. A set of relations that characterize the performance of a BOS measurement is given, with emphasis on the design of background pattern and spatial placement of optical components.

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Section: Introductionmentioning

confidence: 99%

Measurement sensitivity and resolution for background oriented schlieren during image recording

Gojani

Kamishi

Obayashi

2013

J Vis

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“…The schlieren work principle is based on the flow visualization of the light refraction caused by local density gradients in the flow being a very suitable tool for the study of flow non-homogeneities, enabling the visualization of physical phenomena, as for example, shock waves, expansion waves and shock wave boundary layer interactions. More details about this technique can be found in Merzkirch [14].…”

Section: Description Of the Experimentsmentioning

confidence: 99%

Analysis of the flow patterns on the fore-body section of a sounding vehicle in the transonic regime

Avelar

Basso

Filho

et al. 2018

J Braz. Soc. Mech. Sci. Eng.

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The present study has the purpose of presenting a numerical and experimental analysis of the flow patterns on the fore-body section of a sounding rocket model in the transonic regime. The measurements were carried out in the Pilot Transonic Wind Tunnel, known as TTP, at the Instituto de Aeronáutica e Espaço (IAE), in São José dos Campos, Brazil, for Mach numbers ranging from 0.6 to 1.06 and zero angle of attack. The experimental techniques of pressure taps, pressure-sensitive paint (PSP) and schlieren visualization method were performed on a 1:34 scaled model of a sounding rocket. Complex phenomena as shock waves, boundary layer detachment, and expansion waves were clearly identified from the PSP pressure field and from the schlieren images. Good agreements between the PSP, pressure taps and numerical simulation results were observed, except around the tip of the model because of the curvature and also in details that were not captured by the camera.

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“…A knife edge is placed close to the focal point to block those deflected light rays, which pass through the schlieren and deviate from the focal point. This key manipulation increases the sensitivity to refractive index gradient, and distinguishes the schlieren method from direct shadowgraph method. ,, One of the research areasusually utilizing schlieren shadowgraphy to obtain information, is visualization of the combustion process in a diesel engine. To investigate the combustion efficiency of the engine, a chamber with high temperature and pressure is usually utilized to simulate the engine conditions. − Schlieren imaging has also been adopted in the field of analytical chemistry research to visualize processes in the ionization techniques such as desorption electrospray ionization, direct analysis in real time, flowing atmospheric pressure afterglow, , and inductively coupled plasma .…”

Section: Introductionmentioning

confidence: 99%

“…The deflected light rays gradually deviate from the undeflected beams as they travel in the optical system. 60,64 Consequently, while the undeflected light rays are converged to a focal point by a focusing mirror or a lens, the deflected light rays are distributed around the focal point. A knife edge is placed close to the focal point to block those deflected light rays, which pass through the schlieren and deviate from the focal point.…”

Section: ■ Introductionmentioning

confidence: 99%

High-Speed Schlieren Imaging of Vapor Formation in Electrospray Plume

Li,

Prabhu,

Buchowiecki

et al. 2024

J. Am. Soc. Mass Spectrom.

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Previous mechanistic descriptions of electrosprays mostly focused on the dynamics of Taylor cones, initial droplets, and progeny droplets. However, vapor formation during droplet desolvation in an electrospray plume has not been discussed to a great extent. Here, we implement a double-pass on-axis schlieren high-speed imaging system to observe generation and propagation of vapors in an offline electrospray source under different conditions. Switching between turbulent and laminar vapor flow was observed for all of the scanned conditions, which may be attributed to randomly occurring disturbances in the sample flow inside the electrospray emitter. Calculation of mean vapor flow velocity and analysis of vapor flow patterns were performed using in-house developed image processing programs. Experiments performed at different electrospray voltages (0−6 kV), solvent flow rates (100−600 μL min −1 ), and methanol concentrations (50−100%), indicate only a weak dependency between electrospray voltage and mean vapor velocity, implying that the vapor is mostly neutral; thus, the vapor is not accelerated by electric field. On the other hand, electrospraying solutions of analytes (with mass 151 Da or 12 kDa) did not remarkably increase the overall vapor flow velocity. The source of vapor's velocity is attributed to the inertia of the electrospray droplets. Although there are some differences between a modern electrospray ionization (ESI) setup and the setup used in our experiment (e.g., using a higher flow rate and larger emitter), we believe the findings of our study can be projected to a modern ESI setup.

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Density-Based Techniques

Cited by 6 publications

References 23 publications

Measurement sensitivity and resolution for background oriented schlieren during image recording

Measurement sensitivity and resolution for background oriented schlieren during image recording

Analysis of the flow patterns on the fore-body section of a sounding vehicle in the transonic regime

High-Speed Schlieren Imaging of Vapor Formation in Electrospray Plume

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