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Showing 1 to 20 of 34 for “"Schlieren Imaging"”.
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Adaptive synthetic Schlieren imaging
Traditional schlieren photography has several important disadvantages when designing a system to image refractive index gradients including the relatively high cost of parabolic mirrors and the fact that the technique does not easily yield quantitative data. Both these issues are resolved by using …
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Calibrating Schlieren imaging for understanding local film deformation for a range of wetting and intrusions in soap films
… by Su and Bourouiba [30] by showing that the Schlieren spot size produced by large objects is not affected by size or wetting properties of the object. The spot size in soap films is primarily affected by the film thickness, consistent with prior results on water films (without surfactant).
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Quantification of the Depth-of-Field in a Self-Aligned Focusing Schlieren System
<p>This thesis investigates self-aligned focusing schlieren (SAFS) as a step toward future volumetric and quantitative measurements of three-dimensional compressible flows. Conventional schlieren imaging provides valuable visualization of density gradients, but it records only a line-of-sight …
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DEVELOPMENT OF KRYPTON PLANAR LASER INDUCED FLUORESCENCE METHODS FOR THE MEASUREMENT OF HYPERSONIC FLOW CONDITIONS
… as hypersonic flow conditions are achieved. Schlieren and shadowgraph imaging methods have been used successfully for decades as a method of non-intrusive flow visualization. However, these methods become obsolete when the path of light is obstructed, which is a common problem when analyzing …
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Measurement of flame propagation through step changes in mixture composition
… movement of the flame front through high speed Schlieren imaging. Both methods demonstrated good correlation with the literature for homogeneous charges. However, the analysis necessarily assumes a spherical flame, but the Schlieren video showed that the laser ignition system induced a …
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Hot jet ignition delay characterization of methane and hydrogen at elevated temperatures
… rate up to 300 kHz, as well as high speed Schlieren imaging with a recorded frame rate up to 20,833 frame per seconds. Results shows an overall increase in ignition delay with increasing equivalence ratio. High temperature of the main chamber blend was found not to affect hot jet ignition …
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Fundamental physics and application of plasma actuators for high-speed flows
… conducted in quiescent air and analyzed with schlieren photography to determine the effectiveness of a plasma pulse to produce an instantaneous flow perturbation. Examination of phase averaged schlieren images revealed that a blast was produced by the emission and could be used to alter a flow …
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Ultrafast dynamic ellipsometry of laser driven shock waves
… was used in conjunction with high-speed schlieren imaging to determine the nature of the insult provided by ablation of a thin titanium film in optical detonators.
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Analysis of a laser induced plasma in high pressure SF6 gas for high-voltage, high-current switching
… produce acceptable switch run-time and jitter. Schlieren imaging and electrical length measurements using a capacitive probe are also used to obtain laser induced spark lengths. Spectroscopy is used to estimate laser plasma temperature from which plasma resistivity is calculated.</p>
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Characterization and Analysis of Supersonic Flow Through De Laval Nozzles at Varied Design Conditions
… pressure measurements and flow visualization via schlieren imaging were collected.</p> <p>The investigation uncovered distinctive characteristics of overexpanded flow in planar nozzles, including internal separation and a well-defined shock structure. Decreasing the operating nozzle pressure ratio …
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Autoignition and flame speed of premixed liquefied petroleum gas in a rapid compression machine: experimental results and reduced chemical kinetic mechanism
… analyzing the propagating flame with high speed schlieren imaging. Zero-dimensional simulations of published autoignition experiments were performed using Chemkin-Pro with several detailed chemical kinetic mechanisms to determine their suitability at predicting ignition delay periods. Multiple …
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Novel Ignition Approaches for Improved Hydrogen Ignition
… core temperature. Analysis methods: high-speed schlieren imaging, pressure trace analysis, jet mixing modeling, and constant-pressure homogeneous reactor (CHR) simulations. At 1000K, the 1st injection advanced 2nd injection ignition delay, reducing it from 9.66ms (single-injection) to 0.62ms …
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Aerodynamic characterization of a Griffith-type transonic, laminar-flow airfoil
… surface-oil flow visualization, PIV, and Schlieren imaging were performed to identify the suction influence on boundary-layer transition, momemtum deficit alleviation in the wake, and stability of transonic shocks. It was observed from the pressure distributions that the flow control …
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Coalescence of nonlinear acoustic waves, with application to supersonic jet noise
… The interacting waves are tracked using schlieren imaging to compare waveform steepening in coalescing and non-coalescing waves. High frame-rate schlieren images of sound waves propagating from the post potential core region of a laboratory-scale Mach 3 jet are captured in a narrow field …
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Active and hybrid flow control in S-ducts and diffusers
… diagnostics, including electrical measurements, schlieren imaging, surface flow visualization and particle image velocimetry. Two important features of the actuator - the blast wave (traveling at nearly sonic speeds) and the heated plume - were observed via schlieren imaging. At each actuation …
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A study of direct-current surface discharge plasma for a Mach 3 supersonic flow control
… (~100 W) constricted mode. High speed laser schlieren imaging suggests that the diffuse mode plasma actuation is rapid as it occurs on a time scale that is less than 100 [mu]sec. Rotational (gas) and vibrational temperatures within the discharge are estimated by emission spectral line fits of …
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Investigating the Interaction of a Supersonic Single Expansion Ramp Nozzle and Sonic Wall Jet
… aft deck is characterized using time-resolved schlieren imaging, stereo PIV measurements, deck mounted pressure transducers, and far-field microphones. These experiments are performed at the Skytop Turbulence Laboratory at Syracuse University. LES data by The Ohio State University are paired …
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Design and development of a rectangular supersonic wind tunnel facility for the study of shock/boundary layer interactions
… velocimetry. Visual diagnostic techniques of schlieren imaging, surface oil flow visualization, and particle image velocimetry were conducted to study the effects of the ramped vanes on shock wave/boundary layer interactions. The vanes were observed to produce two distinct vortex pairs that …
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Computational Fluid Dynamics-Informed Analysis of Diaphragm-Free Shock Tubes and Insert Designs
… generated x-t diagrams, numerical Schlieren imaging, pressure contours, and test time pressure and temperature data. Valve-based and diaphragm-based configurations are compared to analyze the impact of valve opening speed, pressure ratio, and insert geometry on shock uniformity and …
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Investigating the Structures of Turbulence in a Multi-stream, Rectangular, Supersonic Jet
… supersonic nozzle are studied via time-resolved schlieren imaging, stereo PIV measurements, dynamic pressure transducers, and far-field acoustics. Experiments are carried out in the anechoic chamber at Syracuse University, and focus primarily on the flow-field. An extensive data set is generated, …
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