Reflected shock-initiated ignition probed via simultaneous lateral and endwall high-speed imaging with a transparent, cylindrical test-section

AbstractThe interaction of a cylindrical converging shock wave with an initially perturbed gaseous interface is studied experimentally. The cylindrical converging shock is generated in an ordinary shock tube but with a specially designed test section, in which the incident planar shock wave is directly converted into a cylindrical one. Two kinds of typical initial interfaces involving gas bubble and gas cylinder are employed. A high-speed video camera combined with schlieren or planar Mie scattering photography is utilized to capture the evolution process of flow structures. The distribution of baroclinic vorticity on the interface induced by the cylindrical shock and the reflected shock from the center of convergence results in distinct phenomena. In the gas bubble case, the shock focusing and the jet formation are observed and the turbulent mixing of two fluids is promoted because of the gradually changed shock strength and complex shock structures in the converging part. In the gas cylinder case, a counter-rotating vortex pair is formed after the impact of the converging shock and its rotating direction may be changed when interacting with the reflected shock for a relatively long reflection distance. The variations of the interface displacements and structural dimensions with time are further measured. It is found that these quantities are different from those in the planar counterpart because of the shock curvature, the Mach number effect and the complex shock reflection within the converging shock tube test section. Therefore, the experiments reported here exhibit the great potential of this experimental method in study of the Richtmyer-Meshkov instability induced by converging shock waves.

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Hydrofoil Cavitation Under Strong Thermodynamic Effect

Journal of Fluids Engineering ◽

10.1115/1.2953297 ◽

2008 ◽

Vol 130 (9) ◽

Cited By ~ 17

Author(s):

Jonas P. R. Gustavsson ◽

Kyle C. Denning ◽

Corin Segal

Keyword(s):

Test Section ◽

High Speed ◽

Static Pressure ◽

Cold Water ◽

Cavitation Number ◽

Gradual Transition ◽

Ambient Conditions ◽

High Speed Imaging ◽

Sheet Cavitation ◽

Thermodynamic Effect

Cavitation was studied for a NACA0015 hydrofoil using a material that simulates cryogenic behavior. Several angles of attack and flow speeds up to 8.6m∕s were tested. The material used, 2-trifluoromethyl-1,1,1,2,4,4,5,5,5-nonafluoro-3-pentanone, hereafter referred to as fluoroketone, exhibits a strong thermodynamic effect even under ambient conditions. Static pressures were measured at seven chordwise locations along the centerline of the hydrofoil suction side and on the test section wall immediately upstream of the hydrofoil. Frequency analysis of the test section static pressure showed that the amplitude of the oscillations increased as the tunnel speed increased. A gradual transition corresponding to the Type II-I sheet cavitation transition observed in water was found to occur near σ∕2α=5 with Strouhal numbers based on chord dropping from 0.5 to 0.1 as the cavitation number was reduced. Flash-exposure high-speed imaging showed the cavity covering a larger portion of the chord for a given cavitation number than in cold water. The bubbles appeared significantly smaller in the current study and the pressure data showed increasing rather than constant static pressure in the downstream direction in the cavitating region, in line with observations made in literature for other geometries with fluids exhibiting strong thermodynamic effect.

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Cavitating flow around a tandem of 2D hydrofoils: high-speed imaging and PIV measurements

Proceeding of THMT-18. Turbulence Heat and Mass Transfer 9 Proceedings of the Ninth International Symposium On Turbulence Heat and Mass Transfer ◽

10.1615/thmt-18.400 ◽

2018 ◽

Author(s):

Konstantin S. Pervunin ◽

Mikhail V. Timoshevskiy ◽

Dmitriy M. Markovich

Keyword(s):

High Speed ◽

Cavitating Flow ◽

High Speed Imaging ◽

Piv Measurements

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Experimental Measurement of In-Plane Rolling Nonpneumatic Tire Vibrations Using High-Speed Imaging

Tire Science and Technology ◽

10.2346/tire.18.470101 ◽

2019 ◽

Vol 47 (3) ◽

pp. 196-210

Author(s):

Meghashyam Panyam ◽

Beshah Ayalew ◽

Timothy Rhyne ◽

Steve Cron ◽

John Adcox

Keyword(s):

High Speed ◽

Image Correlation ◽

Dynamic Mode Decomposition ◽

Dynamic Mode ◽

High Speed Imaging ◽

Correlation Algorithm ◽

Mode Decomposition ◽

Series Of Experiments ◽

Plane Deformations ◽

Dominant Frequencies

ABSTRACT This article presents a novel experimental technique for measuring in-plane deformations and vibration modes of a rotating nonpneumatic tire subjected to obstacle impacts. The tire was mounted on a modified quarter-car test rig, which was built around one of the drums of a 500-horse power chassis dynamometer at Clemson University's International Center for Automotive Research. A series of experiments were conducted using a high-speed camera to capture the event of the rotating tire coming into contact with a cleat attached to the surface of the drum. The resulting video was processed using a two-dimensional digital image correlation algorithm to obtain in-plane radial and tangential deformation fields of the tire. The dynamic mode decomposition algorithm was implemented on the deformation fields to extract the dominant frequencies that were excited in the tire upon contact with the cleat. It was observed that the deformations and the modal frequencies estimated using this method were within a reasonable range of expected values. In general, the results indicate that the method used in this study can be a useful tool in measuring in-plane deformations of rolling tires without the need for additional sensors and wiring.

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