Time-resolved quantitative visualization of complex flow field emitted from an open ended shock tube using a wavefront measuring camera

Abstract

Quantitative visualization of shock induced complex flow field emanating from the open end of a miniaturized hand-driven shock tube (Reddy tube) is presented. During operation, the planar shock wave of Mach number M i =1.33 (±0.6%) is discharged through the low-pressure driven-section, kept open to ambient atmosphere. From the moment of shock discharge, its aftereffects of evolving flow field are recorded for 300 s  near the exit of the tube by using our newly developed high resolution (16Mpixel) home built wavefront measuring camera setup. The ability of the camera to identify the amplitude and phase of the incident light wave is utilized to measure the flow induced change in phase of the interrogating light beam quantitatively. Information of the evolving flow field with a spatial resolution of 16μm/pixel and time resolution of 50 s  is recorded in repeated runs. The measured phase information is used in an iterative refraction tomographic scheme to recover the 3D-density distribution of the flow field, which reveals the internal features of the domain. Computational fluid dynamic (CFD) simulation is carried out for the same experimental conditions and it is found that recovered experimental density distribution shows good agreement with the results obtained through CFD simulation.

An Optical Measurement System to Measure Velocity and Provide Shock Wave Pressure Diagrams

“…The first group of sensors are time detectors with laser [9], cinematography [10], X-ray flash [11], electromagnetic sensors, shadowgraph, high-speed cameras, Schlieren [12,13], and other innovative techniques [14], which are also visible in some of these methods such as the high-speed cameras, Schlieren, and some laser methods, as well as the shape of the wavefront. In all of these methods, the need for an external supply is to receive changes from the sensor.…”