Seedless velocimetry is gaining interest in many industrial and research applications. We report on a comparative study of time-resolved optical using traditional, mirror-type knife-edge schlieren optics versus Background-Oriented Schlieren (BOS) subsonic round turbulent helium jets air at Red = 5,890 11,300. Digital images with 1024 pixels streamwise resolution (0 < x/d 200) were captured 6000...

A fueled cavity in a supersonic crossflow was ignited via pulse detonator (PD) producing detonation waves that were then decoupled to produce varying degrees of shock-flame separation at the exit PD tube. This decoupling allowed for observation ignition mechanism, and key parameters required successful identified. Measurements made using high-frame-rate OH Planar Laser-Induced Fluorescence (PLI...

We present a method that allows for reconstructing non-stationary, time-varying gas flows around moving objects. Our work extends the background oriented Schlieren tomography (3D-BOS) acquisition technique to capture gas flows also in the presence of occluding objects. An algorithm is presented that exploits the unique properties of BOS background patterns to robustly segment occluding objects....

The dense plasma phase of a dynamic z-pinch working at a high filling pressure is studied. By using the Schlieren-technique it is found that the compressed plasma column, though macroscopically stable for times less than 1 /us develops quickly from a homogeneous state to a turbulent one with a perturbation scale length of typically some millimeters. Quantitative measurements of light deflection...

2014 It is shown that the piezooptic effect allows direct observation of Dauphiné twins in 03B1-quartz under uniaxial stress in X direction by use of the Schlieren technique. In conjunction with measurements of the piezoelectric polarization charge as a function of applied force this method may be used to study the dynamics of twinning. A sequence of pictures is presented showing the formation ...

An attempt is made to describe and review the most widely used methods for flow visualization. The first part described the basis and applications of different visualization methods for subsonic and supersonic flow in wind and water tunnels. This part concentrates on optical methods (shadow, schlieren and interferometry) and their application in compressibe flow visualization. Almost all presen...

We present an implementation of the analysis of dynamic near field scattering (NFS) data using a graphics processing unit. We introduce an optimized data management scheme thereby limiting the number of operations required. Overall, we reduce the processing time from hours to minutes, for typical experimental conditions. Previously the limiting step in such experiments, the processing time is n...