Ludwieg Tube Group - GALCIT Current Research One of the two current research projects focuses on the mechanisms of tripping between regular and Mach reflection in the dual solution domain. In order to facilitate experimentation in the dual solution domain a Mach 4.0 nozzle will replace the current Mach 2.3 Ludwieg Tube nozzle. Part of the research into Mach reflections includes an improved theoretical approximation of the height of the Mach stem. The image below shows a comparison of the computed shock structure with that calculated by theory. Recently Completed Research The most recently completed research project focused on the development of a 3D-PTV (Three Dimensional Particle Triangulation Velocimetry) system, this system is based on the DDPIV system developed by the Gharib Research Group for use in water tunnels. The system was adapted for use in supersonic flows. The 3D-PTV system has been used to image a supersonic jet. The system finds approximately 25 vectors per cubic centimeter. The image below shows stream-surfaces with the color representing the speed of the flow. The 3D-PTV system has also been used for solid surface measurements. An example of the results obtained by the system are shown below. It is important to note that the image is simply the raw data with no filtering, only interpolation between the points has been done. The image was taken of a doll's face and the green box represents a cube with a side length of 5mm.