Design and Characterization of Jet Injection Using Particle Image Velocimetry

This paper presents the design and experimental characterization of the jet exit velocity from a supersonic nozzle injecting into a low-pressure vacuum chamber using Particle Image Velocimetry (PIV). The study investigates the injection cases for a nitrogen jet injected into an acrylic chamber filled with low pressure air. The PIV method is employed to overcome limitations encountered in prior experiments characterizing a jet-in-crossflow, such as qualitative shock visualization and insufficient data on jet exit properties. The previous set of experiments used Classical Schlieren to visualize the flow as well as emission measurement with IR detectors. For the fuel injection cases, particular emphasis is placed on preventing condensation within the injection line and at the nozzle exit due to under expanded conditions in the chamber. A new injection system is developed to maintain required thermodynamic conditions while also seeding particles into the injecting flow. Results from PIV measurements provide spatially resolved velocity fields at the nozzle exit, enabling accurate analysis of flow behavior under varying operating conditions.