Particle-laden underexpanded jets: An experimental study

It is well-known that in turbulent two-phase flows with enough mass loading, the added inertial particles can modulate the surrounding flows via momentum transfer and flow interactions with particle wakes. However, most existing work is limited to the incompressible flow regime, with little known about how inertial particles modulate compressible and supersonic flows. In particular, the large slip velocity between the two phases can sometimes lead to the formation of bow shocks around the particles. Although small and local, these shocks can significantly affect the pressure and gas density in the adjacent areas and could merge with other ambient shock structures and lead to flow modulations that are entirely different from the incompressible counterpart. In this work, an experiment was conducted by tracking both the particle and gas phases of a sonic jet. A systematic study was performed to understand particle and gas dynamics as a function of the total pressure ratio, particle diameter, particle volume fraction, and mass loading. These results will be compared with high-fidelity simulations performed at the University of Michigan in the companion presentation titled, "Particle-laden underexpanded jets: A numerical study."