Turbulence Generated by a Randomly Pulsed Through Flow Jet-Array

We study the turbulence generated by a through flow jet-array in our newly constructed vertical water tunnel. This apparatus was designed to facilitate the measurement of dynamics of sedimenting particles in turbulence. It circulates water through a vertical, square channel, passing through a grid of 40 water jets that each fire at two 45 degree angles from the horizontal axis. We pulse the jet-array in several randomized patterns and intensities, while maintaining a constant total flow rate for each configuration. In its minimum turbulence configuration, the jets eject no fluid, allowing the jet-array to essentially function as a passive grid. When the jets are activated, the jet-array maintains a constant number of jets that will be on at any moment, an average duration for each jet to remain on, a through-flow rate, and a total jet-flow rate. This thesis characterizes the flow generated by the jet-array with different jet configurations and intensities. We see turbulence that is highly isotropic in the lateral plane, and homogeneous in the upper half of the test section. We also see varying levels of skewness of the flow with a high dependence on the number of jets firing. We study the flow at 36 cm, 60 cm, 90 cm, and 120 cm above the jet-array to analyze how various properties of the turbulence dissipate through space.