Investigation of Circular Hydraulic Jump Behavior in Microgravity

The behavior of the circular hydraulic jump has been studied, under conditions of reduced gravity aboard the NASA C-9 microgravity research aircraft, for Reynolds numbers based on jet diameter between 27,000 and 58,000 and Weber numbers between 1000 and 4600. The steady-state jump radius was observed to increase under conditions of reduced gravity, relative to its magnitude during hypergravity at the same flowrate. The measured jump radius achieved a steady-state value in approximately 3 to 5 s, which corresponded to the time for the establishment of steady reduced gravity conditions during each parabola. Jump radius in reduced gravity increased in a nearly linear fashion versus jet flowrate. Comparisons with available theories were incomplete due to unsuccessful attempts to measure the upstream and downstream jump depths.