CORRELATION OF TRANSITION TO TURBULENCE IN A CONSTANT-ACCELERATION PIPE FLOW.
An experiment was conducted to determine the conditions for transition to turbulence in a pipe flow started from rest at a constant rate of mean velocity increase. The data were taken at the Naval Underwater Systems Center's Unsteady Flow Loop Facility, which has a 5-centimeter-diameter test section approximately 30 meters long, fitted with static pressure, fluctuating pressure, and surface shear stress sensors, as well as a laser Doppler velocimeter and a transient flowmeter. A downstream control valve produced uniform mean flow accelerations varying from 2 to 12 meters/second. In each of the 37 cases run, the time of transition to turbulence was constant to within 3 percent throughout the pipe, indicating that a global instability occurs.