Pitot Tube Turbulent Jet — Velocity Profile Analysis

This experiment characterized a turbulent free jet by mapping the velocity field of an air stream at multiple downstream distances using a pitot tube mounted on a 2-axis traverse system. The goal was to verify self-similar behavior in a fully developed turbulent jet and compare measured profiles against theoretical predictions.

The experimental setup used a steady nozzle flow with a pitot tube sweeping a planar cross-section of the jet cone at downstream distances of 1D, 5D, 7D, and 9D (where D is the nozzle diameter). At each position, velocity data was collected across the jet width and processed to extract the mean velocity profile. Reynolds number analysis confirmed fully turbulent conditions (Re ≥ 10⁴) at all measurement planes.

Data was normalized by the local centerline velocity and plotted against the similarity variable to verify self-similar collapse — a hallmark of developed turbulent jets. Turbulence intensity profiles were also extracted to identify the laminar potential core near the nozzle exit and the fully turbulent mixing region further downstream. Results matched the theoretical Gaussian profile and confirmed the hypothesis.