Local Propeller Blade Flows in Uniform and Sheared Onset Flows Using LDV (Laser Doppler Velocimetry) Techniques

Laser Doppler Velocimetry techniques were used to measure local propeller blade flows in the DTNSRDC 24-inch water tunnel. Velocity measurements were made upstream, downstream, and between blades. Measurements were made near the blade surface to identify potential flow surface pressure coefficients and streamwise boundary layer profiles. Blade surface flow visualization was correlated with the measured boundary layer characteristics. Blade pressure distributions and streamwise boundary layer growth were compared with theory. Exploratory velocity measurements were made ahead of a propeller operating in an axisymmetric sheared inflow, and velocity and thrust correlations were made with theory. Measured velocities about the propeller showed good agreement with potential theory ahead of the propeller with discrepancies occurring downstream of the propeller due to viscous effects. Measured boundary layer growth at mid-span of the propeller blade was approximated well by two-dimensional boundary layer theory. Boundary layer profile measurements verified the location of transition determined from flow visualization technique. Presented at the 15th ONR Symposium, Hamburg, Germany, Sep 84.