MEASUREMENTS OF TWO-POINT VELOCITY CORRELATIONS IN TURBULENT JET USING EXTENDED LASER DOPPLER VELOCITY PROFILE SENSOR

摘要

We report on a novel system for measuring velocities at closely located points in turbulent flows. The system consists of a laser Doppler velocity profile sensor and dual detection volumes. The flow velocities are simultaneously evaluated at two spatially independent points with a micrometer resolution. It is designed to overcome the inevitable issues of poor spatial resolution and large ambiguity for measuring flow velocities at two closely located points with conventional techniques. The basic development and the performance of the new system are examined and further applied in a turbulent free jet. Two-point correlations in time and in space are measured with the new system at different streamwise locations both along the jet centerline and in the shear layer.