Effect of measuring volume length on two-component laser velocimeter measurements in a turbulent boundary layer

✍ Scribed by P. L. Johnson; R. S. Barlow

• Publisher: Springer
• Year: 1989
• Tongue: English
• Weight: 695 KB
• Volume: 8
• Category: Article
• ISSN: 0723-4864
• DOI: 10.1007/bf00195787

✦ Synopsis

The effects of finite measuring volume length on laser velocimetry measurements of turbulent boundary layers were studied. Four different effective measuring volume lengths, ranging in spanwise extent from 7 to 44 viscous units, were used in a low Reynolds number (Re o = 1440) turbulent boundary layer with high data density. Reynolds shear stress profiles in the near-wall region show that <u v) strongly depends on the measuring volume length; at a given y-position, <u v) decreases with increasing measuring volume length. This dependence was attributed to simultaneous validations on the U and V channels of Doppler bursts coming from different particles within the measuring volume. Moments of the streamwise velocity showed a slight dependence on measuring volume length, indicating that spatial averaging effects well known for hot-films and hot-wires can occur in laser velocimetry measurements when the data density is high.