Comparison of turbulence length scales assessed with three measurement systems in increasingly complex turbulent flows

This paper proposes to compare turbulence length scales measured with three different experimental systems commonly used in aerodynamic measurements, namely hot wire anemometer, Laser Doppler Velocimetry and Particle Image Velocimetry, using turn-key systems from Dantec and TSI, and for three different turbulent flows: a homogeneous and isotropic turbulent flow, a homogeneous shear flow and the wake of a porous disc. This study will show that Taylor macro scale assessment is not clearly dependent on the experimental system used, except for nonconstant shear, where the measurement volume size seems to be a critical parameter. On the other hand, Taylor micro-scale is highly dependent on the space or time resolution of the correlation and on the presence of random measurement noise. Among the three systems, only the hot wire anemometer seems to provide the right requirements to properly assess the Taylor micro-scale.