TY - JOUR

T1 - Error Due to Assuming Constant Through-sheet Velocity When Applying Correction for the Viewing Angle to Particle Tracking Velocimetry Data Obtained in the Wake of a Model Car

AU - McCutcheon, G.

AU - McColgan, A. H.

AU - Percario, S.

AU - Hurst, D.

AU - Grant, I.

PY - 2001

Y1 - 2001

N2 - The common optical configuration for two-component, particle tracking studies places the light sheet such that the mean velocity vector is coplanar with the illuminated area. In other, innovative studies, it has been found advantageous to place the sheet normal to the mean flow. Using this geometry it is necessary to apply a correction to the perceived, in-plane particle displacements to allow for the systematic error due to through-sheet motion. This correction has been made in the past by assuming a constant, through-sheet velocity, necessitated by the limited two-component measurement regime. This paper describes the errors in obtaining in-plane velocity components when assuming, constant, through-sheet motion. An illustration is presented where the viewing corrections were applied to images obtained in the study of the wake of a model road vehicle using PTV in the Particle Tracking Velocimetry (PTV) mode. Assuming a constant through-sheet velocity, it was shown that there were potentially, significant errors in the measured velocity. This was confirmed by measuring the freestream velocity at a matrix of points on the sheet then comparing the calculated in plane-motion using this variable in-plane velocity for correction. The differences in the velocity, drag and lift distributions and total induced drag and total lift using this approach were calculated and are reported in this paper.

AB - The common optical configuration for two-component, particle tracking studies places the light sheet such that the mean velocity vector is coplanar with the illuminated area. In other, innovative studies, it has been found advantageous to place the sheet normal to the mean flow. Using this geometry it is necessary to apply a correction to the perceived, in-plane particle displacements to allow for the systematic error due to through-sheet motion. This correction has been made in the past by assuming a constant, through-sheet velocity, necessitated by the limited two-component measurement regime. This paper describes the errors in obtaining in-plane velocity components when assuming, constant, through-sheet motion. An illustration is presented where the viewing corrections were applied to images obtained in the study of the wake of a model road vehicle using PTV in the Particle Tracking Velocimetry (PTV) mode. Assuming a constant through-sheet velocity, it was shown that there were potentially, significant errors in the measured velocity. This was confirmed by measuring the freestream velocity at a matrix of points on the sheet then comparing the calculated in plane-motion using this variable in-plane velocity for correction. The differences in the velocity, drag and lift distributions and total induced drag and total lift using this approach were calculated and are reported in this paper.

KW - Aerodynamics

KW - Induced drag

KW - Particle image velocimetry

KW - Particle tracking velocimetry

KW - Road vehicles

KW - Through-sheet velocity correction

KW - Wake survey

UR - http://www.scopus.com/inward/record.url?scp=36448954700&partnerID=8YFLogxK

M3 - Article

VL - 3

SP - 357

EP - 367

JO - Journal of Visualization

JF - Journal of Visualization

SN - 1343-8875

IS - 4

ER -