A multi-time-delay approach for correction of the inherent error in single-component molecular tagging velocimetry

Abstract

A technique is proposed to correct the bias error associated with one-component molecular tagging velocimetry (1c-MTV). 1c-MTV is typically used to capture the velocity component normal to a single or multiple lines of tagged fluid molecules with very high spatial resolution. However, the measurements are affected by an inherent error, which arises from the presence of a velocity component parallel to the lines. In the present study, a Taylor-series-based approach is used to derive a general mathematical expression for this error. The derived expression, which is validated using simulated MTV measurements in laminar channel flow with suction/blowing, is used as the basis for introducing a correction method involving the acquisition of MTV images at multiple time delays. To examine the effectiveness of this 'multi-time-delay' approach for correcting 1c-MTV data, an experiment is conducted whereby a known bias error is deliberately imposed on measurements in laminar channel flow. The corrected measurements agree with the true velocity profile to better than 2%, thus validating the correction method.