Small-scale characteristics and turbulent statistics of the flow in an external gear pump by time-resolved PIV

Recent technology advancements in Particle Image Velocimetry (PIV) technique offers a new possibility to study the complex turbulent flows over a wide range of scales. It can be used for the estimation of the turbulent kinetic energy dissipation rate including spatial derivatives of the velocity fluctuation components. In this study the flow characteristics of an external gear pump were studied with time-resolved Particle Image Velocimetry. Measurements were performed for two different spatial resolution configurations and various interrogation areas to estimate the dissipation rate of the turbulent kinetic energy. Results show that the spatial resolution is a critical factor in the accuracy of the measurements in the dissipation rate estimations. The optimal results can be achieved if the interrogation area is neither too large (sampling phenomenon) nor too small (noise in the measurement data). The effect of number of samples employed in the ensemble-averaging was considered as well.