Athanasia Kalpakli

Dean vortices in turbulent flows: rocking or rolling?

Graphical Abstract

Hot-Wire Calibration at Low Velocities: Revisiting the Vortex Shedding Method

The necessity to calibrate hot-wire probes against a known velocity causes problems at low velocities, due to the inherent inaccuracy of pressure transducers at low differential pressures. The vortex shedding calibration method is in this respect a recommended technique to obtain calibration data at low velocities, due to its simplicity and accuracy. However, it has mainly been applied in a low and narrow Reynolds number range known as the laminar vortex shedding regime. Here, on the other hand, we propose to utilize the irregular vortex shedding regime and show where the probe needs to be placed with respect to the cylinder in order to obtain unambiguous calibration data.

Experimental investigation on the effect of pulsations on exhaust manifold-related flows aiming at improved efficiency

The gas flowing through the exhaust manifold of the internal combustion engine to the inlet of the turbine side of a turbocharger is highly pulsating and turbulent. The gas enters the turbine after ...

The Characteristics of Turbulence in Curved Pipes under Highly Pulsatile Flow Conditions

High speed stereoscopic particle image velocimetry has been employed to provide unique data from a steady and highly pulsatile turbulent flow at the exit of a 90 degree pipe bend. Both the unsteady behaviour of the Dean cells under steady conditions, the so called “swirl switching” phenomenon, as well as the secondary flow under pulsations have been reconstructed through proper orthogonal decomposition. The present data set constitutes – to the authors’ knowledge – the first detailed investigation of a turbulent, pulsatile flow through a pipe bend.