Numerical and Experimental Assessment of a Linear Aerospike

In the present work a linear aerospike nozzle model has been studied with cold flow experiments in various working conditions. A series of numerical 3D RANS simulations have been performed in order to directly compare numerical and experimental results. Mean pressure distributions have been measured on the nozzle model symmetry plane, in order to characterize the flow evolution along the walls of the plug. The presented results show a good agreement between numerical and experimental results

Proportional Opposition Control of Turbulence

Proportional opposition control of sweep events in a turbulent boundary layer has been carried out using a wall-normal jet. Changes to the turbulence structure in the region closer to the wall have been examined using hot-wire anemometry. Control of each detected sweep event has been obtained by using multiple injections whose number is proportional to the duration of the event. Differently from the more conventional opposition control technique with a single injection of a longer duration, the proposed technique with multiple injections allows to control the sweep event over its whole duration without changing the working parameters of the jet actuator

On the Sensor Placement for Flow Field Estimations

PIV09-002

On the Near Field of an Axisymmetric Synthetic Jet

The axisymmetric synthetic jet produced by an oscillating piston has been investigated experimentally. The study was performed in water using digital particle image velocimetry for the instantaneous velocity planar measurements. The near field, up to x/d0 ≈ 6, was investigated for three different Reynolds numbers. The self-similarity of the flow field is already fully reached for the mean velocity profiles at x/d0 ≈ 4 while longer distances are needed for the turbulent intensity profiles. The flow structure investigation shows that a single vortex ring or a train of vortex rings characterizes the near field during the blowing phase, depending on the jet flow parameters. The details of the flow field have also been described in terms of phase-averaged flow analysis and of triple decomposition of the instantaneous velocity field. The near flow fields investigated do not seem to be influenced by the Reynolds number

Opposition control of sweep events in a turbulent boundary layer

Proportional opposition control of sweep events in a turbulent boundary layer has been carried out using a wall-normal jet. Hot-wire anemometry has been used in order to observe the changes to the turbulence structure in the region closer to the wall. Control of each detected sweep event has been obtained by using multiple injections whose number is proportional to the duration of the event. The proposed technique with multiple injections allows to control the sweep event over its whole duration without changing the working parameters of the jet actuato