Flow dynamics and wall-pressure signatures in a high-Reynolds-number overexpanded nozzle with free shock separation

A delayed detached eddy simulation of an overexpanded nozzle flow with shock-induced separation is carried out at a Reynolds number of, based on nozzle throat diameter and stagnation chamber properties. In this flow, self-sustained shock oscillations induce local unsteady loads on the nozzle wall as well as global off-axis forces. Despite...

Insulated multinozzle system for electrohydrodynamic atomization in the simple-jet mode

In this study, a multinozzle electrohydrodynamic atomization device was designed and studied for electrosprays in the simple-jet mode. Results have shown that the proposed device produces droplets with similar diameter in all nozzles, that the electric field creates a unique dispersion of the charged droplets and that it can operate under...

Three-dimensional vortex analysis and aeroacoustic source characterization of jet core breakdown

The three-dimensional behavior of jet core breakdown is investigated with experiments conducted on a free water jet at Re = 5000 by time-resolved tomographic particle image velocimetry (TR-TOMO PIV). The investigated domain encompasses the range between 0 and 10 jet diameters. The characteristic pulsatile motion of vortex ring shedding and...

Large-eddy simulation of highly underexpanded transient gas jets

Large-eddy simulations (LES) based on scale-selective implicit filtering are carried out in order to study the effect of nozzle pressure ratios on the characteristics of highly underexpanded jets. Pressure ratios ranging from 4.5 to 8.5 with Reynolds numbers of the order 75?000–140?000 are considered. The studied configuration agrees well with...

Monodisperse water microdroplets generated by electrohydrodynamic atomization in the simple-jet mode

Experiments were conducted in order to investigate the influences of flow rate, applied voltage, and electric conductivity on droplet size and size distribution of water electrosprays in the simple-jet mode. The results show that the electric potential decreases significantly the relative standard deviation (RSD) of the spray size distribution,...

Three-dimensional evolution of flow structures in transitional circular and chevron jets

The three-dimensional behavior of flow transition in circular and 6-chevron jets at Re?=?5000 is investigated with experiments conducted on a free water jet by time-resolved tomographic particle image velocimetry. The emphasis is on the unsteady organization of coherent flow structures, which play a role in the generation of acoustic noise....

Influence of rarefaction on the flow dynamics of a stationary supersonic hot-gas expansion

The gas dynamics of a stationary hot-gas jet supersonically expanding into a low pressure environment is studied through numerical simulations. A hybrid coupled continuum-molecular approach is used to model the flow field. Due to the low pressure and high thermodynamic gradients, continuum mechanics results are doubtful, while, because of its...

Vortex wake investigation behind a wing-flap model with jet simulations

To get a better insight in the effect of jets on vortex development and decay, stereo-PIV measurements were performed in a towing tank behind a flapped aircraft model. The experimental data set yields the wake vortex behavior in a range that extends from the vortex formation stage up to the mid-field (approximately t* =2 corresponding to 100...

Experiments on single event electrospraying

In order to use electrospraying as an on demand deposition method, well defined and reproducible single electrospraying events have been studied. To generate a single electrospraying event, rectangular voltage pulses superimposed on a constant bias voltage were applied, and optimum settings of the bias dc voltage for starting such an event were...

Particle imaging velocimetry-based identification of coherent structures in normally impinging multiple jets

To gain a better insight into the effects of eddy structure and their thermal imprint on the impinging surface, we applied several methods to identify coherent structures in two arrangements of multiple jets. High-resolution particle imaging velocimetry measurements of the instantaneous fluid velocity have been performed to provide data for...

Scour manual

The action of submerged jets on moveable material

Laboratory research on the effect of jets on erodible bed. Studies of scour hole shape. Includes measured data.