Numerical Analysis of Low-Prandtl Jets in Turbulent Forced Convection Regimes

The current need to ensure an effective and prompt transition of the energy sector towards zero-carbon has renewed the interest for nuclear technology. Small Modular Reactors (SMRs) seem particularly interesting for their reduced capital cost, operational flexibility and enhanced safety and security. Different SMR concepts are being developed...

Aeroacoustics of Jet-Surface Interaction and Passive Solutions for Mitigating Jet-Installation Noise

Aircraft noise levels have been significantly reducedwith the introduction of high-bypass ratio turbofan engines, particularly jet noise due to turbulence mixing. This, however, has led to engines with larger diameters and a closer coupling between them and the airframe. As a result, interactions between the exhaust jet flow and the wing give...

Plasma synthetic jet actuators for active flow control

In the last few decades, active flow control (AFC) technology has been developed to minimize the aerodynamic drag of transportation vehicles and maximize the propulsion efficiency of thermodynamic engines. The key of this technology is the actuators. Among all the actuators that have been proposed (i.e. fluidic, moving object, or plasma-based),...

Gas Jets in Granular Matter: Observed by a High Speed X-ray Tomography System

High speed X-ray tomography is a promising tool to visualize the time-resolved gas distribution for fluidized beds. The tomography unit at Delft University of Technology is composed of three X-ray tubes and three double-layer detector arrays. The X-ray tubes are places at 120? around the fluidized bed. The detector arrays are placed opposite to...

Spray combustion in moderate and intense low-oxygen conditions: An experimental study

Nitric oxides (NOx) are formed as a byproduct of combustion and contribute to ground-level ozone formation and the creation of conditions harmful for human health. In response to air pollutant emissions regulations, technologies for controlling NOx formation for a entire spectrum of fuels ranging from gaseous, liquid, coals, biomass and residue...

On the excavation process of a moving vertical jet in cohesive soil

In dredging practice jetting is widely used for the excavation of soil. In this study the jetting process of a moving vertical jet in cohesive soil has been investigated. A number of jet tests were conducted on artificially prepared cohesive soil samples. The observed failure mechanisms are discussed. A calculation model to predict the jet...

3D flow organization and dynamics in subsonic jets: Aeroacoustic source analysis by tomographic PIV

To meet the increasingly stringent noise regulation, aircraft manufacturers are searching for solutions to jet noise. This, which constitutes a significant amount of the total noise emitted by civil aircrafts, is generated by the mixing processes between the exhaust flow leaving the engine and the atmosphere. A detailed understanding of such...

Advances in tomographic PIV

This research deals with advanced developments in 3D particle image velocimetry based on the tomographic PIV technique (Tomo-PIV). The latter is a relatively recent measurement technique introduced by Elsinga et al. in 2005, which is based on the tomographic reconstruction of particle tracers in three-dimensional space from a small number of its...

Electrohydrodynamic Atomization in the Simple-Jet Mode: Out-scaling and Application

Electrohydrodynamic Atomization, often called electrospraying, is a way to disintegrate a liquid into droplets by exposing it to a strong electric field. Although William Gilbert has reported about the deformation of a liquid meniscus under the influence of an electric field already more than four centuries ago, the interest about electrostatic...

On the scaling and unsteadiness of shock induced separation

Shock wave boundary layer interactions (SWBLI) are a common phenomenon in transonic and supersonic flows. The presence of shock waves, induced by specific geometrical configurations, causes a rapid increase of the pressure, which can lead to flow separation. Examples of such interactions are found in amongst others rocket engine nozzles and on...

Adaptive image interrogation for PIV: Application to compressible flows and interfaces

As an experimental tool, Particle Image Velocimetry has quickly superseded traditional point-wise measurements. The inherent image processing has become standardized though the performances are strongly dependent on user experience. Moreover, the arduously selected image interrogation parameters are applied uniformly throughout the image...

Aeroacoustics of compressible subsonic jets: Direct Numerical Simulation of a low Reynolds number subsonic jet and the associated sound field

Jet noise is an extensively studied phenomenon since the deployment of the first civil jet aircraft more than 50 years ago. Jet noise makes up a considerable portion of the total noise of jet aircraft, and the expansion of the numbers of airplanes and airports has only been possible by keeping the noise of airplanes under control. However, while...

LES, RANS and combined simulation of impinging flows and heat transfer

This thesis reports on a numerical study of a round, isothermal turbulent jet of incompressible fluid, impinging normally on a flat wall at a different temperature. The aim was to generate detailed information about the ime-dependent three-dimensional velocity and temperature field, and, based on this, to extract statistically averaged flow and...

Multiple impinging jet arrays. An experimental study on flow and heat transfer

Because of their high efficiency and their ability to provide high heat transfer rates, impinging jets are applied for rapid cooling and heating in a wide variety of industrial processes. However, the physical phenomena controlling the heat transfer from impinging jets are to a large degree unknown. The goal of the present project was to gain a...

Air entrainment by plunging water jets

Gas entrainment caused by the impact of liquid jets upon liquid pool surfaces is a subject which has received too little attention. This well-known phenomenon,which occurs In nature and in numerous industrial operations, has only recently received interest from scientific workers. The influence on product quality and applications in waste water...

Jet diffusion in stagnant ambient fluid

Submarine outfall disposal of domestic and industrial sewage is a method of disposal of steadily growing importance. The flow from an ocean outfall is essentially that of a submerged horizontal or vertical jet. Thus a study of the hydrodynamics of such jets is needed to evaluate the dilution of the sewage flow. A study of this kind is presented...