A jet engine operating near the ground at low aircraft speeds, high thrust, and subject to a crosswind, can experience a flow separation region on the windward inlet lip and the formation of a vortex that extends from the ground to the engine fan face, known as the inlet vortex. This structure forms from a single point on the ground and is ingested by the engine. Inlet vortices are often observed during engine power-up at the start of the take-off run. They create considerable stagnation pressure losses and flow distortions at the engine fan face, compromising fan efficiency, thrust, and increasing the potential for compressor surge. Inlet vortices have enough suction power to kick up sand and rocks that are then sucked into the engine when an aircraft is operating near the ground and especially over poorly-maintained tarmac. Thus foreign object damage (FOD) becomes a serious threat for an engine under these conditions, and may lead to compressor blade erosion, deteriorating engine performance and reducing service life. The work presented here used ANSYS FLUENT to model a jet engine under crosswind. The 3-D Navier-Stokes equations were solved for compressible, unsteady flow. The mesh generated contained 5.6 million tetrahedral and wedge elements. The goal of this research was to better understand the inlet vortex formation mechanisms by studying its transient formation process, and to provide new information for future development of vortex prevention techniques. This work has shown multiple smaller inlet vortices coexisting on the ground plane during the first 0.9s of the formation process. After about 1s, these vortices are shown to coalesce and form one single inlet vortex, containing the circulation of all the smaller vortices combined. The smaller vortices were weak enough to not present danger of FOD, but once coalesced could lift up a 16cm diameter chunk of tarmac asphalt. The conclusion of this work is a recommendation for the development of a solution to the inlet vortex problem focused on preventing the coalescing of the vortex during its formation, thus eliminating the threat of FOD.

Superparamagnetic nanoparticles have potential applications in targeted drug delivery and as magnetic resonance imaging contrast agents. Magnetite clusters are of particular interest for these applications because they provide higher magnetic flux (under a magnetic field) than individual magnetite nanoparticles, are biocompatible, and their size and compositions can be controlled. This thesis involves the controlled synthesis and characterization of clusters composed of magnetite nanoparticles stabilized with an amphiphilic block copolymer. It outlines a method to design and form well-defined and colloidally stable magnetite clusters. A Multi Inlet Vortex mixer (MIVM) was used because it is a continuous process that yields particles with relatively narrow and controlled size distributions. In the MIVM, four liquid streams collide under turbulent conditions in the mixing chamber where clusters form within milliseconds. The formation of magnetite clusters was studied in the presence of amphiphilic block copolymers containing poly (ethylene oxide) to provide steric stabilization and control of size distributions using flash nanoprecipitation. First, the mixer was tested using β-carotene as a model compound to form nanoparticles stabilized with an amphiphilic triblock copolymer poly(propylene oxide)-b-poly(ethylene oxide) (F127) at different Reynolds numbers and supersaturation values. Size analysis was done using dynamic light scattering and nanoparticle tracking analysis techniques. The cluster structure was studied using electron microscopy and magnetite compositions were measured using thermogravimetric analysis. Finally, the stability of magnetite clusters was studied over time and the effect of an applied magnetite field on the colloidal stability was investigated. / Master of Science

This diploma thesis contains several individual parts. It's especially about summary in the area of one-way inlets: the energy efficiency of the inlets and influence of the neighbouring inlets on them, the phases of creation of surface vortices, the influence on the vortex structures by the mutual operation of the neighbouring inlets and also the methods used to determine the critical and safe depth of dive of inlet against the creation of surface vortices. It also includes the description of process and the evaluation of laboratory tests, which are focused on the assessment of the effect of the mutual operation of inlets on their energy efficiency and the creation of higher intensity surface vortices. Important part of this diploma thesis is also a comparison of the achieved results with the results of the authors who have dealt with this issue.