The diploma thesis describes search for propriate change of small jet engine exhaust, based on temperature and velocity flowfield analysis in CFD code Fluent V6.

This diploma thesis deals with the area of ejectors. In the intoduction, an ejector is classed as an hydraulic machine. There is also an introduction of the principle and application of this machine there. The next part describes two different ways of calculation and there is a suggestion how to get characteristics, that were achieved by calculation in MS Excel, projected. The purpose of this diploma thesis is to confront this mathematical model with the experiment done in school laboratory at Kaplan department of hydraulic machines. The description of this experiment and the evaluation procedure of measured values is described in the final part of this diploma thesis.

The matter of this thesis is to find the influence of the diameter of the nozzle on the 3D printer´s print quality. The first part briefly characterizes the Rapid Prototyping technology and describes the RepRap project. The second part describes the construction of the experimental FMD 3D printer. The following section deals with technical printing parametres and their influence on the printed product. The experimental part of the thesis is focused on the impact of the discharge nozzle diameter on the mechanical properties, surface quality and shape accuracy of the final product and on the following recommendations of operational parametres.

Ces travaux s'inscrivent dans le cadre du projet ESSENCYELE, projet visant à développer un nouveau modèle de véhicule hybride. L'étude thermique présentée porte sur le refroidissement de machines électriques par jets impactant. Afin d'optimiser le refroidissement des bobinages de la partie fixe de la machine (stator), des travaux ont été menés dans le but d'étudier localement les échanges de chaleur lors de l'impact d'un jet. Deux fluides ont été considérés, l'air et l'huile. Le dispositif expérimental, associé à un programme de post-traitement par méthode inverse, permet de relever la température à la surface d'un cylindre lisse lors de l'impact d'un jet. L'influence de la distance jet/surface, de la géométrie de l'injecteur ou encore des propriétés du fluide ont été testées. Des travaux numériques ont permis de donner des informations supplémentaires sur l'évolution de l'écoulement au sein des injecteurs. Pour terminer, les configurations les plus intéressantes obtenues pour l'air et pour l'huile ont été testées sur le refroidissement des bobinages de stator. / The present work is a part of an industrial project named ESSENCYELE. The main objective of this project is to develop a new hybrid vehicle. The present study is about the electrical machine cooling system by impinging jets. To improve the end winding cooling, experiments has been made to study the local heat transfers during a jet impingement. Two fluids were considered, air and oil. The experimental device, with an inverse method post-processing program, allowed to estimate the temperature at the surface of a smooth cylinder. The influence of the jet/surface distance, the nozzle geometry or the fluid properties were tested. Numerical studies have provided additional information on the fluid flow evolution inside the nozzle. Finally, the most interesting configuration obtained with air jet and oil jet were tested.

In 2016 it is 70 years since the first patent for a two-stage servovalve was filed, and 60 years since the double nozzle-flapper two-stage valve patent was granted. This paper reviews the many alternative servovalve designs that were investigated at that time, focusing on two-stage valves. The development of single-stage valves – otherwise known as direct drive or proportional valves – for industrial rather than aerospace application is also briefly reviewed. Ongoing research into alternative valve technology is then discussed, particularly focussing on piezoelectric actuation and the opportunities afforded by additive manufacturing.

A parametrical study is performed of coolant dump gas ejectors for a sandwich rocket nozzle design. Five geometrical variations are simulated in four ambient conditions (static, subsonic, supersonic, vacuum) using an in-house CFD solver. The test cases are compared with a baseline case and the resulting thrust and ISP are evaluated on a local and global level. A longer dump wall is found to give the best performance in all ambient cases, with a second possibility of reducing the circumference of the nozzle end stiffener. The possibility of post-ejection coolant gas combustion is encountered for high ambient pressure, high subsonic velocity flight.

No description available.

No description available.

No description available.

No description available.