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The effect of a nozzle’s internal geometry was studied experimentally to determine the breakup of the emitted water jet when it was injected perpendicularly into a quiescent atmosphere or a subsonic air crossflow. The nozzle’s diameter, nominal surface roughness, length-to-diameter ratio and contraction angle were varied, together with the injection pressure, to find the water column’s breakup length. Photographs of the water jet at the nozzle’s exit, gave a clue as to identify the occurrence of cavitation and a hydraulic flip. On the other hand the water column’s breakup length and trajectory, in a subsonic crossflow, were measured by using a stroboscope in conjunction with a high speed CCD camera. Results agreed with previous literature that the breakup length grew with greater liquid/air momentum flux ratios for non-cavitating flows. This was true regardless of the injector nozzle. The rate of increase decreased at the inception of cavitation. On the other hand even shorter breakup lengths were observed at the inception of a hydraulic flip due to the detachment of the water jet from the internal surface of the nozzle. Increasing the nozzle’s length-to-diameter ratio eliminated the occurrence of hydraulic flip. The jet’s trajectory was correlated with the liquid/air momentum flux ratio and the nozzle’s exit diameter. The results showed that higher water jet trajectories were measured under non-cavitating conditions. Even shorter jet trajectories were measured at the inception of a hydraulic flip.

Hawk Turbine AB tillverkar mindre jetmotorer som ofta används i små obemannade och radiostyrda flygplan. I flygplansmodellen Lockheed T-33 Shooting Star är motorn monterad inuti planet varför luften måste ledas ut till atmosfären. För bästa möjliga prestanda måste ejektorn och utblåsröret som leder luften dimensioneras efter motor och flyghastighet. En 3-dimensionell CAD modell av flygplanets installation skapades och därefter simulerats i en virtuell vindtunnel med hjälp av datorprogrammet SolidWorks Flow Simulation. Flera olika utblåsrör i varierande storlekar samt olika former har testats för att avgöra om ändringar kan förbättra prestandan ytterligare. Simulationsresultat visar att det går att förbättra nuvarande konfiguration med 5,99 % om diametern på utblåsröret minskas från 75 mm till 70 mm med en bibehållen form på utblåsröret. / Hawk Turbine AB is a company that manufactures small jet engines which are often used in smaller unmanned and radio-controlled aircrafts. In the Lockheed T-33 Shooting Star aircraft the engine is mounted in the center of the aircraft and therefore requires ducts to be used for directing the exhaust to the atmosphere. For optimum performance the ejector and the exhaust manifold must be designed for the engine and the flight velocity. A 3-dimentional CAD model of the aircrafts ducts was created. The model was then used in virtual wind tunnel testing using the software SolidWorks Flow Simulation. Different shapes and sizes of the manifolds were tested in the simulations to determine if modifications can further improve the performance. The simulations show that the performance of the current manifold can be improved by 5,99 % if the diameter of the manifold is reduced from 75 mm to 70 mm while keeping the shape of the manifold unaltered.

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Fusion power has the potential to produce clean and safe energy that can contribute significantly to the worlds energy system. The road to this promising energy resource has been long, but with one of the biggest projects in the scientific area that is now on going, a fusion project called ITER, the end of the road is ahead of us. Experiments with a new reactor wall are now in progress at the fusion test reactor JET in Oxford, England.  The experiment is a pre study of a possible reactor wall for the new fusion reactor ITER in Cadarache in Provence-Alpes-Côte-d'Azur, France. The ITER like reactor wall (ILW) contains Beryllium and has theoretically favourable properties for achieving better reactor conditions, compared to the old Carbon based wall (CW). One reason for changing the wall is to decrease the fuel dilution, i.e. amount of particles that the reactor wall contributes to the fusion plasma. This is an important factor to minimize; 1% of fuel dilution with Carbon will cause a loss in power up to 12%, while the corresponding value for Beryllium is 8%. For Deuterium fuelled plasmas at JET, the fuel dilution can be quantified by the ratio of the Deuterium and electron densities, nd/ne. In this work, nd/ne is estimated using data from the neutron emission spectrometer TOFOR, along with measurements of the electron density (ne) and temperature (Te). In this report it is investigated how sensitive these fuel dilution measurements are to uncertainties in the measurements of ne and Te. The fuel dilution measurements changed relatively in a span of 10% to 23% when changing Te and ne with 10% in the fuel dilution model. To determine the differences in fuel dilution between the Carbon and ITER like reactor wall, a comparison has to be made between the old reactor wall and the new ILW. To do this, similar plasma scenarios need to be represented during fusion discharges with both walls. In this report, JET’s database is searched through using different search criteria, in order to enable a fair comparison between the walls. The comparison showed a tendency of lower fuel dilution, i.e. cleaner plasmas, for discharges with the ILW, but the data points are quite scattered and the ILW discharges have, in general, a lower temperature than the CW discharges, which makes the comparison difficult. Therefore, it is too early to definitely tell anything about a possible improvement of the fuel dilution levels after the installation of the ILW.