In this thesis, the effect of a surging and pitching motion of a floating wind turbine on its wake as well as the effect of a surging, pitching and yawing motion on a stationary downstream turbine are analysed. Two experiments are conducted in order to address both points. The turbine models used are scale models of the DTU 10 MW turbine, and the upstream turbine is placed onto a kinematic robot which can move in all 6 degrees of freedom. The first objective is studied using Particle Tracking Velocimetry and the second objective using load cell measurements. It is found that pitch has a larger effect on the flow field in the wake than surge and that the effects of low frequency motion are more visible than those of high frequency motion. Moreover, it is found that the tracing particles are concentrated in specific areas, affecting the accuracy of the results. In future research, it should be examined why this is the case and how it can be improved. Additionally, low frequency pitch and surge had the greatest effect on the loads. A clear sinusoidal motion is visible and the mean thrust, torque, and power is increased. The effect of the high frequency motions is not visible in the results. In future studies, the wake behind a downstream turbine can also be examined using Particle Tracking Velocimetry. Moreover, the downstream turbine can also be moving rather than standing still and more movements of the turbine can be examined.

The effect of pulsations in a catalyst converter is investigated with the aim of determining if a steady flow captures the same physical phenomena as the pulsating flow. For this specific case, guide vanes are mounted in the sudden expansion to obtain a uniform inlet flow to the catalytic layers. The test rig is successfully validated against other similar measurements, done with a steady flow. The experiments are carried out with a Reynolds number of 10 , a Womersley number orders of magnitude larger than 1, but with an ratio between the fluid though time and pulsation period below one. This last part results in a quasi-static boundary condition. For the present setup different amplitudes and pulsation frequencies are investigated. It is thus shown experimentally that they have no influence on the mean flow. A repeatability study has been conducted which shows an overall repeatability of around 2%. An error is observed, where unwanted fractions of the packing block parts of the catalyst dummy. These fractions influence the velocity fields by clogging the hules of the catalyst dummy, but the influence is assumed to be small. Based on the results it is concluded that the mean flow field for this case is independent of the pulsations. When air enters the system a vortex ring appears in front of the catalyst dummy. @en