An Experimental Study of the Vortical Flow Induced by a Free-surface Piercing Plate
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
In this thesis the vortical flow induced by a free-surface piercing plate is investigated using several methods. The plate has a beveled edge and is inserted perpendicular to the flow in a water channel. The flow pattern dependency of the Froude number is investigated using flow visualisation to map the flow around the plate and how it develops with increasing insertion depth and velocity. The conclusion of the investigation is that waves originate at both sides of the plate for different values of the Froude number. For Froude number equal to 2.2504 waves was produced in the depression downstream from the plate. The flow pattern for a small insertion depth and varying velocity is investigated with the result that the recirculation area grows larger with increasing velocity until 0.2475 m/s when it is significantly smaller again. The reattachment and separation point of the flow is investigated using both flow visualisation and particle image velocimetry. The results from the two methods differ significantly, indicating that the reattachment and separation point is not located at a constant position. The results from the investigations with particle image velocimetry is analysed using proper orthogonal decomposition to find hidden structures in the data and thereby find a frequency in the shedding of vortices. The angle of the flow under the plate is investigated and a dependency of the Reynolds number is suggested. The surface level difference upstream and downstream of the plate is also investigated which generated a function of the Froude number.Finally is an investigation of the reconnection of the vortical flow with the free surface initiated, which resulted in a conclusion that the deformation of the surface is dependent on the flow velocity.
Place, publisher, year, edition, pages
2013. , 70 p.
Teknik, vortical flow, vertical plate, water channel, free surface, experimental, Froude number, Reynolds number, waves, recirculation, separation, reattachment, surface deformation, flow visualisation, particle image velocimetry, proper orthogonal decomposition, frequency, surface level, rotation, shear deformation, laser, hydrogen bubbles
IdentifiersURN: urn:nbn:se:ltu:diva-46156Local ID: 3cb36f5c-5a18-440d-ab7b-ceb2ab110f2fOAI: oai:DiVA.org:ltu-46156DiVA: diva2:1019469
Subject / course
Student thesis, at least 30 credits
Engineering Physics and Electrical Engineering, master's level
Lundström, StaffanSheridan, John
Validerat; 20130914 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved