Experimental investigation of lift and drag on the NACA 4412 near the water surface

This thesis deals with hydrofoils, appendages which are a growing trend in yacht design and aimed at alleviating boats (this reduces the wetted area and therefore the drag). This thesis acknowledges the research previously done relating to hydrofoils and the testing of hydrofoils from the 1900's until now, from a military and sailing point of view. It goes through the methodology used to extract lift and drag data from tank testing in Cran field University. It goes through the approach to design a test process to extract consistent results from different foils in later stages. The works also details the manufacturing of the rig to test a hydrofoil in near surface conditions: the pro file studied is the NACA 4412, the submergence ranges from 2.5 chords to 0.1 chords, the angle of attack ranges from 10 to -1 degrees and Reynolds Number ranging from 1500000 to 910000 (0.5 to 3.0 m/s). The resulting data showed that lift decreased as the foil got closer to the free surface. With signifi cant effects being seen from a submergence of 1 chord. This project also points outs the limitations of tank testing and the effects of side struts holding the hydrofoil.