Force Measurement Device for Semi-Submerged Bodies

Abstract

Submerged and semi-submerged bodies experience unique forces acting upon them. This thesis will experimentally investigate the drag and resultant forces acting on submerged and semi-submerged bodies with varying velocities and angles of attack. A sphere was used to calibrate the experimental test apparatus to ensure data collected was valid in comparison to historical data. A test apparatus was designed out of aluminium sections and a 1KN load cell was used to measure the forces acting on each of the test objects. The output from the load cell was averaged over 60 measured data points for each fixed velocity and angle of attack. The result, when converted into coefficient form, was a close match to historical data which implied the experimental test apparatus is accurate. It can then be used to explore the forces involved in more complex shapes in semi-submerged/ planning conditions. Data for a ski shape was taken and the result was an exponential Cd v Re curve which aligns with the graph for the drag equation as expected. Overall the results taken in tests with the experimental test apparatus align with theoretical and historical values which proves that the apparatus functions as intended and can be used as a method of measuring forces on submerged and semi-submerged objects in the future.