Laboratory tests of propeller blade profile pressure distribution under ice contact. Volume II

A test series of propeller blade profile pressure distribution during ice interaction was performed in a small ice tank in February and March 1993. The profile geometry was in scale 1:1 with a part of an existing propeller design. The impact speed and kinetic energy were produced by means of a pendulum rig. The pendulum was able to give the blade profile a speed of 8 m/s. The ice sheet thicknesses grown from natural sea water were 20 cm. The main parameters in the test matrix were the angle of attack and width of the cut ice. Altogether 46 individual tests were performed. The pressure distribution was measured with piezoelectric pressure sensitive elements. In addition to the pressure distribution, global loads and accelerations of the blade profile were measured. Visual observations were made with high speed filming. Thin sections were made of ice samples at the location of indentation. The interaction process was found to be cyclic. Ice was crushed and extruded cyclically when the blade proceeded. The cycles were associated with peaks in the load time histories. With normal angles of attack the majority of the pressures were acting on the back side of the blade and the face side received very small loads. The ice flaked and spalled away from the leading edge towards the free edge of ice before any real contact was developed at the face side. The resultant load was acting on the face side only when the angle of attack was large and when there was no contact at the back side. The load was concentrated in a very small area behind the leading edge. The absolute values of the pressures were not very high but they were clearly temperature dependant. The full set of time histories are presented in this report, volume II. The tests and their analysis are presented in detail in volume I.