Abstract
Shipping in arctic and other ice conditions is
increasing. Modern propulsion systems often utilize
azimuthing thrusters in their various forms. When
operating azimuthing thruster equipped ships in ice
conditions, the thruster will interact with ice. One such
interaction type is an impact type contact of ice block
and thruster. The contact causes certain loading to
thruster. The contact load problem can be considered as
ice impact to steel structure. In a research project
related to developing Finnish-Swedish ice class rules,
the impact forces due to ice contact to steel structure
are dealt with a simple theoretical model and
experimental approach is used for model validation. In
this paper, the experiment setup and result examples are
presented. The experimental setup presented was used for
studying the contact force during an impact type contact.
Impacts were hit to solid ice and floating ice block,
contact point was submerged. The test device is
representing a ship and thruster structure, and is
laboratory scale equipment. The test device is a pendulum
mass with changeable impact contact head. The device
provides impact contact load measurement, pendulum motion
measurement and the ice movement measurement. In
addition, synchronized video recording was made. Tests
were performed on sea ice during March 2013. The speed
range capability for the test device is representative
for ship speed in ice channel operation. In the tests,
impact energy was varied by varying the pendulum start
level. Two sizes of hemispherical contact geometries were
used. Test results indicate distribution of energy in the
impact event, i.e. ice kinetic energy, impacting mass
kinetic energy and the rest is assumed to be drag and ice
crushing energy. The test setup can very simply be tuned
to different dynamic state to represent different
stiffness of thruster installation to ship, and it can
accommodate different contact geometries.
| Original language | English |
|---|---|
| Title of host publication | Proceedings of the 22nd IAHR International Symposium on Ice |
| Place of Publication | Singapore |
| Publisher | Nanyang Technological University |
| Pages | 410-417 |
| ISBN (Print) | 978-981-09-0750-1 |
| Publication status | Published - 2014 |
| MoE publication type | A4 Article in a conference publication |
| Event | 22nd IAHR International Symposium on Ice, ICE 2014 - Singapore, China Duration: 11 Aug 2014 → 15 Aug 2014 |
Conference
| Conference | 22nd IAHR International Symposium on Ice, ICE 2014 |
|---|---|
| Abbreviated title | ICE 2014 |
| Country/Territory | China |
| City | Singapore |
| Period | 11/08/14 → 15/08/14 |
Keywords
- azimuth thrusters
- ice loads
- marine propulsion
- ships
