Performance simulations of a hydraulic-mechanical damper for a steerable thruster
Tiainen, Olli (2017)
2017
Automaatiotekniikka
Teknisten tieteiden tiedekunta - Faculty of Engineering Sciences
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Hyväksymispäivämäärä
2017-06-07
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201705241465
https://urn.fi/URN:NBN:fi:tty-201705241465
Tiivistelmä
This master’s thesis consists of designing and modelling a damper system for a Wärtsilä Steerable Thruster. Aim is to reduce torque peaks caused by ice impacts on the propeller shaft of the thruster. A passive ideal damper as well as a novel hydraulic-mechanical damper are modelled and the effects of the damper are simulated in varied ice impact scenarios.
Simulated ice impact cases are generated to be similar to the ones of Det Norske Veritas regulations. In addition further custom ice impacts with variable sinusoidal impact lengths are generated. Simulations are conducted without a damper, with a passive ideal damper and with the novel hydraulic-mechanical damper. A validated simulation model of the WST-14 propulsion system is given for use in this master’s thesis by Tampere University of Technology Laboratory of Automation and Hydraulics.
Novel hydraulic-mechanical damper is a rotating dual-mass torsional damper. Damper consists of two main inertias; a damper case and a damper wheel, as well as hydraulic spring and damping elements. Both active and semi-active variations of the damper are considered.
Simulation results of the hydraulic-mechanical damper are studied and it is acknowledged that the damper has reasonable effect on reducing torque peaks on some impact cases and negligible or even inverse effects on certain impact cases. Most significant results of the hydraulic-mechanical damper are torque peak reduction of 8.6 % in the propeller shaft and maximum peak-to-peak reduction of over 40 %. In certain ice impact cases the simulation results show a falling torque peak reduction of maximum of 9 kNm, or over 15 % of the falling torque, resulting in prevention of gear hammering.
Simulated ice impact cases are generated to be similar to the ones of Det Norske Veritas regulations. In addition further custom ice impacts with variable sinusoidal impact lengths are generated. Simulations are conducted without a damper, with a passive ideal damper and with the novel hydraulic-mechanical damper. A validated simulation model of the WST-14 propulsion system is given for use in this master’s thesis by Tampere University of Technology Laboratory of Automation and Hydraulics.
Novel hydraulic-mechanical damper is a rotating dual-mass torsional damper. Damper consists of two main inertias; a damper case and a damper wheel, as well as hydraulic spring and damping elements. Both active and semi-active variations of the damper are considered.
Simulation results of the hydraulic-mechanical damper are studied and it is acknowledged that the damper has reasonable effect on reducing torque peaks on some impact cases and negligible or even inverse effects on certain impact cases. Most significant results of the hydraulic-mechanical damper are torque peak reduction of 8.6 % in the propeller shaft and maximum peak-to-peak reduction of over 40 %. In certain ice impact cases the simulation results show a falling torque peak reduction of maximum of 9 kNm, or over 15 % of the falling torque, resulting in prevention of gear hammering.