Ice Propulsion Performance Calculation As per Alternative System of Propeller-Hull Interaction Coefficients

Abstract

Propulsion performance of icebreakers cannot be calculated as per the classic system of propeller-hull interaction coefficients due to high negative values of wake fractions. To overcome this difficulty, this paper applies an alternative system of propeller-hull interaction coefficients. This system consists of thrust deduction fraction, coefficient of hull effect upon thrust and coefficient of hull effect upon torque. The method suggested in this paper was used to analysis the data of ice trials for Vladivostok and Novorossiysk icebreakers. The input data in this analysis are speed in the ice field and required power. The sought values are propeller rotations per minute (RPM) and ice resistance. Propeller RPM values are compared versus the results of full-scale ice trials. Ice resistance values are compared versus the predictions based on the model test data obtained in ice basin of Krylov State Research Centre (KSRC). It is shown that at low speeds in the ice field (0.5–5.0 knots), calculated propeller RPMs have good correlation with the full-scale measurement data. This paper also gives propulsion performance calculation for Vladivostok icebreaker in 1.5-m thick ice field.