Prediction of resistance reduction for ice-going ships installed with air-bubbling systems

Abstract

To investigate the drag reduction mechanism and variation in the efficiency of the air-bubbling system, we designed and conducted model ship experiments under an ice floe channel using a self-designed navigation device, force measurement system, camera observation system, and prototype of an air-bubbling system, based on a polypropylene non-refrigerated model ice. During the experiments, the navigation device allowed the ship to pitch, roll, and heave, while adjusting the air-bubbling system's gas flow rate, ship speed, and ice concentration to explore factors affecting the efficiency of the air-bubbling system. Building upon the model ship experiments, we further explored the drag reduction mechanism and effects of the air-bubbling system through coupled CFD-DEM numerical simulations. The research findings indicate that the drag reduction rate of the air-bubbling system decreases approximately linearly with increasing ice concentration and ship speed. Conversely, increasing the gas flow rate synchronously increases the drag reduction effect, albeit with a more pronounced marginal utility. Additionally, we conducted numerical calculations on the drag reduction rates of two additional ship types equipped with the air-bubbling system. Using multi-parameter linear fitting, we derived an empirical formula for estimating the drag reduction rate of the air-bubbling system under different conditions.