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This paper reports a theoretical study of the power performance and environmental footprint of high-speed vessels in calm deep water, paying particular attention to a high-speed catamaran cargo vessel Faltinsen [1]. The power analysis uses a modified version of the method of Doctors and Day [2]. One modification to their approach is that the wave resistance and free surface wave profiles, have been numerically predicted using two different linear potential flow field theories; Michell thin-ship theory (Yeung and Wan [3]) and the 3D Rankine panel method (Hess and Smith [4]), respectively. We have based the latter method on the combination of the Dawson [5] upstream finite difference operator and the ‘staggered grid’ technique (Jensen et al. [6]). In addition, this paper shows how the viscosity effects modeled on the free surface layer influence the behavior of the wave resistance curves as predicted by Michell’s thin ship theory. This was done by adopting the approaches described by Tuck [7] and Lazauskas [8]. The wave resistance models were verified and validated using the examples of Wigley monohull (Lazauskas [8], Tarafder and Suzuki [9]) and catamaran (Yeung and Wan [3], Tarafder and Suzuki [10]) analytical forms, as well as on the Tuck parabolic strut (Tuck [7]). Furthermore, the resistance models were extended using free surface profile estimates at selected Froude numbers and applied to the case of a high-speed catamaran cargo vessel. The numerical results obtained were compared with published results and their accuracy and application feasibility is discussed from the perspective of preliminary high-speed vessel design. Based on the discussion above, suitable wave resistance models were selected and combined with the modified Doctors and Day [2] method giving the total resistance of the high-speed catamaran cargo vessel in the interval of Froude numbers. Having the estimates of total resistance, enables the effective power to be found. The results were compared with known results and were found to be in good agreement. Through combination of the effective power and propulsion factors, the brake power of the generic propulsion system is predicted. Taking into account the type of vessel being analyzed, the most common type of the propulsion diesel engine was selected. Finally, knowing the indicative environmental footprint of the selected engine, emission levels of Green House Gases (GHG) and solid particles were obtained. The emission results are further discussed in an ecologically friendly high-speed vessel design perspective (IMO [11, 19]). |
