Abstract
The hydrodynamic effect exerted by a nozzle placed in front of a KP505 propeller on the propulsive performances is studied by using extensive numerical simulations. The influence of a NACA 0015 nozzle with a chord length of 0.3 of the propeller diameter, D, mounted at 0.2 D in front of the propeller plane is studied for a various range of relevant nozzle diameters and different angles of attack. A detached eddy simulation (DES)-based hybrid technique implemented on the ISIS-CFD finite volume solver of the Numeca’s FineTM/Marine environment is proposed to fit the purpose. Systematically conducted simulations have proven that the net thrust reflecting the overall drag, which includes the nozzle, depends on the duct size. The duct presence determines two regions of the inflow into the propeller. One is the inner region of the nozzle where the high-speed flow exists because of the contraction of the duct. The other is the outer region of the nozzle where the flow decelerates due to the duct wake. Lower- and higher-pressure coefficients on the suction and pressure sides, cover a significantly wider area than those of the case without the nozzle, leading therefore to greater thrust and torque. The existence of a critical attack angle for which the magnitude of the relative axial force becomes maximum for the smallest nozzle diameter has been noticed.
Highlights
Greenhouse gas (GHG hereafter) emissions trap and hold heat in the atmosphere and contribute to climate change
The time step was chosen depending on the minimum grid size, such that the resulting Courant number be less than unit in all the computations, as it will be described in the following
The present paper described a set of numerical simulations of the 3D viscous flow around a NACA0015 nozzle placed in front of the five-bladed KP505 propeller
Summary
Greenhouse gas (GHG hereafter) emissions trap and hold heat in the atmosphere and contribute to climate change. Intensive studies have proven that a uniform wake can be obtained by placing several flow control devices in front of the propeller They were initially devised for improving the propulsive efficiency, it has been proven that the cavitation behavior, vibration levels and maneuverability performances could be improved based on an appropriate design process. Given the multitude of the parameters that usually contribute to the performances of a tandem energy-saving device (ESD) and a propeller (nozzle diameter, the angle of attack, the relative distance between the two and so on), a series of systematic studies are still required to grasp a better understanding on how this ensemble may work efficiently from the propulsive point of view. Based on the mutual interaction between the incoming flow particulars determined by the particulars of the nozzle and propeller, a better physical insight into the flow is expected to help in designing an optimal ESD
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