Numerical analysis of performance of wavebreakers exposed to regular waves in static and floating configuration

In the present paper we investigate, through numerical analysis, the hydrodynamic behavior of wavebreakers both in static and in floating configuration. The aim is to evaluate and compare the performance of wavebreakers in regular waves in the range of intermediate depth waters. The analysis is performed through evaluation of the waves transmitted downward and reflected back and the dissipative behavior of the wavebreaker. We simulate numerically the fluid dynamic field using the Unsteady Reynolds Averaged Navier Stokes equations (URANS) with the k − ε turbulence model, both for the water and the air phases, using the Volume of Fluid (VOF) method to detect the interface. We simulate a numerical wave tank, generating the waves at a lateral boundary of the domain and allowing its own propagation into the domain. First we study the static configuration of the wavebreaker, so it is considered fixed in space. Afterward, we consider the wavebreaker as a rigid body with a Single Degree of Freedom (SDOF) in the vertical direction and we analyze the interaction between the wave system and the structure. With this purpose we use the URANS equations over a dynamic mesh in conjunction with a Fluid–Structure-Interaction (FSI) algorithm, where the mesh displacement is associated to the body’s motion through a diffusive Laplace equation; the motion of the solid body is evaluated using the momentum equation of a rigid body subject to hydrodynamic loading. We study two different wavebreakers, the rectangular one and the Π shape one, and evaluate the differences in terms of transmitted, reflected and dissipated energy. First we assess the algorithm of generation and propagation of the regular waves comparing numerical results with analytical data. Afterward, we evaluate the performance of the two wavebreakers in terms of coefficients of transmission, reflection and dissipation and we compare our numerical results with data from the standard Wiegel Theory, 1960 and successive modifications. Finally, we study the performance of the wave system in presence of the floating body. This is done in two steps: we initially validate the results with those of the analytical solution of the governing equation of a SDOF rigid body forced by regular wave trains; successively we calculate the transmission coefficients for a number of waves with different length and height and compare the results with literature empirical formulas

Modelling and Simulation of Variable Displacement Vane Pumps for IC Engine Lubrication

The paper presents geometric, kinematic and fluid-dynamic modelling of variable displacement vane pumps for low pressure applications in internal combustion engines lubrication. All these fundamental aspects are integrated in a simulation environment and form the core of a design tool leading to the assessment of performance, critical issues, related influences and possible solutions in a well grounded engineering support to decision

Displacement vs flow control in IC Engines lubricating pumps

Scope of this work is to analyse potentials in terms of efficiency of two pump units belonging to two families: the first intervening on the maximum volume generated by variable volume chambers (e.g. a vane pump where eccentricity is varied), the second that changes the quantity of fluid being sucked or delivered (e.g. a gear pump with variable timing). In more detail the comparison will be established between a vane pump where displacement is varied through eccentricity and an internal gear pump of Gerotor type where flow rate is controlled through a rotating sector that alters the effective geometry of kidney ports. A detailed simulation of the two solutions brings to evidence the advantages of the first approach with respect to the second as confirmed by experimental investigations

Mechanical combustion-engine-driven fluid pump (Magnetorheological Electrodynamic Permanent Magnet Clutch) [US9976606 - US2015260240A1]

A mechanical combustion-engine-driven fluid pump includes an input shaft driven by a combustion engine, a pumping unit comprising a pump rotor, and a clutch arranged between the input shaft and the pump rotor. The clutch comprises an input clutch body, an output clutch body, an electroconductive element, a permanent magnet element, and an actuator. The clutch transfers a rotation of the input clutch body to the output clutch body in an engaged clutch state. The closed clutch liquid gap is formed between the input clutch body and the output clutch body, and is filled with a magneto-rheological clutch liquid. The electroconductive element co-rotates with the output clutch body. The permanent magnet element co-rotates with the input clutch body and is shiftable between an engaged position and a disengaged position. The actuator moves the permanent magnet element between the engaged position and the disengaged position

Mechanical combustion-engine-driven fluid pump (Magnetorheological Multidisk Permanent Magnet Clutch) [US10024322 - US2015308432A1]

A fluid pump includes an input shaft, a pumping unit comprising a pump rotor, and a clutch arranged between the input shaft and the pump rotor. The clutch comprises at least two input clutch disks, at least two output clutch disks, a permanent magnet element, and an actuator. The at least two input clutch disks and the at least two output clutch discs together define at least two clutch liquid gaps which are filled with a magneto-rheological clutch liquid. The permanent magnet element shifts between an engaged position wherein a magnetic field of the permanent magnet element penetrates the at least two clutch liquid gaps with a high magnetic flux, and a disengaged position wherein the magnetic field of the permanent magnet element is less than in the engaged position. The actuator moves the permanent magnet element between the engaged position and the disengaged position