Journal Papers by Stefano Gaggero
Journal of Marine Science and Engineering, 2023
A pre-swirl fin (PSF), pre-swirl duct (PSD) and wake-equalizing duct (WED) energy-saving devices ... more A pre-swirl fin (PSF), pre-swirl duct (PSD) and wake-equalizing duct (WED) energy-saving devices (ESD) are designed for the Duisburg Test Case (DTC). To this aim, a simulation-based design optimization method, combining RANSE analyses (ship resistance) with BEM calculations
(unsteady propeller performances) in a simplified optimization process realized through a parametric description of ESD geometries, was employed. Fully resolved RANSE analyses were used to validate
the outcomes of this affordable design process, which identifies devices capable of saving energy in the delivered power for this type of challenging test case by up to 2.6%. Comparisons with model-scale calculations, furthermore, permit us to discuss the influence of each appendage in different flowfields (model- and full-scale, as well as under the action of the simplified or the resolved propeller) and the reliability of the full-scale extrapolation methods recently proposed for these types
of devices.
Ocean Engineering, 2023
The design of pumpjet propulsors (PJP) is addressed through a simulation-based design optimizatio... more The design of pumpjet propulsors (PJP) is addressed through a simulation-based design optimization approach built on a parametric description of the main geometrical characteristics of the system, a RANSE solver with mixing plane interface capabilities and a genetic algorithm. Both Rotor/Stator (PJP-R/S) and Stator/Rotor (PJP-S/R) configurations are considered and optimal designs from a multi-objective optimization process aimed at maximizing the propulsive efficiency at the lowest possible cavitation inception index are compared to a reference ducted propeller with decelerating nozzle (Gaggero et al., 2012), which served as baseline during the design. Detached Eddy Simulations (DES) were finally carried out to highlight, in addition to the performance improvements provided by the PJPs, also the influence of the rotor/stator/nozzle interactions on the vortical structures shed by the propulsor.
Ocean Engineering, 2023
The objective of the present study is to investigate, by means of velocimetric measurements, the ... more The objective of the present study is to investigate, by means of velocimetric measurements, the flow field generated by a marine propeller running with inclined shaft. Measurements have been carried out on a scaled model of a propeller in the cavitation tunnel of UNIGE using Laser Doppler Velocimetry (LDV) and the acquired data have been post-processed applying the ensemble average technique. The propeller configuration includes shaft appendages as in a typical twin screw vessel configuration. The tests have been performed also without propeller, considering different velocities, in order to characterize the incoming flow field and analyse possible effects on propeller flow. The complete 3-D flow field has been measured considering four transverse sections at different longitudinal locations, from upstream to downstream of the propeller, focusing on the near field wake. A longitudinal plane containing the propeller shaft has been considered as well. A dedicated interpolation technique is presented to improve the spatial resolution of data and allow advanced analyses. Results allow analysing the main characteristics of the flow field, including the evolution of its main structures. The effects of non uniform inflow conditions caused by the oblique flow are analysed focusing on the dynamics of vortexes and in particular on the trajectories and strength of the vortexes.
Engineering Applications of Artificial Intelligence, 2023
For propeller-driven vessels, cavitation is the most dominant noise source producing both structu... more For propeller-driven vessels, cavitation is the most dominant noise source producing both structure-borne and radiated noise impacting wildlife, passenger comfort, and underwater warfare. Physically plausible and accurate predictions of the underwater radiated noise at design stage, i.e., for previously untested geometries and operating conditions, are fundamental for designing silent and efficient propellers. State-ofthe-art predictive models are based on physical, data-driven, and hybrid approaches. Physical models (PMs) meet the need for physically plausible predictions but are either too computationally demanding or not accurate enough at design stage. Data-driven models (DDMs) are computationally inexpensive ad accurate on average but sometimes produce physically implausible results. Hybrid models (HMs) combine PMs and DDMs trying to take advantage of their strengths while limiting their weaknesses but state-of-the-art hybridisation strategies do not actually blend them, failing to achieve the HMs full potential. In this work, for the first time, we propose a novel HM that recursively correct a state-of-the-art PM by means of a DDM which simultaneously exploits the prior physical knowledge in the definition of its feature set and the data coming from a vast experimental campaign at the Emerson Cavitation Tunnel on the Meridian standard propeller series behind different severities of the axial wake. Results in different extrapolating conditions, i.e., extrapolation with respect to propeller rotational speed, wakefield, and geometry, will support our proposal both in terms of accuracy and physical plausibility.
Journal of Marine Science and Engineering, 2023
Tip loading is a common strategy to increase the propulsive efficiency of propellers. Solutions s... more Tip loading is a common strategy to increase the propulsive efficiency of propellers. Solutions such as contracted and tip-loaded (CLT) and “New generation” CLT propellers exploit the presence of an endplate (“true” or as the result of a dedicated modification of the rake distribution) to sustain the increased load at the tip of the blade, at the cost of more complex vortical structures. Their evolution, and the mutual interaction of secondary vortices originated by the endplate itself, however, has not
been completely and deeply investigated. The current paper addresses this topic by improved delayed detached eddy simulations (IDDES) of the flow field around two propellers of this type at different loading conditions. The presence of secondary vortices from the endplate root (or from the bended blade at tip), partially observed in recent experiments, is evidenced by high-fidelity CFD calculations.
The interaction mechanism with the primary vortices (those from the endplate tip), and the resulting strengthening of the vortical structures, also through the interactionwith the blade trailing vortical wake that promote the leapfrogging phenomenon, is discussed as well, comparing the phenomena in the case of two optimally designed geometries (a CLT and a New Generation CLT propeller) exploiting the same pressure side tip-loading concept in a slightly different way. Results show a rather different instability mechanism depending on the endplate configuration and open the discussion on the effectiveness of splitting a single tip vortex into pairs of vortical structures that may induce similar (or even worse) side effects in terms of pressure minima in the wake and earlier wake destabilization.
Applied Ocean Research, 2022
A Simulation Based Design Optimization method for marine propellers design using a two-fidelity l... more A Simulation Based Design Optimization method for marine propellers design using a two-fidelity levels metamodel for global design space exploration and optimization is presented. Response surfaces are built using the co-Kriging approximation, i.e. a multi-output Gaussian process that combines large low-fidelity dataset with few, costly, high-fidelity data. The method is applied for the hydrodynamic shape optimization of the E779A propeller using, as fidelity levels, two different physical models for the propeller performances prediction, namely an inviscid, potential based Boundary Element Method (low-fidelity) and a viscous, finite volume RANS solver (high-fidelity). Results demonstrate the feasibility of multi-objective, constrained, design procedures, like those involving marine propellers, using these multi-fidelity response surfaces. At the same time, the need of good correlations between low-and high-fidelity data feeding the response surfaces is highlighted as a requisite for robust and reliable predictions using these approximated methods.
Applied Ocean Research, 2021
The performances of different Propeller Boss Cap Fins devices, designed with the aid of a Simulat... more The performances of different Propeller Boss Cap Fins devices, designed with the aid of a Simulation Based Design Optimization approach, are analysed and compared. A novel configuration, i.e., a PBCF inside a nozzle, is investigated in an effort to mitigate possible side effects of conventional Propeller Boss Cap Fins, such as secondary vortical structures from the fins tip, increased pressure pulses and radiated noise, without excessive worsening of the beneficial effects (increased propulsive efficiency) provided by this energy saving device. Detailed analyses reveal, instead, the destabilizing effect of the hub vortical structures on the blade tip vortex evolution, determining a substantial increase of the radiated noise of this type of propulsors.
Ship Technology Research, 2021
Pre-and post-swirl fins-based energy-saving devices (ESD) are designed to improve the propulsive ... more Pre-and post-swirl fins-based energy-saving devices (ESD) are designed to improve the propulsive performances of a twin-screw ship. To this aim, BEM and RANSE calculations are employed. Depending on the application, a simple actuator disc model (post-swirl) with radially varying load or a combined BEM/RANSE method for self-propulsion prediction (preswirl) are required. Both the approaches are included in a framework for a design by optimization, where systematic variations of the ESD geometry are used to explore the design space and maximize the energy-saving effect of the devices. Considering the particularity of the case selected for the study, results show encouraging improvements that reach a promising 5% in the case of the combined action of both devices.
Ocean Engineering, 2021
A design method for pre-swirl stators energy saving devices, using a combined BEM-RANSE approach,... more A design method for pre-swirl stators energy saving devices, using a combined BEM-RANSE approach, is proposed. RANSE calculations, using actuator disks, are employed to provide the required thrust and the effective wake to an unsteady Boundary Element Method through which the rate of revolution of the propeller and its averaged performance in self-propulsion are evaluated. An automatic variation of the pre-swirl geometry, driven by an optimization algorithm that operates on the parameters defining the device, realizes an automatic "try-and-error" process, which is used as a design tool for the maximization of the energy saving effect. Results obtained for different numbers of stator fins show outstanding improvements, up to a reduction of the required shaft power of about 8%.
Ships and Offshore Structures, 2020
The numerical study presented in Part I (Gaggero, 2020), focused on the prediction of the laminar... more The numerical study presented in Part I (Gaggero, 2020), focused on the prediction of the laminar-to-turbulent boundary layer transition on model scale propellers, is extended to cavitating conditions. In the previous study, the application of the γ-Re θ Local Correlation Transition Model allowed for significant improvements in model scale performance prediction and highlighted the role of the turbulence intensity on the transition onset. In this second part of the study, the influence of the same transition model on the inception and development of cavitation is considered. To this aim, a modification of the Schnerr-Sauer mass transfer model, useful for engineering-oriented applications, is proposed to account for the role of the laminar boundary layer in the inception and development of the leading edge sheet cavitation. The proposed analyses, compared with the available measurements at the cavitation tunnel, confirm the improvements of the numerical predictions using the modified model.
Ships and Offshore Structures, 2020
The influence of the laminar-to-turbulent boundary layer transition on model scale propellers cha... more The influence of the laminar-to-turbulent boundary layer transition on model scale propellers characteristics is investigated using the γ-Re θ model. OpenFOAM and StarCCM+ RANSE solversare used for the investigation, which is carried out for two test cases. Available measurements at a sufficiently low rate of shaft revolution (i.e. Reynolds number)are used to assess the capabilities of the model in improving model scale predictions. This first part of the study is focused on fully wetted conditions, considering the influence of grid resolution and inflow turbulent intensity on the transition onset predicted by the model. The influence of the laminar-to-turbulent transition on the inception and development of cavitation, and the capabilities of predicting such phenomena using a modified mass transfer model, are discussed in the second part of the study (Gaggero, 2020. Influence of Laminar-to-Turbulent transition on model scale propeller performances. Part II: cavitating conditions. Ship and Offshore Structures).
EDIT: the paper can be downloaded for free from: https://www.tandfonline.com/eprint/VBGASVDDGSMCR5NSHYXY/full?target=10.1080/17445302.2020.1863658
Ocean Engineering, 2020
The representation and the variation of hull shapes are two challenging problems in naval archite... more The representation and the variation of hull shapes are two challenging problems in naval architecture due to the complexity of the geometry and to the need to ensure the fairness of the surfaces. Conventional CAD techniques are widely used to accurately describe the hull shape. However, they are rather complex to be easily used to generate hull shape variations due to the great number of variables involved. We propose a study to highlight the pro and cons of the application of space reduction techniques, usually referred to as Reduced Order Models (ROMs), to create a parametric model for both global and local hull shape variations. A geometric transformation relying on the Proper Orthogonal Decomposition (POD) method is applied on top of a combined subdivision surface-Free Form Deformation (FFD) approach conceived for modeling and variation of hull shapes. The analysis focuses on highlighting the geometric meaning of the new POD basis functions and on how this model affects the variability of the explored design space. Two studies are developed in order to show possible applications of this technique. In the first one a new set of selection criteria for the POD modes based on geometric considerations are proposed to use it on uncorrelated geometric domains. In the latter the large-dimensional space of the so-called Design Velocities (DV), related to the shape sensitivity, is reduced by using the POD approach to create a new transformation of the hull shape.
Ocean Engineering, 2020
The importance of reducing the noise impact of ships is being recognised worldwide. Consequently,... more The importance of reducing the noise impact of ships is being recognised worldwide. Consequently, the inclusion of this principle among the objectives and constraints of new designs is becoming a standard. For this reason, considerable attention is given to the propeller being often the dominant source of underwater radiated noise, especially when cavitation occurs, as it happens in most cases when a ship sails at design speed. The designers of quieter propulsion systems require the availability of predictive tools able to verify the compliance with noise requirements and to compare the effectiveness of different design solutions. In this context, tools able to provide a reliable estimate of propeller noise spectra based just on the information available during propeller design represent a fundamental tool to speed up the design process avoiding model scale tests. This work focuses on developing a tool able to predict the cavitating marine propeller generated noise spectra at design stage exploiting the most recent advances in Deep Learning, able to take advantage of both structured and unstructured data, and in hybrid modelling, able to exploit both data and physical knowledge about the problem. For this purpose authors will make use of a dataset collected by means of dedicated model scale measurements in a cavitation tunnel combined with the detailed flow characterisation obtainable by calculations carried out with a Boundary Element Method. The performance of the proposed approaches are analysed considering different scenarios and different definitions of the input and output variable used during the modelisation.
Journal of Marine Science and Engineering, 2020
Ducted propellers are unconventional systems that are usually adopted for ship propulsion. These ... more Ducted propellers are unconventional systems that are usually adopted for ship propulsion. These devices have recently been studied with medium-fidelity computational fluid dynamics code (based on the potential flow hypothesis) with promising results. However, these tools, even though they provide a good prediction of the forces and moments generated by the blades and the duct, are not able to provide insight into the flow field characteristics due to their crude flow approximations. On the contrary, modern high-fidelity viscous-based computational fluid dynamics codes could give a better description of the near and far-field flow of these particular devices. In the present paper, forces and the most significant features of the flow field around two ducted propellers are analyzed by means of both experimental and computational fluid dynamics approaches. In particular, accelerating and decelerating ducts are considered, and we demonstrate the ability of the adopted solver to accurately predict the performance and the flow field for both types. These results, in particular for the less-studied decelerating duct, designate CFD as a useful tool for reliable designs.
Applied Ocean Research, 2020
Wake equalizing duct (WED) Hydrodynamic shape optimization Reynolds averaged navier stokes (RANS)... more Wake equalizing duct (WED) Hydrodynamic shape optimization Reynolds averaged navier stokes (RANS) Simulation based design optimization (SBDO) Japab bulk carrier (JBC) A B S T R A C T We propose a Simulation-Based Design Optimization (SBDO) approach for the design of an Energy Saving Device (ESD) based on the Wake Equalizing Duct (WED) concept. Pre-Ducts, like Wake Equalizing Ducts, reduce the wake losses, improve the propeller-hull interaction and generate an additional thrust. An integrated design approach, relying on a parametric description of the duct geometry of the WEDs and on a RANSE method, managed by a global convergence optimization algorithm, is developed to maximize the delivered thrust. The Japan Bulk Carrier (JBC) test case, for which model scale experimental data on the effectiveness of the WED are available in the literature, is considered as a baseline. Results obtained by using the adaptive, fully automated proposed design framework highlight significant improvements of the overall propulsive efficiency when the Pre-Duct design is tailored to the actual hull wake shape. In addition, off-design conditions are considered to verify the robustness of the proposed designs with respect to variations of the working point and discuss the opportunity of a robust optimization process.
Applied Ocean Research, 2020
A simulation-based design optimization (SBDO) tool is proposed for the design of rim driven thrus... more A simulation-based design optimization (SBDO) tool is proposed for the design of rim driven thrusters. The optimization framework consists of a parametric description of the rim blade geometry and a multi-objective optimization algorithm which makes use of the results from high-fidelity RANS calculations to drive the choice towards optimal blade shapes. Maximization of the propulsive efficiency and minimization of cavitation, monitored through the simplest cavitation inception criterion based on the analysis of the non-cavitating pressure distribution over the blade, are the contrasting objectives selected for the design. A constraint on the delivered thrust fixes the functioning condition of the devised propellers. Four distinct design runs, changing the number of blades, from three to six, are considered. The reference performance are those of a ducted propeller operating in a decelerating nozzle which is exactly used in the case of rim configuration. Results of the optimizations prove the flexibility and the reliability of the SBDO framework in dealing with unconventional configurations. A generalized reduction of the risk of cavitation is observed regardless the number of blades; five-and six-bladed propulsors ensure remarkable (about 40%) higher margins with respect to any (leading edge and midchord) cavitating phenomena at the cost only of a slight reduction of efficiency. Also, the structure of the tip vortexes results significantly modified.
Applied Ocean Research, 2019
Achieving a reliable and accurate numerical prediction of the self-propulsion performance of a sh... more Achieving a reliable and accurate numerical prediction of the self-propulsion performance of a ship is still an open problem that poses some relevant issues. Several CFD methods, ranging from boundary element methods (BEM) to higher-fidelity viscous Reynolds averaged Navier-Stokes (RANS) based solvers, can be used to accurately analyze the separate problems, i.e. the open water propeller and the hull calm water resistance. However, when the fully-coupled self-propulsion problem is considered, i.e. the hull advancing at uniform speed propelled by its own propulsion system, several complexities rise up. Typical flow simplifications adopted to speed-up the simulations of the single analysis (hull and propeller separately) lose their validity requiring a more complex solver to tackle the fully-coupled problem. The complexity rises up further when considering a maneuver condition. This aspect increases the computational burden and, consequently, the required time which becomes prohibitive in a preliminary ship design stage. The majority of the simplified methods proposed in literature to include propeller effects, without directly solve the propeller flow, in a high-fidelity viscous solver are not able to provide all the commonly required self-propulsion coefficients. In this work, a new method to enrich the results from a body force based approach is proposed and investigated, with the aim to reduce as much as possible the computational burden without losing any useful result. This procedure is tested for validation on the KCS hull form in self-propulsion and maneuver conditions.
Applied Ocean Research, 2019
A computational framework for hydrodynamic shape optimization of complex ship hull form is propos... more A computational framework for hydrodynamic shape optimization of complex ship hull form is proposed and applied to improve the calm water performance of the KRISO Container Ship (KCS). The framework relies on three key features: a novel shape morphing method based on a combination of subdivision surfaces and free form deformations, a robust three dimensional viscous computational fluid dynamic solver based on the openFOAM open-source libraries and a Gaussian process-response surface method (GP-RSM) based on ordinary Kriging model which has been created to speed-up the evaluation of the quantity of interest (QoI) of the design process. The accuracy of the hydrodynamic solver is proven by comparing the obtained results against available experimental measurements. A preliminary sensitivity analysis on the mesh size has been carried out aiming at reducing the computational burden required by the CFD predictions. Three GP-RSMs have been trained relying on increasing number of hull designs. Each surrogate model has been cross-validated by both leave-one-out and k-fold techniques. The behaviours of these multi-dimensional surfaces have been analyzed in details by sampling the investigated design space with 10 7 points according to a Full-Factorial algorithm, highlighting the regions of maximum deviation with respect to the resistance of the reference hull. The three optimum designs provided by the corresponding GP-RSM models have been verified by using high-fidelity CFD simulations with a refined mesh configuration. Calm water resistance, wave patterns and pressure distributions over the selected hull surfaces have been discussed in the light of the generated shape variations.
Ship and Offshore Structures, 2019
A proper orthogonal decomposition (POD)-based method is proposed to reduce the dimensions of the ... more A proper orthogonal decomposition (POD)-based method is proposed to reduce the dimensions of the design space for the shape optimisation of marine propellers. The effectiveness of the proposed approach is proven in the case of the INSEAN-E779A propeller, which blade shape is modified to maximise efficiency while reducing suction side cavitation. The 23-dimensions design space defined by the conventional shape representation is reduced by the POD method to 5, 12 and 15 dimensions, retaining up to the 98% of the geometric variance of the original space. A multi-objective optimisation algorithm drives the simulation-based design optimisation (SBDO) process in the new design spaces using BEM for the hydrodynamic predictions. Finally, optimal designs are verified using RANSE to assess the correlation between the performance improvements, the dimensionality reduction and the corresponding geometric variance. The effectiveness of the proposed POD-SBDO framework is discussed with respect to a design by optimisation process relying on the conventional parametric representation of the blade geometry.
In the context of the low speed and high drift angles manoeuvres, a limited number of experimenta... more In the context of the low speed and high drift angles manoeuvres, a limited number of experimental test cases are available in open literature. Consequently, the ability to reliably predict the hull forces (and the related hydrodynamic coefficients) via computational fluid dynamics calculations may represent a significant added value to further tune or to generate new simplified hull forces models to be employed in a manoeuvring code. Even if some applications can be found in the literature for selected cases and conditions, as those considered in the present work, a more systematic comparison is mandatory to confirm the reliability of these numerical approaches. In light of this, in the present work a systematic application of the open-source viscous-based flow solver OpenFOAM to predict forces at low-speed manoeuvring conditions for two ship test cases (the KCS and the KVLCC) is presented. The proposed numerical setup, specifically designed to be applied in the early ship design stage (limiting computational effort), shows a satisfactory accuracy to cope with the strong off-design conditions related to these specific ship operative conditions. Keywords Slow speed manoeuvrability · CFD viscous code · OpenFOAM · CFD verification and validation
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Journal Papers by Stefano Gaggero
(unsteady propeller performances) in a simplified optimization process realized through a parametric description of ESD geometries, was employed. Fully resolved RANSE analyses were used to validate
the outcomes of this affordable design process, which identifies devices capable of saving energy in the delivered power for this type of challenging test case by up to 2.6%. Comparisons with model-scale calculations, furthermore, permit us to discuss the influence of each appendage in different flowfields (model- and full-scale, as well as under the action of the simplified or the resolved propeller) and the reliability of the full-scale extrapolation methods recently proposed for these types
of devices.
been completely and deeply investigated. The current paper addresses this topic by improved delayed detached eddy simulations (IDDES) of the flow field around two propellers of this type at different loading conditions. The presence of secondary vortices from the endplate root (or from the bended blade at tip), partially observed in recent experiments, is evidenced by high-fidelity CFD calculations.
The interaction mechanism with the primary vortices (those from the endplate tip), and the resulting strengthening of the vortical structures, also through the interactionwith the blade trailing vortical wake that promote the leapfrogging phenomenon, is discussed as well, comparing the phenomena in the case of two optimally designed geometries (a CLT and a New Generation CLT propeller) exploiting the same pressure side tip-loading concept in a slightly different way. Results show a rather different instability mechanism depending on the endplate configuration and open the discussion on the effectiveness of splitting a single tip vortex into pairs of vortical structures that may induce similar (or even worse) side effects in terms of pressure minima in the wake and earlier wake destabilization.
EDIT: the paper can be downloaded for free from: https://www.tandfonline.com/eprint/VBGASVDDGSMCR5NSHYXY/full?target=10.1080/17445302.2020.1863658
(unsteady propeller performances) in a simplified optimization process realized through a parametric description of ESD geometries, was employed. Fully resolved RANSE analyses were used to validate
the outcomes of this affordable design process, which identifies devices capable of saving energy in the delivered power for this type of challenging test case by up to 2.6%. Comparisons with model-scale calculations, furthermore, permit us to discuss the influence of each appendage in different flowfields (model- and full-scale, as well as under the action of the simplified or the resolved propeller) and the reliability of the full-scale extrapolation methods recently proposed for these types
of devices.
been completely and deeply investigated. The current paper addresses this topic by improved delayed detached eddy simulations (IDDES) of the flow field around two propellers of this type at different loading conditions. The presence of secondary vortices from the endplate root (or from the bended blade at tip), partially observed in recent experiments, is evidenced by high-fidelity CFD calculations.
The interaction mechanism with the primary vortices (those from the endplate tip), and the resulting strengthening of the vortical structures, also through the interactionwith the blade trailing vortical wake that promote the leapfrogging phenomenon, is discussed as well, comparing the phenomena in the case of two optimally designed geometries (a CLT and a New Generation CLT propeller) exploiting the same pressure side tip-loading concept in a slightly different way. Results show a rather different instability mechanism depending on the endplate configuration and open the discussion on the effectiveness of splitting a single tip vortex into pairs of vortical structures that may induce similar (or even worse) side effects in terms of pressure minima in the wake and earlier wake destabilization.
EDIT: the paper can be downloaded for free from: https://www.tandfonline.com/eprint/VBGASVDDGSMCR5NSHYXY/full?target=10.1080/17445302.2020.1863658
analysis: thrust/advance coefficient or torque/advance coefficient ratio are the most used variables to assess
the ship propulsion point or to match, at each selected ship speed, the selected propeller with the ship engine.
The advantages of this robust and well established procedure (standard propeller open water measures
only at some pitch ratios around the design configuration, availability of large databases and extrapolation
laws) however, turn into the drawbacks for the inclusion of different constraints and objectives, further than
the minimum fuel consumption, in the matching algorithm. On the other hand modern numerical tools and
available hardware resources let to partially substitute, in the design stage, experimental campaigns and to
collect large amount of information on propeller performances, including cavitation. In this sense numerical
computations make out of date approaches just developed to overcome the deficiency of experimental
measures. On the basis of these numerical data new algorithms for the engine-propeller matching can be developed
capable of investigate different objectives and the influence of different constraints on the traditional
optimum points.
and by propellers in particular. The main noise-generating mechanism within ship propellers is cavitation,
associated to the growing and collapse of vapour bubbles resulting from the unsteady hydrodynamic
pressure field generated on the blades. The control of propeller underwater radiated noise is therefore strictly
related to the control of cavitation phenomena, which are responsible for a larger part of the radiation. The activity
within work package 2 of the collaborative project AQUO (Achieve QUiter Oceans by shipping noise
footprint reduction, www.aquo.eu) of the 7th FP of the EU focuses on this aspect, which is analysed both from
the experimental and numerical viewpoint. The present paper reports motivations, aims and achievements of
such activity in the first year of the project.