The Experts below are selected from a list of 3768 Experts worldwide ranked by ideXlab platform
Viviani Michele - One of the best experts on this subject based on the ideXlab platform.
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Predicting the cavitating marine Propeller Noise at design stage: A deep learning based approach
'Elsevier BV', 2020Co-Authors: Miglianti Leonardo, Cipollini Francesca, Oneto Luca, Tani Giorgio, Gaggero Stefano, Coraddu Andrea, Viviani MicheleAbstract: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
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HYDRO-ACOUSTIC CHARACTERIZATION OF \u201cTHE PRINCESS ROYAL\u201d Propeller AS PART OF A ROUND ROBIN TEST CAMPAIGN
2017Co-Authors: Tani Giorgio, Viviani Michele, Aktas Batuhan, Atlar MehmetAbstract:Nowadays underwater radiated Noise is concerned as one of shipping detrimental emissions and so its study has gained significant importance in context of research in naval architecture. In particular, the Propeller, when cavitating, represents the main contributor to the total Noise radiated by the ship. Despite the continuous development of numerical codes for radiated Noise computation, this topic is still largely studied through model scale experiments in dedicated facilities. However also this approach presents several issues to be overcome in order to achieve a consistent evaluation of cavitating Propeller radiated Noise. Model scale experiments are always affected by scale effects and for Propeller Noise measurements, these regard a wide range of physical aspects. Due to this, institutes performing such activities are continuously involved in researches aimed to the enhancement of test and post-processing procedures. Furthermore, results of model scale tests, especially Noise, are strongly influenced by the characteristics of the facility, by the setup adopted and the experimental procedures which should be always reported in details with results. In this context, knowledge exchange between different facilities represents an effective way to improve measurements techniques, test and post processing procedures (to be standardized as far as possible). Actually, this is one of the aims of the Noise Community of Practice of the Hydro Testing Forum (HTF). In particular, a round robin campaign has been undertaken by almost all the members regarding Noise measurements for the Propeller of the \u201cPrincess Royal\u201d, based on the extensive campaign carried out at Emerson Cavitation Tunnel. In this paper tests carried out at University of Genova (UNIGE) are presented together with part of the extensive experimental campaign carried out at the Emerson Cavitation Tunnel, which was the starting point of the Round Robin campaign
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A study on the influence of hull wake on model scale cavitation and Noise tests for a fast twin screw vessel with inclined shaft
'SAGE Publications', 2017Co-Authors: Tani Giorgio, Viviani Michele, Villa Diego, Ferrando MarcoAbstract:The study of ship underwater radiated Noise is nowadays a topic of great and largely recognized importance. This is due to the fact that in the last decades, the problem of the impact of anthropogenic Noise on marine life has been addressed with higher emphasis, giving rise to different efforts aimed to the analysis of its effects on different organisms and, in parallel, to means for the reduction of shipping Noise. In this context, attention is focused on the Propeller Noise, which, in cavitating conditions, may represent the most important Noise source of the ship. The Propeller Noise has been studied for long time with different approaches. One of the most effective approaches is represented by model scale testing in cavitation tunnels or similar facilities. Despite having been adopted for several years, radiated Noise experiments in model scale are usually affected by significant scale effects and technical issues. One of these aspects is represented by the correct modelling of the Propeller inflow; different techniques are adopted, depending on the facility, in order to reproduce a certain target wake. One of the main problems is to define this target wake, which should in principle coincide with the ship wake; as it is well known, it is usually derived from model scale towing tank measurements, with the necessity for the prediction of the full-scale wake field. Starting from the outcomes of a previous work on the influence of different approaches for the prediction of the full-scale wake field for a single screw ship, in this work, attention is focused on the case of a fast twin screw vessel, analysing the different issues which may be connected to this hull form
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Ship Propeller side effects: pressure pulses and radiated Noise
De Gruyter, 2016Co-Authors: Gaggero Stefano, Tani Giorgio, Villa Diego, Gaggero Tomaso, Rizzuto Enrico, Viviani MicheleAbstract:The present paper deals with the side effects of Propellers cavitation, i.e. pressure pulses and radiated Noise. These effects are gaining more and more importance for commercial ships for different reasons. Pressure pulses significantly affect comfort onboard, thus their reduction is of utmost importance for all ships carrying passengers. As regards the underwater radiated Noise, in the last decade interest has shifted from navy applications to commercial ships, due to the concern for the rising background Noise in the oceans. The Propellers, generating Noise directly in water, represent one of the main contributions to the overall underwater Noise emitted from ships. Due to the complexity of the mechanisms of Propeller Noise generation, different complementary strategies have to be followed to properly analyze the problem, ranging from induced pressure pulses to broadband Noise and cavitation. In the present work, part of the activities carried out in the framework of the collaborative EU FP7 project AQUO (Achieve QUieter Oceans by shipping Noise footprint reduction, www.aquo.eu) are reported. The paper presents the investigations carried out on a specific test case represented by a single screw research vessel, which is analyzed with three different strategies: numerical calculations, model scale investigations and fullscale measurements
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Ship Propeller side effects: pressure pulses and radiated Noise
'Walter de Gruyter GmbH', 2016Co-Authors: Gaggero Stefano, Tani Giorgio, Villa Diego, Gaggero Tomaso, Rizzuto Enrico, Viviani MicheleAbstract:The present paper deals with the side effects of Propellers cavitation, i.e. pressure pulses and radiated Noise. These effects are gaining more and more importance for commercial ships for different reasons. Pressure pulses significantly affect comfort onboard, thus their reduction is of utmost importance for all ships carrying passengers. As regards the underwater radiated Noise, in the last decade interest has shifted from navy applications to commercial ships, due to the concern for the rising background Noise in the oceans. The Propellers, generating Noise directly in water, represent one of the main contributions to the overall underwater Noise emitted from ships. Due to the complexity of the mechanisms of Propeller Noise generation, different complementary strategies have to be followed to properly analyze the problem, ranging from induced pressure pulses to broadband Noise and cavitation. In the present work, part of the activities carried out in the framework of the collaborative EU FP7 project AQUO (Achieve QUieter Oceans by shipping Noise footprint reduction, www.aquo.eu) are reported. The paper presents the investigations carried out on a specific test case represented by a single screw research vessel, which is analyzed with three different strategies: numerical calculations, model scale investigations and full scale measurement
Tani Giorgio - One of the best experts on this subject based on the ideXlab platform.
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Predicting the cavitating marine Propeller Noise at design stage: A deep learning based approach
'Elsevier BV', 2020Co-Authors: Miglianti Leonardo, Cipollini Francesca, Oneto Luca, Tani Giorgio, Gaggero Stefano, Coraddu Andrea, Viviani MicheleAbstract: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
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HYDRO-ACOUSTIC CHARACTERIZATION OF \u201cTHE PRINCESS ROYAL\u201d Propeller AS PART OF A ROUND ROBIN TEST CAMPAIGN
2017Co-Authors: Tani Giorgio, Viviani Michele, Aktas Batuhan, Atlar MehmetAbstract:Nowadays underwater radiated Noise is concerned as one of shipping detrimental emissions and so its study has gained significant importance in context of research in naval architecture. In particular, the Propeller, when cavitating, represents the main contributor to the total Noise radiated by the ship. Despite the continuous development of numerical codes for radiated Noise computation, this topic is still largely studied through model scale experiments in dedicated facilities. However also this approach presents several issues to be overcome in order to achieve a consistent evaluation of cavitating Propeller radiated Noise. Model scale experiments are always affected by scale effects and for Propeller Noise measurements, these regard a wide range of physical aspects. Due to this, institutes performing such activities are continuously involved in researches aimed to the enhancement of test and post-processing procedures. Furthermore, results of model scale tests, especially Noise, are strongly influenced by the characteristics of the facility, by the setup adopted and the experimental procedures which should be always reported in details with results. In this context, knowledge exchange between different facilities represents an effective way to improve measurements techniques, test and post processing procedures (to be standardized as far as possible). Actually, this is one of the aims of the Noise Community of Practice of the Hydro Testing Forum (HTF). In particular, a round robin campaign has been undertaken by almost all the members regarding Noise measurements for the Propeller of the \u201cPrincess Royal\u201d, based on the extensive campaign carried out at Emerson Cavitation Tunnel. In this paper tests carried out at University of Genova (UNIGE) are presented together with part of the extensive experimental campaign carried out at the Emerson Cavitation Tunnel, which was the starting point of the Round Robin campaign
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A study on the influence of hull wake on model scale cavitation and Noise tests for a fast twin screw vessel with inclined shaft
'SAGE Publications', 2017Co-Authors: Tani Giorgio, Viviani Michele, Villa Diego, Ferrando MarcoAbstract:The study of ship underwater radiated Noise is nowadays a topic of great and largely recognized importance. This is due to the fact that in the last decades, the problem of the impact of anthropogenic Noise on marine life has been addressed with higher emphasis, giving rise to different efforts aimed to the analysis of its effects on different organisms and, in parallel, to means for the reduction of shipping Noise. In this context, attention is focused on the Propeller Noise, which, in cavitating conditions, may represent the most important Noise source of the ship. The Propeller Noise has been studied for long time with different approaches. One of the most effective approaches is represented by model scale testing in cavitation tunnels or similar facilities. Despite having been adopted for several years, radiated Noise experiments in model scale are usually affected by significant scale effects and technical issues. One of these aspects is represented by the correct modelling of the Propeller inflow; different techniques are adopted, depending on the facility, in order to reproduce a certain target wake. One of the main problems is to define this target wake, which should in principle coincide with the ship wake; as it is well known, it is usually derived from model scale towing tank measurements, with the necessity for the prediction of the full-scale wake field. Starting from the outcomes of a previous work on the influence of different approaches for the prediction of the full-scale wake field for a single screw ship, in this work, attention is focused on the case of a fast twin screw vessel, analysing the different issues which may be connected to this hull form
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Ship Propeller side effects: pressure pulses and radiated Noise
De Gruyter, 2016Co-Authors: Gaggero Stefano, Tani Giorgio, Villa Diego, Gaggero Tomaso, Rizzuto Enrico, Viviani MicheleAbstract:The present paper deals with the side effects of Propellers cavitation, i.e. pressure pulses and radiated Noise. These effects are gaining more and more importance for commercial ships for different reasons. Pressure pulses significantly affect comfort onboard, thus their reduction is of utmost importance for all ships carrying passengers. As regards the underwater radiated Noise, in the last decade interest has shifted from navy applications to commercial ships, due to the concern for the rising background Noise in the oceans. The Propellers, generating Noise directly in water, represent one of the main contributions to the overall underwater Noise emitted from ships. Due to the complexity of the mechanisms of Propeller Noise generation, different complementary strategies have to be followed to properly analyze the problem, ranging from induced pressure pulses to broadband Noise and cavitation. In the present work, part of the activities carried out in the framework of the collaborative EU FP7 project AQUO (Achieve QUieter Oceans by shipping Noise footprint reduction, www.aquo.eu) are reported. The paper presents the investigations carried out on a specific test case represented by a single screw research vessel, which is analyzed with three different strategies: numerical calculations, model scale investigations and fullscale measurements
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Ship Propeller side effects: pressure pulses and radiated Noise
'Walter de Gruyter GmbH', 2016Co-Authors: Gaggero Stefano, Tani Giorgio, Villa Diego, Gaggero Tomaso, Rizzuto Enrico, Viviani MicheleAbstract:The present paper deals with the side effects of Propellers cavitation, i.e. pressure pulses and radiated Noise. These effects are gaining more and more importance for commercial ships for different reasons. Pressure pulses significantly affect comfort onboard, thus their reduction is of utmost importance for all ships carrying passengers. As regards the underwater radiated Noise, in the last decade interest has shifted from navy applications to commercial ships, due to the concern for the rising background Noise in the oceans. The Propellers, generating Noise directly in water, represent one of the main contributions to the overall underwater Noise emitted from ships. Due to the complexity of the mechanisms of Propeller Noise generation, different complementary strategies have to be followed to properly analyze the problem, ranging from induced pressure pulses to broadband Noise and cavitation. In the present work, part of the activities carried out in the framework of the collaborative EU FP7 project AQUO (Achieve QUieter Oceans by shipping Noise footprint reduction, www.aquo.eu) are reported. The paper presents the investigations carried out on a specific test case represented by a single screw research vessel, which is analyzed with three different strategies: numerical calculations, model scale investigations and full scale measurement
Mehme Atla - One of the best experts on this subject based on the ideXlab platform.
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cavitation tunnel tests for the princess royal model Propeller behind a 2 dimensional wake screen
Ocean Engineering, 2019Co-Authors: Giorgio Tani, Fabiana Miglianti, Atuha Aktas, Naz Yilmaz, Marco Ferrando, Michele Viviani, Mehme AtlaAbstract:Abstract Propeller Noise, especially in the presence of cavitation, is usually the main contributor to the acoustic signature of ships. Due to this fact, considerable efforts have been devoted to the study of underwater radiated Noise induced by Propeller cavitation during years: firstly, for military reasons; more recently, for other reasons relevant for merchant vessels, such as comfort on board and mitigation of the undesired impacts on marine fauna. Different approaches are available for the study and prediction of the cavitation Noise, including statistical and CFD based methods as well as approaches based on model tests in cavitation tunnels or depressurised tanks. Amongst these approaches, the model test based approach is still the most reliable and commonly adopted method. However, when the aim of the model experiments is the prediction of Noise radiated by a full-size ship, scale effects need to be analysed and taken into account to interpret model scale data and to achieve consistent prediction. Within this framework, each testing facility follows a procedure, which is developed through its own experience, theoretical considerations and possibly semi-empirical approaches to manage the different possible issues. The definition and harmonisations of the standards for the Noise test and post-processing procedures of the Propeller Noise are still within the current tasks of the ITTC Specialist Committee on Hydrodynamic Noise and other standardization institutes. This results in more uncertainty compared to other more established tests such as resistance and self-propulsion. This paper presents the model scale tests carried out at the University of Genova (UNIGE) cavitation tunnel on the model Propeller of the Newcastle University research catamaran, "The Princess Royal". Tests have been carried out using a 2D wake screen to approximate the real ship condition. The details of the experimental setup and results are presented and compared with the full-scale measurements in terms of cavitation and underwater radiated Noise. This allows to explore the issues of the scale effects associated with these phenomena, focusing the attention on possible problems related to small-medium size cavitation tunnel.
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cavitation tunnel tests for Propeller Noise of a frv and comparisons with full scale measurements
4th International Sypmosium on Cavitation, 2001Co-Authors: Mehme Atla, Emi Korku, Ali Ca Takinaci, Noriyuki Sasaki, Takeshi AonoAbstract:This study presents the results of cavitation tunnel tests carried out with model Propeller of a Fisheries Research Vessel (FRV) and those of Noise measurements with its full-scale Propeller to validate the low-Noise performance of this Propeller. The tests involve the simulation of a target wake using a wake screen and the determination of the nature and extent of the observed cavitation behind the simulated wake. The measurements for the Noise levels of the model Propeller and their analyses are also part of the study. The net Noise levels of the model Propeller are extrapolated to full-scale using the scaling law recommended by the 18th ITTC Cavitation Committee. The extrapolated results are compared with the criteria recommended by the International Council for the Extrapolation of the Sea (ICES) as well as against the full-scale measurements carried out with this vessel in Japan.
Candade A.a. - One of the best experts on this subject based on the ideXlab platform.
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Horizontal Tailplane-Tip Mounted Tractor Propeller Interaction Effects
2015Co-Authors: Candade A.a.Abstract:Advanced Propeller propulsion systems potentially provide a significant reduction in fuel burn compared to traditional turbofans. An alternative to the conventional aft-fuselage mounted pusher layout is the horizontal tailplane-tip mounted tractor Propeller concept. The aim of this thesis is an experimental investigation of the aeroacoustic and aerodynamic interaction effects of the tailplane-tip mounted tractor Propeller configuration, including the effects of elevator deflections. The experimental study was conducted at TU Delft’s Low Speed Laboratory in the Vertical Tunnel and the Low Turbulence Tunnel with two different models. From the aeroacoustic study, it was concluded that the installation of the pylon behind the Propeller affects both the directivity and the tonal levels of the Propeller Noise field, with the broadband acoustic levels remaining unchanged. It was determined that the overall sound pressure level (SPL) across the range of directivity angles considered is inversely proportional to the Propeller-pylon spacing. For a spacing of 50% Propeller diameter, the overall SPL was comparable to the case of the isolated Propeller. A unique characteristic of installation of the pylon was the development of a trough in the directivity for an observer position in the pylon plane caused by the cancelling of the steady Noise field by unsteady blade loading Noise. This arises due to inflow distortion due to potential effects caused by the pylon. This unsteady blade loading is a function of the Propeller-pylon spacing, and hence the levels in the trough decrease with decreasing Propeller-pylon spacing. For directivity angels in the pylon plane, for spacing below 30% of the Propeller diameter, the unsteady loading is further influenced by the elevator deflection and was the main mechanism of the interaction Noise. For Propeller-pylon spacing’s above 30% of the Propeller diameter, the interaction of the slipstream (either the Propeller Noise field, or the slipstream impingement) with the elevator was determined to be the main interaction mechanism. From the PIV and performance evaluations, it was concluded that for the given Propeller-pylon spacing (43% and 85% Propeller diameter), there was indeed negligible upstream interaction effect due to the trailing pylon, including the case of the deflected elevator Pylon loads obtained from an external balance showed that for symmetric inflow conditions, operation of the thrusting Propeller increased elevator effectiveness by 20% compared to the case with no Propeller present. A numerical simulation using XROTOR was used for the validation of the test data and had a relative error of 3% with the experimentally evaluated Propeller thrust for the lowest advance ratio. A slipstream propagation model based on the computed Propeller induced velocities showed acceptable trends when compared to the experimentally determined induced Propeller velocity profiles. However, the numerical model overpredicts the velocity profile in the tip region, owing to the tool’s limitation in predicting stall at the blade tip. A VLM based numerical analysis which included the effects of the Propeller slipstream, was able to predict the pylon lift to within 3% of the lift computed from the surface pressure measurements, but failed in the prediction of the drag of the model.Flight Performance and PropulsionAerodynamics, Wind Energy, Flight Performance and PropulsionAerospace Engineerin
A. A. Candade - One of the best experts on this subject based on the ideXlab platform.
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Horizontal Tailplane-Tip Mounted Tractor Propeller Interaction Effects
2015Co-Authors: A. A. CandadeAbstract:Advanced Propeller propulsion systems potentially provide a significant reduction in fuel burn compared to traditional turbofans. An alternative to the conventional aft-fuselage mounted pusher layout is the horizontal tailplane-tip mounted tractor Propeller concept. The aim of this thesis is an experimental investigation of the aeroacoustic and aerodynamic interaction effects of the tailplane-tip mounted tractor Propeller configuration, including the effects of elevator deflections. The experimental study was conducted at TU Delft’s Low Speed Laboratory in the Vertical Tunnel and the Low Turbulence Tunnel with two different models. From the aeroacoustic study, it was concluded that the installation of the pylon behind the Propeller affects both the directivity and the tonal levels of the Propeller Noise field, with the broadband acoustic levels remaining unchanged. It was determined that the overall sound pressure level (SPL) across the range of directivity angles considered is inversely proportional to the Propeller-pylon spacing. For a spacing of 50% Propeller diameter, the overall SPL was comparable to the case of the isolated Propeller. A unique characteristic of installation of the pylon was the development of a trough in the directivity for an observer position in the pylon plane caused by the cancelling of the steady Noise field by unsteady blade loading Noise. This arises due to inflow distortion due to potential effects caused by the pylon. This unsteady blade loading is a function of the Propeller-pylon spacing, and hence the levels in the trough decrease with decreasing Propeller-pylon spacing. For directivity angels in the pylon plane, for spacing below 30% of the Propeller diameter, the unsteady loading is further influenced by the elevator deflection and was the main mechanism of the interaction Noise. For Propeller-pylon spacing’s above 30% of the Propeller diameter, the interaction of the slipstream (either the Propeller Noise field, or the slipstream impingement) with the elevator was determined to be the main interaction mechanism. From the PIV and performance evaluations, it was concluded that for the given Propeller-pylon spacing (43% and 85% Propeller diameter), there was indeed negligible upstream interaction effect due to the trailing pylon, including the case of the deflected elevator Pylon loads obtained from an external balance showed that for symmetric inflow conditions, operation of the thrusting Propeller increased elevator effectiveness by 20% compared to the case with no Propeller present. A numerical simulation using XROTOR was used for the validation of the test data and had a relative error of 3% with the experimentally evaluated Propeller thrust for the lowest advance ratio. A slipstream propagation model based on the computed Propeller induced velocities showed acceptable trends when compared to the experimentally determined induced Propeller velocity profiles. However, the numerical model overpredicts the velocity profile in the tip region, owing to the tool’s limitation in predicting stall at the blade tip. A VLM based numerical analysis which included the effects of the Propeller slipstream, was able to predict the pylon lift to within 3% of the lift computed from the surface pressure measurements, but failed in the prediction of the drag of the model.
