The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform
Serra Francesco - One of the best experts on this subject based on the ideXlab platform.
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Propeller Geometry optimization for pressure pulses reduction: an analysis of the influence of the rake distribution
2017Co-Authors: Gaggero Stefano, Tani Giorgio, Villa Diego, Viviani Michele, Leonardo Pietro Miglianti, Ausonio Pierluigi, Travi Piero, Izzarri Giovanni, Serra FrancescoAbstract:The evaluation of pressure pulses is a current issue for any high-performance Propeller design. It has been addressed experimentally, by means of model tests, and numerically but in most cases the analysis has been limited to the verification of a given Geometry (or, at least of few configurations) identified at the end of a traditional design loop. A more direct inclusion of pressure pulses evaluation in the design procedure, for instance by very attractive multi-objective optimization approaches, could be beneficial, especially if more accurate codes may be exploited. Among the others, BEM represent an acceptable compromise between computational costs and accuracy with the further advantage, with respect to lower fidelity approaches, to account for effects of geometrical haracteristics (such as rake distribution) which are often defined only according to designer experience and special needs. However, if the ability of the BEM methods to predict Propeller performance and cavitation extension is well documented, the direct computation of pressure pulses may be less reliable, especially in correspondence to heavy cavitating conditions, requiring further validations in particular when the influence of characteristics such as rake distribution, hardly addressed in literature also from the experimental point of view, are considered. Cavitation tunnel test, BEM and RANS calculations have been consequently carried out for two Propellers, designed for the same functioning conditions with different rake distributions, in order to stress the capabilities and the limitations of the numerical approaches in dealing with cavitation, pressure pulses predictions and the capability to discriminate between slightly different geometries in the light of their possible application in a design by optimization procedure
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Experimental investigation of pressure pulses and radiated noise for two alternative designs of the Propeller of a high-speed craft
'Elsevier BV', 2017Co-Authors: Tani Giorgio, Gaggero Stefano, Villa Diego, Viviani Michele, Ausonio Pierluigi, Travi Piero, Izzarri Giovanni, Serra FrancescoAbstract:The present paper is focused on an experimental investigation of pressure pulses and radiated noise for two alternative designs of a Propeller of a high-speed craft. The Propellers have been designed in the context of a research project starting from two different rake distributions (forward rake to increase thrust and efficiency, backward rake to reduce cavitation), using different techniques (traditional lifting line / lifting surface and optimization algorithm coupled with a panel code), leading thus to rather different geometries. Propellers have been tested through cavitation tunnel experiments. The activity represents an interesting case study for this kind of measurement in presence of rather large cavitation extensions. The effects of cavitation on different components of pressure pulses and noise are investigated for the different rake distributions adopted. Results clearly shows the effects of this geometrical characteristic on cavitation and pressure pulses pointing out that, in some cases, Propeller hydrodynamic performances may determine pressure pulses intensity more than cavitation extensions. A simplified numerical approach, adopting stationary RANS calculations, for the evaluation of the effects of Propeller Geometry, has been proposed. Results show a good correlation with measurements allowing to have an insight into the phenomenon and confirming the effect of the rake
X. Chang - One of the best experts on this subject based on the ideXlab platform.
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Strength assessment method of ice-class Propeller under the design ice load condition
Elsevier, 2019Co-Authors: C.y. Guo, C. Wang, C.h. Wang, X. ChangAbstract:The strength assessment is the most important part at the design of ice-class Propeller. Based on ice rules for ice-class Propeller in IACS URI3 and FEM, the strength assessment method of ice-class Propeller is established in this paper. To avoid the multifarious meshing process of Propeller blade, an automatic meshing method has been developed by dividing the Propeller Geometry into a number of 8-node hexahedron elements along radial, chordwise and thickness directions, then the loaded areas in five cases can easily be calculated and identified. The static FEM is applied to calculate the stress and deformation of Propeller blade. The fair agreements between the results of the present method and ANSYS/Workbench demonstrate its robust and the feasibility, and also the method is able to produce smooth gradient field. The blade stress and deformation distributions for five load cases are studied, and then the strength of the whole blade is checked. Keywords: Strength assessment, Ice-class Propeller, Meshing method, Finite element method (FEM
As Nootebos - One of the best experts on this subject based on the ideXlab platform.
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Analysis and Design of a Small-ScaleWingtip-Mounted Pusher Propeller
'American Institute of Aeronautics and Astronautics (AIAA)', 2019Co-Authors: Stokkermans T.c.a., As Nootebos, Veldhuis L.l.m.Abstract:The wingtip-mounted pusher Propeller, which experiences a performance benefit from the interaction with the wingtip flowfield, is an interesting concept for distributed propulsion. This paper examines a Propeller design framework and provides verification with RANS CFD simulations by analyzing the wing of a 9-passenger commuter airplane with a wingtip-mounted Propeller in pusher configuration. In the taken approach, a wingtip flowfield is extracted from a CFD simulation, circumferentially averaged and provided to a lower order Propeller analysis and optimisation routine. Possible propulsive efficiency gains for the Propeller due to installation are significant, up to 16% increase at low thrust levels, decreasing to approximately 7:5% at the highest thrust level, for a range of thrust from 5% up to 100% of the wing drag. These gains are found to be independent of Propeller radius for thrust levels larger than 30% of the wing drag. Effctively, the Propeller Geometry is optimized for the required thrust and to a lesser degree for the non-uniformity in the flowfield. Propeller blade optimization and installation result in higher profile eciency in the blade root sections and a more inboard thrust distribution.Flight Performance and Propulsio
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Aerodynamic Analysis and Optimisation of Wingtip-Mounted Pusher Propellers: An investigation into the propulsive gains and optimal Geometry of small-scale Propellers
2018Co-Authors: As NootebosAbstract:Ever since the late seventies great engineering effort has gone into increasing the fuel efficiency and reduction of the noise profile of aircraft. A concept that has been explored is the wingtip-mounted (pusher) Propeller. In all wings energy is lost due to the lift-induced vortex at the wingtip. Wingtip-mounted pusher Propellers can recover some of this energy if rotating opposite to the wingtip vortex rotation. The required Propeller shaft power and wing induced drag could be reduced. Nevertheless, no aircraft utilise this setup because of aeroelastic problems and one-engine-out requirements. Nowadays this can be resolved by scaling down the Propeller and using (distributed) electric propulsion. Recent developments in personal air transport and multi-rotor aircraft have sparked interest in wingtip-mounted Propellers. The goal of this research is to obtain quantified insight into the propulsive efficiency gains and optimal Geometry of a pusher Propeller placed in a wingtip flow field.In the first part of this research a CFD simulation of the wingtip flow field was implemented and validated with available experimental data. A simple Spalart-Allmaras turbulence model proved to be most suitable and accurate. The flow field of the Tecnam P2006T aircraft was modelled to provide a realistic wingtip flow field to which the Propeller would be subjected.In the second part of this research a lower-order tool called PROPR was built and proved to be a fast Propeller aerodynamic analysis tool. Validation with experimental data showed a deviation of less than 15% in obtained thrust- and torque coefficients found. PROPR was integrated in an optimisation routine for fast optimisation of Propeller Geometry and operating conditions for non-uniform inflow. Total thrust, torque and their distributions obtained from PROPR and an implemented CFD model showed identical trends and were overestimated approximately 5% by PROPR.In the final research part the Tecnam wing with installed Propeller was investigated. A wingtip-mounted pusher Propeller enables more than 12% increase in propulsive efficiency over the entire Propeller thrust regime evaluated. Propeller optimisation was done for a thrust range of 50 < Tdes < 350 N, wing induced drag was 240 N. Relative reductions in power requirement were constant for the thrust regime. Absolute power decrease did not decrease with increasing design thrust. No airfoil optimisation was performed to enable fast and stable optimization. From optimisation of a fictitious Propeller with constant airfoil Geometry it was concluded that the airfoil geometries are a limiting factor in fully capturing the benefits of the wingtip flow field. In optimised (installed) Propeller Geometry blade loadings shift towards the blade root. A smaller chord length and lower RPM are preferred given the used baseline Propeller Geometry.A CFD simulation in which the Propeller was represented as an actuator disk was constructed. The up- stream effect of an installed Propeller was negligible. Thus, the incoming flow field was independent of pro- peller thrust within the considered thrust range. With this the implemented methodology was proven to be valid. Also, the overall power reduction of the combined setup is thus equal to the power reduction of the Propeller. Comparison with transient CFD simulations of the wing with installed Propeller showed great cor- respondence with results from PROPR.In further research it is recommended to include optimisation of (root section) airfoil geometries in the Propeller design. Evaluation of Propellers at higher thrust levels would provide insight in power reduction at these higher thrust levels. Finally, investigation of the Propeller at additional downstream locations, in- cidence angles and azimuthal positions would further validate the benefits of wingtip-mounted Propellers suggested in this research
Uce Colbourne - One of the best experts on this subject based on the ideXlab platform.
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automated marine Propeller Geometry generation of arbitrary configurations and a wake model for far field momentum prediction
International shipbuilding progress, 2001Co-Authors: Pengfei Liu, N Ose, Uce ColbourneAbstract:This paper first describes procedures and methodologies to automatically produce marine Propeller Geometry with optional auxiliary bodies such as nozzles, blockages and rudders. This process is designed and implemented for a general boundary element method (the panel method) to deal with both lifting body and non-lifting body flows. The generated Geometry is represented by quadrilateral and triangular panels that can be used by other mesh generation codes to produce 3D volumetric mesh for CFD work. The vertices of these generated panels are set so that the normal of the surfaces points inside the body. The order of the panels and their side indices are aligned for numerical procedures such as differentiation of the perturbation doublet potential for surface tangential velocities and Kutta condition at the trailing edge. A DXF file format was also implemented as one of the output files that can be used for Propeller manufacturing via CNC and for commercial CFD codes that use Geometry data input. Based on the near field wake modeling studies performed by the authors and previous experimental investigations on far wake turbulent jet measurements, a far wake model for a Propeller panel method is implemented to enhance the capability of predicting the velocities and momentum impact on the risers under a floating production storage off-loading (FPSO) system during operation. This far wake model consists of contraction wake (within one Propeller diameter downstream), transition wake (one to two diameters downstream), and inflation wake (two diameters beyond). Near field velocity prediction of this far wake model is validated using previous LDV measurement. Further experimental studies are scheduled for LDV/PIV measurement up to 20-diameter downstream.
Gaggero Stefano - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of pressure pulses and radiated noise for two alternative designs of the Propeller of a high-speed craft
'Elsevier BV', 2017Co-Authors: Tani Giorgio, Gaggero Stefano, Villa Diego, Viviani Michele, Ausonio Pierluigi, Travi Piero, Izzarri Giovanni, Serra FrancescoAbstract:The present paper is focused on an experimental investigation of pressure pulses and radiated noise for two alternative designs of a Propeller of a high-speed craft. The Propellers have been designed in the context of a research project starting from two different rake distributions (forward rake to increase thrust and efficiency, backward rake to reduce cavitation), using different techniques (traditional lifting line / lifting surface and optimization algorithm coupled with a panel code), leading thus to rather different geometries. Propellers have been tested through cavitation tunnel experiments. The activity represents an interesting case study for this kind of measurement in presence of rather large cavitation extensions. The effects of cavitation on different components of pressure pulses and noise are investigated for the different rake distributions adopted. Results clearly shows the effects of this geometrical characteristic on cavitation and pressure pulses pointing out that, in some cases, Propeller hydrodynamic performances may determine pressure pulses intensity more than cavitation extensions. A simplified numerical approach, adopting stationary RANS calculations, for the evaluation of the effects of Propeller Geometry, has been proposed. Results show a good correlation with measurements allowing to have an insight into the phenomenon and confirming the effect of the rake
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Propeller Geometry optimization for pressure pulses reduction: an analysis of the influence of the rake distribution
2017Co-Authors: Gaggero Stefano, Tani Giorgio, Villa Diego, Viviani Michele, Leonardo Pietro Miglianti, Ausonio Pierluigi, Travi Piero, Izzarri Giovanni, Serra FrancescoAbstract:The evaluation of pressure pulses is a current issue for any high-performance Propeller design. It has been addressed experimentally, by means of model tests, and numerically but in most cases the analysis has been limited to the verification of a given Geometry (or, at least of few configurations) identified at the end of a traditional design loop. A more direct inclusion of pressure pulses evaluation in the design procedure, for instance by very attractive multi-objective optimization approaches, could be beneficial, especially if more accurate codes may be exploited. Among the others, BEM represent an acceptable compromise between computational costs and accuracy with the further advantage, with respect to lower fidelity approaches, to account for effects of geometrical haracteristics (such as rake distribution) which are often defined only according to designer experience and special needs. However, if the ability of the BEM methods to predict Propeller performance and cavitation extension is well documented, the direct computation of pressure pulses may be less reliable, especially in correspondence to heavy cavitating conditions, requiring further validations in particular when the influence of characteristics such as rake distribution, hardly addressed in literature also from the experimental point of view, are considered. Cavitation tunnel test, BEM and RANS calculations have been consequently carried out for two Propellers, designed for the same functioning conditions with different rake distributions, in order to stress the capabilities and the limitations of the numerical approaches in dealing with cavitation, pressure pulses predictions and the capability to discriminate between slightly different geometries in the light of their possible application in a design by optimization procedure
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Design and analysis of a new generation of CLT Propellers
'Elsevier BV', 2016Co-Authors: Gaggero Stefano, Gonzalez Adalid Jua, Sobrino, Mariano PerezAbstract:In this work, the design and the analysis of the performance of an improved tip loaded Propeller Geometry are proposed. Based on the experimental data and on the numerical results collected at SISTEMAR and at the University of Genoa in the case of Contracted and Tip Loaded (CLT) Propellers, a new tip loaded Propeller Geometry is devised in order to mitigate some of the downsides of the CLT geometries increasingly adopted to improve full-scale Propeller efficiency. The modified tip loaded Propeller, i.e. a mix between a tip rake and a Contracted and Tip Loaded Propeller, is designed via an optimization strategy using a Boundary Elements Method (BEM), a custom parametric description of the unconventional blade Geometry and an optimization algorithm (of genetic type) within the modeFRONTIER environment. The reliability of the design process and of the improvements achievable with the modified tip loaded Propeller are extensively verified with dedicated RANSE calculations. At first, the accuracy of the BEM, adopted for the design by optimization, is verified in terms of predicted Propeller performance in order to assess its applicability for the analysis of modified tip geometries and check its confidence with respect to the allowable modifications of the blade shape. As a second step, viscous calculations are adopted to confirm the improvements of the newly designed geometries, in terms of both cavitation and predicted velocity field downstream the Propeller, as a result of a better adaptation of the end plate Geometry to the incoming flow. Finally, a set of unsteady calculations, by using the unsteady BEM, is carried out to verify the amplitude of the induced pressure pulses and, by comparing these numerical results with the available measurements and calculations in the case of a reference CLT Propeller, to confirm the effectiveness of the modified Propeller tip shap
