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278 results on '"Gennaretti, M."'

18. A New Comprehensive Analysis Tool for the Preliminary Design and Design Evaluation of Helicopters - the CORAL Project

Author

Nitzsche F., Spies C., Leibbrandt R., Gennaretti M., Bernardini G., Serafini J., Porcacchia F., Riziotis V., Papadakis G., Spyropoulos N., Siami A., Hilewit D., Rafiee M., Nitzsche, F., Spies, C., Leibbrandt, R., Gennaretti, M., Bernardini, G., Serafini, J., Porcacchia, F., Riziotis, V., Papadakis, G., Spyropoulos, N., Siami, A., Hilewit, D., and Rafiee, M.

Published
2021

31. Time-dependent coefficient reduced-order model or unsteady aerodynamics of proprotors

Author

Gennaretti, M. and Greco, L.

Subjects
Airplanes, Model -- Testing, Aerospace and defense industries, Business, Science and technology
Abstract

This work presents a methodology for the identification of a periodic-coefficient reduced-order model (ROM) for the prediction of perturbation aerodynamic loads on tiltrotor propellers in cruise flight. Although the result is a periodic-coefficient model, the process requires only frequency-domain aerodynamic solutions. Assuming the unperturbed proprotor in axial flow, the matrix that collects the aerodynamic transfer functions between blade perturbative boundary conditions and generalized aerodynamic forces is first derived. Then its rational matrix approximation, followed by combination with the equations describing the wing/pylon/proprotor kinetic coupling, yields the aerodynamic ROM. This ROM is expressed in terms of a set of linear equations that relate the time evolution of the aerodynamic loads acting on the proprotor blades to wing/pylon and deformable-blade degrees of freedom. Numerical results concerning a three-bladed proprotor connected to a bending and twisting wing will show that the unsteady aerodynamic loads predicted by the proposed ROM are in excellent agreement with those obtained through direct time-marching aerodynamic solutions.

Published
2005

33. Study of reduced-order models for gust-response analysis of flexible wings

Author

Gennaretti, M. and Mastroddi, F.

Subjects
Aerodynamics -- Analysis, Aerospace and defense industries, Business, Science and technology
Abstract

Three types of aeroelastic reduced-order models (ROMs) for flutter and gust-response analyses are examined, one of which is introduced here. One is based on the finite-state description of unsteady aerodynamics obtained through a rational-matrix approximation of the frequency-domain transcendental aerodynamic operator. Coupling this with the equations of the structural dynamics yields the aeroelastic ROM. The drawback of this approach is that some aerodynamic states have to be added to the structural states in the state-space format description of the aeroelastic system. The second model that is discussed yields directly the finite-state description of the aeroelastic operator without altering the dimensions of the state space. This model is iterative in nature, in that it requires an estimate of aeroelastic eigenvectors and eigenvectors from the original eigenproblem. Finally, an alternate ROM formulation for the gust-response problem is proposed. It combines good level of accuracy with reduction of additional aerodynamic states and thus can be conveniently used in preliminary design process and control-law synthesis.

Published
2004

39. Assessment of Permeable Boundary Integral Formulations for Rotating Blades Noise Prediction

Author

Porcacchia, F., Claudio Testa, Zaghi, S., Muscari, R., Gennaretti, M., International Congress on Sound and Vibration, Porcacchia, Federico, Testa, Claudio, Zaghi, S., Muscari, R., and Gennaretti, M.

Subjects
Ffowcs Williams and Hawkings Equation, Acoustic, Noise, FWHE-P
Abstract

In this work the Ffowcs Williams and Hawkings Equation for permeable surfaces (FWHE-P) is used for the prediction of the noise generated by marine propellers and horizontal-axis wind turbines. Aim of the paper is to assess a boundary integral formulation yielding the acoustic pressure outside a permeable surface surrounding the rotating body and "all" possible nonlinear sources of sound. The acoustic effects of placement and extension of the surface are investigated, facing the issue of the outflow-disk that may be source of inaccuracies in the noise prediction. A cylindrical surface rigidly moving with the blades is choosen as integration domain of the P- FWHE whereas a zero-th Boundary Element Method (BEM) is used to solve the integral formu- lation. Steady RANS (Reynolds Averaged Navier Stokes) and DES (Detached Eddy Simulation) solvers are used to detect the sources of sound upon the porous surface, for the turbine and pro- peller, respectively. Numerical results compare the acoustic signals from the P-FWHE and those carried out directly by the RANS or DES simulations; drawbacks and goodness of the choices done about the porous surface are discussed.

Published
2017

47. Acoustical Methods Towards Accurate Prediction of Rotorcraft Fuselage Scattering

Author

Barbarino, M., Bianco, D., Yin, J., Lummer, M., Reboul, G., Gennaretti, M., Bernardini, G., Claudio Testa, European Rotorcraft Forum, Barbarino, M., Bianco, D., Yin, J., Lummer, M., Reboul, G., Gennaretti, Massimo, Bernardini, Giovanni, and Testa, Claudio

Subjects
Boundary Element Method, noise Propagation, Computational Aero-Acoustics, Helicopter Acoustics, Rotorcraft Fuselage Scattering, GARTEUR
Published
2016

48. Finite element analysis of horizontal axis wind turbines performance

Author

Calabretta A., Testa C., Greco L., and Gennaretti M.

Subjects
Physics::Fluid Dynamics, Finite element method, Wind turbines, Rotor aeroelasticity
Abstract

This paper presents an aeroelastic formulation based on the Finite Element Method (FEM) to predict the performance of an isolated horizontal axis wind turbine. Hamilton's principle is applied to derive the equations of blade(s) aeroelasticity, based on a nonlinear beam model coupled with Beddoes-Leishman unsteady sectional aerodynamics. A devoted fifteen-degrees of freedom finite element, able to accurately model the kinematics and elastic behavior of rotating blades, is introduced and the spatial discretization of the aeroelastic equations is carried-out yielding a set of coupled nonlinear ordinary differential equations that are then solved by a time-marching algorithm. The proposed formulation may be enhanced to face the analysis of advanced blade shapes, including the presence of the tower, and represents the first step of an ongoing activity on wind energy based on a FEM approach. Due to similarities between wind turbine and helicopter rotor blades aeroelasticity, validation results firstly concern with the aeroelastic response of a helicopter rotor in hovering. Next, the performance of a wind turbine in terms of blade elastic response and delivered power are predicted and compared with available literature data.

Published
2015

49. Finite element analysis of horizontal axis wind turbines performance

Author

Calabretta, A., Testa, C., GrecoL, L., and Gennaretti, M.

Subjects
Finite element method, Marine engineering, Wind turbines, Rotor Aeroelasticity, Finite Element Method, Matemàtiques i estadística::Anàlisi numèrica::Mètodes en elements finits [Àrees temàtiques de la UPC]
Abstract

This paper presents an aeroelastic formulation based on the Finite Element Method (FEM) to predict the performance of an isolated horizontal axis wind turbine. Hamilton’s principle is applied to derive the equations of blade(s) aeroelasticity, based on a nonlinear beam model coupled with Beddoes-Leishman unsteady sectional aerodynamics. A devoted fifteen-degrees of freedom finite element, able to accurately model the kinematics and elastic behavior of rotating blades, is introduced and the spatial discretization of the aeroelastic equations is carried-out yielding a set of coupled nonlinear ordinary differential equations that are then solved by a time-marching algorithm. The proposed formulation may be enhanced to face the analysis of advanced blade shapes, including the presence of the tower, and represents the first step of an ongoing activity on wind energy based on a FEM approach. Due to similarities between wind turbine and helicopter rotor blades aeroelasticity, validation results firstly concern with the aeroelastic response of a helicopter rotor in hovering. Next, the performance of a wind turbine in terms of blade elastic response and delivered power are predicted and compared with available literature data.

Published
2015

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