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Rotorcraft
Dynamics
This
research is focused on the rotorcraft dynamics analysis by means of
multibody/multidisciplinary codes. The objective of this is the
development of multibody analytical models and methods to predict the
dynamic response, aeroelastic stability, and blade loading of
helicopters and tiltrotors. Comprehensive rotorcraft-based multibody
analyses enable modeling of the rotor system to a high level of detail
such that complex mechanics and nonlinear effects associated with
control system geometry and joint deadband may be considered .
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Multibody
Simulation
Formulation, implementation and development of
a
multibody multidisciplinary global modeling analysis code, named MBDyn,
for the integrated analysis of complex kinematic and dynamic systems,
aeroservoelastic models, electric and hydraulic networks. The code is
being implemented in mixed language (FORTRAN, C, C++) on Linux/UNIX
platforms and is highly Object Oriented. My main task are related to:
development of a parallel solver for a PC Cluster by means of MPI
(further
information here
in
Italian);implementation of a Newton-Iterative Matrix-Free solver;
development of a modal element to represent the
aerodynamic unsteady loads; enhancements of the aerodynamic modules
(see
Fluid Structure Interactions above). MBDyn code is actually released
under GPL.
Give
it a try!
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Fluid-Structure Interactions
for
Rotorcraft Dynamics
Rotorcraft
integrated dynamics analysis is a very difficult task, which showed
only partially successful results in current practice. On the rotor
dynamics side, it is worth recalling that a general reduction of
vibratory loads transmitted to the cabin and of the generated noise are
perceived as major goals to be achieved by the rotary wing industries,
so a tool for accurate aeroelastic analysis is needed.
A new ideal tool, as required to tackle this challenge, will need to
combine all the expertise developed in each field (structural dynamics,
fluid dynamics...) to reach a satisfactory global solution. It seems
reasonable to prospect the possibility and the feasibility of e active
and efficient coupling of existing, and possibly state of the art,
software. A library for coupling existing software in an integrated
solution scheme, without limiting requirements on the functionality of
the software that are coupled has been developed.
The idea pursued here is to create a toolbox of modeling paradigms for
aerodynamic loads prediction, where each one is capable to address by
itself a specific aspect of the fluid flow, but at the same time to
interact with other paradigms to achieve a higher degree of precision
for the whole model. The goal is to develop a sort of domain
decomposition on a physical basis of the flow field so that,
depending on the specific weight of each phenomena inside the flow
field, it is possible to choose the model which represents an optimal
trade-off between accuracy and computational costs.
The connection between the
multibody code and
the
free-wake analysis has been already successfully completed while the
addition of the CFD module is under development right now.
Puma helicopter wake in forward flight (color
intensity is related to vorticity distribution)
To
see some movies of wakes simulations click on the following links
Wake
development in hover
Wake
in forward flight
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Aeroservoelasticity
Different
research project are under development in the aeroservoelasticity
field. They are all interconnected in order to create a single
simulation/synthesis environment for the investigation of the
stability of aeroservoelastic systems and the synthesis of control
systems.
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State-Space
Modeling of Aeroelastic Systems
The main focus is on the development of robust
and
reliable technique
for the creation of minimal state-space realizations of the aerodynamic
unsteady loads related to flexible modes and gusts.
An
aeroservoelastic
analysis tool in a problem solving environment (like Matrix-X or
Matlab) has been crated.
The code provides the ability to: create a minimal state-space
residualization of the aerodynamic unsteady loads starting from data
obtained by means of various aerodynamic codes; run flutter analysis
with Mach number matching, Mach - Altitude flutter diagrams, static
divergence, time response, gust response, response to stochastic
inputs, correction of stability's derivative, hinges freeplay modeling,
complex actuator modeling, parametric analysis and more. This project
is supported by
Aermacchi,
a Finmeccanica Company.
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Fluid-structure
interaction for Fixed Wing
Aircrafts
Development of methodologies for the
integrated
analysis of flexible
aircraft structure with a CFD (either with Euler or Navier-Stokes
equations) for the stability analysis and the response of the system
when flying in the transonic regime. Among the different thread of this
research we focused on: development of reliable and conservative
interface algorithms; robust and computationally efficient
grid
deformation module; grid adaptations techniques for time marching
solution based on the adjoint solutions; interactions with commercial
CFD solvers; application of the transpiration technique for the
deformation emulation.
Scheme
of possible aeroservoelastic CFD analysis
CSD-CFD
grids interface
 
Grid Deformation following the first bending
mode.
Mach contour plot in transonic conditions.
To
see a movie of a simulation of post-flutter instability for the
classica test AGARD 445.5 wing click on the following links.
agard445.6 post flutter
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Reduced
Order Model for Aerodynamic Unsteady Loads
The
integrated simulation environment can be used as an information
source that allows to create reduced order model for complex
aeroelastic system which operate in flow conditions where significant
nonlinear effects are present (shock waves, large separations).
Reduced model are the basis for the synthesis of nonlinear controls
and/or for real time simulations of complex phenomena.
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Usage
of MEMS for Fluid Flow Control
The
goal of this research is to capitalize the ability of MEMS to
integrate sensors, actuators, driving circuitry and control hardware
to obtain a system for active flow management. To assess the
potential of this technology in shear flow control, the multifield
simulation environment capable of modeling concurrently the
mechanic, aerodynamic and electrostatic domain may be used. Possible
application of this technology may be finalized also to the control
of macroscopic effects such as that of roll moment on delta wings.
Other possibilities are related to turbulent
boundary layers flow control for drag reduction.
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Real
Time Simulations
The
project RT-MBDyn uses the multibody MBDyn
solver together
with The Linux OS Real-time extension RTAI
to
produce real-time simulation of complex
rigid and flexible mechanism
such as robots and similar. The plan is to extend this
project to
realize and engine for flight simulation of fixed and rotary wing
aircrafts.
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