Massimo Gennaretti

Bio: Massimo Gennaretti is an academic researcher from Roma Tre University. The author has contributed to research in topics: Aerodynamics & Aeroelasticity. The author has an hindex of 16, co-authored 150 publications receiving 1146 citations.

Novel Boundary Integral Formulation for Blade-Vortex Interaction Aerodynamics of Helicopter Rotors

Abstract: A direct panel method based on a novel boundary integral formulation for the velocity potential is presented and applied to helicopter rotors experiencing blade-vortex interaction. It avoids the numerical instabilities arising in the standard direct panel method in case of blade/wake impingement. This aerodynamic formulation yields a unified approach for the calculation of free-wake evolution and the blade-pressure field; it is fully 3-D, includes body-thickness effects, and can be applied to blades with arbitrary shape and motion. Blade-pressure predictions and the corresponding acoustic fields correlate well with wind-tunnel test data for helicopter rotors in descent flight, in which severe blade-vortex interaction occurs.

Adverse rotorcraft-pilot coupling: Recent research activities in Europe

Abstract: Unintended and unexpected oscillations or divergences of the pilot-rotorcraft system have become a critical issue for augmented helicopters with modern flight control systems. The rapid advances in the field of high response actuation and highly augmented flight control systems have increased the sensitivity to aspects that lead to complex oscillations related to unfavourable Aircraft-Pilot Coupling (APC) and Rotorcraft-Pilot Coupling (RPC). The understanding, prediction and prevention of adverse RPCs are demanding tasks and require the analysis and simulation of the complete feedback loop: pilot – control system – rotorcraft. Based on numerous flight events in the past, several types of RPCs have been observed differing in the frequency contents as well as in the underlying physics and human behaviour.

Aeroelastic response of helicopter rotors using a 3D unsteady aerodynamic solver

Abstract: The prediction of blade deflections and vibratory hub loads concerning helicopter main rotors in forward flight is the objective of this work. They are determined by using an aeroelastic model derived through the coupling between a nonlinear blade structural model and a boundary integral equation solver for three-dimensional, unsteady, potential aerodynamics. The Galerkin method is used for the spatial integration, whereas the periodic blade response is determined by a harmonic balance approach. This aeroelastic model yields a unified approach for aeroelastic response and blade pressure prediction that may be used for aeroacoustic purposes, with the possibility of including effects from both blade-vortex interaction and multiple-body aerodynamic interaction. Quasi-steady aerodynamic models with wake-inflow from the three-dimensional aerodynamic solver are also applied, in order to perform a comparative study. Numerical results show the capability of the aeroelastic tool to evaluate blade response and vibratory hub loads for a helicopter main rotor in level flight conditions, and examine the sensitivity of the predictions on the aerodynamics model used.

Surface integral methods in computational aeroacoustics—From the (CFD) near-field to the (Acoustic) far-field

Abstract: A review of recent advances in the use of surface integral methods in Computational AeroAcoustics (CAA) for the extension of near-field CFD results to the acoustic far-field is given. These integral formulations (i.e. Kirchhoff's method, permeable (porous) surface FfowcsWilliams Hawkings (FW-H) equation) allow the radiating sound to be evaluated based on quantities on an arbitrary control surface if the wave equation is assumed outside. Thus only surface integrals are needed for the calculation of the far-field sound, instead of the volume integrals required by the traditional acoustic analogy method (i.e. Lighthill, rigid body FW-H equation). A numerical CFD method is used for the evaluation of the flow-field solution in the near field and thus on the control surface. Diffusion and dispersion errors associated with wave propagation in the far-field are avoided. The surface integrals and the first derivatives needed can be easily evaluated from the near-field CFD data. Both methods can be extended in orde...

Dynamics, vibration and control of rotating composite beams and blades: A critical review

Abstract: Rotating composite beams and blades have a wide range of applications in various engineering structures such as wind turbines, industrial fans, and steam turbines. Therefore, proper understanding of such structures is of a great importance. As a result, the behavior of rotating composite beam structures has received a lot of attention. This paper presents a comprehensive review of scholarly articles about rotating composite beams as published in the past decades. The review addresses analytical, semi-analytical and numerical studies dealing with dynamical problems involving adaptive/smart/intelligent materials (e.g. piezoelectric materials, electrorheological fluids, shape memory alloys, etc.), damping and vibration control, advanced composite materials (e.g. functionally graded materials and nanocomposites), complicating effects and loadings (e.g. added mass, tapered beams, initial curve and twist, etc.), and experimental methods. Moreover, the influence of Vlasov or restrained warping, out-of-plane warping, transverse shear, arbitrary cross-sectional geometry, trapeze phenomena, swept tip, size-dependent effect, as well as other areas that have been considered in research, are reviewed in depth. The review concludes with a presentation of the remaining challenges and future research needs.

Modern helicopter aerodynamics

Abstract: ▪ Abstract Modern helicopter aerodynamics is challenging because the flow field generated by a helicopter is extremely complicated and difficult to measure, model, and predict; moreover, experiments are expensive and difficult to conduct. In this article we discuss the basic principles of modern helicopter aerodynamics. Many sophisticated experimental and computational techniques have been employed in an effort to predict performance parameters. Of particular interest is the structure of the rotor wake, which is highly three-dimensional and unsteady, and the rotor-blade pressure distribution, which is significantly affected by the strength and position of the wake. We describe the various modern methods of computation and experiment which span the range from vortex techniques to full three-dimensional Navier-Stokes computations, and from classical probe methods to laser velocimetry techniques. Typical results for the structure of the wake and the blade pressure distribution in both hover and forward fligh...

Novel Boundary Integral Formulation for Blade-Vortex Interaction Aerodynamics of Helicopter Rotors

Abstract: A direct panel method based on a novel boundary integral formulation for the velocity potential is presented and applied to helicopter rotors experiencing blade-vortex interaction. It avoids the numerical instabilities arising in the standard direct panel method in case of blade/wake impingement. This aerodynamic formulation yields a unified approach for the calculation of free-wake evolution and the blade-pressure field; it is fully 3-D, includes body-thickness effects, and can be applied to blades with arbitrary shape and motion. Blade-pressure predictions and the corresponding acoustic fields correlate well with wind-tunnel test data for helicopter rotors in descent flight, in which severe blade-vortex interaction occurs.