Abstract The surface correction to the quadrupole source term of Ffowcs Williams and Hawkings integral in frequency domain suffers from computation high-order derivatives Green’s function. far-field approximations function have been used without derivation verification previous work. In this work, we provide detailed derivations binomial expansions for condition are employed during circumvent d...

A hybrid approach is used to investigate the noise generated by a simplified landing gear without small scale parts such as hydraulic lines and fasteners. The Ffowcs Williams and Hawkings equation is used to predict the noise at far-field observer locations from flow data provided by an unsteady computational fluid dynamics calculation. A simulation with 13 million grid points has been complete...

The main objective of this paper is to study the characteristics of flow-induced noise in high pressure reducing valve (HPRV) and to provide some guidance for noise control. Based on computational fluid dynamics (CFD), numerical method was used to compute flow field. Ffowcs Williams and Hawkings Model was applied to obtain acoustic signals. The unsteady flow field shows that noise sources are l...

In this paper, the aerodynamic characteristic of a ducted tail rotor in hover has been numerically studied using CFD method. An analytical time domain formulation based on Ffowcs Williams-Hawkings (FW-H) equation is derived for the prediction of the acoustic velocity field and used as Neumann boundary condition on a rigid scattering surface. In order to predict the aerodynamic noise, a hybrid m...

In the present work we perform numerical characterization of hydrodynamic and hydroacoustic field a notional submarine geometry (the BB2 submarine). Starting from model-scale CFD simulation, full scale acoustic signature is derived. We use large eddy simulation with wall-layer model laboratory-scale experiments at value Reynolds number equal to 1.2×106. The conditions are those wind-tunnel test...

The unsteady viscous flow fields of a cross-flow fan are computed by time-accurately solving the two-dimensional incompressible Navier-Stokes equations with the unstructured triangular mesh solver algorithms. Based on pressure fluctuation data acquired at the surfaces of 35 rotating blades and stabilizer, acoustic pressures are predicted by the Ffowcs Williams-Hawkings equation. The aerodynamic...

In a situation where traffic, railway or aircraft noise sources are not present, as it happens in shielded areas, other sources might become relevant in terms of annoyance. This is the case of typical turbomachinery elements, such as fans, compressors or turbines, where sound is generated aerodynamically. As a part of the Sonorus project, where all noise sources in urban environments are consid...

The effects of sound pressure level at two observation positions a fixed and varied blade pitch angle Low-Mach unsteady incompressible Reynolds-Average Navier-Stokes flow approach, on an H-rotor Vertical Axis Wind Turbine. objective the study is to compare noise dissipation output power/energy airfoil blades design vertical axis wind turbine in residential zones. Ffowcs Williams-Hawkings (FHWH)...

The use of a synthetic jet as the flow control technique to modulate turbulent incompressible round was explored and assessed by numerical simulations. response characterised in terms statistics acoustic far-field. A quasi-Direct Numerical Simulation (qDNS) strategy used predict effects. Ffowcs-Williams Hawkings (FWH) analogy employed compute far-field response. An amplification effect instabil...