In this study, cavitation flow around a hydrofoil and its radiated hydro-acoustic fields were numerically investigated, with an emphasis on the effects of viscous flux vectors. The full three-dimensional unsteady compressible Reynolds-averaged Navier–Stokes equations were numerically solved. The mass transfer model was adopted to model phase changes between liquid water and vapor. To resolve th...

This paper documents results to date from the Rotorcraft Acoustic Characterization and Mitigation activity under the NASA Subsonic Rotary Wing Project. The primary goal of this activity is to develop a NASA rotorcraft impulsive noise prediction capability which uses first principles fluid dynamics and structural dynamics. During this effort, elastic blade motion and co-processing capabilities h...

Unsteady flow computations are presented for a Gulfstream aircraft model in landing configuration, i.e., flap deflected 39° and main landing gear deployed. The simulations employ the lattice Boltzmann solver PowerFLOW to simultaneously capture the flow physics and acoustics in the near field. Sound propagation to the far field is obtained using a Ffowcs Williams and Hawkings acoustic analogy ap...

This paper presents an atmospheric propagation model, based on ray acoustics, that accounts for realistic weather conditions in the evaluation of noise footprint aircraft. Noise sources, obtained using Ffowcs Williams and Hawkings acoustic analogy applied to scale-resolved flow simulation data, are stored a hemisphere surrounding vehicle. These sources propagated model takes into account vertic...

This paper presents a computational study of flow incidence effects on the aeroacoustics propeller operating at low blade-tip Mach numbers. The numerical solution is obtained by using Lattice-Boltzmann/Very Large Eddy Simulation method, while far-field noise computed through Ffowcs-Williams & Hawkings' acoustic analogy applied surface. presence an angular inflow leads to: (i) radiation tonal lo...

A new formulation for the Ffowcs Williams{ Hawkings quadrupole source, which is valid for a fareld in-plane observer, is presented. The fareld approximation is new and unique in that no further approximation of the quadrupole source strength is made and integrands with r 2 and r 3 dependence are retained. This paper focuses on the development of a retarded-time formulation in which time derivat...

A Lattice-Boltzmann model for high-speed non-isothermal subsonic flows is used to simulate the unsteady jet exhausting from a short-cowl axisymmetric coaxial nozzle and the associated noise. The primary and secondary jet exit Mach numbers are 0.87 and 0.90, respectively, the secondary jet Reynolds number is 2.8 · 10, and the primary to secondary temperature ratio is 2.7. The far-field is comput...

A meteorologically challenging situation that represents a demanding control task (rotational speed, pitch and yaw) for wind turbine is presented its implementation in simulation described. high-fidelity numerical process chain, consisting of the computational fluid dynamics (CFD) solver FLOWer, multi-body system (MBS) software SIMPACK Ffowcs Williams-Hawkings code ACCO, used. With it, aerodyna...

Unsteady computational simulations of a multi-element, high-lift configuration are performed. Emphasis is placed on accurate spatio-temporal resolution of the free shear layer in the slat-cove region. The excessive dissipative effects of the turbulence model, so prevalent in previous simulations, are circumvented by switching off the turbulence-production term in the slat cove region. The justi...

Noise radiation is of importance for the performance of centrifugal pumps. Aiming at exploring noise radiation patterns of a typical centrifugal pump at different flow rates, a three-dimensional unsteady hydro/aero acoustic model with large eddy simulation (LES) closure is developed. Specifically, the Ffowcs Williams-Hawkings model (FW-H) is employed to predict noise generation by the impeller ...