by Junye Wang A computational study is carried out to investigate the noise generated by a ten-bladed rotor ingesting low-Mach-number turbulent flow. Two types of turbulent inflows are considered: homogeneous and isotropic turbulence mimicking gridgenerated turbulence in a previous experiment and a turbulent cylinder wake. A hybrid computational approach combining LES with Lighthill’s aeroacous...

The Lighthill acoustic analogy, as embodied in the Ffowcs Williams{Hawkings (FW{H) equation, is compared with the Kirchho formulation for moving surfaces. A comparison of the two governing equations reveals that the main Kirchho advantage (namely nonlinear ow e ects are included in the surface integration) is also available to the FW{H method if the integration surface used in the FW{H equation...

An airfoil with a porous trailing edge has low noise emission; thus, using medium is good technique for further reduction of wind turbine noise. In this paper, to reduce while minimizing the negative influence on aerodynamic performance, new filling method proposed such that only used in suction side half edge, which more sensitive generation. The large eddy simulation (LES) flow and Ffowcs Wil...

This paper presents initial results on the aeroacoustic and aerodynamic effects of morphing trailing-edge flap 30P30N aerofoil, over five deflections (5–25°), at an 8° angle attack a Reynolds number Re=9.2×105. The Ffowcs-Williams–Hawkings acoustic analogy estimates far-field noise, whilst flow field is solved using URANS with four-equation Transition SST model. Aerodynamic simulation data for ...

Flapping-foil thrusters are systems that operate at a substantially lower frequency compared with marine propellers and characterized by much smaller power concentration. These biomimetic devices able to very efficiently, offering desirable levels of thrust required for the propulsion small vessels or autonomous underwater vehicles (AUVs), can be used standalone augmenting ship in waves, allevi...

The accordion reed is an example of a blown-closed free reed. Unlike most oscillating valves in wind musical instruments, self-sustained oscillations occur without acoustic coupling. Flow visualizations and measurements in water show that the flow can be supposed incompressible and potential. A model is developed and the solution is calculated in the time domain. The excitation force is found t...

The low frequency noise from heat recovery steam generator (HRSG) makes dominant contribution to the noise on the boundary of plant, which generation mechanism is investigated in this presentation. The non-stationary flow field and aeroacoustic noise is studied with hybrid numerical simulation, which is comprised of CFD method based on Large Eddy Simulation (LES) and acoustic analogy by using F...

This paper describes computational aeroacoustic methods that are being applied to predict the noise radiated by wind turbines. Since the wind turbine noise problem is very challenging, only some of the important noise sources and mechanisms are being considered. These are airfoil self-noise, the effects of blade rotation, and the propagation of sound over large distances. Two aspects of airfoil...

In the present study, a large number of acoustic simulations are carried out for a low noise airfoil with different Trailing Edge Serrations (TES). The Ffowcs Williams-Hawkings (FWH) acoustic analogy is used for noise prediction at trailing edge. The acoustic solver is running on the platform of our in-house incompressible flow solver EllipSys3D. The flow solution is first obtained from the Lar...

Based on the shear stress transfer (SST) k-ω model, Ffowcs-Williams and Hawkings (FW–H) equation, Lilley sound source flow field of high-temperature high-pressure steam ejectors are simulated. The entrainment performance, near-field source, far-field noise ejector discussed. influences working parameters including primary pressure, secondary back pressure analyzed. results show that under desig...