Ciarán J. O'Reilly

Noise Source Location in Turbomachinery Using Coherence Based Modal Decomposition

Coherence based source analysis techniques can be used to identify the contribution of turbomachinery core noise sources to pressure measurements in the far-field. The usual approach is to locate a ...

Numerical Investigation of a Realistic Nose Landing Gear

A hybrid approach is used to study the noise generated by a realistic full-scale nose land- ing gear configuration. Compressible Detached-Eddy Simulations are performed to com- pute the flow field ...

Aerodynamic noise prediction for a wind turbine using numerical flow simulations and semi-empirical modelling approaches

In this paper, aerodynamic and aero-acoustic simulations are performed for a small horizontal axis wind turbine, suitable for the integration of wind energy in urban and peri-urban areas. Detached- ...

Identification of noise sources on a realistic landing gear using numerical phased array methods applied to computational data

The aerodynamic sound sources on a realistic landing gear are investigated using numerical phased array methods, based on array data extracted from compressible Detached-Eddy Simulations of the flo ...

Simulation of aerodynamically generated noise using the wave expansion method

Although it is possible to directly solve an entire flow-acoustics problem in one computation, this approach remains prohibitively large in terms of the computational resource required for most practical applications. Aeroacoustic problems are therefore usually split into two parts; one consisting of the source computation and one of the source propagation. Although both these parts entail great challenges on the computational method, in terms of accuracy and efficiency, it is still better than the direct solution alternative. The source usually consists of highly turbulent flows, which for most cases will need to be, at least partly, resolved. Then, acoustic waves generated by these sources often have to be propagated for long distances compared to the wavelength and might be subjected to scattering by solid objects or convective effects by the flow. Numerical methods used solve these problems therefore have to possess low dispersion and dissipation error qualities for the solution to be accurate and resource efficient.The wave expansion method (WEM) is an efficient discretization technique, which is used for wave propagation problems. The method uses fundamental solutions to the wave operator in the discretization procedure and will thus produce accurate results at two to three points per wavelength. This thesis presents a method that uses the WEM in an aeroacoustic context. Addressing the propagation of acoustic waves and transfer of sources from flow to acoustic simulations. The proposed computational procedure is applied to a co-rotating vortex pair and a cylinder in cross-flow. Overall, the computed results agree well with analytical solutions.Although the WEM is efficient in terms of the spatial discretization, the procedure requires that a Moore-Penrose pseudo-inverse is evaluated at each unique node-neighbour stencil in the grid. This evaluation significantly slows the procedure. In this thesis, a method with a regular grid is explored to speed-up this process.

Aeroacoustic study of a submerged air inlet using an IDDES/FW-H approach and sound source modelling through direct numerical beamforming

The flow-generated sound from an air inlet at a low Mach number is studied using detached eddy simulation and direct numerical beamforming. The flow is solved through RANS and compressible detached ...

Numerical simulation of flow-induced sound generation from an orifice in a low Mach number ducted flow

Aero-acoustic simulations are performed for an orifice plate mounted in a straight duct in a low-Mach number flow. The flow field is calculated by solving the filtered Navier-Stokes equations by means of direct numerical simulation (DNS), using a high-order finite difference scheme. The scheme uses summation-by-parts (SBP) finite difference operators with simultaneous approximation terms (SAT) to impose boundary conditions. Both the scattering of the sound (passive part) as well as the sound generation (active part) are studied in the low frequency plane wave range. An acoustic two-port model is applied to describe the sound in the duct. The results are compared with experimental data for the same configuration. The efficiency and robustness of the numerical technique are also examined.

An Assessment of Jet Noise Shielding Prediction Parameters

On-going research and development by the European aeronautical community towards the reduction of civil aircraft noise has been investigating the shielding of engine noise sources by airframe compo ...

Advancing energy efficient early-stage vehicle design through inclusion of end-of-life phase in the life cycle energy optimisation methodology

Environmentally-friendly energy-efficient vehicles are an important contributor to meet future global transportation needs. To minimise the environmental impact of a vehicle throughout its entire life cycle, the life cycle energy optimisation (LCEO) methodology has been proposed. Using the proxy of life cycle energy, this methodology balances the energy consumption of vehicle production, operation and end-of-life scenarios. The overall aim is to design a vehicle where life cycle energy is at a minimum. While previous work only included vehicle production and operation, this paper aims at advancing the LCEO methodology by including an end-of-life phase. A simplified design study was conducted to illustrate how vehicle design changes when end-of-life treatment is included. Landfilling, incineration and recycling have been compared as end-of-life treatments, although the focus was put on recycling. The results reveal that the optimal design not only changes with the inclusion of an end-of-life phase but it changes with specific end-of-life treatment.

Pass-by noise signature of aerodynamic sound sources in urban environment : A numerical approach

A numerical methodology is presented to simulate the sound field generated by moving aerodynamic sound sources in a simplified urban environment. The framework is described step by step from source ...