Ciarán O'Reilly, Ph.D.

Contact

Phone: +46 8 790 79 03

E-mail: ciaran@kth.se

Address: KTH, Teknikringen 8, 100 44 Stockholm

Education

2009 Ph.D. (Aeroacoustics), University of Dublin, Trinity College, Dublin, Ireland.

2007 P.Grad.Dip. in Statistics with Distinction, University of Dublin, Trinity College, Dublin, Ireland.

2004 B.A.I. (Mechanical and Manufacturing Engineering) with First Class Honours, University of Dublin, Trinity College, Dublin, Ireland.

2004 B.A., University of Dublin, Trinity College, Dublin, Ireland.
 

Research Interests

• Jet noise source modelling for shielding applications.
• Aeroacoustic simulation of the generation and propagation of sound in ducts using of higher-order accurate methods.
• Self-oscillating shock acoustics in external compressible flows.
• Higher-order modal propagation in ducts.
• Wave-based methods for the propagation of linear fluctations in large-scale problems.

Research Profile

My research is devoted to the investigation of aeroacoustic problems with a focus on novel low-noise vehicle applications. The aim of my research is to study the fundamentals of aeroacoustic phenomena in order to gain a deepened understanding of the underlying physics, and to apply this knowledge to improve the design of the vehicles of tomorrow. To this end, I work with both high-fidelity reliable numerical simulations of the governing non-linear Navier-Stokes equations and pragmatic modelling or semi-empirical approaches.

In my Ph.D. studies at TCD (Trinity College Dublin), I investigated the acoustics of installed subsonic jets for novel airframe shielding concepts. This work was undertaken in collaboration with industrial and academic partners in the EU FP6 project New Aircraft Concepts Research (NACRE). In this project, a number of champion concepts were investigated with a view to developing the necessary knowledge base for the design of future aircraft. I developed an efficient design evaluation methodology for the assessment of airframe shielding concepts. As the majority of research on jet noise has focused on the acoustics of isolated jet flows, my research has provided a new understanding of the relative importance of various shielding parameters when it comes to attempting to block the transmission of aero-engine noise towards the community below. This new knowledge will feed into the next stage of the development of low-noise aircraft.

During my post-doctoral time at TCD, I investigated the propagation of higher-order acoustic modes in ducts, as part of the EU FP7 project Turboshaft Engine Exhaust Noise Identification(TEENI). I worked on the development of efficient physically based numerical scheme known as the wave expansion method (WEM), which may be used to solve for acoustic propagation in inhomogeneous potential flows for complex geometries such as vehicle interiors or exteriors. With ever-greater computational resources available, the challenge is to develop new numerical methods, such as this, to maximise the potential of this resource.

Since moving to KTH in late 2009, I have worked mostly on the numerical simulation of sound generation and propagation in low-Mach-number ducted flows. I am using a higher-order accurate finite difference code, in collaboration with researchers at UIUC (University of Illinois), to perform direct numerical simulation (DNS) of a flow through an orifice plate in a duct. This is a basic component of ducted flows in many vehicle applications. I am seeking to improve understanding of the fundamentals of sound generation in such flows using modal decomposition techniques and relating the flow structures to the propagated acoustics. I am also examining the passive effect of the orifice and flow on sound propagating through the system. This new understanding will lead to improved aeroacoustic designs.

I am also investigating at present, the acoustics of self-sustained shock-oscillations on aerofoils in transonic flows, as part of a Vinnova funded NFFP5 project called Strut Noise. This project is concerned with aeroacoustic source description for the prediction of structural loads. In this work a detached eddy simulation (DES) is used to evaluate acoustic sources defined by Howe's analogy. I am attempting to establish, through examining a localised source region and the sound field propagated from this, that this sound generation mechanism is responsible for in-flight measured values. I am continuing to develop approaches, that allow complex sound-generating flows around vehicles to be modelled in ways, that may be used as a tool in the design of new conceptual vehicles.

Publications

This list may not be up-to-date.