Change search
Link to record
Permanent link

Direct link
BETA
O'Reilly, Ciarán J., Associate ProfessorORCID iD iconorcid.org/0000-0003-0176-5358
Alternative names
Publications (10 of 45) Show all publications
Rasam, A., Pouransari, Z., Bolin, K. & O'Reilly, C. J. (2018). Detached-eddy simulation of a horizontal axis wind turbine. In: Progress in Hybrid RANS-LES Modelling: Papers Contributed to the 6th Symposium on Hybrid RANS-LES Methods, 26-28 September 2016, Strasbourg, France (pp. 357-367). Springer
Open this publication in new window or tab >>Detached-eddy simulation of a horizontal axis wind turbine
2018 (English)In: Progress in Hybrid RANS-LES Modelling: Papers Contributed to the 6th Symposium on Hybrid RANS-LES Methods, 26-28 September 2016, Strasbourg, France, Springer, 2018, p. 357-367Chapter in book (Refereed)
Abstract [en]

Aerodynamic simulations of a small horizontal-axis wind turbine, suitable for integration of wind energy in urban and peri-urban areas, are performed using the improved delayed detached-eddy simulation method. Simulations are carried out for three rotation rates and inlet conditions. Aerodynamic characteristics of the wind turbine such as forces, power production, pressure distribution as well as flow topologies are presented. The effect of different rotation rates as well as the effect of free stream turbulence on the turbine aerodynamics are discussed.

Place, publisher, year, edition, pages
Springer, 2018
Series
Notes on Numerical Fluid Mechanics and Multidisciplinary Design, ISSN 1612-2909 ; 137
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-225019 (URN)10.1007/978-3-319-70031-1_30 (DOI)2-s2.0-85043779042 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, 608554
Note

QC 20180328

Available from: 2018-03-28 Created: 2018-03-28 Last updated: 2018-03-28Bibliographically approved
Pignier, N., O'Reilly, C. J. & Boij, S. (2017). Identifying equivalent sound sources from aeroacoustic simulations using a numerical phased array. Journal of Sound and Vibration, 394C, 203-219
Open this publication in new window or tab >>Identifying equivalent sound sources from aeroacoustic simulations using a numerical phased array
2017 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 394C, p. 203-219Article in journal (Refereed) Published
Abstract [en]

An application of phased array methods to numerical data is presented, aimed at identifying equivalent flow sound sources from aeroacoustic simulations. Based on phased array data extracted from compressible flow simulations, sound source strengths are computed on a set of points in the source region using phased array techniques assuming monopole propagation. Two phased array techniques are used to compute the source strengths: an approach using a Moore-Penrose pseudo-inverse and a beamforming approach using dual linear programming (dual-LP) deconvolution. The first approach gives a model of correlated sources for the acoustic field generated from the flow expressed in a matrix of cross- and auto-power spectral values, whereas the second approach results in a model of uncorrelated sources expressed in a vector of auto-power spectral values. The accuracy of the equivalent source model is estimated by computing the acoustic spectrum at a far-field observer. The approach is tested first on an analytical case with known point sources. It is then applied to the example of the flow around a submerged air inlet. The far-field spectra obtained from the source models for two different flow conditions are in good agreement with the spectra obtained with a Ffowcs Williams-Hawkings integral, showing the accuracy of the source model from the observer's standpoint. Various configurations for the phased array and for the sources are used. The dual-LP beamforming approach shows better robustness to changes in the number of probes and sources than the pseudo-inverse approach. The good results obtained with this simulation case demonstrate the potential of the phased array approach as a modelling tool for aeroacoustic simulations.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
sound sources, modelling, phased array, beamforming, simulations, dual-LP beamforming
National Category
Fluid Mechanics and Acoustics
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-192164 (URN)10.1016/j.jsv.2017.01.051 (DOI)000395606700014 ()2-s2.0-85011589602 (Scopus ID)
Note

QC 20160921

Available from: 2016-09-06 Created: 2016-09-06 Last updated: 2019-10-09Bibliographically approved
Pignier, N., O'Reilly, C. J. & Boij, S. (2016). Aeroacoustic study of a submerged air inlet using an IDDES/FW-H approach and sound source modelling through direct numerical beamforming. In: 22nd AIAA/CEAS Aeroacoustics Conference: . Paper presented at 22nd AIAA/CEAS Aeroacoustics Conference, 2016, 30 May 2016 through 1 June 2016. American Institute of Aeronautics and Astronautics
Open this publication in new window or tab >>Aeroacoustic study of a submerged air inlet using an IDDES/FW-H approach and sound source modelling through direct numerical beamforming
2016 (English)In: 22nd AIAA/CEAS Aeroacoustics Conference, American Institute of Aeronautics and Astronautics, 2016Conference paper, Published paper (Other academic)
Abstract [en]

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 eddy simulation for various velocity ratios, defined as the ratio between the flow speed at the duct entrance and in the free stream. Results for the flow show very good agreement with experimental data from the National Advisory Committee for Aeronautics (NACA). Pressure data is extracted at the position of a virtual microphone array inside the simulation domain, outside of the unsteady flow region. The array data is beamformed on a source test grid over the inlet using standard beamforming and Linear Programming deconvolution approaches. As beamforming is performed from simulated data directly in the acoustically resolved domain, the method is referred to as Direct Numerical Beamforming (DNB). The results give information about the location, amplitude and frequency content of the sound sources around the inlet. The resulting incoherent sound sources can be used as a model for the sound radiated from the inlet. Using a simple Green's function, the corresponding far-field spectrum is computed for two velocity ratios, showing a very good agreement with the spectra obtained from a Ffowcs Williams and Hawkings integral.

Place, publisher, year, edition, pages
American Institute of Aeronautics and Astronautics, 2016
Keywords
Acoustic generators, Aeroacoustics, Air intakes, Flow separation, Linear programming, Mach number, Numerical methods, Transients, Velocity, Deconvolution approach, Detached eddy simulations, Far field spectra, Frequency contents, National advisory committee for aeronautics, Simulation domain, Standard beamforming, Virtual microphone, Beamforming
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-195502 (URN)10.2514/6.2016-2838 (DOI)2-s2.0-84982893795 (Scopus ID)9781624103865 (ISBN)
Conference
22nd AIAA/CEAS Aeroacoustics Conference, 2016, 30 May 2016 through 1 June 2016
Note

QC 20161125

Available from: 2016-11-25 Created: 2016-11-03 Last updated: 2019-03-19Bibliographically approved
Pignier, N., O'Reilly, C. & Boij, S. (2016). Aerodynamic and aeroacoustic analyses of a submerged air inlet in a low-Mach-number flow. Computers & Fluids, 133, 15-31
Open this publication in new window or tab >>Aerodynamic and aeroacoustic analyses of a submerged air inlet in a low-Mach-number flow
2016 (English)In: Computers & Fluids, ISSN 0045-7930, E-ISSN 1879-0747, Vol. 133, p. 15-31Article in journal (Refereed) Published
Abstract [en]

Computational aerodynamic and aeroacoustic analyses of a submerged air inlet are performed at a low Mach number. A hybrid method is used, in which the flow in the vicinity of the inlet is solved through detached eddy simulation (DES) and the acoustic pressure in the far-field is computed through the use of a Ffowcs Williams and Hawkings integral. Several surfaces of integration are used, both solid and permeable. The inlet design is based on an experimental inlet developed by the National Advisory Committee for Aeronautics (NACA). The flow is solved first through steady-state RANS simulation, then time-dependent DES is run from the converged results. The results from both RANS simulations and DES show good agreement with experimental data from NACA, both in terms of integral quantities and surface pressure coefficients. Pressure fluctuations are observed on both sides of the lip of the inlet, and are greater at low velocity ratios, with the velocity ratio defined as the ratio between the flow velocity at the duct entrance and in the free stream. A transition is observed between a quasi-laminar flow at a velocity ratio of 0.8 and a turbulent flow at velocity ratios of 0.6 and 0.4. This turbulent behaviour at low velocity ratios is associated with much higher acoustic levels in the far-field. At low velocity ratios, the acoustic spectra in the far-field exhibit a broadband character with maximum levels distributed around a characteristic frequency given by the ratio between the flow velocity at the duct entrance and the duct entrance depth. At high velocity ratios, the spectra show tonal characteristics with peaks at around 90 percent of this characteristic frequency and at the corresponding harmonics. A comparison between the spectra from solid and permeable surfaces reveals that volume sound sources are negligible at this low Mach number. A visualization of the integrands in the Ffowcs Williams and Hawkings integral show that sound sources are located on both sides of the lip of the inlet, at the position of impact of the vortices, and along the vortex wakes. Some observations regarding the use of solid and permeable surfaces of integration are made.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
submerged air inlet, NACA duct, NACA inlet, detached eddy simulation, DES, Ffowcs Williams and Hawkings
National Category
Fluid Mechanics and Acoustics
Research subject
Vehicle and Maritime Engineering; Aerospace Engineering; Engineering Mechanics
Identifiers
urn:nbn:se:kth:diva-174180 (URN)10.1016/j.compfluid.2016.04.010 (DOI)000377740000002 ()2-s2.0-84963936303 (Scopus ID)
Note

QC 20160523

Available from: 2015-10-01 Created: 2015-10-01 Last updated: 2017-12-01Bibliographically approved
Rasam, A., Botha, J. D. M., Karl, B., O'Reilly, C. J., Efraimsson, G. & Rice, H. J. (2016). Aerodynamic noise prediction for a wind turbine using numerical flow simulations and semi-empirical modelling approaches. In: 22nd AIAA/CEAS Aeroacoustics Conference: . Paper presented at 22nd AIAA/CEAS Aeroacoustics Conference, 2016, Lyon, France, 30 May 2016 through 1 June 2016,. American Institute of Aeronautics and Astronautics
Open this publication in new window or tab >>Aerodynamic noise prediction for a wind turbine using numerical flow simulations and semi-empirical modelling approaches
Show others...
2016 (English)In: 22nd AIAA/CEAS Aeroacoustics Conference, American Institute of Aeronautics and Astronautics, 2016Conference paper, Published paper (Other academic)
Abstract [en]

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-eddy simulation (DES) of compressible flow is performed to compute the flow field over the wind turbine. The far-field noise is computed using the Ffowcs - Williams and Hawkings acoustic analogy. Furthermore, the blade element momentum theory is used with a semi-empirical acoustic modeling approach to predict the wind turbine noise. The acoustic modeling approach is based on a semi-empirical formulation for airfoil self noise and an analytic formulation for inflow noise.

Place, publisher, year, edition, pages
American Institute of Aeronautics and Astronautics, 2016
Keywords
Acoustic noise, Aeroacoustics, Aerodynamics, Turbomachine blades, Wind power, Acoustic analogy, Aero-acoustic simulation, Aerodynamic noise, Blade element momentum theory, Detached eddy simulations, Horizontal axis wind turbines, Numerical flow simulations, Wind turbine noise
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-185035 (URN)10.2514/6.2016-2846 (DOI)2-s2.0-85057294577 (Scopus ID)
Conference
22nd AIAA/CEAS Aeroacoustics Conference, 2016, Lyon, France, 30 May 2016 through 1 June 2016,
Note

QC 20160613

Available from: 2016-04-08 Created: 2016-04-08 Last updated: 2019-03-19Bibliographically approved
O'Reilly, C. J. (2016). Creative engineers: Is abductive reasoning encouraged enough in degree project work?. Procedia CIRP, 50, 547-552
Open this publication in new window or tab >>Creative engineers: Is abductive reasoning encouraged enough in degree project work?
2016 (English)In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 50, p. 547-552Article in journal (Refereed) Published
Abstract [en]

Creativity is considered to be an important ability for an engineer to have, and it is therefore important that the development of this ability is structured into the education of engineering students, along with the ability to apply, analyse and evaluate based on existent knowledge. In this paper, the importance of abduction in creative engineering processes is briefly reviewed. It has been shown that abductive reasoning plays a key role in design as it is the only logical operation that introduces new ideas. Its encouragement within the KTH Royal Institute of Technology's degree projects at the Department of Aeronautical and Vehicle Engineering is analysed by examining the stated intended learning outcomes, and through interviewing students. It is found that abductive reasoning is not explicitly encouraged within the intended learning outcomes of these degree project courses, despite its importance in creative thinking. Although, it is very likely that at least some abduction takes place in the project work, its absence from the intended learning outcomes means that students may not have a felt need to demonstrate their abductive reasoning, and supervisors may encourage only non-creative deductive or inductive reasoning. A more explicit inclusion of abductive reasoning in the intended learning outcomes would help both students and supervisors to include creative thinking in the degree project courses. 

Place, publisher, year, edition, pages
Elsevier, 2016
National Category
Learning Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-185450 (URN)10.1016/j.procir.2016.04.155 (DOI)000387666600092 ()2-s2.0-84986564699 (Scopus ID)
Note

QC 20160623

Available from: 2016-04-18 Created: 2016-04-18 Last updated: 2017-11-30Bibliographically approved
Rasam, A., Karl, B. & O'Reilly, C. J. (2016). Detached-eddy simulation of a horizontal-axis wind turbine. In: 6th Symposium on Hybrid RANS-LES Methods: . Paper presented at 6th Symposium on Hybrid RANS-LES Methods, Strasbourg, France, 26 - 28 September.
Open this publication in new window or tab >>Detached-eddy simulation of a horizontal-axis wind turbine
2016 (English)In: 6th Symposium on Hybrid RANS-LES Methods, 2016Conference paper, Published paper (Other academic)
Abstract [en]

Aerodynamic simulations of a small horizontal-axis wind turbine, suit- able for integration of wind energy in urban and peri-urban areas, are performed. Im- proved delayed detached-eddy simulation is used in the computations. Simulations are carried out for three rotation rates and inlet conditions. Aerodynamic charac- teristics of the wind turbine such as forces, power production, pressure distribution as well as flow topology are presented. The effect of different rotation rates on the turbine aerodynamics is discussed. 

National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-192165 (URN)
Conference
6th Symposium on Hybrid RANS-LES Methods, Strasbourg, France, 26 - 28 September
Note

QC 20160921

Available from: 2016-09-06 Created: 2016-09-06 Last updated: 2016-09-21Bibliographically approved
O'Reilly, C. J. & Göransson, P. (2016). Economic and ecological influences on the design and adoption of new vehicle concepts. In: 22nd International Sustainable Development Research Society Conference, ISDRS: . Paper presented at 22nd International Sustainable Development Research Society Conference, ISDRS (pp. 413-420). , 2
Open this publication in new window or tab >>Economic and ecological influences on the design and adoption of new vehicle concepts
2016 (English)In: 22nd International Sustainable Development Research Society Conference, ISDRS, 2016, Vol. 2, p. 413-420Conference paper, Published paper (Refereed)
Abstract [en]

Integration of economic and ecological considerations with engineering ones in new vehicle concepts presents many challenges, not least of which is overcoming long established expectations of vehicles and their performance. Design choices are not only influenced by clear rational factors but also by many imperfectly rational ones, which interact in a complex way to shape the final vehicle artefact. It should therefore be of interest to model and explore how such factors interact and influence the design process, particularly when it comes to targeting limited resources towards achieving the maximum improvement in the design. The aim is to find out under what circumstances can specific improvements penetrate into the established vehicle design and where are the critical phase boundaries over which significant advancement may be achieved. This is especially relevant in light of the on-going adoption of new technologies aimed at reducing the environmental impacts of vehicles. This insight may enable the design and adoption of radically different vehicles that represent a tipping point for sustainable transportation. A methodology is introduced to dynamically explore the trade-offs in vehicle design. The engineered vehicle is recognised as being a sub-system within a much wider surrounding world. A broad model is introduced to include both rational performance properties and imperfectly rational forces, and the system is stepped forward in time. The methodology is applied to a case study in which new knowledge is introduced into the established design paradigm and its adoption is tracked under a number of starting conditions and assumptions. The results illustrate where a targeted improvement that compensates for inherent inertia may lead to greater adoption that is beneficial from a broader long-term perspective. The model behaves reasonably in the vicinity of boundary conditions but more work is needed to explore and refine the behaviour across multiple variables. 

National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-185451 (URN)
Conference
22nd International Sustainable Development Research Society Conference, ISDRS
Note

QC 20160509

Available from: 2016-04-18 Created: 2016-04-18 Last updated: 2017-04-10Bibliographically approved
O'Reilly, C. J., Göransson, P., Funazaki, A., Suzuki, T., Edlund, S., Gunnarsson, C., . . . Potting, J. (2016). Life-cycle energy optimisation: A proposed methodology for integrating environmental considerations early in the vehicle engineering design process. Journal of Cleaner Production, 135, 750-759
Open this publication in new window or tab >>Life-cycle energy optimisation: A proposed methodology for integrating environmental considerations early in the vehicle engineering design process
Show others...
2016 (English)In: Journal of Cleaner Production, ISSN 0959-6526, Vol. 135, p. 750-759Article in journal (Refereed) Published
Abstract [en]

To enable the consideration of life cycle environmental impacts in the early stages of vehicle design, a methodology using the proxy of life cycle energy is proposed in this paper. The trade-offs in energy between vehicle production, operational performance and end-of-life are formulated as a mathematical problem, and simultaneously balanced with other transport-related functionalities, and may be optimised. The methodology is illustrated through an example design study, which is deliberately kept simple in order to emphasise the conceptual idea. The obtained optimisation results demonstrate that there is a unique driving-scenario-specific design solution, which meets functional requirements with a minimum life cycle energy cost. The results also suggest that a use-phase focussed design may result in a solution, which is sub-optimal from a life cycle point-of-view.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Life-cycle energy, vehicle design, optimization, functional conflicts
National Category
Vehicle Engineering Environmental Engineering
Identifiers
urn:nbn:se:kth:diva-175827 (URN)10.1016/j.jclepro.2016.06.163 (DOI)000382792900065 ()2-s2.0-84990218392 (Scopus ID)
Note

QC 20160623

Available from: 2015-10-22 Created: 2015-10-22 Last updated: 2019-02-08Bibliographically approved
Majić, F., Efraimsson, G. & O'Reilly, C. J. (2016). Potential improvement of aerodynamic performance by morphing the nacelle inlet. Aerospace Science and Technology, 54, 122-131
Open this publication in new window or tab >>Potential improvement of aerodynamic performance by morphing the nacelle inlet
2016 (English)In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 54, p. 122-131Article in journal (Refereed) Published
Abstract [en]

In this work numerical investigations of the aerodynamic performance of an adaptive turbofan-engine inlet is performed. The adaptation is made on the inner front part of the symmetric inlet by changing the positions of two contour knots, which acts as a possible inlet struc- ture morphing. The contour knots are moved in the axisymmetric and radial directions of the inlet, respectively. The numerical calcula- tions are performed using Reynolds Averaged Navier-Stokes (RANS) simulations and are made for climb and cruise flight conditions. The evaluation of the aerodynamic performance is based on the absolute total pressure recovery at the fan plane. The results show that the adaptation of only a small part of the inlet contour gives benefits in the performance at different flight conditions. The radial position in- crease of the knot closer to the leading edge gives overall increase of the pressure recovery level for both flight conditions. The radial posi- tion change of the knot close to the throat diameter leads to the global maximum of absolute total pressure recovery almost independent of the axial position change of the same knot, for both flight conditions. These maximums are attained at different radial positions of the knot close to the throat diameter, for the two flight conditions.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Aerodynamics, Nacelle inlet, Turbo-fan engine, Total pressure recovery, Morphing geometry
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-182666 (URN)10.1016/j.ast.2016.04.006 (DOI)000378441000011 ()2-s2.0-84964786323 (Scopus ID)
Note

QC 20160420

Available from: 2016-02-22 Created: 2016-02-22 Last updated: 2017-11-30Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0176-5358

Search in DiVA

Show all publications