Pub Date : 2022-09-01DOI: 10.1177/1475472X221107365
J. Delfs, M. Mößner, S. Proskurov, R. Ewert
In appreciation of Ffowcs-Williams and Hawkings’ seminal contribution on describing the sound radiation from moving objects, this article discusses a concept of taking into account local non-trivial flow effects on the sound propagation. The approach is motivated by the fact that the numerical simulation of the sound propagation from complete full scale aircraft by means of volume-discretizing (CAA = Computational AeroAcoustics) methods is prohibitively expensive. In fact, a homogeneous use of such CAA approach would waste computational resources since for low speed conditions the sound propagation around the aircraft is subject to very mild flow effects almost everywhere and may be treated by more inexpensive methods. The part of the domain, where the sound propagation is subject to strong flow effects and thus requiring the use of CAA is quite restricted. These circumstances may be exploited given a consistent coupling of methods. The proposed concept is based on the strong (alternatively weak) coupling of a volume discretizing solver for the Acoustic Perturbation Equations (APE) and a modified Ffowcs-Williams and Hawkings (FW-H) type acoustic integral. The approach is established in the frequency domain and requires two basic ingredients, namely a) a volume discretizing solver for the APE, or for Möhring-Howe’s aeroacoustic analogy, to take into account strong non trivial flow effects like refraction at shear flows wherever necessary, and b) an aeroacoustic integral equation for the propagation part in areas where non-potential mean flow effects are negligible. The coupling of this aeroacoustic integral and the APE solver may be realized in a strong (i.e. two-ways) form in which both components feed back information into one another, or in a weak form (i.e. one-way), in which the sound field output data from the APE solver serves as given input for the integral equation. If an aircraft geometry has minor influence on the sound radiation to arbitrary observer positions, the aeroacoustic integrals may simply be evaluated explicitly. If on the other hand, the presence of the geometry has an important influence on the sound radiation, then the acoustic integral equation is implicit and requires some sort of numerical solution, in this case a Fast Multipole Boundary Element solver. While conceptually the weak coupling follows the spirit of the FW-H approach to describe sound propagation from aeroacoustic sources the underlying aeroacoustic integral is not based on Lighthill’s analogy, but the aeroacoustic analogy of Möhring-Howe. This is a consequence of the fact that in the two way-coupling the acoustic particle velocity in a moving medium needs to be determined, which is non-trivial based on an acoustic integral. As an important feature of the strong coupling the acoustic integral also provides practically perfect non-reflection boundary conditions even when the desireably small CAA domain does not extend into the far field. The validity of the p
{"title":"Extension of the concept of Ffowcs-Williams and Hawkings type wave extrapolation to non-trivial flow effects and exterior surfaces","authors":"J. Delfs, M. Mößner, S. Proskurov, R. Ewert","doi":"10.1177/1475472X221107365","DOIUrl":"https://doi.org/10.1177/1475472X221107365","url":null,"abstract":"In appreciation of Ffowcs-Williams and Hawkings’ seminal contribution on describing the sound radiation from moving objects, this article discusses a concept of taking into account local non-trivial flow effects on the sound propagation. The approach is motivated by the fact that the numerical simulation of the sound propagation from complete full scale aircraft by means of volume-discretizing (CAA = Computational AeroAcoustics) methods is prohibitively expensive. In fact, a homogeneous use of such CAA approach would waste computational resources since for low speed conditions the sound propagation around the aircraft is subject to very mild flow effects almost everywhere and may be treated by more inexpensive methods. The part of the domain, where the sound propagation is subject to strong flow effects and thus requiring the use of CAA is quite restricted. These circumstances may be exploited given a consistent coupling of methods. The proposed concept is based on the strong (alternatively weak) coupling of a volume discretizing solver for the Acoustic Perturbation Equations (APE) and a modified Ffowcs-Williams and Hawkings (FW-H) type acoustic integral. The approach is established in the frequency domain and requires two basic ingredients, namely a) a volume discretizing solver for the APE, or for Möhring-Howe’s aeroacoustic analogy, to take into account strong non trivial flow effects like refraction at shear flows wherever necessary, and b) an aeroacoustic integral equation for the propagation part in areas where non-potential mean flow effects are negligible. The coupling of this aeroacoustic integral and the APE solver may be realized in a strong (i.e. two-ways) form in which both components feed back information into one another, or in a weak form (i.e. one-way), in which the sound field output data from the APE solver serves as given input for the integral equation. If an aircraft geometry has minor influence on the sound radiation to arbitrary observer positions, the aeroacoustic integrals may simply be evaluated explicitly. If on the other hand, the presence of the geometry has an important influence on the sound radiation, then the acoustic integral equation is implicit and requires some sort of numerical solution, in this case a Fast Multipole Boundary Element solver. While conceptually the weak coupling follows the spirit of the FW-H approach to describe sound propagation from aeroacoustic sources the underlying aeroacoustic integral is not based on Lighthill’s analogy, but the aeroacoustic analogy of Möhring-Howe. This is a consequence of the fact that in the two way-coupling the acoustic particle velocity in a moving medium needs to be determined, which is non-trivial based on an acoustic integral. As an important feature of the strong coupling the acoustic integral also provides practically perfect non-reflection boundary conditions even when the desireably small CAA domain does not extend into the far field. The validity of the p","PeriodicalId":49304,"journal":{"name":"International Journal of Aeroacoustics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47152784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-11DOI: 10.1177/1475472X221107497
S. Glegg, Máté Szőke, W. Devenport
In this paper we will develop a model for the acoustic transmission loss and self-noise generated by a Kevlar wind tunnel wall. It is shown that the porosity of the fabric is the most important controlling factor of the transmission loss, and the effect of wind tunnel flow speed is to increase the losses, as observed in experiments. In addition, a model is developed for the weave noise generated by a Kevlar wind tunnel wall, which is found to be caused by the pumping of the fluid through the pores in the Kevlar and depends on their open area ratio. The mechanism for this sound generation is similar to the roughness noise mechanism for a turbulent boundary layer in that the pore spacing couples with the small wavelength disturbances in the boundary layer to cause acoustic radiation at the sum and difference frequencies.
{"title":"Acoustic transmission loss and noise from Kevlar wind tunnel walls","authors":"S. Glegg, Máté Szőke, W. Devenport","doi":"10.1177/1475472X221107497","DOIUrl":"https://doi.org/10.1177/1475472X221107497","url":null,"abstract":"In this paper we will develop a model for the acoustic transmission loss and self-noise generated by a Kevlar wind tunnel wall. It is shown that the porosity of the fabric is the most important controlling factor of the transmission loss, and the effect of wind tunnel flow speed is to increase the losses, as observed in experiments. In addition, a model is developed for the weave noise generated by a Kevlar wind tunnel wall, which is found to be caused by the pumping of the fluid through the pores in the Kevlar and depends on their open area ratio. The mechanism for this sound generation is similar to the roughness noise mechanism for a turbulent boundary layer in that the pore spacing couples with the small wavelength disturbances in the boundary layer to cause acoustic radiation at the sum and difference frequencies.","PeriodicalId":49304,"journal":{"name":"International Journal of Aeroacoustics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42570460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-04DOI: 10.1177/1475472X221107366
D. Lockard
This paper considers potential sources of error when using the Ffowcs Williams-Hawkings equation to make predictions of airframe noise, which entails a relatively low-speed, uniform incoming flow encountering geometry of varying complexity. Numerical simulations are used to investigate several model problems where Ffowcs Williams-Hawkings integration surfaces are placed on solid surfaces as well as in the flow. Comparisons with the pressure obtained directly from the simulations reveal that when solid surfaces are used, the acoustic calculations can produce erroneous results in upstream directions and when scattering bodies block the line of sight from observers to the source. Using solid surface input data implies ignoring all volumetric source effects, which include noise generation as well as flow effects. Nonuniform flow alone, such as is found in a steady boundary layer, was not found to be a significant source of error, so the amplitude and phase changes induced by turbulent eddies in massively separated flow regions is speculated to be the primary cause of the error.
{"title":"Airframe noise predictions using the Ffowcs Williams-Hawkings equation","authors":"D. Lockard","doi":"10.1177/1475472X221107366","DOIUrl":"https://doi.org/10.1177/1475472X221107366","url":null,"abstract":"This paper considers potential sources of error when using the Ffowcs Williams-Hawkings equation to make predictions of airframe noise, which entails a relatively low-speed, uniform incoming flow encountering geometry of varying complexity. Numerical simulations are used to investigate several model problems where Ffowcs Williams-Hawkings integration surfaces are placed on solid surfaces as well as in the flow. Comparisons with the pressure obtained directly from the simulations reveal that when solid surfaces are used, the acoustic calculations can produce erroneous results in upstream directions and when scattering bodies block the line of sight from observers to the source. Using solid surface input data implies ignoring all volumetric source effects, which include noise generation as well as flow effects. Nonuniform flow alone, such as is found in a steady boundary layer, was not found to be a significant source of error, so the amplitude and phase changes induced by turbulent eddies in massively separated flow regions is speculated to be the primary cause of the error.","PeriodicalId":49304,"journal":{"name":"International Journal of Aeroacoustics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46897284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-01DOI: 10.1177/1475472X221107372
M. Roger, Daniel Acevedo-Giraldo, Marc C. Jacob
The present work addresses the combined aerodynamic and acoustic installation effects observed as a subsonic propeller is partly crossing the near-wake of a wing. Only the tonal noise at multiples of the blade passing frequency is considered. The aerodynamic effect is the onset of additional sound sources caused by blade-wake interaction, compared to the case of the isolated propeller. The acoustic effect is the scattering by the wing. The work is aimed at demonstrating the ability of analytical models to estimate separately these effects, which is of primary interest for the preliminary design steps of a system. A basic experiment carried out in an anechoic, open-jet facility, is described, for validation purposes. The far-field sound measurements are compared to the predictions and some key outcomes are presented. In particular, the model provides guidelines to avoid configurations of excessive noise.
{"title":"Acoustic versus aerodynamic installation effects on a generic propeller-driven flying architecture","authors":"M. Roger, Daniel Acevedo-Giraldo, Marc C. Jacob","doi":"10.1177/1475472X221107372","DOIUrl":"https://doi.org/10.1177/1475472X221107372","url":null,"abstract":"The present work addresses the combined aerodynamic and acoustic installation effects observed as a subsonic propeller is partly crossing the near-wake of a wing. Only the tonal noise at multiples of the blade passing frequency is considered. The aerodynamic effect is the onset of additional sound sources caused by blade-wake interaction, compared to the case of the isolated propeller. The acoustic effect is the scattering by the wing. The work is aimed at demonstrating the ability of analytical models to estimate separately these effects, which is of primary interest for the preliminary design steps of a system. A basic experiment carried out in an anechoic, open-jet facility, is described, for validation purposes. The far-field sound measurements are compared to the predictions and some key outcomes are presented. In particular, the model provides guidelines to avoid configurations of excessive noise.","PeriodicalId":49304,"journal":{"name":"International Journal of Aeroacoustics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44887360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-28DOI: 10.1177/1475472X221107377
Eric Greenwood, K. Brentner, Robert F. Rau, Ze Feng Ted Gan
A new class of electric aircraft is being developed to transport people and goods as a part of the urban and regional transportation infrastructure. To gain public acceptance of these operations, these aircraft need to be much quieter than conventional airplanes and helicopters. This article seeks to review and summarize the aeroacoustic research relevant to this new category of aircraft. First, a brief review of the history of electric aircraft is provided, with an emphasis on how these aircraft differ from conventional aircraft. Next, the physics of rotor noise generation are reviewed, and the noise sources most likely to be of concern for electric aircraft are highlighted. These are divided into deterministic and nondeterministic sources of noise. Deterministic noise is expected to be dominated by the unsteady loading noise caused by the aerodynamic interactions between components. Nondeterministic noise will be generated by the interaction of the rotor or propeller blades with turbulence from ingested wakes, the atmosphere, and self-generated in the boundary layer. The literature for these noise sources is reviewed with a focus on applicability to electric aircraft. Challenges faced by the aeroacoustician in understanding the noise generation of electric aircraft are then identified, as well as the new opportunities for the prediction and reduction of electric aircraft noise that may be enabled by advances in computational aeroacoustics, flight simulation, and autonomy.
{"title":"Challenges and opportunities for low noise electric aircraft","authors":"Eric Greenwood, K. Brentner, Robert F. Rau, Ze Feng Ted Gan","doi":"10.1177/1475472X221107377","DOIUrl":"https://doi.org/10.1177/1475472X221107377","url":null,"abstract":"A new class of electric aircraft is being developed to transport people and goods as a part of the urban and regional transportation infrastructure. To gain public acceptance of these operations, these aircraft need to be much quieter than conventional airplanes and helicopters. This article seeks to review and summarize the aeroacoustic research relevant to this new category of aircraft. First, a brief review of the history of electric aircraft is provided, with an emphasis on how these aircraft differ from conventional aircraft. Next, the physics of rotor noise generation are reviewed, and the noise sources most likely to be of concern for electric aircraft are highlighted. These are divided into deterministic and nondeterministic sources of noise. Deterministic noise is expected to be dominated by the unsteady loading noise caused by the aerodynamic interactions between components. Nondeterministic noise will be generated by the interaction of the rotor or propeller blades with turbulence from ingested wakes, the atmosphere, and self-generated in the boundary layer. The literature for these noise sources is reviewed with a focus on applicability to electric aircraft. Challenges faced by the aeroacoustician in understanding the noise generation of electric aircraft are then identified, as well as the new opportunities for the prediction and reduction of electric aircraft noise that may be enabled by advances in computational aeroacoustics, flight simulation, and autonomy.","PeriodicalId":49304,"journal":{"name":"International Journal of Aeroacoustics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45939270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-23DOI: 10.1177/1475472X221107359
Chitrarth Prasad, S. Hromisin, P. Morris
Noise source imaging based on phased array measurements is an essential tool in the aeroacoustic analysis of new nozzle designs, especially at full-scale. This investigation aims to assess the capability of a deconvolution-based beamforming technique to accurately estimate the changes in noise sources for model-scale heated military jets when fluid inserts are used for noise control. This goal is achieved by performing well-validated Large Eddy Simulations (LES) to complement the experimental measurements. The LES data is segregated into its hydrodynamic, acoustic and thermal components using Doak’s Momentum Potential Theory (MPT). The near-field MPT-derived components are subjected to Spectral Proper Orthogonal Decomposition (SPOD) to compare with the frequency-dependent noise source maps obtained directly from experiments. It is shown that fluid inserts alter the naturally occurring Kelvin-Helmholtz (K-H) instability in the jet shear layer, which leads to a change in the directivity of the noise radiated in the near-field. The upstream shift in the noise source distribution resulting from the modified K-H instability is accurately captured by the deconvolution-based source imaging technique using just the far-field measurements. These changes in source locations as a function of frequency are documented.
{"title":"Leveraging large eddy simulations to assess noise source imaging of a controlled supersonic jet","authors":"Chitrarth Prasad, S. Hromisin, P. Morris","doi":"10.1177/1475472X221107359","DOIUrl":"https://doi.org/10.1177/1475472X221107359","url":null,"abstract":"Noise source imaging based on phased array measurements is an essential tool in the aeroacoustic analysis of new nozzle designs, especially at full-scale. This investigation aims to assess the capability of a deconvolution-based beamforming technique to accurately estimate the changes in noise sources for model-scale heated military jets when fluid inserts are used for noise control. This goal is achieved by performing well-validated Large Eddy Simulations (LES) to complement the experimental measurements. The LES data is segregated into its hydrodynamic, acoustic and thermal components using Doak’s Momentum Potential Theory (MPT). The near-field MPT-derived components are subjected to Spectral Proper Orthogonal Decomposition (SPOD) to compare with the frequency-dependent noise source maps obtained directly from experiments. It is shown that fluid inserts alter the naturally occurring Kelvin-Helmholtz (K-H) instability in the jet shear layer, which leads to a change in the directivity of the noise radiated in the near-field. The upstream shift in the noise source distribution resulting from the modified K-H instability is accurately captured by the deconvolution-based source imaging technique using just the far-field measurements. These changes in source locations as a function of frequency are documented.","PeriodicalId":49304,"journal":{"name":"International Journal of Aeroacoustics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45856128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-22DOI: 10.1177/1475472X221107368
Dong Yang, Juan Guzmán-Iñigo, A. Morgans
For a single-component perfect gas, entropy perturbations are associated with the difference between the overall density fluctuation and that coming from the acoustic perturbation. Entropy perturbations can generate sound when accelerated/decelerated by a non-uniform flow and this is highly relevant to thermoacoustic instabilities for gas turbines and rocket engines, and to noise emission for aero-engines. Widely used theories to model this entropy-generated sound rely on quasi-1D assumptions for which questions of validity were raised recently from both numerical and experimental studies. In the present work, we build upon an acoustic analogy theory for this problem. This theory was initiated by Morfey (J. Sound Vib. 1973) and Ffowcs Williams and Howe (J. Fluid Mech. 1975) about 50 years ago and extended recently by Yang, Guzmán-Iñigo and Morgans (J. Fluid Mech. 2020) to study the effect of non-plane entropy waves at the inlet of a flow contraction on its sound generation. Comparisons against both numerical simulations and previous theory are performed to validate the results.
{"title":"Sound generated by axisymmetric non-plane entropy waves passing through flow contractions","authors":"Dong Yang, Juan Guzmán-Iñigo, A. Morgans","doi":"10.1177/1475472X221107368","DOIUrl":"https://doi.org/10.1177/1475472X221107368","url":null,"abstract":"For a single-component perfect gas, entropy perturbations are associated with the difference between the overall density fluctuation and that coming from the acoustic perturbation. Entropy perturbations can generate sound when accelerated/decelerated by a non-uniform flow and this is highly relevant to thermoacoustic instabilities for gas turbines and rocket engines, and to noise emission for aero-engines. Widely used theories to model this entropy-generated sound rely on quasi-1D assumptions for which questions of validity were raised recently from both numerical and experimental studies. In the present work, we build upon an acoustic analogy theory for this problem. This theory was initiated by Morfey (J. Sound Vib. 1973) and Ffowcs Williams and Howe (J. Fluid Mech. 1975) about 50 years ago and extended recently by Yang, Guzmán-Iñigo and Morgans (J. Fluid Mech. 2020) to study the effect of non-plane entropy waves at the inlet of a flow contraction on its sound generation. Comparisons against both numerical simulations and previous theory are performed to validate the results.","PeriodicalId":49304,"journal":{"name":"International Journal of Aeroacoustics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48957494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-15DOI: 10.1177/1475472X221107375
Aharon Z. Karon, K. Ahuja
Often the measurements from different jet noise studies, which are thought to have been acquired at or corrected to identical jet conditions, do not match when compared to each other. This study looks at the nozzle-exit boundary layer as a possible factor for these differences. The nozzle-exit boundary layer state can easily be changed depending on the design of the jet-facility or the nozzle. To this end, jet noise measurements and nozzle-exit velocity profile measurements were acquired for nozzles where the nozzle-exit boundary state was changed either by using different types of nozzles, ASME nozzles versus conical nozzles, or extensions were added to the nozzles straight section. It is shown that as the laminar boundary layer transitions to turbulent, the high-frequency jet noise is reduced. In addition, development of a novel empirical correction for these effects was attempted.
{"title":"Role of nozzle-exit boundary layer in producing jet noise","authors":"Aharon Z. Karon, K. Ahuja","doi":"10.1177/1475472X221107375","DOIUrl":"https://doi.org/10.1177/1475472X221107375","url":null,"abstract":"Often the measurements from different jet noise studies, which are thought to have been acquired at or corrected to identical jet conditions, do not match when compared to each other. This study looks at the nozzle-exit boundary layer as a possible factor for these differences. The nozzle-exit boundary layer state can easily be changed depending on the design of the jet-facility or the nozzle. To this end, jet noise measurements and nozzle-exit velocity profile measurements were acquired for nozzles where the nozzle-exit boundary state was changed either by using different types of nozzles, ASME nozzles versus conical nozzles, or extensions were added to the nozzles straight section. It is shown that as the laminar boundary layer transitions to turbulent, the high-frequency jet noise is reduced. In addition, development of a novel empirical correction for these effects was attempted.","PeriodicalId":49304,"journal":{"name":"International Journal of Aeroacoustics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44623287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-13DOI: 10.1177/1475472X221107356
A. Dowling
I first met Shôn in October 1973. I had just started Part III of the Cambridge Mathematical Tripos – a post-graduate course that was retrospectively awarded a Masters’ Degree in Mathematics. After a summer job working with Ted Broadbent on aircraft noise at the Royal Aircraft Establishment in Farnborough, I had decided do a PhD in Aeroacoustics. I asked Sir James Lighthill for advice and he told me that he was now focused on biomechanics but a new professor had recently arrived in the Cambridge Department of Engineering and that I should ask him. I made contact with Shôn, saw him in his office that afternoon, and he agreed to supervise me for a PhD. As quickly and simply as that, I was on a path that for me was transformational, not only an exciting research future, but the start of my transition from mathematics into engineering. Throughout my career, Shôn continued to be a major influence on me as he has for many others.
{"title":"Professor John Eirwyn Ffowcs Williams FREng: Engineer, educator, researcher and entrepreneur, Cambridge Professor and Master of Emmanuel College 25 May 1935–12 December 2020","authors":"A. Dowling","doi":"10.1177/1475472X221107356","DOIUrl":"https://doi.org/10.1177/1475472X221107356","url":null,"abstract":"I first met Shôn in October 1973. I had just started Part III of the Cambridge Mathematical Tripos – a post-graduate course that was retrospectively awarded a Masters’ Degree in Mathematics. After a summer job working with Ted Broadbent on aircraft noise at the Royal Aircraft Establishment in Farnborough, I had decided do a PhD in Aeroacoustics. I asked Sir James Lighthill for advice and he told me that he was now focused on biomechanics but a new professor had recently arrived in the Cambridge Department of Engineering and that I should ask him. I made contact with Shôn, saw him in his office that afternoon, and he agreed to supervise me for a PhD. As quickly and simply as that, I was on a path that for me was transformational, not only an exciting research future, but the start of my transition from mathematics into engineering. Throughout my career, Shôn continued to be a major influence on me as he has for many others.","PeriodicalId":49304,"journal":{"name":"International Journal of Aeroacoustics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48319625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：