This file was created by the Typo3 extension sevenpack version 0.7.16 --- Timezone: CEST Creation date: 2021-10-24 Creation time: 01-06-09 --- Number of references 37 article Noack20200701 ERCIM News 2020 122 30-31 Reduced-order modelling and system identification can help us figure out the elementary degrees of freedom and theunderlying mechanisms from the high-dimensional and nonlinear dynamics of fluid flow. Machine learning has broughtnew opportunities to these two processes and is revolutionising traditional methods. We show a framework to obtain asparse human-interpretable model from complex high-dimensional data using machine learning and first principles. https://ercim-news.ercim.eu/images/stories/EN122/EN122-web.pdf 0926-4981 N.Deng L. R.Pastur B. R..Noack article Noack02102020 Journal of Fluid Mechanics 2020 884 A37 1-39 We propose the first least-order Galerkin model of an incompressible flow undergoingtwo successive supercritical bifurcations of Hopf and pitchfork type. A key enableris a mean-field consideration exploiting the symmetry of the mean flow and theasymmetry of the fluctuation. These symmetries generalize mean-field theory,e.g. no assumption of slow growth rate is needed. The resulting five-dimensionalGalerkin model successfully describes the phenomenogram of the fluidic pinball, atwo-dimensional wake flow around a cluster of three equidistantly spaced cylinders.The corresponding transition scenario is shown to undergo two successive supercriticalbifurcations, namely a Hopf and a pitchfork bifurcation on the way to chaos. Thegeneralized mean-field Galerkin methodology may be employed to describe othertransition scenarios. bifurcation, low-dimensional models, wakes https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/loworder-model-for-successive-bifurcations-of-the-fluidic-pinball/31E74B80FB2571D10D5166039B991BB3# 0022-1120 https://dx.doi.org/10.1017/jfm.2019.959 N.Deng B. R.Noack M.Morzyński L. R.Pastur article Noack_20042020 Journal of Fluid Mechanics 2020 893 1 1-29 The control of bluff-body wakes for reduced drag and enhanced stability hastraditionally relied on the so-called direct-wake control approach. By the use ofactuators or passive devices, one can manipulate the aerodynamic loads that act on therear of the model. An alternative approach for the manipulation of the flow is to movethe position of the actuator upstream, hence interacting with an easier-to-manipulateboundary layer. The present paper comprises a bluff-body flow study via large-eddysimulations to investigate the effectiveness of an upstream actuator (positioned atthe leading edge) with regard to the manipulation of the wake dynamics and itsaerodynamic loads. A rectangular cylinder with rounded leading edges, equippedwith actuators positioned at the front curvatures, is simulated at Re = 40 000. Agenetic algorithm (GA) optimization is performed to find an effective actuation thatminimizes drag. It is shown that the GA selects superharmonic frequencies of thenatural vortex shedding. Hence, the induced disturbances, penetrating downstreamin the wake, significantly reduce drag and lateral instability. A comparison witha side-recirculation-suppression approach is also presented, the latter case beingworse in terms of reduced drag (only 8 % drag reduction achieved), despite thetotal suppression of the side recirculation bubble. In contrast, the GA optimizedcase contributes to a 20 % drag reduction with respect to the unactuated case. Inaddition, the large drag reduction is associated with a reduced shedding motion andan improved lateral stability. https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/upstream-actuation-for-bluffbody-wake-control-driven-by-a-genetically-inspired-optimization/19BE0FE035B7FAB78E947B2E693B21C5 https://doi.org/10.1017/jfm.2020.220 G.Minelli T.Dong B. R.Noack S.Krajnovic article Zhang2019 Combustion Science and Technology 2019 191 1520 - 1540 This work assesses the effect of using different closure concepts for the spatially filtered mean reaction rate on the resolved spectral response of turbulent heat release in large eddy simulations (LESs). Two well-known combustion models, the turbulent flame speed closure (TFC) and the dynamically thickened flame (DTF) models have been applied to a premixed turbulent jet flame with otherwise identical numerical setups. Although the flame front is artificially thickened in the DTF model, it reproduces a thinner flame and, hence, stronger flame–turbulence interactions compared to the TFC model. As the time-averaged quantities from both methods are comparable, the DTF approach shows overall higher fluctuations of local and integral heat release rates in the spectral domain compared to the TFC model, particularly in the high-frequency range. A better agreement with measured sound pressure density is observed for TFC in the low-frequency range and for DTF in the high-frequency range. TFC simulations with different source formulations, that is, ω˙¯¯c∝c˜(1−c˜) and ω˙¯¯c∝∣∣∇c˜∣∣, showed comparable flame thicknesses and spectra of heat release, but the averaged flow quantities calculated with ω˙¯¯c∝∣∣∇c˜∣∣, however, deviate largely from measured data for the current setup. In the second step, the same formulations for the mean rate are applied to an excited plane-jet flame (two-dimensional (2D)) using equidistant grid cells and forced inflow conditions, thereby excluding the influence of varying grid resolution and broadband turbulent fluctuations. This setup is specifically tailored for a detailed analysis of flame response to flow unsteadiness and grid resolution. The formulation of the reaction rate according to the TFC approach again results in a considerably thicker flame compared to results obtained from the DTF model and direct numerical simulation, even on a sufficiently fine mesh. Therefore, the DTF formulation of the reaction rate shows overall stronger responses of heat release rates to forced fluctuations than the TFC formulation. Differences are smaller in the low-frequency range, indicating a stronger damping of heat release fluctuations with increasing frequency for the TFC formulation. Coarsening the grid leads to a much stronger damping of heat release fluctuations in the DTF formulation compared with the TFC formulation, so that the benefit of the DTF formulation decreases with decreasing grid resolution. This reflects the different sensitivity behavior of these models with respect to unsteady flows and grid resolutions, which is of great importance for computing thermoacoustic problems with LES, for example, combustion noise. Large eddy simulation, turbulent premixed flame, turbulent flame speed, thickened flame approach, OpenFOAM https://doi.org/10.1080/00102202.2018.1558218 English 10.1080/00102202.2018.1558218 F.Zhang T.Zirwes P.Habisreuther H.Bockhorn T.Dimosthenis H.Nawroth C. O.Paschereit article Marten2017 Aerospace Research Central, AIAA SciTech Forum 2017 The open source wind turbine simulation code QBlade, based on a Lifting Line Free Vortex Wake formulation to evaluate the unsteady aerodynamics, recently integrated the PROJECTCHRONO FEA library that, by using Euler-Bernoulli beams in a corotational formulation, solves for the structural dynamics to achieve an aeroelastic coupling. To validate the newly implemented structural model its performance is compared to literature data and two other finite element computer codes. The comparison is based on a modal analysis and aeroelastic simulations of the SNL 34m VAWT testbed, for which the aerodynamic and structural properties are well known. The structural loads are obtained from IE C 61400-1 design load cases. In one of the calculated load cases an aeroelastic instability could be observed which confirms similar observations that have previously been reported in the literature. 35th Wind Energy Symposium 9 - 13 January 2017 Grapevine, Texas http://dx.doi.org/10.2514/MWES17 10.2514/6.2017-0452 D.Marten M.Lennie G.Pechlivanoglou C. O.Paschereit N. V.Dy I.Paraschivoiu F.Saeed article Grewe2016 Meteorologische Zeitschrift 2016 10 139 1 - 15 Air traffic is important to our society and guarantees mobility especially for long distances. Air traffic is also contributing to climate warming via emissions of CO2 and various non-CO2 effects, such as contrail-cirrus or increase in ozone concentrations. Here we investigate the climate impact of a future aircraft design, a multi fuel blended wing body (MF-BWB), conceptually designed within the EU-project AHEAD. We re-calculate the parameters for the contrail formation criterion, since this aircraft has very different characteristics compared to conventional technologies and show that contrail formation potentially already occurs at lower altitudes than for conventional aircraft. The geometry of the contrails, however, is similar to conventional aircraft, as detailed LES simulations show. The global contrail-cirrus coverage and related radiative forcing is investigated with a climate model including a contrail-cirrus parameterisation and shows an increase in contrail-cirrus radiative forcing compared to conventional technologies, if the number of emitted particles is equal to conventional technologies. However, there are strong indications that the AHEAD engines would have a substantial reduction in the emission of soot particles and there are strong indications that this leads to a substantial reduction in the contrail-cirrus radiative forcing. An overall climate impact assessment with a climate-chemistry response model shows that the climate impact is likely to be reduced by 20 % to 25 % compared to a future aircraft with conventional technologies. We further tested the sensitivity of this result with respect to different future scenarios for the use of bio fuels, improvements of the fuel efficiency for conventional aircraft and the impact of the number of emitted soot particles on the radiative forcing. Only the latter has the potential to significantly impact our findings and needs further investigation. Our findings show that the development of new and climate compatible aircraft designs requires the inclusion of climate impact assessments already at an early stage, i.e. pre-design level. Online veröffentlicht: Oct 14, 2016 Manuskript akzeptiert: Jun 22, 2016 Manuskript-Revision erhalten: Jun 16, 2016 Manuskript-Revision angefordert: Jan 2, 2014 Manuskript erhalten: Nov 18, 2015 AHEAD project • Multi fuel blended wing body • contrails • climate impact • air traffic http://www.schweizerbart.de/papers/metz/detail/prepub/87038/Assessing_the_climate_impact_of_the_AHEAD_multi_fuel_blended_wing_body Schweizerbart Science Publishers

Stuttgart, Germany

online Oct 14, 2016 10.1127/metz/2016/0758 V.Grewe L.Bock U.Burkhardt K.Dahlmann K.Gierens L.Hüttenhofer S.Unterstrasser A. G.Rao A.Bhat F.Yin T. G.Reichel C. O.Paschereit Y.Leshayahou article Kabiraj2015 Chaos: An Interdisciplinary Journal of Nonlinear Science 2015 25 2 - http://scitation.aip.org/content/aip/journal/chaos/25/2/10.1063/1.4906943 10.1063/1.4906943 L.Kabiraj A.Saurabh N.Karimi A.Sailor E.Mastorakos A. P.Dowling C. O.Paschereit article Darvish2015a Journal of Turbomachinery 2015 137 10 TURBO-15-1063 101500-1 (9 pages) ASME 0889-504X 10.1115/1.4030498 M.Darvish S.Frank C. O.Paschereit inproceedings Dolan2015a 2015 AIAA paper no. 2015-0929 AIAA SciTech, 53rd Aerospace Sciences Meeting, 5-9 January, Kissimmee, Florida, USA 10.2514/6.2015-0929 B.Dolan R.Gomez H.Nawroth S.Pack E. J.Gutmark article Kruger2014 Journal of Fluid Science and Technology 2014 9 3 1--12 10.1299/jfst.2014jfst0040 O.Krüger C.Duwig S.Terhaar C. O.Paschereit article LacosteMDLS2013 Journal of Engineering for Gas Turbines and Power 2013 8 30 135 10 101501 (7 pages) 0742-4795 (online), 1528-8919 (print) 10.1115/1.4024961 D. A.Lacoste J. P.Moeck D.Durox C. O.Laux T. S.Schuller article Krueger2013 Journal of Engineering for Gas Turbines and Power 2013 1 3 135 2 021501 (10 pages) http://link.aip.org/link/?GTP/135/021501/1 ASME 0742-4795 (online), 1528-8919 (print) 10.1115/1.4007718 O.Krüger S.Terhaar C. O.Paschereit C.Duwig article Albin2013b Fuel Processing Technology 2013 107 27--35 Global burning velocities of methane–air–steam mixtures are measured on prismatic laminar Bunsen flames and lifted turbulent V-flames for various preheating temperatures, equivalence ratios and steam mixture fractions at atmospheric pressure. Experiments are conducted on a new rectangular slot-burner. Experimental burning velocities are compared to computed flame speeds of one dimensional adiabatic premixed flames using detailed mechanisms (Konnov 0.5 and GRI Mech 3.0). Mean profiles of radicals OH* are also extracted from these flames and compared to simulation results. http://www.sciencedirect.com/science/article/pii/S0378382012002652 0378-3820 10.1016/j.fuproc.2012.06.027 E.Albin H.Nawroth S.Göke Y.D'Angelo C. O.Paschereit article DuroxMBMVSC2013 Combustion and Flame 2013 160 9 1729--1742 10.1016/j.combustflame.2013.03.004 D.Durox J. P.Moeck J.-F.Bourgouin P.Morenton M.Viallon T. S.Schuller S.Candel article MoeckBDSC2013 Experiments in Fluids 2013 54 4 1-17 0723-4864 (print), 1432-1114 (online) 10.1007/s00348-013-1498-2 J. P.Moeck J.-F.Bourgouin D.Durox T. S.Schuller S.Candel inproceedings Lacoste2013 2013 ASME paper GT2013-94769 V01AT04A054 (9 pages) Proc. ASME Turbo Expo 2013, June 3-7, San Antonio, Texas, USA 978-0-7918-5510-2 10.1115/GT2013-94769 D. A.Lacoste J. P.Moeck D.Durox C. O.Laux T. S.Schuller inproceedings Hodzic2013 2013 AIAA paper 2013-3080 1--13 http://arc.aiaa.org/doi/abs/10.2514/6.2013-3080 American Institute of Aeronautics and Astronautics 21th AIAA Computational Fluid Dynamics Conference, June 24-27, 2013, San Diego, California, USA 10.2514/6.2013-3080 E.Hodizc C.Duwig R.Szasz O.Krüger L.Fuchs inproceedings Kruger2013a 2013 1--6 Japan Society of Mechanical Engineers Proceedings of 4th International Conference on Jets, Wakes and Separated Flows (ICJWSF), Sep 17-21, 2013, Nagoya, Aichi, Japan 978-4-88898-234-4 (CD) O.Krüger C.Duwig S.Terhaar C. O.Paschereit inproceedings Kruger2013b 2013 AIAA paper 2013-2953 1--16 http://arc.aiaa.org/doi/abs/10.2514/6.2013-2953 American Institute of Aeronautics and Astronautics 21th AIAA Computational Fluid Dynamics Conference, June 24-27, 2013, San Diego, California, USA 10.2514/6.2013-2953 O.Krüger C.Duwig S.Terhaar C. O.Paschereit inproceedings Bourgouin2013 2013 ASME paper GT2013-95010 V01BT04A007 (13 pages) Proc. ASME Turbo Expo 2013, June 3-7, San Antonio, Texas, USA 978-0-7918-5511-9 10.1115/GT2013-95010 J.-F.Bourgouin D.Durox J. P.Moeck T. S.Schuller S.Candel article Winkler2012 AIAA Journal 2012 50 7 1614--1620 10.2514/1.J051578 M.Winkler K.Becker C.Doolan F.Kameier C. O.Paschereit article MoeckBDSC2012 Combustion and Flame 2012 159 8 2650-2668 The interaction of a helical mode with acoustic oscillations is studied experimentally in a turbulent swirl-stabilized premixed flame. In addition to a precessing vortex core (PVC), the helical mode features perturbations in the outer shear layer of the burner flow. Measurements of the acoustic pressure, unsteady velocity field and flame emission are made in different regimes including self-sustained combustion oscillations and stable regimes with and without acoustic forcing. The acoustic oscillation and the helical mode create a pronounced rotating heat release rate perturbation at a frequency corresponding to the difference of the frequencies of the two individual mechanisms. Measurements over a wide range of operating conditions for different flow rates and equivalence ratios show that while the helical mode is always present, with a constant Strouhal number, self-excited thermoacoustic oscillations exist only in a narrow region. The interaction can be observed also in cases of thermoacoustically stable conditions when external acoustic modulation is applied to the system. The evolution of the helical mode with the forcing amplitude is examined. High-speed imaging from the downstream side of the combustor demonstrates that the heat release rate perturbation associated with the nonlinear interaction of the helical mode and the acoustic oscillations produces a ”yin and yang” -type pattern rotating with the interaction frequency in the direction of the mean swirl. At unstable conditions, the oscillation amplitude associated with the interaction is found to be significantly stronger in the heat release rate than in the velocity signal, indicating that the nonlinear interaction primarily occurs in the flame response and not in the aerodynamic field. The latter is, however, generally possible as is demonstrated under non-reacting conditions with acoustic forcing. Based on a second-order analysis of the G-equation, it is shown that the nonlinear flame dynamics necessarily generate the observed interaction component if the flame is simultaneously perturbed by a helical mode and acoustic oscillations. http://www.sciencedirect.com/science/article/pii/S0010218012001216 10.1016/j.combustflame.2012.04.002 J. P.Moeck J.-F.Bourgouin D.Durox T. S.Schuller S.Candel article Candel2012 Comptes Rendus Mécanique 2012 340 11--12 758--768 http://www.sciencedirect.com/science/article/pii/S163107211200188X 1631-0721 10.1016/j.crme.2012.10.024 S.Candel D.Durox T. S.Schuller P.Palies J.-F.Bourgouin J. P.Moeck inproceedings Moeck2012b 2012 ASME paper GT2012-69626 1213-1224 (12 pages) Proc. ASME Turbo Expo 2012, June 11-15, Bella Center, Copenhagen, Denmark 978-0-7918-4468-7 10.1115/GT2012-69626 J. P.Moeck J.-F.Bourgouin D.Durox T. S.Schuller S.Candel inproceedings Kruger2012 2012 ASME paper GT2012-69446 1081-1094 (14 pages) Proc. ASME Turbo Expo 2012, June 11-15, Bella Center, Copenhagen, Denmark 978-0-7918-4468-7 10.1115/GT2012-69446 O.Krüger C.Duwig S.Terhaar C. O.Paschereit inproceedings Albin2012 2012 The Eleventh International Conference on Combustion and Energy Utilization (11th ICCEU) E.Albin H.Nawroth S.Göke Y.D'Angelo C. O.Paschereit inproceedings Schuller2012 2012 AIAA paper no. 2012-0985 http://arc.aiaa.org/doi/pdfplus/10.2514/6.2012-985 50th AIAA Aerospace Science Meeting, Nashville, Tennessee, USA, Jan. 9-12 10.2514/6.2012-985 T. S.Schuller A.Cuquel P.Palies J. P.Moeck D.Durox S.Candel inproceedings Krueger2012 2012 http://www.iccfd.org/iccfd7/assets/pdf/papers/ICCFD7-3403_paper.pdf Seventh International Conference on Computational Fluid Dynamics (ICCFD7), Big Island, Hawaii, July 9-13 O.Krüger C.Duwig S.Terhaar C. O.Paschereit inproceedings Kruger2011c 2011 AIAA paper 2011-3549 1--14 The isothermal flow dynamics of a generic swirl burner are studied employing large eddy simulation (LES). A sensitivity analysis was conducted, considering different mesh sizes and subgrid-scale models and the results were compared to experimental data. It was found that the overall influence of the computational grid and the subgrid-scale model was neglectable and the simulations were in line with the experiments. A dominant frequency was found in the turbulent kinetic energy spectrum representing a coherent structure. Moreover, by applying the proper orthogonal decomposition (POD) this structure could be identified as a convective helical instability. This helical instability and can be represented by a pair of modes, and is assumed to be triggered by a precessing vortex core (PVC). 20th AIAA Computational Fluid Dynamics Conference, June 27-30, 2011, Honolulu, Hawaii, USA O.Krüger C.Duwig K.Göckeler S.Terhaar C.Strangfeld C. O.Paschereit L.Fuchs inproceedings Kruger2011b 2011 1--6 The present study employs large eddy simulations (LES) to investigate a generic swirl-stabilized burner operated with methane at ultra-wet conditions. In order to investigate the reactive flow, a customized solver for handling low Mach number flows based on an implicit LES approach was developed. A reduced 4 steps / 7 species global scheme was used as combustion model . To compare the simulations with experiments, OH chemiluminescence pictures served as a reference. Kruger2011b.pdf Proceedings of the European Combustion Meeting 2011, Jun 29 – Jul 1, Cardiff, UK O.Krüger C.Duwig S.Göke C. O.Paschereit L.Fuchs inproceedings Kruger2011a 2011 ASME paper GT2011-45866 The present study focuses on the numerical investigation of a generic swirl-stabilized burner operated with methane at ultra-wet conditions. The burner is fed with a preheated homogeneous mixture formed by steam and air. As a set of operating conditions atmospheric pressure, inlet temperature of 673 K, equivalence ratio of 0: 85 and a steam content of 30% is applied. Large eddy simulations have been performed to investigate the flow features. In a first step the non-reacting flow field was in-vestigated with water as working medium. Comparison with Par-ticle Image Velocimetry (PIV) and Laser-Doppler Velocimetry (LDV) measurements conducted in a water tunnel facility showed that an excellent agreement within the experimental uncertainty is obtained for the flow field. A dominant frequency in the tur-bulent energy spectrum was identified, which corresponds to the motion associated with a precessing vortex core (PVC). In order to investigate the reactive flow in a second step, a customized solver for handling low Mach number reacting flows based on an implicit LES approach was developed. As reaction mechanism a reduced 4 steps / 7 species global scheme was used. To compare the simulations qualitatively with a wet flame, OH chemiluminescence pictures serve as a reference. The simula-tions showed a more compact flame compared to the OH pic-tures. Nevertheless, the prolongation and position of the flame were found to be reasonable. The reduced mechanism captures the main effects, such as the reduction of the peak and mean temperatures. Furthermore, the presence of a PVC in the react- ing flow could be determined and was not suppressed by heat- release. Proc. ASME Turbo Expo 2011: Advancing Clean and Efficient Turbine Technology (GT2011), June 6-10, Vancouver, BC, Canada O.Krüger C.Duwig S.Göke K.Göckeler C. O.Paschereit L.Fuchs article Konle2009 International Journal of Spray and Combustion 2009 1 2 251-281 Thermo-acoustic investigations require reliable measurement techniques in hot environments for pressure, density fluctuations with a high dynamic range and acoustic particle velocity. This paper presents recent developments of optical measurement techniques in combustion diagnostics. A fibre-optic microphone based on the interferometric detection of membrane deflections was designed to measure acoustic pressure oscillations. Due to the heat resistant design, the sensor has an upper temperature limitation of approximately 970 K. Rayleigh-Scattering measurements, using the density dependent intensity of scattered light were performed in an unconfined flame with approximately 1600 K to study amplitude and phase distribution of the flame pulsation. Acoustic particle velocity can be determined applying acoustic PIV (particle image velocimetry) technique. This paper shows a way to measure simultaneously the acoustic particle velocity and the locally resolved mean flow velocity of a turbulent flow. Together these non-invasive techniques are applicable to study thermo-acoustic processes and sound generation in combustion chambers or turbines. http://lambda.qsensei.com/content/164v7m H. J.Konle A.Rausch A.Fischer U.Doll C.Willert C. O.Paschereit I.Röhle inproceedings Albrecht2009 2009 ASME paper GT2009-59181 125-135 A premixed pilot injection with reduced NOx formation is proposed as a fail-safe and simple control method to extend the operating range of gas turbines. Different pilot locations within the combustion chamber were chosen to see the impact of pilot injection flames on the local extinction behavior and on the NOx formation. The pilot flame injector (PFI) represents a device for premixed pilot injection and was located in the center of the swirl burner cone. Moreover, the premixed pilot could be ignited by an embedded spark plug inside the PFI so that the main flame, especially near the lean limit, can be provided with additional radicals at the lower stagnation point of the central recirculation zone. A second pilot injection was located at the combustor dump to inject the pilot fuel/air mixture axially into the shear layer between the central and side recirculation zone. It could be shown for different main air preheat temperatures and with activated PFI flame (at 110 Hz spark frequency), that the premixed pilot is the most efficient control method for local extinction prevention without CO emission increase. Also the NOx emissions keep on similar level as the baseline case. The spark plug might also be replaced by a laser ignition device. The efficiency of laser spark plugs could be already demonstrated under atmospheric conditions in Moesl2008 [1] where different ignition devices are proposed to ignite a swirl-stabilized kerosine mixture. Moreover, former tests with the PFI flame indicate also a method to control instabilities so that high amplitude of p[prime] oscillations could be suppressed. http://link.aip.org/link/abstract/ASMECP/v2009/i48838/p125/s1 ASME Proc. ASME Turbo Expo 2009: Power for Land, Sea, and Air (GT2009), June 8-12, Orlando, Florida, USA 978-0-7918-4883-8 (online) 10.1115/GT2009-59181 P.Albrecht C. O.Paschereit S.Bade F.Dinkelacker E. J.Gutmark inproceedings Singh2008 2008 4 ASME paper ESDA2008-59509 ASME 2008: 9th Biennial Conference on Engineering Systems Design and Analysis (ESDA2008), July 7-9, 2008 , Haifa, Israel 978-0-7918-4838-8 10.1115/esda2008-59509 Y.Singh D.Greenblatt N. K.Depuru Mohan C. N.Nayeri C. O.Paschereit article Polifke2001 International Journal of Acoustics and Vibration 2001 6 3 135-146 W.Polifke C. O.Paschereit K.Döbbeling article Polifke2001a Journal of Sound and Vibration 2001 245 3 483-510 W.Polifke A.Poncet C. O.Paschereit K.Döbbeling inproceedings Polifke1999 1999 Sixth International Congress on Sound and Vibration, July 5-8, 1999, Lyngby, Denmark W.Polifke C. O.Paschereit K.Döbbeling