A5030695108- Aerodynamics and Acoustics in Jet Flows
- Acoustic Wave Phenomena Research
- Wind and Air Flow Studies
- Aerodynamics and Fluid Dynamics Research
- Fluid Dynamics and Turbulent Flows
- Computational Fluid Dynamics and Aerodynamics
- Vehicle Noise and Vibration Control
- Aerosol Filtration and Electrostatic Precipitation
- Plasma and Flow Control in Aerodynamics
- Heat Transfer Mechanisms
- Cavitation Phenomena in Pumps
- Combustion and flame dynamics
- Seismic Waves and Analysis
- Nuclear Engineering Thermal-Hydraulics
- Underwater Acoustics Research
- Engineering Applied Research
- Geophysical Methods and Applications
- Optical and Acousto-Optic Technologies
- Tribology and Lubrication Engineering
- Fluid dynamics and aerodynamics studies
- Flow Measurement and Analysis
- Meteorological Phenomena and Simulations
- Magnetic Bearings and Levitation Dynamics
Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)
2015-2025
Université Laval
2005-2006
Systematic testing of the microstructural and aeroacoustic properties porous metals applicable as low-noise trailing-edge (TE) treatments has been initiated within Collaborative Research Center SFB 880-Fundamentals High-Lift for Future Civil Aircraft.Generic TE noise experiments were performed at Re = 0.8 × 10 6 to 1.2 in DLR's open-jet AWB facility.Complementary flow measurements closed test section MUB wind-tunnel TU Braunschweig served quantify induced aerodynamic effects.The presented...
Abstract This paper presents the activities performed in GARTEUR Action Group HC/AG-26 to study acoustic and aerodynamic characteristics of small rotor configurations, including influence rotor-rotor interactions. will focus on comparisons between numerical wind tunnel results a provided by DLR. The models included Rotor/Rotor/Pylon isolated, tandem coaxial configuration. experiments for acoustics were DLR’s Acoustic Wind Tunnel Braunschweig (AWB) PIV test CIRA within joint CIRA/DLR program....
<title>Abstract</title> This paper presents the activities performed in GARTEUR Action Group HC/AG-26 to study acoustic and aerodynamic characteristics of small rotor configurations, including influence rotor-rotor interactions. will focus on comparisons between numerical wind tunnel results a provided by DLR. The models included Rotor/Rotor/Pylon isolated, tandem coaxial configuration. experiments for acoustics were DLR’s Acoustic Wind Tunnel Braunschweig (AWB) PIV test CIRA within joint...
The main goal of the present study is to explore noise mitigation potential using an active control strategy based on rotor phase synchronization. This work focused effects inflow velocity interference effect. does not affect at which phenomenon observed, as expected. On other hand, intensity pressure fluctuations influenced by for all shift conditions investigated. Specifically, increases, maintaining a constant rotational speed, in Overall Sound Pressure Level graphs, reduction...
The effect of turbulent boundary-layer flows on Helmholtz resonance pinhole-mounted sensors for the measurement wall pressure fluctuations is investigated. With different pinhole sizes and volumes behind pinholes, amplitudes frequencies are produced. test cover a large range momentum thickness ([Formula: see text]) Reynolds numbers, [Formula: text], include favorable adverse gradients. results show that amplitude frequency depend flow conditions. modification damping factor determined with...
This paper presents a consistent theory of self-similarity and equilibrium in the outer region turbulent boundary layers that explains recent experimental findings on subject, including new ones presented here. The is first general form where scales are left unspecified it not assumed mean velocity defect Reynolds stresses share common scale. It shown main results traditional similarity remain valid even this case. Common scaling with Zagarola-Smits length then chosen. A pressure gradient...
Abstract This paper addresses the acoustic and aerodynamic characteristics of small rotor configurations, including influence rotor–rotor interactions. For this purpose, a Rotor/Rotor/Pylon configuration is chosen for both test numerical simulations. The wind tunnel experiments on various were performed in DLR’s Acoustic Wind Tunnel Braunschweig (AWB). involve isolated rotors, rotors tandem coaxial hover forward flight. simulations, an unsteady free wake 3D panel method (UPM) used to account...
The ultimate goal of the present study is elaboration an empirical noise prediction model applicable in early development stage low-noise aircraft. To this end, a series aeroacoustic tests were performed to investigate characteristics flap side-edge noise. Two generic models, isolated flap and a high-lift wing selected for experiments. Measurements sound pressure levels as well directivity were done using dedicated microphone arrays. Moreover, acoustic investigation was complemented by...
In this paper, the relation between noise generated at flap side-edges (FSE) and mean flow characteristics in vicinity of FSE solid surface is investigated.Of interest (1) identification features near tip which are important to generation, (2) extraction quantitative parameters relating settings emitted levels and, finally, (3) formulation a prediction scheme based on these observations.The results investigation demonstrate that can be properly represented by summed contributions two...
A laser-generated sound source is used to generate a nearly omni-directional sound field. This field investigated experimentally reveal its characteristics as a function of the surrounding medium mean velocity. It found that source approximately has monopole character when generated in stagnant medium. Increas- ing flow velocity leads positive Doppler-shift combined with a convective amplification for an observer downstream while reverse is observed upstream source. The laser behaves...
The framework for a semi-empirical model the prediction of aerodynamically generated trailing edge sound from subsonic low Mach number 2D airfoils with mildly separated turbulent boundary layers is presented. Aerodynamic and acoustic measurements were performed results indicate that flow noise can be modeled in similar fashion to by attached layers. Comparisons aeroacoustic show agreement between prediction and results.
A laser-generated non-intrusive impulsive sound source is used to perform shield- ing experiments in the acoustic wind tunnel Braunschweig at a generic 2D wing with NACA0012 profile. The was already shown previous reports have a monopole-like character with nearly omni-directional radiation pattern, both in stagnant medium and flow field. In current report, emphasis first put on analysis of data post-processing steps required for obtention correct spectral time domain laser source....
This paper presents a multi-rotor test rig designed for the investigation of aerodynamics and acoustics small-scale propellers, relevant urban air mobility vehicles applications. The allows testing isolated rotors, rotors in coaxial configurations tandem various parametric combinations. Selected results are presented to emphasize impact aerodynamic acoustic interaction effects on characteristics emissions from configurations. indicate that amplification harmonics sub-harmonics noise...
The effect of turbulent boundary layer flows on the Helmholtz resonance pinhole-mounted sensors for measurement wall pressure fluctuations is investigated. With different pinhole sizes and volumes behind pinholes, amplitudes frequencies are produced. test cover a large range Reynolds numbers, 2100 < Re θ 14500, include favorable adverse gradients. results show that amplitude frequency depend flow conditions. modification damping factor determined with acoustic excitation, flow-induced can be...
The paper presents part of the experimental activities carried out in GARTEUR Action Group RC/AG-26 to study acoustic and aerodynamic characteristics small rotor configurations, including influence rotor-rotor interactions. Two rotors, equipped with two-bladed propellers a diameter D=330.2 mm, were operated at two rotating speeds 8025 RPM 10120 arranged different configurations. Isolated coaxial configurations hover conditions assessed. loads slipstream characterisation, terms flow field...
This paper is concerned with an experimental validation methodology for DLR’s acoustic shielding prediction boundary element code BEMPAR. in turn will be integrated into the overall aircraft noise tool PANAM of DLR. The presented concept based on a novel laser-based sound source. Almost perfect monopole-type test signals may produced frequency content up to roughly 100kHz combination very small source extension. These characteristics make this technique especially attractive...
The introduction of quiet short take-off and landing for civil aircraft operations in close proximity to the population poses important technological challenges. One critical aspect is realization extreme lift augmentation at low acoustic emissions. concept selected achieve this goal a high-lift system equipped with an active flow-control non-slotted flap droop nose. For specific configuration, trailing edge noise becomes dominant source. Porous materials as passive means trailing-edge...
First experimental results on investigations of the shielding characteristics three unconventional aircraft configurations are presented. DLR's Low Noise Aircraft, a scaled-down version NASA's Hybrid Wing Body configuration and F17E Unmanned Combat Air Vehicle all investigated in acoustic plenum of DNW-NWB wind tunnel at DLR Braunschweig. Using a laser-based non- intrusive impulsive point source, various effective engine placements were investigated for selected model settings....
The interaction of the jet with deployed flaps causes a substantial increase low-frequent aircraft noise. Noise reduction technologies (NRTs) were studied for their potential to diminish JFI effect: wing was equipped various permeable or porous (flap) trailing edges which cover last 10% clean chord length. first test conducted at Aeroacoustic Wind tunnel in Braunschweig (AWB) on cruise model, i.e. engine not installed. Beneath testing materials and concepts, design parameter study about...
Besides turbulent boundary layer induced excitation noise, jet noise is the second most important aeroacoustic source for aircraft cabin noise. A goal within DLR project ECCO (Enhanced Cabin Comfort Computations) was to improve current pre- diction approaches. Within framework of project ECCO RANS (Reynolds Averaged Navier Stokes) and CAA (Computational Aero Acoustics) computations at cruise conditions have been carried out. Especially at high cruise Mach numbers forward ight e�ects...