The newly refurbished vertical tunnel (V-tunnel) at Delft University of Technology has been redesigned as a state-of-the-art facility for research in aeroacoustics (A-tunnel), well fundamental studies laminar-turbulent transition and flow control. This manuscript focuses on the design refurbishment aspects facility, including description main modifications supporting structures drive system fan, with details conditioning anechoic performance. A rigorous aeroacoustic aerodynamic...

Functional beamforming is a state-of-the-art nonlinear algorithm based on the conventional frequency domain beamformer. In general, it found to provide improved array spatial resolution and dynamic range. The computational time required for functional approximately same as that beamformer and, in notably shorter than those of deconvolution methods. this paper, several simulations are presented comparing performance with other imaging Moreover, technique applied 115 flyover measurements...

In this article, a high-resolution extension of CLEAN-SC is proposed: high-resolution-CLEAN-SC. Where uses peak sources in ‘dirty maps’ to define so-called source components, high-resolution-CLEAN-SC takes advantage the fact that components can likewise be derived from points at some distance peak, as long these ‘source markers’ are on main lobe point spread function. This very useful when closely spaced together, such their functions interfere. Then, alternative markers sought which...

Trailing edge serrations designed to reduce airfoil self-noise are retrofitted on a NACA 0018 airfoil. An investigation of the boundary layer flow statistical properties is performed using time-resolved stereoscopic PIV. Three streamwise locations over compared. analysis results indicates that, while there no upstream effect, experiences significant changes as it convects and toward its edges. Among most important, reduced shear stress modifications turbulence spectra suggest beneficial in...

Most acoustic imaging methods assume the presence of point sound sources and, hence, may fail to correctly estimate emissions distributed sources, such as trailing-edge noise. In this contribution, three integration techniques are suggested overcome issue based on models considering a single source, line and several respectively. Two simulated benchmark cases featuring employed compare performance these with respect other well-known methods. The considered provide best in retrieving source...

The recently introduced high-resolution (HR)-CLEAN-SC algorithm for acoustic imaging provides ‘super-resolution’, i.e. the ability to discern sound sources located closer than Rayleigh resolution limit. This is achieved by allowing source markers be relocated from actual locations within a certain constraint avoid combined influence of other sources. freedom relocate increase performance depends on maximum sidelobe level array used. paper presents an ‘enhanced’ version HR-CLEAN-SC which...

Wind turbines represent an encouraging option for sustainable energy but their noise emissions can be issue public acceptance. Noise reduction measures, such as trailing-edge serrations or permeable inserts, seem to offer promising results in reducing wind turbine levels. This manuscript presents a novel holistic approach perception-based evaluation of and the performance measures using synthetic sound auralization. To demonstrate its feasibility, case study featuring four state-of-the-art...

Literature suggests that psychoacoustic metrics, which are established by models firmly based on the human auditory system, able to better approximate perceptual attributes of sounds in a quantitative manner than conventional metrics sound pressure level. Therefore, commonly used as quality indicators practical applications, such product design or environmental noise assessment, perception plays an important role. However, their calculation is not straightforward and non-availability...

Enforcing noise control environmental laws around airports is a difficult task due to the large variability in levels observed for flyovers of same aircraft type under similar conditions. These variations are not properly considered by current models, such as noise-power-distance tables. In this research, measurements were used assess and investigate its causes. 115 landing recorded using 32-microphone phased array. It was assumed that main cause change emitted noise, previous studies showed...

The noise emissions of a full-scale nose landing gear (NLG), measured in wind tunnel and obtained from computational simulations, are compared with those three regional aircraft types recorded flyover measurements. A comparison is made the prediction models Fink, Guo, German Aerospace Center (DLR). good agreement was found between all spectra. up to 1.2 kHz were scale sixth power flow velocity, as usual; however, spectra at higher frequencies collapsed better when scaled seventh power,...

The landing gear system is the dominant airframe noise source for most modern commercial aircraft during approach. This manuscript reports results from ALLEGRA (Advanced Low Noise Landing (Main and Nose) Gear Regional Aircraft) project. project assessed performance of several highly realistic low–noise technologies (LNTs) applied to a detailed full–scale nose (NLG) model in aeroacoustic wind–tunnel experiments. Four individual concepts tested, namely ramp door spoiler, solid wheel axle...

The impingement of a propeller slipstream on downstream surface causes unsteady loading, which may lead to vibrations responsible for structure-borne noise. A low-speed wind-tunnel experiment was performed quantify the potential flow-permeable leading edge alleviate slipstream-induced loading. For this purpose, tractor installed at tip pylon featuring replaceable leading-edge insert in region impingement. Tests were carried out with four inserts, different hole diameters and cavity depths,...

Accurate predictions of aircraft noise levels are desirable to enforce control regulations around airports and evaluate abatement procedures. The current best practice contour prediction models assume certain default net thrust values depending on the engine type altitude. This Paper proposes a method for calculating fan settings (and, hence, thrust) directly from audio recordings. was tested with large number Airbus A330–300 Boeing 777–200 flyover A significant correlation found between...

Abstract. This study investigates the relationship between sound quality metrics (SQMs) and noise annoyance caused by airborne wind energy systems (AWESs). In a controlled listening experiment, 75 participants rated their on International Commission Biological Effects of Noise (ICBEN) scale in response to recordings from in-field measurements two fixed-wing one soft-wing ground-generation AWES. All were normalized an equivalent A-weighted pressure level 45 dBA. The results revealed that...

Distributed propulsion systems are developed to power a new generation of aircraft. However, it is not known yet which noise emissions these produce, psychoacoustic characteristics such exhibit, and how the generated perceived. This paper investigates fans with fewer stator than rotor blades affect perception distributed system intended for an urban air mobility vehicle, equipped 26 low-speed ducted fans. Three fan designs different tonal broadband ratio opposite dominant radiation...

Conventional beamforming with a microphone array is well-established method for localizing and quantifying sound sources. It provides estimates the source strengths on predefined grid by determining agreement between pressures measured those modeled located at point under consideration. As such, conventional can be seen as an exhaustive search locations that provide maximum match pressures. In this contribution, authors propose to, instead of search, use efficient global optimization to...

The noise emissions of the nose landing gear a full-scale model tested in wind tunnel, and three regional aircraft types flyover measurements are compared this contribution.The geometries gears all cases were similar.Microphone arrays beamforming algorithms used to determine sound gears.A good agreement was found between overall trends frequency spectra cases.Moreover, expected 6 th power law with flow velocity confirmed for both experiments.On other hand, strong tonal peaks (at around 2200...

Airframe noise is becoming increasingly important during approach, even reaching higher levels than the engines in some cases.More people are affected due to low flight altitudes and fixed traffic routing associated with typical approaches.For most aircraft types, landing gear system a dominant airframe source.However, this element can only be modeled an approximate manner wind tunnel experiments.In research, flyovers of were recorded using 32 microphone array.Functional beamforming was...

The trailing edge of a NACA 0018 airfoil is modified through the attachment serrations with different degrees permeability. Acoustic beamforming used to inspect turbulent boundary layer-trailing noise emissions from unmodified and serrated edges. Different freestream velocities angles attack are investigated. serration permeability prescribed by having slits cut into solid surface in two configurations. results indicate that certain benefit reduction obtained mixed solid/slitted...