Investigations and measures to improve the acoustic characteristics of the German-Dutch Wind Tunnel DNW-LLF

Holthusen, Hermann; Bergmann, Andreas; Sijtsma, Pieter

doi:10.2514/6.2012-2176

Cited by 10 publications

(5 citation statements)

References 5 publications

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“…The wind tunnel is known to have a low background noise level, which was further improved by recent upgrades of the turning vane geometry and the heat exchanger -flow straightener assembly. 10 An overview of the test setup is shown in Fig. 1.…”

Section: A Wind Tunnel Facility and Modelsmentioning

confidence: 99%

Aerodynamic and Aeroacoustic Effects of Pylon Trailing Edge Blowing on Pusher Propeller Installation

Sinnige

Lynch

Ragni

et al. 2015

21st AIAA/CEAS Aeroacoustics Conference

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The aerodynamic and aeroacoustic effects of pylon trailing edge blowing on the propulsive performance and noise emissions of a propeller installed in a pusher configuration were studied in a wind tunnel. A propeller model and a pylon equipped with a trailing edge blowing system were installed in the large low-speed facility of the German-Dutch wind-tunnels (DNW-LLF). Particle image velocimetry measurements of the flow field downstream of the pylon confirmed a wake re-energization obtained through blowing, with a momentum deficit recovery of 80% compared to the unblown case. For the symmetric inflow conditions considered, the effect of pylon installation on the propulsive performance was found small. Increases in thrust and torque of 1% up to 6% were measured at high and low thrust settings, which was comparable to the measurement variability. Acoustic data obtained using out-of-flow microphones confirmed the strong interaction effects resulting from the installation of the upstream pylon, with an increase in noise levels due to the presence of the pylon of up to 12 dB at a medium propeller thrust setting. The application of pylon trailing edge blowing successfully eliminated the installation effects, resulting in noise levels equal to those of the isolated propeller over the entire axial directivity range. At higher thrust settings the change in blade angle of attack due to the pylon wake impingement is smaller, and the steady blade loads are larger compared to the unsteady loads experienced during the wake passage. Consequently, in this operating regime the propeller noise emissions were dominated by steady sources for all but the most upstream observer positions.

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Section: A Wind Tunnel Facility and Modelsmentioning

confidence: 99%

Aerodynamic and Aeroacoustic Effects of Pylon Trailing Edge Blowing on Pusher Propeller Installation

Sinnige

Lynch

Ragni

et al. 2015

21st AIAA/CEAS Aeroacoustics Conference

View full text Add to dashboard Cite

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“…The main contributors to the background noise are the fans noise, the turning vane aerodynamic design or the turbulence screen. These kinds of large investments have been successfully driven by other wind tunnel operators [6,7]. In the present case, it seems to be too ambitious and thus can impact the overall windtunnel performance to fully redesign the fan in order to reduce the noise generated by the fans.…”

Section: Background Noise Reduction Challenge In S1ma Large Wind Tunn...mentioning

confidence: 92%

“…Finally, the improvement of the facility itself is mandatory to measure accurately even lower noisy aeronautical devices. Several worldwide facilities operated modifications in order to improve the background noise [6,7] in the test section. These modifications can be optimisation of the fan, redesign and lining of the turning vane and redesign of the turbulence filter.…”

Section: Introductionmentioning

confidence: 99%

Design, manufacturing and experimental assessment of an acoustic liner demonstrator for a turning vane of S1MA large wind tunnel facility

Méry

Roncen

Simon

et al. 2022

28th AIAA/CEAS Aeroacoustics 2022 Conference

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“…The low background noise levels of the tunnel were further improved by recent upgrades of the turning vane geometry and the heat exchanger -flow straightener assembly. 18 A modern tractor propeller model was used together with detachable SRVs to perform tests for the cases with and without the SRVs installed. A photograph of the test setup is shown in Fig.…”

Section: A Wind Tunnel Facility and Modelsmentioning

confidence: 99%

The Effects of Swirl Recovery Vanes on Single-Rotation Propeller Aerodynamics and Aeroacoustics

Sinnige

Kuijk

Lynch

et al. 2015

21st AIAA/CEAS Aeroacoustics Conference

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A preliminary assessment of the aerodynamic and aeroacoustic impact of swirl recovery vanes (SRVs) installed downstream of a single-rotating propeller model was performed at the large low-speed facility of the German-Dutch wind tunnels (DNW-LLF). The SRVs are designed to recover the swirl in the rotor slipstream, thereby increasing the propulsive efficiency without the added complexity of contra-rotating systems. The performance data acquired with a rotating shaft balance showed that the upstream effect of the SRVs on the time-averaged rotor performance was negligible. Particle image velocimetry measurements in the slipstream of the propeller with and without SRVs substantiated the efficacy of the vanes in reducing the swirl in the propeller slipstream. Integrated in the radial direction, installation of the vanes reduced the swirl kinetic energy by 50% at a medium propeller thrust setting. An additional slipstream contraction was observed with vanes installed. The acoustic data measured with out-of-flow microphones showed that installation of the SRVs increased the total sound pressure levels by 2 to 6 dB compared to the isolated propeller.

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Investigations and measures to improve the acoustic characteristics of the German-Dutch Wind Tunnel DNW-LLF

Cited by 10 publications

References 5 publications

Aerodynamic and Aeroacoustic Effects of Pylon Trailing Edge Blowing on Pusher Propeller Installation

Aerodynamic and Aeroacoustic Effects of Pylon Trailing Edge Blowing on Pusher Propeller Installation

Design, manufacturing and experimental assessment of an acoustic liner demonstrator for a turning vane of S1MA large wind tunnel facility

The Effects of Swirl Recovery Vanes on Single-Rotation Propeller Aerodynamics and Aeroacoustics

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