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Simulation of Transient On-Road Conditions in a Closed Test Section Wind Tunnel using a Wing System with Active Flaps

FKFS-Andreas Wagner, Jochen Wiedemann
German Aerospace Center DLR-Henning Wilhelmi, James Bell, Daniela Heine, Claus Wagner
  • Technical Paper
  • 2020-01-0688
To be published on 2020-04-14 by SAE International in United States
There is a high interest to improve the static approach of wind tunnel testing by simulating realistic transient flow conditions. To determine these conditions, different driving maneuvers (driving behind, passing) were conducted in previous experiments on a runway. The transient, incoming flow and the vehicle’s surface pressure were measured. To create the realistic inflow conditions in a wind tunnel, a new system of four symmetric airfoils with active flaps was developed for the Side-Wind Facility Göttingen (SWG), a closed loop, closed test-section facility with a moving belt and suction system. The airfoils heights are half the test section’s height and the trailing third of their chords are active flaps. The reduced inertia - resulting from only one third of the airfoil moving - allows for individual high-speed, rotational movements of the flap at with up to 50 Hz and angles of up to ±20°. Time-resolved velocity component measurements in the empty test section were conducted with an array of eleven 5-hole probes connected to an ESP64HD pressure transducer system for various flap configurations. These measurements…
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Aerodynamic Design and Analysis of a Formula SAE Drag Reduction System (DRS)

University of Manitoba-David J. Penner
  • Technical Paper
  • 2020-01-0685
To be published on 2020-04-14 by SAE International in United States
Formula SAE vehicles, like many other vehicles within the realm of motorsport, often employ rear mounted aerodynamic devices to improve cornering performance, these devices can however have a significant amount of aerodynamic drag. Additional speed can be gained by reducing the impact of the rear wing on the straightaways of the track through the use the aptly named Drag Reduction System (DRS), which works by reducing the angle of attack of the rear wing flap(s). A DRS can however introduce other performance losses, including the losses from having a gap between the rear wing flaps and endplate to prevent friction, the potential to stall the rear wing from improper opening angles of the flaps, and from the wake of the DRS actuator if positioned in front of the airfoils. An additional concern is the time it takes for the rear wing performance to return upon DRS deactivation, which will affect how long before corner entry the driver must disable the system. Insight into each of these problems as well as the optimum opening angles was…

Flow Disruption Devices for the Reduction of High Lift System Noise

  • Magazine Article
  • TBMG-35792
Published 2020-01-01 by Tech Briefs Media Group in United States

During airport approach and landing, airstream noise is a dominant aircraft noise source, and the noise that is generated at the side edges of the deployed flaps, elevons, and slats is an important component of that noise. The noise radiating from these side edges is caused by their interaction with the strong vortex systems that are present along these edges. The purpose of flow disruption devices is to reduce that noise.

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Developing a Theory for Active Grille Shutter Aerodynamics-Part 2: Effect of Flap Thickness and Shape

Dr. Ing. h.c. F. Porsche AG-Thomas Wolf
  • Technical Paper
  • 2019-01-5095
Published 2019-11-19 by SAE International in United States
A recently developed theory for the description of the aerodynamic behaviour of active grille shutters is extended by the influence of the thickness of the cooling air flaps. The analysis of the resulting equations shows that the thickness of the flaps has no influence on the characteristic curve of an active grille shutter. To validate the theoretical results, wind tunnel measurements are carried out on a vehicle with an active grille shutter, and both the thickness and the shape of the flaps are specifically modified. The experimental results confirm the analytical results and show that not the thickness but the shape of the cooling air flaps is the decisive influencing factor. The experiments further show that aerodynamically unfavourable flap shapes, even with small relative thicknesses, lead to a significant change in the characteristic curve and to significant losses in cooling airflow with fully opened flaps. In contrast to this, with flow-optimized flap shapes, relative thicknesses of up to 30% of the flap length are possible without changing the characteristic curves or significantly reducing the cooling…
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Advanced Assembly Solutions for the Airbus RACER Joined-Wing Configuration

University of Nottingham-David Bainbridge, Konstantinos Bacharoudis, Andrea Cini, Alison Turner, Atanas Popov, Svetan Ratchev
Published 2019-09-16 by SAE International in United States
The Rapid And Cost Effective Rotorcraft (RACER) is being developed by Airbus Helicopters (AH) to demonstrate a new Vertical Take-Off and Landing configuration to fill the mobility gap between conventional helicopters and aeroplanes. RACER is a compound rotorcraft featuring wings and multiple rotors. The wing arrangement suggested by AH is defined as a staggered bi-plane joined configuration with an upper and a lower straight wing, either side of the fuselage, connected at their outboard extent to form a triangular structure. The ASTRAL consortium, consisting of the University of Nottingham and GE Aviation Systems, are responsible for the design, manufacture, assembly and testing of the wings. Producing an optimised strategy to assemble a joined-wing configuration for a passenger carrying rotorcraft is challenging and novel. The objective of this work concerns all aspects of assembling the joined-wing structure.The joined-wing and fuselage structures will be produced independently and mated together during the final RACER assembly. A multi-stage process will deliver the joined-wing assembly and ensure it will fit to the fuselage. Producing the individual wing structures requires a…
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Computational Analysis of Flap Camber and Ground Clearance in Double-Element Inverted Airfoils

Delhi Technological University-Vishesh Kashyap, Sourajit Bhattacharjee
Published 2019-06-11 by SAE International in United States
Drag and lift are the primary aerodynamic forces experienced by automobiles. In competitive automotive racing, the design of inverted wings has been the subject of much research aimed at improving the performance of vehicles. In this direction, the aerodynamic impact of change in maximum camber of the flap element and ground effect in a double-element inverted airfoil was studied. The National Advisory Committee for Aeronautics (NACA) 4412 airfoil was taken as the constant main element. The camber of the flap element was varied from 0% to 9%, while ground clearance was varied from 0.1c to 1.0c. A two-dimensional (2D) Computational Fluid Dynamics (CFD) study was performed using the realizable k-ε turbulence model in ANSYS Fluent 18.2 to analyze the aerodynamic characteristics of the airfoil. Parameters such as drag coefficient, lift coefficient, pressure distribution, and wake flow field were investigated to present the optimum airfoil configuration for high downforce and low drag. It was observed that while an increase in flap camber improves the lift coefficient substantially, this change is dependent on the angle of attack…
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Flap Assemblies, Rotary Flap Peening

AMS B Finishes Processes and Fluids Committee
  • Aerospace Standard
  • AS2592A
  • Current
Published 2019-02-21 by SAE International in United States
This Aerospace Standard covers components of rotary flap assemblies to be used with portable equipment for peening of metal parts. The flap assemblies consist of a flap attached to a mandrel and shall be of the following sizes.
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Variable-Camber Compliant Wing

  • Magazine Article
  • TBMG-32470
Published 2018-08-01 by Tech Briefs Media Group in United States

In the early years of manned flight, wing warping was used for lateral control of an aircraft. This technique consisted of a system of pulleys and cables used to twist the trailing edges of the wings in opposite directions. Because most wing warping designs involved flexing of structural members, they were difficult to control, and the risk of structural failure was high. As aircraft further developed, wing warping was replaced by multiple, independent, rigid flight control surfaces — such as ailerons, leading edge slats, and flaps — and while this approach is still in use, it is not without problems.

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Numerical Investigation on Aerodynamic Effects of Vanes and Flaps on Automotive Underbody Diffusers

Delhi Technological University-T. P. Aniruddhan Unni
Published 2017-09-19 by SAE International in United States
The automotive underbody diffuser is an expansion device which works by speeding up the air flowing underneath a vehicle. This reduces the pressure below the vehicle thereby increasing downforce. When designed properly, it can lead to a massive gain in downforce and even a reduction in drag. However, a majority of the research and development is restricted to motorsport teams and supercar manufacturers and is highly secretive. Most of the publicly available research has been done for very simple shapes (bluff bodies) to study the effects of ground clearance and rake angle. Very little research has been done for complex geometries with vanes, flaps and vortex generators. This paper aims to investigate the effects of the addition of vanes/strakes and flaps, their location as well as angle, on diffuser performance. Computational Fluid Dynamics simulations have been carried out using three dimensional, steady state RANS equations with the k-ε turbulence model on STAR CCM+ V9.06. The simulation methodology has been verified using experimental data first. The diffuser geometry is based on the Formula SAE car developed…
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Structural Concept of an Adaptive Shock Control Bump Spoiler

DLR German Aerospace Center-Markus Kintscher, Hans Peter Monner
Published 2017-09-19 by SAE International in United States
Drag reduction technologies in aircraft design are the key enabler for reducing emissions and for sustainable growth of commercial aviation. Laminar wing technologies promise a significant benefit by drag reduction and are therefore under investigation in various European projects. However, of the established moveable concepts and high-lift systems, thus far most do not cope with the requirements for natural laminar flow wings. To this aim new leading edge high-lift systems have been the focus of research activities in the last five years. Such leading edge devices investigated in projects include a laminar flow-compatible Kruger flap [1] and the Droop Nose concept [2, 3] and these can be considered as alternatives to the conventional slat. Hybrid laminar flow concepts are also under investigation at several research institutes in Europe [4]. Another challenge associated with laminar wings aside from the development of leading edge moveables is the need to address the control of aerodynamic shocks and buffeting as laminar wings are sensitive to high flow speeds. One possible method of decreasing the wave drag caused by the…
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