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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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Adaptive Base-Flaps Under Variable Cross-Wind

Imperial College London-J. Marcos Garcia de la Cruz, Rowan D. Brackston, Jonathan F. Morrison
Published 2017-08-25 by SAE International in United States
Road vehicles usually operate within windy environments. The combination of typical wind distributions and vehicle speeds, imposes on such vehicles aerodynamic yaw angles, β, which are often almost uniform up to 6° and relevant up to 14°. Drag saving devices are often optimized for zero cross-wind scenarios, minimizing drag only around these design conditions. This work presents the drag saving increase that an adaptive system can provide over a classic boat-tail.In the experimental set up employed, two flaps are located at the rear lateral edges of an Ahmed body and respectively set at angles θ1 and θ2 with respect to the model. To evaluate the efficacy of different flap positioning strategies under cross-wind, the model was tested in a wind tunnel, , with and without flaps at yaw angles β = 0°, 3°, 6° or 9°. The flap sizes tested, δ, were 9% or 13% of the body width. For each β and δ, the maps of drag against the two flap angles were obtained.The minimum drag is generally not located at the symmetric flap…
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Aircraft Landing Noise Reduction Liners

  • Magazine Article
  • TBMG-27199
Published 2017-07-01 by Tech Briefs Media Group in United States

NASA Langley Research Center has developed two new implementations of acoustic liners for aircraft noise reduction whereby curved channels within tight spaces can be outfitted to provide noise reduction. The two implementations are flap side edge liners and landing gear door liners for airframe noise reduction. In these applications, the acoustic liner is designed primarily to reduce aircraft noise that occurs during landing, which will help aircraft comply with increasingly stringent airport noise restrictions.

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Closed Wheel Race Vehicle Aerodynamic Lift-Off

SAE International Journal of Passenger Cars - Mechanical Systems

Richard Childress Racing-Daniel B. Honeycutt
UNC Charlotte Motorsports Engineering-Mesbah Uddin
  • Journal Article
  • 2017-01-1516
Published 2017-03-28 by SAE International in United States
Although, the implementation of lift-off prevention devices such as the NASCAR roof flaps have greatly reduced the frequency and severity of race vehicle aerodynamic lift-off incidents, airborne incidents still occur occasionally in motorsports. The effectiveness of existing lift-off prevention measures and future trends in lift-off prevention are addressed in this paper. The results and analysis presented in this paper will be of paramount interest to race vehicle designers and sanctioning bodies because the effects of aerodynamics on vehicle lift-off need to be comprehended, but there exists a scarcity of reliable data in this area.
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