Experimental Study of the Corner Flow Separation on a Simplified Junction

Gand, Fabien; Monnier, Jean-Claude; Deluc, J.-M.; Choffat, A.

doi:10.2514/1.j053771

Cited by 18 publications

(12 citation statements)

References 27 publications

(35 reference statements)

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“…This behavior is consistent with Simpson (2001), who reports a stronger HSV with increasing AoA. Gand et al (2015) showed experimentally that the onset of corner separation is delayed by a stronger HSV, since fluid of higher momentum is pushed into the blade boundary layer. This beneficial inductive effect likewise depends on the distance to the blade.…”

Section: The Effect On Flow Separation and Its Driving Parameterssupporting

confidence: 89%

“…This phenomenon is typically found in the junction of the wing and the fuselage of transport aircraft (Levy et al, 2014;Vassberg et al, 2008) or in turbo-machinery cascades (Knezevici et al, 2010). Corner flows are highly influenced by a complex vortex system of primary and secondary vortices and have been investigated in great detail in experimental work addressing the effect of the horseshoe vortex (HSV) near the leading edge (see review paper of Simpson, 2001) and more recently by Gand et al (2015), also focusing on the trailing edge and analyzing the corner vortex. The latter authors found particular evidence that the Reynolds stresses are not aligned with the mean shear tensor, which means that anisotropy of turbulence is present in the region of corner flow separation.…”

Section: Corner Flow Separation Of Aerodynamically Shaped Junctionsmentioning

confidence: 99%

“…For this reason, a priori simulations of the simplified wing-body junction test case of Gand et al (2015) have been performed. In principle, this is a wing mounted on a flat plate of a certain length operating at an AoA of 12 • .…”

Section: Appendix A: the Effect Of The Turbulence Model On Corner Sepmentioning

confidence: 99%

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Numerical analyses and optimizations on the flow in the nacelle region of a wind turbine

et al. 2018

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Abstract. The present study investigates flow dynamics in the hub region of a wind turbine focusing on the influence of nacelle geometry on the root aerodynamics by means of Reynolds averaged Navier-Stokes simulations with the code FLOWer. The turbine considered is a generic version of the Enercon E44 converter incorporating blades with flat-back-profiled root sections. First, a comparison is drawn between an isolated rotor assumption and a setup including the baseline nacelle geometry in order to elaborate the basic flow features of the blade root. It was found that the nacelle reduces the trailed circulation of the root vortices and improves aerodynamic efficiency for the inner portion of the rotor; on the other hand, it induces a complex vortex system at the juncture to the blade that causes flow separation. The origin of these effects is analyzed in detail. In a second step, the effects of basic geometric parameters describing the nacelle have been analyzed with the purpose of increasing the aerodynamic efficiency in the root region. Therefore, three modification categories have been addressed: the first alters the nacelle diameter, the second varies the blade position relative to the nacelle and the third comprises modifications in the vicinity of the blade-nacelle junction. The impact of the geometrical modifications on the local flow physics are discussed and assessed with respect to aerodynamic performance in the blade root region. It was found that increasing the nacelle diameter deteriorates the root aerodynamics, since the flow separation becomes more pronounced. Possible solutions identified to reduce the flow separation are a shift of the blade in the direction of the rotation or the installation of a fairing fillet in the junction between the blade and the nacelle.

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Section: The Effect On Flow Separation and Its Driving Parameterssupporting

confidence: 89%

Section: Corner Flow Separation Of Aerodynamically Shaped Junctionsmentioning

confidence: 99%

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Numerical analyses and optimizations on the flow in the nacelle region of a wind turbine

et al. 2018

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“…The surface streamlines pattern observed in Figs. 10c and 10f is also comparable to the flow separation that occurs at wing-body junctions at higher angles of attack [39], although the effective increase in angle of attack is, in this case, a consequence of slipstream contraction. In order to further investigate the flowfield at the square duct's corner, the flow's axial vorticity is shown in Fig.…”

Section: Time-averaged Effects (Ad Simulation)mentioning

confidence: 53%

Aerodynamic Performance and Interaction Effects of Circular and Square Ducted Propellers

Bento

Vries

Veldhuis

2020

AIAA Scitech 2020 Forum

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Ducted propellers constitute an efficient propulsion-system alternative to reduce the environmental impact of aircraft. These systems are able to increase the thrust-to-power ratio of a propeller system by both producing thrust and by lowering tip losses of propellers. In this research, steady and unsteady RANS CFD simulations were used to analyze the possible impact of modifying a propeller duct shape from a circular to a square geometry. Initially, the two duct designs and the propeller were studied separately, in order to estimate the numerical errors and to compare with existing data. In the installed simulations, the propeller was first modelled as an actuator disk, and afterwards with a full blade model, in order to understand the time-averaged influence of the propeller on the duct before studying the complete unsteady propeller-duct interaction. In the current design, the square duct corners were found to be prone to separation, and to contribute towards the generation of strong vortices. Furthermore, due to the reduced leading-edge suction on the square duct, the square ducted system was found to be 4.5% less efficient than the circular one, for the conditions tested. By relating the aerodynamic interaction phenomena to the performance of the system, this study provides and important basis for the design of unconventional ducted systems.

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“…Subsequently, the investigators re-designed the experiment with a twisted NACA 0015 wing on a plate. 25 This time, the corner flow separated in the experiment. Details were provided at a chord Reynolds number of 1.2 × 10 6 and angle of attack of 12 • , although other conditions were also investigated.…”

Section: Introductionmentioning

confidence: 97%

The NASA Juncture Flow Experiment: Goals, Progress, and Preliminary Testing (Invited)

Rumsey

Neuhart

Kegerise

2016

54th AIAA Aerospace Sciences Meeting

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NASA has been working toward designing and conducting a juncture flow experiment on a wing-body aircraft configuration. The experiment is planned to provide validation-quality data for CFD that focuses on the onset and progression of a separation bubble near the wing-body juncture trailing edge region. This paper describes the goals and purpose of the experiment. Although currently considered unreliable, preliminary CFD analyses of several different configurations are shown. These configurations have been subsequently tested in a series of "risk-reduction" wind tunnel tests, in order to help down-select to a final configuration that will attain the desired flow behavior. The risk-reduction testing at the higher Reynolds number has not yet been completed (at the time of this writing), but some results from one of the low-Reynolds-number experiments are shown.

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Experimental Study of the Corner Flow Separation on a Simplified Junction

Cited by 18 publications

References 27 publications

Numerical analyses and optimizations on the flow in the nacelle region of a wind turbine

Numerical analyses and optimizations on the flow in the nacelle region of a wind turbine

Aerodynamic Performance and Interaction Effects of Circular and Square Ducted Propellers

The NASA Juncture Flow Experiment: Goals, Progress, and Preliminary Testing (Invited)

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