Experimental Investigation of Intake Ground Vortices During Takeoff

Murphy, John P.; MacManus, David G.; Sheaf, C. T.

doi:10.2514/1.45896

Cited by 26 publications

(25 citation statements)

References 8 publications

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“…Most recently, Brix et al (2000)'s experiments suggested that even without an ambient flow an inlet vortex would form. Murphy et al (2010) proposed that, under quiescent condition, the source of vorticity is the boundary layer which is generated by the interaction of the intake-induced flow and the ground surface.…”

Section: Introductionmentioning

confidence: 99%

Unsteady characteristics of inlet vortices

Wang

Gursul

2012

Exp Fluids

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An experimental study of the unsteady characteristics of inlet vortices has been conducted using a high-frame-rate digital particle image velocimetry (DPIV) system. The results revealed the formation of a pair of counter rotating inlet vortices for the no-wind configuration and one single inlet vortex when there was crosswind. In all measurement = Circulation (m 2 /s) ω y = Vorticity in the vertical plane perpendicular to the axis of the inlet model (s-1) ω z = Vorticity in the horizontal planes parallel to the ground (s-1

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Section: Introductionmentioning

confidence: 99%

Unsteady characteristics of inlet vortices

Wang

Gursul

2012

Exp Fluids

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“…Due to the modelling simplifications, the latter tool is less accurate but is more instructive in understanding the fundamental mechanisms associated with headwind ground vortex formation. The third technique, however, uses the simple analytical model in conjunction with a core embedded level of empiricism to achieve a greater level of accuracy The paper is structured by first describing the methodology of the model-scale experiments that have been conducted which are described in more detail in [7][8][9][10]. This is followed by a summary of the key experimental results under headwind conditions that are pertinent to the vortex strength models.…”

Section: Introductionmentioning

confidence: 99%

Intake Ground Vortex Prediction Methods

Murphy

MacManus

2011

Journal of Aircraft

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For an aircraft turbofan engine in ground operations or during the takeoff run a ground vortex can occur which is ingested and could potentially adversely affect the engine performance and operation. The vortex characteristics depend on the ground clearance, intake flow capture ratio and the relative wind vector. It is a complex flow for which there is currently very little appropriate quantitative preliminary design information. These aspects are addressed in this work where a range of models are developed to provide a method for estimating the key metrics such as the formation boundary and the ground vortex size and strength. Three techniques are presented which utilize empirical, analytical and semi-empirical approaches. The empirical methods are primarily based on a large dataset of model-scale experiments which quantitatively measured the ground vortex characteristics for a wide range of configurations. These include the effects of intake ground clearance, approaching boundary layer thickness, intake Mach number and capture velocity ratio. Overall the models are able to predict some of the key measured behaviours such as the velocity ratio for maximum vortex strength. With increasing empiricism for key sub-elements of the model construction, an increasing level of agreement is found with the experimental results. Overall the three techniques provide a relatively quick and easy method in establishing the important vortex characteristics for a given headwind configuration which is of significant use from a practical engineering perspective.

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“…The entry positions of the vortices are mostly at the bottom of the intake [4,5,11]. This flow asymmetry causes the ground vortices to affect the distortion of the engine inflow [12]. The total pressure distortion was shown to increase monotonically with the thrust coefficient when the wind tunnel wall was synchronized with the free stream velocity (the wind tunnel wall was replaced by a moving belt) to eliminate the boundary layer on the ground.…”

Section: Introductionmentioning

confidence: 97%

“…For the headwind condition, which is the situation of our investigation, ground vortices are generated by the suction of vorticity (wall-parallel components) existed near the ground into wall-normal component [3]. These vortex near the ground are ascribed to the far field boundary layer [3,7,8]; moreover, these vorticity could also be generated by the pressure gradient on the ground induced by the propeller suction according to the vorticity generation equation [ 9 ]. For the take-off condition, the wall-parallel components of vorticity are generated by the pressure gradient on the ground solely.…”

Section: Introductionmentioning

confidence: 99%

Spatial-temporal and modal analysis of propeller induced ground vortices by particle image velocimetry

et al. 2016

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. Spatial-temporal and modal analysis of propeller induced ground vortices by particle image velocimetry. Physics of Fluids, 28. https://doi.org/10.1063/1.4964685 Important noteTo cite this publication, please use the final published version (if applicable). Please check the document version above. CopyrightOther than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons. Takedown policyPlease contact us and provide details if you believe this document breaches copyrights. We will remove access to the work immediately and investigate your claim. AbstractDuring the ground operation of aircraft, there is potentially a system of vortices generated from the ground toward the propulsor, commonly denoted as ground vortices. Although extensive research has been conducted on ground vortices induced by turbofans which were simplified by suction tubes, these studies cannot well capture the properties of ground vortices induced by propellers, e.g. the flow phenomena due to intermittent characteristics of blade passing and the presence of slipstream of the propeller. Therefore, the investigation of ground vortices induced by a propeller is performed to improve understanding to these phenomena. The distributions of velocities in two different planes containing the vortices were measured by high frequency Particle Image Velocimetry (PIV). These planes are a wall-parallel plane in close proximity to the ground and a wall-normal plane upstream of the propeller. The instantaneous flow fields feature highly unsteady flow in both of these two planes. The spectral analysis is conducted in these two flow fields and the energetic frequencies are quantified. The flow fields are further evaluated by applying the Proper Orthogonal Decomposition (POD) analysis to capture the coherent flow structures. Consistent flow structures with strong contributions to the turbulent kinetic energy are noticed in the two planes.

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Experimental Investigation of Intake Ground Vortices During Takeoff

Cited by 26 publications

References 8 publications

Unsteady characteristics of inlet vortices

Unsteady characteristics of inlet vortices

Intake Ground Vortex Prediction Methods

Spatial-temporal and modal analysis of propeller induced ground vortices by particle image velocimetry

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