Aerodynamic Performance and Interaction Effects of Circular and Square Ducted Propellers

Bento, Hugo Mourão; Vries, R. de; Veldhuis, L.L.M.

doi:10.2514/6.2020-1029

Cited by 11 publications

(6 citation statements)

References 26 publications

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“…Although the duct can, in principle, reduce the unsteady loading and noise of the propeller (or "fan", in this case), this may not be required for small propellers placed near to the trailing edge. Moreover, while the duct itself contributes positively to thrust at high thrust settings [54,55], in cruise it is likely to reduce the L/D of the system due to the increase in wetted area [56]. If a duct is required, then a two-dimensional "envelope" duct comparable to the concept of Fig.…”

Section: A) Otwdp Configuration (Top View) C) Conventional Configurat...mentioning

confidence: 99%

Aerodynamic Performance Benefits of Over-the-Wing Distributed Propulsion for Hybrid-Electric Transport Aircraft

Vries

Vos

2023

Journal of Aircraft

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The goal of this study is to analyze how the aeropropulsive benefits of an over-the-wing distributed-propulsion (OTWDP) system at the component level translate into an aeropropulsive benefit at the aircraft level, as well as to determine whether this enhancement is sufficient to lead to a reduction in overall energy consumption. For this, the preliminary sizing of a partial-turboelectric regional passenger aircraft is performed, and its performance metrics are compared to a conventional twin-turboprop reference for the 2035 timeframe. The changes in lift, drag, and propulsive efficiency due to the OTWDP system are estimated for a simplified unducted geometry using a lower-order numerical method, which is validated with experimental data. For a typical cruise condition and the baseline geometry evaluated in the experiment, the numerical method estimates a 45% increase in the local sectional lift-to-drag ratio of the wing, at the expense of a 12% reduction in propeller efficiency. For an aircraft with 53% of the wingspan covered by the OTWDP system, this aerodynamic coupling is found to increase the average aeropropulsive efficiency of the aircraft by 9% for a 1500 n mile mission. Approximately 4% of this benefit is required to offset the losses in the electrical drivetrain. The reduction in fuel weight compensates for the increase in powertrain weight, leading to a takeoff mass comparable to the reference aircraft. Overall, a 5% reduction in energy consumption is found, albeit with a [Formula: see text] uncertainty due to uncertainty in the aerodynamic modeling alone.

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Section: A) Otwdp Configuration (Top View) C) Conventional Configurat...mentioning

confidence: 99%

Aerodynamic Performance Benefits of Over-the-Wing Distributed Propulsion for Hybrid-Electric Transport Aircraft

Vries

Vos

2023

Journal of Aircraft

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Section: A) Otwdp Configuration (Top View) C) Conventional Configurat...mentioning

confidence: 99%

“…5 is considered the best option. A two-dimensional 9 duct is sufficient to reduce the non-uniform inflow, since for an unswept wing the inflow conditions to the propeller present no significant spanwise variations, and it presents less wetted area and less corner-flow challenges than adjacent circular or square ducts, respectively [29,54]. In any case, further investigation into the effect of duct shape and position is required.…”

Section: A) Otwdp Configuration (Top View) C) Conventional Configurat...mentioning

confidence: 99%

Aerodynamic Performance Benefits of Over-the-Wing Distributed Propulsion for Hybrid-Electric Transport Aircraft

Vries

Vos

2022

AIAA SCITECH 2022 Forum

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The goal of this study is to analyze how the aero-propulsive benefits of an over-the-wing distributed-propulsion (OTWDP) system at component level translate into an aero-propulsive benefit at aircraft level, and to determine whether this enhancement is sufficient to lead to a reduction in overall energy consumption. For this, the preliminary sizing of a partialturboelectric regional passenger aircraft is performed, and its performance metrics are compared to a conventional twin-turboprop reference for the 2035 timeframe. The changes in lift, drag, and propulsive efficiency due to the OTWDP system are estimated using a simplified numerical method, which is validated with experimental data. For a typical cruise condition and the baseline geometry evaluated in the experiment, the numerical method estimates a 45% increase in the local sectional lift-to-drag ratio of the wing, at the expense of a 12% reduction in propeller efficiency. For an aircraft with 53% of the wing span covered by the OTWDP system, this aerodynamic coupling is found to increase the average aero-propulsive efficiency of the aircraft by 9%, for a 1500 nmi mission. Approximately 4% of this benefit is required to offset the losses in the electrical drivetrain. The reduction in fuel weight compensates the increase in powertrain weight, leading to a take-off mass comparable to the reference aircraft. Overall, a 5% reduction in energy consumption is found, albeit with a ±5% uncertainty due to uncertainty in the aerodynamic modeling.

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“…Moreover, if the tip clearance between the rotor and the wall is small, the local thrust increases not only due to the local reduction in inflow velocity, but also due to the end-plate effect [36]. This leads to local variations in blade loading [25] and tip-vortex strength [37]contrary to ducted rotors, where the tip vortices (if present) can persist inside the boundary layer without azimuthal variations [38].…”

Section: Experimental Investigation Of Over-the-wingmentioning

confidence: 99%

Experimental Investigation of Over-the-Wing Propeller–Boundary-Layer Interaction

et al. 2021

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This experimental study focuses on the aerodynamic interaction between an over-the-wing (OTW) propeller and a wing boundary layer. An OTW propeller is positioned above the hinge line of a wing with a trailing-edge flap. Measurements are carried out with and without axial pressure gradients by deflecting the flap and by extending the flat upper surface of the wing in the streamwise direction, respectively. Surface-pressure taps, microphones, and particle image velocimetry are combined to quantify both the time-averaged and unsteady interaction effects. Results show that the propeller generates an adverse pressure gradient on the wing surface that scales linearly with thrust and decreases with increasing blade-tip clearance. The pressure gradient is partially caused by slipstream contraction, which decelerates the flow near the wall. Additionally, the surface-pressure fluctuations generated beneath the propeller blades and slipstream are stronger than the time-averaged pressure increase due to flow deceleration. Consequently, the propeller triggers flow separation over the hinge line when the flap is deflected. A parametric study of different propeller locations indicates that increasing the tip clearance is not an effective way to mitigate flow separation. However, displacing the propeller half a radius upstream of the hinge line creates a Coandă effect, which allows the flow to remain attached.

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Aerodynamic Performance and Interaction Effects of Circular and Square Ducted Propellers

Cited by 11 publications

References 26 publications

Aerodynamic Performance Benefits of Over-the-Wing Distributed Propulsion for Hybrid-Electric Transport Aircraft

Aerodynamic Performance Benefits of Over-the-Wing Distributed Propulsion for Hybrid-Electric Transport Aircraft

Aerodynamic Performance Benefits of Over-the-Wing Distributed Propulsion for Hybrid-Electric Transport Aircraft

Experimental Investigation of Over-the-Wing Propeller–Boundary-Layer Interaction

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