Aero-Propulsive and Propulsor Cross-Coupling Effects on a Distributed Propulsion System

Perry, Aaron T.; Ansell, Phillip J.; Kerho, Michael F.

doi:10.2514/1.c034861

Cited by 31 publications

(3 citation statements)

References 10 publications

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“…II.B show that the performance is improved if the propeller presents a slight nose-down installation angle. Furthermore, while most OTWDP configurations encountered in literature are ducted [51][52][53], it is unclear whether a duct is beneficial from an aerodynamic-efficiency perspective. 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.…”

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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“…This layout, known as over-the-wing distributed propulsion [17], can partially mitigate the penalties associated with large OTW propellers [18] and, additionally, enables short takeoff and landing operations when installed on a flap [19]. As a consequence, several studies focusing on the aerodynamic characteristics of an array of small propellers or fans placed over the wing have been performed in recent years [20][21][22].…”

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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“…The control aspect of DEP aircraft received limited attention in previous research, only modeling differential thrust [7,8] or designing a simple proportional-integral-derivative (PID) controller, without actively using the PAI effects [9]. Including the PAI effects poses a significant challenge, since this introduces nonlinear behavior and cross-couplings, which are difficult to model accurately [10]. Furthermore, the introduction of extra control effectors introduces the need for a control allocation method, as the aircraft becomes over-actuated [11].…”

Section: Introductionmentioning

confidence: 99%

Incremental Nonlinear Control Allocation for an Aircraft with Distributed Electric Propulsion

Heer

Visser

Hoogendoorn³

et al. 2023

AIAA SCITECH 2023 Forum

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In this paper, a new nonlinear control allocation method is presented for a distributed electric propulsion (DEP) aircraft. As the electric propellers can be used actively for control, in addition to the control surfaces, the DEP aircraft is over-actuated. This freedom in control effectors can be exploited with an appropriate control allocation method. All control effectors are, therefore, captured in the incremental nonlinear control allocation (INCA) method, which allows taking into account effector nonlinearities and interactions introduced by the propellers. The INCA method is based on a real-time updated Jacobian model of the control effectiveness, thereby solving an efficient linear control allocation problem. This paper reformulates the original INCA method to optimize the control allocation for minimal propeller power, resulting in more efficient flight. A model predictive control (MPC) controller is added as an actuator dynamics compensation method. This ensures that the commanded control inputs from the INCA controller are achieved. The new controller is compared to a standard incremental nonlinear dynamic inversion (INDI) controller with a translational and rotational loop. It is shown in simulation that by combining INCA with MPC, the tracking performance is improved and efficiency increased by 6.1%.

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Aero-Propulsive and Propulsor Cross-Coupling Effects on a Distributed Propulsion System

Cited by 31 publications

References 10 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

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

Incremental Nonlinear Control Allocation for an Aircraft with Distributed Electric Propulsion

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