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Luca Scalinci - One of the best experts on this subject based on the ideXlab platform.
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Numerical investigation of the performance of Contra-Rotating Propellers for a Remotely Piloted Aerial Vehicle
Energy Procedia, 2017Co-Authors: Maria Grazia De Giorgi, Donato Fontanarosa, Anna Eva Morabito, Teresa Donateo, Antonio Ficarella, Luca ScalinciAbstract:The present work aims at the numerical prediction of the performance of a Contra-Rotating Propellers (CRP) system for a Remotely Piloted Aerial Vehicles (RPAV). The CRP system was compared with an equivalent counter-rotating Propellers configuration which was set by considering two eccentric Propellers which were rotating at the same speed. Each contra-rotating test case was built by varying the pitch angle of blades of the rear Propeller, while the front Propeller preserved the original reconstructed geometry. Several pitch configurations and angular velocities of the rear Propeller was simulated. Comparisons showed an improvement of the propulsive efficiency of the contra-rotating configuration in case of larger pitch angles combined with slower angular velocities of the rear Propeller.
Sinnige T. - One of the best experts on this subject based on the ideXlab platform.
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Aerodynamic and Aeroacoustic Interaction Effects for Tip-Mounted Propellers: An Experimental Study
2018Co-Authors: Sinnige T.Abstract:Propellers can enable a significant reduction in energy use of future aircraft by offering a higher propulsive efficiency than turbofan engines. This is especially relevant for a new generation of (hybrid-)electric aircraft. However, the integration of Propellers with the airframe remains a challenge, and leads to performance and noise penalties. Yet, by optimally integrating the Propellers with the airframe, these penalties can be minimized or even converted into significant performance benefits. A key example of a potentially beneficial integration approach is the tip-mounted Propeller. This thesis provides an experimental analysis of the aerodynamic and aeroacoustic interactions and potential performance-enhancement strategies for such Propellers. The unique experimental results highlight that tip-mounted Propellers provide a significant efficiency benefit due to tip-vortex attenuation and swirl recovery. For the tractor-Propeller configuration, this led to a measured 15% reduction in drag at typical cruise conditions when compared to a conventional Propeller–wing configuration. For a vehicle with co-rotating Propellers, i.e. Propellers with equal rotation direction on both sides of the aircraft, the tip-vortex interaction would cause asymmetric aerodynamic loading. This was alleviated by installing swirl-recovery vanes, which reduce the swirl in the Propeller slipstream before its interaction with the downstream aerodynamic surface. Besides the time-averaged effects, unfavorable unsteady loads occur on the downstream surface immersed in the Propeller slipstream, possibly leading to structure-borne noise. These unsteady loads were shown to be dominated by the periodic impingement of the Propeller-blade tip vortices, and were reduced by installing a flow-permeable leading edge. For pusher-Propeller configurations, the inflow to the Propeller is nonuniform due to the momentum deficit in the wake of the support pylon or wing positioned upstream of the Propeller. The resulting wake encounter causes unsteady Propeller-blade loads, which resulted in a noise penalty of up to 24 dB. The deficit in the wake was reduced by using a blowing system, installed in the trailing edge of a pylon model. Measurements showed that this alleviated the effects due to the wake encounter, resulting in noise levels comparable to those emitted by the isolated Propeller. The results presented in this thesis emphasize the sensitivity of the aerodynamic and aeroacoustic performance of installed tip-mounted Propeller propulsion systems to interactions between the Propeller and the airframe. It is shown that significant integration benefits can be obtained by exploiting the beneficial interactions, while both active and passive control techniques are available to mitigate the adverse interactions. The knowledge gained from the research study discussed in this thesis can be used to advantage in the design of future highly efficient aircraft.Flight Performance and Propulsio
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Aerodynamic and Aeroacoustic Interaction Effects for Tip-Mounted Propellers: An Experimental Study
2018Co-Authors: Sinnige T.Abstract:Propellers can enable a significant reduction in energy use of future aircraft by offering a higher propulsive efficiency than turbofan engines. This is especially relevant for a new generation of (hybrid-)electric aircraft. However, the integration of Propellers with the airframe remains a challenge, and leads to performance and noise penalties. Yet, by optimally integrating the Propellers with the airframe, these penalties can be minimized or even converted into significant performance benefits. A key example of a potentially beneficial integration approach is the tip-mounted Propeller. This thesis provides an experimental analysis of the aerodynamic and aeroacoustic interactions and potential performance-enhancement strategies for such Propellers. The unique experimental results highlight that tip-mounted Propellers provide a significant efficiency benefit due to tip-vortex attenuation and swirl recovery. For the tractor-Propeller configuration, this led to a measured 15% reduction in drag at typical cruise conditions when compared to a conventional Propeller–wing configuration. For a vehicle with co-rotating Propellers, i.e. Propellers with equal rotation direction on both sides of the aircraft, the tip-vortex interaction would cause asymmetric aerodynamic loading. This was alleviated by installing swirl-recovery vanes, which reduce the swirl in the Propeller slipstream before its interaction with the downstream aerodynamic surface. Besides the time-averaged effects, unfavorable unsteady loads occur on the downstream surface immersed in the Propeller slipstream, possibly leading to structure-borne noise. These unsteady loads were shown to be dominated by the periodic impingement of the Propeller-blade tip vortices, and were reduced by installing a flow-permeable leading edge. For pusher-Propeller configurations, the inflow to the Propeller is nonuniform due to the momentum deficit in the wake of the support pylon or wing positioned upstream of the Propeller. The resulting wake encounter causes unsteady Propeller-blade loads, which resulted in a noise penalty of up to 24 dB. The deficit in the wake was reduced by using a blowing system, installed in the trailing edge of a pylon model. Measurements showed that this alleviated the effects due to the wake encounter, resulting in noise levels comparable to those emitted by the isolated Propeller. The results presented in this thesis emphasize the sensitivity of the aerodynamic and aeroacoustic performance of installed tip-mounted Propeller propulsion systems to interactions between the Propeller and the airframe. It is shown that significant integration benefits can be obtained by exploiting the beneficial interactions, while both active and passive control techniques are available to mitigate the adverse interactions. The knowledge gained from the research study discussed in this thesis can be used to advantage in the design of future highly efficient aircraft.
Veldhuis L.l.m. - One of the best experts on this subject based on the ideXlab platform.
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Aerodynamic Performance of an Aircraft Equipped with Horizontal Tail-Mounted Propellers
'American Institute of Aeronautics and Astronautics (AIAA)', 2019Co-Authors: Van Arnhem N., De Vries R., Vos Roelof, Veldhuis L.l.m.Abstract:This paper presents an experimental and numerical study of the aerodynamic interaction between horizontal tail-mounted Propellers and the airframe. A representative aircraft model was installed in a low-speed wind-tunnel and measurements were taken with an external balance to determine the e_ect of Propeller installation on integral forces and moments. Total pressure measurements were performed downstream of the model for qualitative analysis of the Propeller–airframe interaction. The experimental data were complemented by full blade CFD analyses, which correlate excellently to the experimental data. Balance measurements indicate that the Propeller installation results in an o_set and a change in the slope of the pitching moment curve over the complete range of angles of attack. The extent to which the Propellers contribute to the longitudinal control and stability was shown to be dependent on the angle of attack of the aircraft and the rotation direction of the Propellers. The flowfield and computed Propeller loads show that an inboard-up rotating Propeller results in a neutral contribution to longitudinal stability towards higher angles of attack, while an outboard-up rotation enhances the stability for all positive angles of attack. The non-uniform inflow to the Propeller induced by the airframe leads to a lateral shift of the thrust which influences the trim condition.Flight Performance and Propulsio
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Aerodynamic investigation of an over-the-wing Propeller for distributed propulsion
AIAA, 2018Co-Authors: Marcus E. A.p., De Vries R., Raju Kulkarni A., Veldhuis L.l.m.Abstract:This paper addresses the aerodynamic performance and numerical modeling of over-the-wing Propellers. Installing the Propeller above a wing has the potential to increase wing lift-to-drag ratio, high-lift capabilities, and to reduce flyover noise. However, the prediction of its performance is difficult, since research on the aerodynamic interaction effects of over-the-wing Propellers has been limited so far. For this reason, an exploratory wind tunnel campaign was performed with a wing featuring a fowler flap. A single Propeller was installed above the wing at different chordwise locations and inclination angles. Wing surface-pressure and wake-pressure measurements showed strong, bilateral aerodynamic coupling between the Propeller and wing. A configuration with the Propeller attached to the flap showed wing lift increases of 8% and 3% in cruise and high-lift conditions, respectively. The key findings of the wind tunnel campaign were used to validate a low-fidelity numerical tool, which combines a non-uniform inflow blade-element model for the Propeller, a panel method for the wing, and a vortex lattice model for the Propeller slipstream. The numerical model was used to assess the effect of Propeller axial location and diameter. Results indicated that the optimal axial Propeller position is near the trailing edge of the wing, and that reducing the Propeller diameter at constant thrust coefficient at this location is beneficial for distributed propulsion applications. The tool allows a rapid computation of over-the-wing Propeller and wing performance in cruise conditions. This enables an efficient design space exploration during the conceptual design process of such configurations.
Maria Grazia De Giorgi - One of the best experts on this subject based on the ideXlab platform.
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Numerical investigation of the performance of Contra-Rotating Propellers for a Remotely Piloted Aerial Vehicle
Energy Procedia, 2017Co-Authors: Maria Grazia De Giorgi, Donato Fontanarosa, Anna Eva Morabito, Teresa Donateo, Antonio Ficarella, Luca ScalinciAbstract:The present work aims at the numerical prediction of the performance of a Contra-Rotating Propellers (CRP) system for a Remotely Piloted Aerial Vehicles (RPAV). The CRP system was compared with an equivalent counter-rotating Propellers configuration which was set by considering two eccentric Propellers which were rotating at the same speed. Each contra-rotating test case was built by varying the pitch angle of blades of the rear Propeller, while the front Propeller preserved the original reconstructed geometry. Several pitch configurations and angular velocities of the rear Propeller was simulated. Comparisons showed an improvement of the propulsive efficiency of the contra-rotating configuration in case of larger pitch angles combined with slower angular velocities of the rear Propeller.
Mourão Bento Hugo - One of the best experts on this subject based on the ideXlab platform.
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Aerodynamic interaction effects of circular and square ducted Propellers
2019Co-Authors: Mourão Bento HugoAbstract:With the goal of decreasing the environmental impact of aircraft, ducted Propellers emerge as an efficient propulsive alternative. Ducts are able to increase the thrust to power ratio of a Propeller system by both producing thrust and/or lowering tip losses of Propellers. In this thesis, RANS CFD simulations were used to analyse 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 as isolated cases, in order to characterise their aerodynamic performance. In the installed simulations, the Propeller was first modelled as an actuator disk, and afterwards with a full blade model. The results indicate two main disadvantages of square ducts. Square duct corners were found to be prone to separation, and to contribute towards the generation of strong vortices. This research can be important for the future study of unconventional ducted Propellers, for example with applications to distributed propulsion concepts.Flight Performance and Propulsio
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Aerodynamic interaction effects of circular and square ducted Propellers
2019Co-Authors: Mourão Bento HugoAbstract:With the goal of decreasing the environmental impact of aircraft, ducted Propellers emerge as an efficient propulsive alternative. Ducts are able to increase the thrust to power ratio of a Propeller system by both producing thrust and/or lowering tip losses of Propellers. In this thesis, RANS CFD simulations were used to analyse 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 as isolated cases, in order to characterise their aerodynamic performance. In the installed simulations, the Propeller was first modelled as an actuator disk, and afterwards with a full blade model. The results indicate two main disadvantages of square ducts. Square duct corners were found to be prone to separation, and to contribute towards the generation of strong vortices. This research can be important for the future study of unconventional ducted Propellers, for example with applications to distributed propulsion concepts.Aerospace Engineering | Flight Performance and Propulsio
