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The imperative for energy conservation and environmental protection has led to the development of innovative aircraft designs. This study explored a novel thrust control configuration for blended-wing-body (BWB) aircraft with distributed electric boundary-layer ingestion (BLI) propulsors, addressing the issues of sagging and altitude loss during landing. The research focused on a small-scale BWB demonstrator equipped with six BLI fans, each with a 90 mm diameter. Various thrust control configurations were evaluated to achieve significant thrust reduction while maintaining lift, including dual-layer sleeve, separate flap-type, single-stage linkage flap-type, and dual-stage linkage flap-type configurations. The separate flap-type configuration was tested through ground experiments. Control experiments were conducted under three different experimental conditions as follows: deflection of the upper cascades only, deflection of the lower cascades only, and symmetrical deflection of both cascades. For each condition, the deflection angles tested were 0°, 10°, 20°, 30°, 40°, 50°, and 60°. The thrust reductions observed for these three conditions were 0%, 37.5%, and 27.5% of the maximum thrust, respectively, without additional changes in the pitch moment. A combined thrust adjustment method maintaining a zero pitch moment demonstrated a linear thrust reduction to 20% of its initial value. The experiment concluded that the novel thrust control configuration effectively adjusted thrust without altering the BLI fans' rotation speed, solving the coupled lift–thrust problem and enhancing BWB landing stability. [ABSTRACT FROM AUTHOR]

The vortex particle method (VPM) has gained popularity in recent years due to a growing need to predict complex aerodynamic interactions during the preliminary design of electric multirotor aircraft. However, VPM is known to be numerically unstable when vortical structures break down close to the turbulent regime. In recent work, the VPM has been reformulated as a large-eddy simulation (LES) in a scheme that is both meshless and numerically stable without increasing its computational cost. In this study, we build upon this meshless LES scheme to create a solver for interactional aerodynamics. Propeller blades are introduced through an actuator line model following well-established practices for LES. A novel, vorticity-based actuator surface model (ASM) is developed for wings, which is suitable for propeller-wing interactions when a wake impinges on the surface of a wing. This ASM imposes the no-flow-through condition at the airfoil centerline by calculating the circulation that meets this condition and by immersing the associated vorticity in the LES following a pressure-like distribution. Extensive validation of propeller-wing interactions is presented by simulating a tailplane with tip-mounted propellers and a blown wing with propellers mounted midspan. [ABSTRACT FROM AUTHOR]

On Distributed Electric Propulsion (DEP) aircraft, the deployment of numerous high-lift propellers with small diameters on the wing's leading edge significantly enhances lift during low-speed flight. The increase in the number of propellers leads to a decrease in diameter, which increases the disc loading. In this paper, a rapid design method applicable to heavy-loaded propellers is developed and does not require iterative calculations compared to traditional heavy-loaded propeller design methods, enabling rapid completion of the propeller design. The results of CFD computation show that the relative thrust error of the method proposed in this paper is within 5% for disc loading ranging from 600 Pa to 1400 Pa, features a high-accuracy design of propellers with required thrust, and high thrust coefficients are achieved within large advance ratio range. [ABSTRACT FROM AUTHOR]

A study is performed to comprehensively evaluate the aerodynamic performance of a regional aircraft designed for short-haul flights, with a particular focus on the effects of distributed electric propulsion (DEP) on aerodynamic performances. This effort aligns well with a core objective of the Clean Aviation program to decrease carbon emissions within the aviation sector. To address this challenge, we propose a concept that considers incorporating electric motors to complement the conventional propulsion system of a regional aircraft wing. These electric motors have the capability to draw power from either the traditional turboprop engine or exclusively from an on-board electrical generator, providing an innovative pathway for emissions reduction. The central focus of this study revolves around a detailed examination of the aerodynamic efficacy with respect to the placement of engines within the wing. It seeks to ascertain whether optimal aerodynamic efficiency is achieved through the adoption of a greater number of smaller-diameter motors, characterized by reduced power output to the shaft. Alternatively, the study explores the prospect of employing a reduced number of motors, each possessing larger diameters and correspondingly augmented power output. While a larger motor size may intuitively suggest superiority in terms of thrust, it remains imperative to meticulously evaluate the potential influence of the associated drag factor. This research contributes to the growing body of knowledge in the realm of aviation by shedding light on the intricate interaction between aerodynamic efficiency and power output in the context of propulsion system design.

The imperative for energy conservation and environmental protection has led to the development of innovative aircraft designs. This study explored a novel thrust control configuration for blended-wing-body (BWB) aircraft with distributed electric boundary-layer ingestion (BLI) propulsors, addressing the issues of sagging and altitude loss during landing. The research focused on a small-scale BWB demonstrator equipped with six BLI fans, each with a 90 mm diameter. Various thrust control configurations were evaluated to achieve significant thrust reduction while maintaining lift, including dual-layer sleeve, separate flap-type, single-stage linkage flap-type, and dual-stage linkage flap-type configurations. The separate flap-type configuration was tested through ground experiments. Control experiments were conducted under three different experimental conditions as follows: deflection of the upper cascades only, deflection of the lower cascades only, and symmetrical deflection of both cascades. For each condition, the deflection angles tested were 0°, 10°, 20°, 30°, 40°, 50°, and 60°. The thrust reductions observed for these three conditions were 0%, 37.5%, and 27.5% of the maximum thrust, respectively, without additional changes in the pitch moment. A combined thrust adjustment method maintaining a zero pitch moment demonstrated a linear thrust reduction to 20% of its initial value. The experiment concluded that the novel thrust control configuration effectively adjusted thrust without altering the BLI fans’ rotation speed, solving the coupled lift–thrust problem and enhancing BWB landing stability.

Aiming at the overall design parameters and mission profile requirements of commuter aircrafts, according to the hydrogen-lithium propulsion system architecture scheme, the propulsion system parameter matching method and energy dynamic balance management strategy were proposed. A 1 9-seat commuter aircraft was used to select and manage the power plant and reserve energy. According to the selected distributed aerodynamic layout scheme, then the effects of propeller rotation directions on aircraft aerodynamic characteristics were analyzed with full factorial design of experiments, and the optimum propeller rotation direction configuration for aircraft cruise states was obtained. [ABSTRACT FROM AUTHOR]

A conceptual framework is presented to determine the improvement in the aerodynamic performance of a canard aircraft fitted with distributed propellers along its main wing. A preliminary study is described with four airframe–propeller configurations predominantly studied in academic and commercial designs. The leading edge–based tractors and trailing edge–based pushers are identified as configurations of interest for the main study. Subsequently, a Navier–Stokes solver is used to simulate the flow using two numerical approaches–a modified steady-state actuator disk and an unsteady rotating propeller profile. Moving meshes with rotating sub-domains are used with a hybrid RANS-LES-based turbulence model while the actuator disks are modified to include viscous swirl effects. The preliminary study shows a local minimum in the change in C L and C D at 10 ∘ for the pusher and tractor configurations. The main study then demonstrates the outperformance of the pushers over tractors quantified using C L and C L / C D . There is a clear preference for the pushers as they increase the lifting capacity of the aircraft without disproportionately increasing the drag due to the flow smoothening by the suction of the pusher propellers over the main wing. The pushers also delay the separation of the boundary layer whereas the tractors are unable to prevent the formation of the separation bubble despite injecting momentum through their slipstreams into the flow. The results from the two numerical approaches are then compared for accuracy in designing DEP configurations for an airframe. [ABSTRACT FROM AUTHOR]

Distributed electric propulsion tilt-rotor unmanned aerial vehicles (TRUAVs) with a lift-increasing flap in the propulsion wake have better aerodynamic efficiency than traditional tilt-rotor unmanned aerial vehicles and better takeoff/landing capacity than fixed-wing aircraft. However, for this configuration, establishing the propulsion-aerodynamic coupling model between the flap and the duct is difficult. This paper presents a flight dynamics model with propulsion-aerodynamic coupling components and analyzes dynamic characteristics during the transition period for TRUAVs with a distributed-propulsion/flap configuration. The development of the flight dynamics model considers the descriptions of the duct model, the lift-increasing flap model, and the propeller model. The model of the lift-increasing flap in both the duct exhaust jet and the freestream is the key component of the vehicle dynamics equations and is validated with experimental data and computational fluid dynamics results. Based on the dynamics model, the transition corridor of the tilt-rotor aircraft with multiple asynchronous tilting components and a geometrical constraint is calculated and analyzed. Additionally, the longitudinal dynamics stability of the aircraft in different flight speeds and configurations is assessed based on the numerical differentiation method. The results showed that the vehicle flight speed has more influence on longitudinal short-period stability than the angle of attack (AOA) of the flap. Also, the longitudinal long-period stability is affected by both the vehicle flight speed and the AOA of the flap. Finally, a mathematical derivation is developed to analyze the aircraft's unstable state. The presented analysis results show that the stability of the long period is affected by the velocity derivative of the fuselage's lift. [ABSTRACT FROM AUTHOR]

A study is performed to comprehensively evaluate the aerodynamic performance of a regional aircraft designed for short-haul flights, with a particular focus on the effects of distributed electric propulsion (DEP) on aerodynamic performances. This effort aligns well with a core objective of the Clean Aviation program to decrease carbon emissions within the aviation sector. To address this challenge, we propose a concept that considers incorporating electric motors to complement the conventional propulsion system of a regional aircraft wing. These electric motors have the capability to draw power from either the traditional turboprop engine or exclusively from an on-board electrical generator, providing an innovative pathway for emissions reduction. The central focus of this study revolves around a detailed examination of the aerodynamic efficacy with respect to the placement of engines within the wing. It seeks to ascertain whether optimal aerodynamic efficiency is achieved through the adoption of a greater number of smaller-diameter motors, characterized by reduced power output to the shaft. Alternatively, the study explores the prospect of employing a reduced number of motors, each possessing larger diameters and correspondingly augmented power output. While a larger motor size may intuitively suggest superiority in terms of thrust, it remains imperative to meticulously evaluate the potential influence of the associated drag factor. This research contributes to the growing body of knowledge in the realm of aviation by shedding light on the intricate interaction between aerodynamic efficiency and power output in the context of propulsion system design. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Naturalium Universitatis Sunyatseni / Zhongshan Daxue Xuebao is the property of Sun-Yat-Sen University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper deals with the problem of increasing the energy efficiency of a hybrid vertical take-off and landing aircraft. To this end, an innovative aerial vehicle was developed, featuring a distributed electrical propulsion system with ducted-fan rotors. To compare and analyze the effectiveness of the proposed propulsion system, two configurations with a different number of ducted-fan rotors were examined: a four-rotor configuration and a six-rotor configuration. The mathematical model of the four-rotor configuration was derived using the Newton–Euler formalism, allowing the design and implementation of a control strategy for conducting model-in-the-loop simulations. These simulations enabled the evaluation and analysis of the performance of the proposed propulsion system, where the numerical results demonstrated the functionality of both designs and showed that, during the multirotor flight, the configuration with six rotors increased its energy efficiency by up to 11%, providing higher vertical lift with the same power consumption. This was achieved by distributing its weight among a higher number of engines. The incorporation of two additional ducted fans increased the weight and the drag of the six-rotor configuration, resulting in a low augmentation in power consumption of 1%. Finally, this caused a decrease in airspeed by up to 4% during the cruise speed phase. [ABSTRACT FROM AUTHOR]

On Distributed Electric Propulsion (DEP) aircraft, the deployment of numerous high-lift propellers with small diameters on the wing’s leading edge significantly enhances lift during low-speed flight. The increase in the number of propellers leads to a decrease in diameter, which increases the disc loading. In this paper, a rapid design method applicable to heavy-loaded propellers is developed and does not require iterative calculations compared to traditional heavy-loaded propeller design methods, enabling rapid completion of the propeller design. The results of CFD computation show that the relative thrust error of the method proposed in this paper is within 5% for disc loading ranging from 600 Pa to 1400 Pa, features a high-accuracy design of propellers with required thrust, and high thrust coefficients are achieved within large advance ratio range.

The interaction between the slipstream of the propellers and the wing of an aircraft with distributed electric propulsion (DEP) could benefit aerodynamics. A conceptual design and optimization are carried out in order to increase the range of an electric general aviation aircraft without affecting its takeoff and landing velocity in the same fuselage condition. Propellers are modelled using the actuator disk (AD) theory, and the aircraft is modelled using the vortex lattice method (VLM) to obtain DEP aircraft's aerodynamics in conceptual design. The DIRECT method is used for global optimization. To concentrate on the layout of the propellers and wing, a propeller with the same chord distribution, twist distribution, and number of blades is selected. The design and optimization of DEP aircraft's range is carried out with the objective of achieving the maximum product of the lift–drag ratio with propeller efficiency under force balance constrains. Additionally, to decrease the takeoff and landing distance, the DEP aircraft's takeoff and landing performance are optimized with the objective of the smallest velocity at an angle near the tail down angle under the constrains of acceleration bigger than 0 and a Mach number at the tip of blades smaller than 0.7. The CFD simulation was used to confirm the DEP aircraft's pretty accurate aerodynamics. Compared to the reference aircraft, the improved DEP aircraft with 10 high-lift propellers on the leading edge of the wing and 2 wing-tip propellers may boost cruise performance by 6% while maintaining takeoff and landing velocity. Furthermore, it has been shown that the stall speed of DEP aircraft with smaller wings would rise proportionally when compared to conventional design aircraft, and the power need of DEP aircraft will be increased as a result of the operation of high-lift propellers. The conceptual design and optimal approach suggested in this work has some reference value for the design and research of the fixed-wing DEP general aviation aircraft. [ABSTRACT FROM AUTHOR]

The vertical takeoff and landing(VTOL)fixed wing unmanned aerial vehicle(UAV)has many advantages,such as low requirements for takeoff and landing site,good maneuverability,high cruise speed and long endurance,etc.,which is a hot topic in the aviation field.The existing VTOL fixed wing UAV development status and their basic features around the world are described in this paper,and then the technical features faced by these different types of VTOL fixed wing UAV are analyzed.It indicates that the VTOL fixed wing UAV with higher cruise speed,longer battery life,and stronger ability of task load seems to be the main developing direction and inevitable trend in the future.Although the tilting rotor configuration and tail-seat configuration are still the mainstream configuration of the VTOL fixed wing UAV in nowadays,the distributed electric propulsion(DEP)VTOL fixed wing UAV technology will become the hottest issues in the field of aerospace,therefore,it is necessary to enhance the evolutionary research in the new-concept configurations and new principles of the high-performance VTOL fixed wing UAV.

The environmental impact of aviation in terms of noise and pollutant emissions has gained public attention in the last few years. In addition, the foreseen financial benefits of an increased energy efficiency have motivated the transport industry to invest in propulsion alternatives. This work is collocated within the Clean Sky 2 project GENESIS, focused on the environmental sustainability of 50-passenger hybrid-electric aircraft from a life-cycle-based perspective to support the development of a technology roadmap for transitioning towards sustainable and competitive electric aircraft systems. While several studies have already focused on the definition of possible aircraft designs combining several propulsion systems, the novelty of the present work is to consider technology forecasts and more comprehensive indicators in the design phase. These include the performance and emissions on a 200 nmi typical mission, which reflects the most economically attractive range for aircraft in the regional class. The work proposes a complete exploration of three major technology streams for energy storage: batteries, fuel cells, and turbine internal combustion engine generators, also including possible combinations of those technologies. The exploration was carried out through the execution of several designs of experiments aiming at the identification of the most promising solutions in terms of aircraft configuration for three different time horizons: short-term, 2025–2035; medium-term, 2035–2045; and long-term, 2045–2050+. As a result, in the short-term scenario, fuel energy consumption is estimated to be reduced by around 24% with respect to conventional aircraft with the same entry-into-service year thanks to the use of hybrid propulsive systems with lithium batteries. Fuel saving increases to 45% in the medium-term horizon due to the improvement in the energy density of storage systems. By the year 2050, when hydrogen fuel cells are estimated to be mature enough to completely replace kerosene-based engines, the forthcoming hybrid-electric aircraft promise no NOx and CO2 direct emissions, while being approximately 50% heavier than conventional ones. [ABSTRACT FROM AUTHOR]

A conceptual framework is presented to determine the improvement in the aerodynamic performance of a canard aircraft fitted with distributed propellers along its main wing. A preliminary study is described with four airframe–propeller configurations predominantly studied in academic and commercial designs. The leading edge–based tractors and trailing edge–based pushers are identified as configurations of interest for the main study. Subsequently, a Navier–Stokes solver is used to simulate the flow using two numerical approaches–a modified steady-state actuator disk and an unsteady rotating propeller profile. Moving meshes with rotating sub-domains are used with a hybrid RANS-LES-based turbulence model while the actuator disks are modified to include viscous swirl effects. The preliminary study shows a local minimum in the change in CL and CD at 10∘ for the pusher and tractor configurations. The main study then demonstrates the outperformance of the pushers over tractors quantified using CL and CL/CD. There is a clear preference for the pushers as they increase the lifting capacity of the aircraft without disproportionately increasing the drag due to the flow smoothening by the suction of the pusher propellers over the main wing. The pushers also delay the separation of the boundary layer whereas the tractors are unable to prevent the formation of the separation bubble despite injecting momentum through their slipstreams into the flow. The results from the two numerical approaches are then compared for accuracy in designing DEP configurations for an airframe.

The efficiency increase that distributed propulsion could deliver for future hybrid-electric aircraft is in line with the urgent demand for higher aerodynamic performances and a lower environmental impact. Several consolidated proprietary tools (not always available) are developed worldwide for distributed propulsion simulation. Therefore, prediction and comparisons of propeller performances, with computational fluid dynamic codes featuring different implementation of solvers, numerical schemes, and turbulence models, is of interest to a wider audience of research end-users. In this framework, the paper presents a cross-comparison study among different CFD solvers, the SU2 Multiphysics Simulation and Design Software, the CIRA proprietary flow solver UZEN, and the commercial ANSYS-FLUENT code, for the simulation of a wing section with a tractor propeller at different flow attitudes. The propeller is modelled as an actuator disk according to the general momentum theory and is accounted for in the flow solvers as a boundary condition, for the momentum and energy equations. In this study, a propeller with a fixed advance ratio J = 0.63 is considered, while propeller performances are assumed variable along with the radius. To perform the comparisons among the solvers, an in-house procedure, which provides the input thrust and torque distributions in a unified format among the three solvers, is developed. Steady RANS simulations are performed at R e ∞ = 1.7 × 10 6 and M ∞ = 0.11 , for the flowfield of an isolated propeller. Successively, a wing section with a fixed forward-mounted propeller configuration with no nacelle, is studied at α = 0 ∘ , 4 ∘ , and 8 ∘ angles of attack. The comparisons in terms of the lift coefficient show a good agreement among the three flow solvers both in power-off and power-on conditions. Simulations also evidenced the strong stability preserving property of upwind schemes, applied to propeller simulation at low-Mach number. Some discrepancies in the drag coefficient are observed and related to different levels of numerical diffusion between the three codes, which affects the downstream wake. Differences in flow properties in near disk region are observed and explained considering the different hub implementations. [ABSTRACT FROM AUTHOR]

This paper proposes a distributed turbo-electric hybrid propulsion system (TEHPS) architecture for high-power and large-load air–ground aircraft (AGA). The composition of the turboshaft engine, hybrid energy storage system (HESS) as the power unit, distributed electric drive ducted fans, and wheels as the propulsion unit is determined. Firstly, the modeling of each component in the TEHPS is carried out, and system power, energy, and weight analysis are conducted under the different operating modes. Sizing parameters of main components are selected based on a genetic algorithm to obtain the optimal total weight and propulsion efficiency, and the energy management framework from the upper level to the lower level is completed by adopting an equivalent consumption minimum strategy and fuzzy logic control. Under the air–ground amphibious mission profile, the simulation results indicate that the TEHPS can achieve a 21.80% fuel consumption and CO 2 emission optimization rate at the cost of 10.53% increase in the whole aircraft mass compared to the oil-only powertrain. The HESS can account for up to 29% and 33.56% of the energy and power ratios in the TEHPS, and reduce mass by 8.1% and volume by 3.77% compared to the single energy storage, which may provide theoretical insights for the powertrain composition form, sizing, and energy management of future hybrid air–ground aircraft. [ABSTRACT FROM AUTHOR]

• DEP system affects the wing lift and drag through fan tip speed ratio. • Higher fan tip speed ratio enhances the wing lift. • Fan installation angle impacts aerodynamic performance of DEP aircraft. • The wing lift increases with fan installation angle. • DEP system thrust decreases with fan installation angle. The ducted fan, as a quintessential propulsion device utilized in Distributed Electric Propulsion (DEP) aircrafts, exhibits a significant influence on the aero-propulsion coupling effects due to its installation characteristics on the wing. In this paper, we employed steady-state numerical analysis techniques in conjunction with actuator disk models and overset mesh to investigate aero-propulsion coupling effects and installation characteristics of a DEP configuration with 5 ducted fans distributed along the wing's trailing edge. We compared various conditions to the wing baseline airfoil under hover condition and cruise condition of the fan tip speed ratio λ from 1.44 to 4.32 and fan installation angle δ T from 0 to 90°. The results indicate that DEP system affects the flow over the wing downstream of the maximum thickness point of the baseline airfoil profile at an installation angle of 0. A higher tip speed ratio the flow is accelerated in the upper surface region near the wing's trailing edge, whereas the low energy fluid fails to be accelerated at lower λ , instead forming a local flow blocking. With the increase of the fan installation angle, the overall system lift increases, but the thrust decreases, and both trends increase with the increase of the tip speed ratio. Specifically, the thrust provided by the distributed fans is reduced, and the inlet becomes one of the drag sources when the installation angle is high. [ABSTRACT FROM AUTHOR]

• The distributed propeller slipstream generates blown lift and retards stall. • The influence of aero-propulsive coupling effects on the flight dynamics characteristics is mainly reflected in the changes of longitudinal modal. • The lift augmentation effect of distributed propeller slipstream enables UAV to perform rapid ascent capability in actual flight. The distributed electric propulsion tandem-wing unmanned aerial vehicle (UAV) offers higher aerodynamic efficiency than conventional electric vertical takeoff and landing UAV and superior rapid ascent takeoff and landing capabilities compared to regular fixed-wing aircraft. However, for this configuration, the aero-propulsive coupling effects between the propellers and wings are significant. To study the mutual interaction between distributed electric propulsion and aerodynamics on the flight dynamics characteristics and rapid ascent flight capability of UAV, an aero-propulsive coupling model incorporating the effects of propellers slipstream is established. Ground-based blown wing experiment is conducted to validate the modeling accuracy. Subsequently, a theoretical modeling framework based on standard stability derivatives is developed, incorporating the influence of thrust on the dynamics within stability derivatives. The dynamic characteristics of distributed electric propulsion tandem-wing configuration are then studied and aero-propulsive coupling effects on natural modes of motion and flight qualities are analyzed. Finally, flight simulations and actual flight tests are conducted to validate the rapid ascent flight capability of UAV in real-world. The experimental results indicate that UAV can achieve rapid ascent flight with significant pitch angles and high climb rates, showing promising results with more than a 91.9% improvement in takeoff performance compared to conventional rolling takeoff. [ABSTRACT FROM AUTHOR]

Distributed electric propulsion technology has great potential and advantages in the development of drones. In this paper, to study the slipstream effect of distributed propellers, the actuator disk method was used to verify a single propeller, and the calculated thrust was in good agreement with the test results. Then, based on the actuator disk method, the influence of different installation positions on the slipstream effect was studied, and the distributed propeller layout was optimized by a genetic algorithm to improve the low-speed performance of the unmanned aerial vehicle (UAV) during the take-off phase and increase the cruise duration. The analysis results showed that the lift of the wing will be larger when the propellers are higher than the wing. The wing lift and drag of the counter-rotating are less than those of the co-rotating. Compared with the original layout, the lift coefficient of the optimized distributed propeller layout is significantly increased by 30.97%, while the lift/drag ratio is increased by 7.34%. Finally, we designed the test platform and qualitatively verified the calculated results without quantitative verification.

This paper deals with the problem of increasing the energy efficiency of a hybrid vertical take-off and landing aircraft. To this end, an innovative aerial vehicle was developed, featuring a distributed electrical propulsion system with ducted-fan rotors. To compare and analyze the effectiveness of the proposed propulsion system, two configurations with a different number of ducted-fan rotors were examined: a four-rotor configuration and a six-rotor configuration. The mathematical model of the four-rotor configuration was derived using the Newton–Euler formalism, allowing the design and implementation of a control strategy for conducting model-in-the-loop simulations. These simulations enabled the evaluation and analysis of the performance of the proposed propulsion system, where the numerical results demonstrated the functionality of both designs and showed that, during the multirotor flight, the configuration with six rotors increased its energy efficiency by up to 11%, providing higher vertical lift with the same power consumption. This was achieved by distributing its weight among a higher number of engines. The incorporation of two additional ducted fans increased the weight and the drag of the six-rotor configuration, resulting in a low augmentation in power consumption of 1%. Finally, this caused a decrease in airspeed by up to 4% during the cruise speed phase.

Distributed Electric Propulsion (DEP) aircraft presents a highly promising technology aligned with the demands of green aviation due to its superior flight efficiency, reduced energy loss, and diminished noise. This paper firstly designs and establishes a flight dynamics model for DEP aircraft, followed by an analysis of flying qualities, thus laying the foundation for control method design. Secondly, addressing the challenge of detecting subtle control surface faults, a deep learning fault diagnosis method based on Data Dimensionality Reduction (DDR) structure is devised, achieving an accuracy rate of 99.8 %. Finally, an adaptive fault-tolerant control method for the lateral motion mode of DEP aircraft is introduced, utilizing Constrained Multivariable-multiobjective Model Predictive Control (CMMPC). Notably, for the rudder complete fault, adaptive fault-tolerant control is achieved by switching controllers and utilizing differential thrust from distributed redundant propulsion units to mitigate yaw channel anomalies, thus showcasing the advantages of DEP aircraft. Simulation results validate the theoretical soundness of the proposed method, providing a theoretical basis for the future engineering application and advancement of control systems for DEP aircraft. [ABSTRACT FROM AUTHOR]

The interaction between the slipstream of the propellers and the wing of an aircraft with distributed electric propulsion (DEP) could benefit aerodynamics. A conceptual design and optimization are carried out in order to increase the range of an electric general aviation aircraft without affecting its takeoff and landing velocity in the same fuselage condition. Propellers are modelled using the actuator disk (AD) theory, and the aircraft is modelled using the vortex lattice method (VLM) to obtain DEP aircraft’s aerodynamics in conceptual design. The DIRECT method is used for global optimization. To concentrate on the layout of the propellers and wing, a propeller with the same chord distribution, twist distribution, and number of blades is selected. The design and optimization of DEP aircraft’s range is carried out with the objective of achieving the maximum product of the lift–drag ratio with propeller efficiency under force balance constrains. Additionally, to decrease the takeoff and landing distance, the DEP aircraft’s takeoff and landing performance are optimized with the objective of the smallest velocity at an angle near the tail down angle under the constrains of acceleration bigger than 0 and a Mach number at the tip of blades smaller than 0.7. The CFD simulation was used to confirm the DEP aircraft’s pretty accurate aerodynamics. Compared to the reference aircraft, the improved DEP aircraft with 10 high-lift propellers on the leading edge of the wing and 2 wing-tip propellers may boost cruise performance by 6% while maintaining takeoff and landing velocity. Furthermore, it has been shown that the stall speed of DEP aircraft with smaller wings would rise proportionally when compared to conventional design aircraft, and the power need of DEP aircraft will be increased as a result of the operation of high-lift propellers. The conceptual design and optimal approach suggested in this work has some reference value for the design and research of the fixed-wing DEP general aviation aircraft.

The environmental impact of aviation in terms of noise and pollutant emissions has gained public attention in the last few years. In addition, the foreseen financial benefits of an increased energy efficiency have motivated the transport industry to invest in propulsion alternatives. This work is collocated within the Clean Sky 2 project GENESIS, focused on the environmental sustainability of 50-passenger hybrid-electric aircraft from a life-cycle-based perspective to support the development of a technology roadmap for transitioning towards sustainable and competitive electric aircraft systems. While several studies have already focused on the definition of possible aircraft designs combining several propulsion systems, the novelty of the present work is to consider technology forecasts and more comprehensive indicators in the design phase. These include the performance and emissions on a 200 nmi typical mission, which reflects the most economically attractive range for aircraft in the regional class. The work proposes a complete exploration of three major technology streams for energy storage: batteries, fuel cells, and turbine internal combustion engine generators, also including possible combinations of those technologies. The exploration was carried out through the execution of several designs of experiments aiming at the identification of the most promising solutions in terms of aircraft configuration for three different time horizons: short-term, 2025–2035; medium-term, 2035–2045; and long-term, 2045–2050+. As a result, in the short-term scenario, fuel energy consumption is estimated to be reduced by around 24% with respect to conventional aircraft with the same entry-into-service year thanks to the use of hybrid propulsive systems with lithium batteries. Fuel saving increases to 45% in the medium-term horizon due to the improvement in the energy density of storage systems. By the year 2050, when hydrogen fuel cells are estimated to be mature enough to completely replace kerosene-based engines, the forthcoming hybrid-electric aircraft promise no NOx and CO2 direct emissions, while being approximately 50% heavier than conventional ones.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Novel eVTOL aircraft configurations are picking up momentum in the emerging market of urban air mobility (UAM). These configurations feature electrical power systems and distributed propulsion architectures, both uncommon in current aircraft. As such, the design of eVTOL aircraft lies outside the bounds of current established frameworks and poses many challenges in the field of preliminary aircraft design. This paper presents a preliminary design methodology for open rotor eVTOL configurations with batteries as the power source. First, the propeller external dimensions are calculated, and then an optimised blade geometry for cruise condition is computed. Thereupon, the batteries and electric motors are sized. The design framework is then applied to an eVTOL aircraft with a design range of 400 km and a capacity of five occupants (four passengers and one pilot), focusing on the central-European market and aimed to be released in 2030. The final configuration is a battery-powered tandem-wing aircraft with 12 variable-pitch, variable-speed open rotors placed on the leading edges of the wings. These rotors rotate outboard-down and feature six blades. The power source comprises 24 solid-state lithium batteries with a nominal voltage of 500 V and an assumed energy density of 500 Wh/kg. The proposed design methodology offers the possibility of computing the necessary propeller geometry for numerical simulations in the early stages of the design, and of easily obtaining accurate estimates for the mass of the power system which can improve the overall mass estimates for the analysed configuration. [ABSTRACT FROM AUTHOR]

The efficiency increase that distributed propulsion could deliver for future hybrid-electric aircraft is in line with the urgent demand for higher aerodynamic performances and a lower environmental impact. Several consolidated proprietary tools (not always available) are developed worldwide for distributed propulsion simulation. Therefore, prediction and comparisons of propeller performances, with computational fluid dynamic codes featuring different implementation of solvers, numerical schemes, and turbulence models, is of interest to a wider audience of research end-users. In this framework, the paper presents a cross-comparison study among different CFD solvers, the SU2 Multiphysics Simulation and Design Software, the CIRA proprietary flow solver UZEN, and the commercial ANSYS-FLUENT code, for the simulation of a wing section with a tractor propeller at different flow attitudes. The propeller is modelled as an actuator disk according to the general momentum theory and is accounted for in the flow solvers as a boundary condition, for the momentum and energy equations. In this study, a propeller with a fixed advance ratio J=0.63 is considered, while propeller performances are assumed variable along with the radius. To perform the comparisons among the solvers, an in-house procedure, which provides the input thrust and torque distributions in a unified format among the three solvers, is developed. Steady RANS simulations are performed at Re∞=1.7×106 and M∞=0.11, for the flowfield of an isolated propeller. Successively, a wing section with a fixed forward-mounted propeller configuration with no nacelle, is studied at α=0∘,4∘, and 8∘ angles of attack. The comparisons in terms of the lift coefficient show a good agreement among the three flow solvers both in power-off and power-on conditions. Simulations also evidenced the strong stability preserving property of upwind schemes, applied to propeller simulation at low-Mach number. Some discrepancies in the drag coefficient are observed and related to different levels of numerical diffusion between the three codes, which affects the downstream wake. Differences in flow properties in near disk region are observed and explained considering the different hub implementations.

This paper proposes a distributed turbo-electric hybrid propulsion system (TEHPS) architecture for high-power and large-load air–ground aircraft (AGA). The composition of the turboshaft engine, hybrid energy storage system (HESS) as the power unit, distributed electric drive ducted fans, and wheels as the propulsion unit is determined. Firstly, the modeling of each component in the TEHPS is carried out, and system power, energy, and weight analysis are conducted under the different operating modes. Sizing parameters of main components are selected based on a genetic algorithm to obtain the optimal total weight and propulsion efficiency, and the energy management framework from the upper level to the lower level is completed by adopting an equivalent consumption minimum strategy and fuzzy logic control. Under the air–ground amphibious mission profile, the simulation results indicate that the TEHPS can achieve a 21.80% fuel consumption and CO2 emission optimization rate at the cost of 10.53% increase in the whole aircraft mass compared to the oil-only powertrain. The HESS can account for up to 29% and 33.56% of the energy and power ratios in the TEHPS, and reduce mass by 8.1% and volume by 3.77% compared to the single energy storage, which may provide theoretical insights for the powertrain composition form, sizing, and energy management of future hybrid air–ground aircraft.

In this paper, an aerodynamic and structural computation framework was produced to develop a more efficient aircraft configuration considering a wing with a distributed electric propulsion and its use in different flight missions. For that reason, a model of a regional airplane was used as a case study. The considered model was a nine-seat light airplane with a cruise speed of 500 km/h at an altitude 9000 m. The design of the distributed system is introduced, then the aerodynamic and structural aspects of the new wing with distributed electric propulsion system are calculated, and finally flight performances are calculated for the purpose of analysis of the DEP effect. The design of the DEP system aimed at meeting the required landing conditions and the masses of its components, such as the electric motors, the control units and the power source of the DEP system were estimated. Aerodynamic calculations included computations of different wing aspect ratios. These calculations take into account the drag of the existing airplane parts such as fuselage and tail surfaces. A modified lifting-line theory was used as a computational tool for the preliminary study. It was used to calculate the wing drag in cruise regime and to determine the distribution of aerodynamic forces and moments. Next, based on aerodynamic calculations and flight envelope, the basic skeletal parts of the wing were designed and the weight of the wing was calculated. Finally, fuel consumption calculations for different wing sizes were made and compared with the original design. The results show that a wing with a 35% reduction in area can reduce fuel consumption by more than 6% while keeping the same overall weight of the aircraft.

The distributed electric propulsion (DEP) eVTOL aircraft has gained rising interest for its promising potential in high-speed cruise compared with conventional tilt-rotor configuration. The aerodynamic interference of the DEP units and wing could become more complicated with a variable thrust in multiple flight conditions. Thus, it requires considerable effort to trade off in the whole design process. Aimed at improving the design efficiency in iteration cycling of a ducted-fan DEP eVTOL aircraft, a conceptual design and optimization approach is proposed in this paper regarding the single-ducted fan and its surrounding wing section as the basic unit. The optimization of the ducted-fan wing (DFW) unit is targeted at improving both hover and cruise efficiencies. After the verification of the span independence of the lift-and-drag coefficients of the DFW unit, a novel DEP eVTOL aircraft conceptual design approach is established based on the vertical meridional plane DFW unit performance analysis. In the following case study, the optimized DFW unit and the conceptual method are applied on a canard configuration, achieving 720 km/h maximum speed, a hovering efficiency of 76.3%, and a 10.7 cruise lift-to-drag ratio. The remarkable performance and concise workflow in the case study both demonstrated the applicability and effectiveness of the proposed design schemes for DEP eVTOL aircraft.

The Italian research project PROSIB (PROpulsione e Sistemi IBridi per velivoli ad ala fissa e rotante), is a 30-month initiative funded by the Italian Ministry of University and Scientific Research (MIUR) and coordinated by the Leonardo company. The project is aimed to investigate configurations for regional aircraft and rotary wing platforms and architectures for propulsion systems, and is dedicated to the identification of the best strategy for their use, given different on-board energy sources. The reduced environmental impact is the key for the success of the new hybrid/electric aircraft configurations. This not only considers the chemical pollution introduced in the atmosphere, but also the noise produced on the surrounding area of airports. The present paper describes the acoustic impact assessment resulting from the inclusion of new propulsion technologies and new configurations of regional aircraft (ATR42 pax) in a reference airport area. [ABSTRACT FROM AUTHOR]

Distributed electric propulsion (DEP) aircrafts have high propulsion efficiency and low fuel consumption, which is very promising for propulsion. The redundant thrusters of DEP aircrafts increase the risk of fault in the propulsion system, so it is necessary to study fault-tolerant control to ensure flight safety. There has been little research on coordinated thrust control, and research on fault-tolerant control of the propulsion system for DEP aircrafts is also in the preliminary stage. In this study, a mathematical model of DEP aircrafts was built. Aiming at the lateral and longitudinal control of DEP aircrafts, a coordinated thrust control method based on total energy control and total heading control was designed. Furthermore, a fault-tolerant control strategy and control method was developed for faults in the propulsion system. Simulation results showed that the controller could control the thrust to the prefault level. The correctness and effectiveness of the designed coordinated thrust control method and the fault-tolerant control method for DEP aircrafts were theoretically verified. This study provides a theoretical basis for future engineering application and development of the control system for DEP aircrafts.

This paper describes the aerodynamic design and assessment of a blended-wing–body (BWB) configuration under the distributed electric propulsion (DEP) installation constraints. The aerodynamic design rationale and process is described, as well as how the DEP system is considered and simplified in the optimization design process. Both the BWB configuration and the DEP induced effects are numerically simulated and analyzed using the Reynolds Averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) flow solvers. To further demonstrate the feasibility and reliability of the design approach, the wind tunnel tests of a scaled model of the designed BWB configuration are carried out, and both the aerodynamic characteristics and the BWB surface flow are measured and analyzed. The results indicate the reliability and feasibility of the optimization design method introduced in this paper.

New propulsive architectures, with high interactions with the aerodynamic performance of the platform, are an attractive option for reducing the power consumption, increasing the resilience, reducing the noise and improving the handling of fixed-wing unmanned air vehicles. Distributed electric propulsion with boundary layer ingestion over the wing introduces extra complexity to the design of these systems, and extensive simulation and experimental campaigns are needed to fully understand the flow behaviour around the aircraft. This work studies the effect of different combinations of propeller positions and angles of attack over the pressure coefficient and skin friction coefficient distributions over the wing of a 25 kg fixed-wing remotely piloted aircraft. To get more information about the main trends, a proper orthogonal decomposition of the coefficient distributions is performed, which may be even used to interpolate the results to non-simulated combinations, giving more information than an interpolation of the main aerodynamic coefficients such as the lift, drag or pitching moment coefficients.

Novel eVTOL aircraft configurations are picking up momentum in the emerging market of urban air mobility (UAM). These configurations feature electrical power systems and distributed propulsion architectures, both uncommon in current aircraft. As such, the design of eVTOL aircraft lies outside the bounds of current established frameworks and poses many challenges in the field of preliminary aircraft design. This paper presents a preliminary design methodology for open rotor eVTOL configurations with batteries as the power source. First, the propeller external dimensions are calculated, and then an optimised blade geometry for cruise condition is computed. Thereupon, the batteries and electric motors are sized. The design framework is then applied to an eVTOL aircraft with a design range of 400 km and a capacity of five occupants (four passengers and one pilot), focusing on the central-European market and aimed to be released in 2030. The final configuration is a battery-powered tandem-wing aircraft with 12 variable-pitch, variable-speed open rotors placed on the leading edges of the wings. These rotors rotate outboard-down and feature six blades. The power source comprises 24 solid-state lithium batteries with a nominal voltage of 500 V and an assumed energy density of 500 Wh/kg. The proposed design methodology offers the possibility of computing the necessary propeller geometry for numerical simulations in the early stages of the design, and of easily obtaining accurate estimates for the mass of the power system which can improve the overall mass estimates for the analysed configuration.

The Italian research project PROSIB (PROpulsione e Sistemi IBridi per velivoli ad ala fissa e rotante), is a 30-month initiative funded by the Italian Ministry of University and Scientific Research (MIUR) and coordinated by the Leonardo company. The project is aimed to investigate configurations for regional aircraft and rotary wing platforms and architectures for propulsion systems, and is dedicated to the identification of the best strategy for their use, given different on-board energy sources. The reduced environmental impact is the key for the success of the new hybrid/electric aircraft configurations. This not only considers the chemical pollution introduced in the atmosphere, but also the noise produced on the surrounding area of airports. The present paper describes the acoustic impact assessment resulting from the inclusion of new propulsion technologies and new configurations of regional aircraft (ATR42 pax) in a reference airport area.