Turboelectric Distributed Propulsion System Research Articles

Design Factors of High-Speed Turbo-Electric Distributed Propulsion System

Turbo-electric Distributed Propulsion (TeDP) is a promising concept to achieve the operational goals of more electric aircraft. The application of TeDP architecture can achieve the desired weight reduction of an aircraft power system. The use of a superconducting machine is expected to provide the workaround for the weight issue, but its current state of technology has not yet been extensively tested for aircraft applications. Another more practical option is to directly couple the aircraft's propeller system to a high-speed permanent magnet (PM) electrical machine, eliminating the gear part that also contributes to the total weight. A critical part of the design for a high-speed PM machine is choosing the optimum magnet configurations. This study used finite element modelling to analyze the impact of scaling the PM’s critical parameters on the weight and machine speed. A prototype testing of a 2-KW high-speed machine, suitable for a Remotely Piloted Aircraft System (RPAS), was developed and tested. The results confirmed the following critical parameters that should be carefully designed to achieve the optimum output, such as the (a) number of winding turns, (b) stack length, (c) sleeve thickness, and (d) terminal voltage.

Effect of Endogenous Failure Events on the Survivability of Turboelectric Distributed Propulsion System

Recent advancements in aircraft electrification have led to the introduction of turboelectric distributed propulsion (TeDP). For instance, NASA's N3X airplane aims to curb jet fuel emissions with the aid of TeDP. However, it is crucial to analyze the survivability of the TeDP system during extreme conditions. The endogenous failure events are of specific interest as they were found to cause a significant number of accidents for commercial aircraft. While the distribution reconfiguration is necessary to meet the critical load demands under extreme failure events, it can also create a transient overload condition in the turboshaft engine. The power system survivability is further deteriorated in the presence of constant power loads. In this article, a mathematical analysis of the survivability of the system is presented to make the aircraft power system highly resilient to endogenous failure events. A power system collapse mitigation strategy is proposed by adding an energy storage system. Moreover, the analytical expressions are formulated to size the energy storage unit to prevent the system collapse. Various failure conditions are modeled using PSCAD/EMTDC to study the minimum energy storage required to prevent system collapse.

Baseline architecture design for a turboelectric distributed propulsion system using single turboshaft engine operational scenario

Abstract Reducing the carbon footprints of aerial transportation became a major target for both industries and academia. Various solutions have been proposed to develop cleaner alternative methods for green transportation. Full electric, hybrid electric, and turboelectric propulsion system architectures intend to reduce greenhouse gas emissions and fuel consumption of today’s aero gas turbine engines. In this study, a turboelectric propulsion system, which is considered as the most promising technology for future aviation is selected for modelling and simulation. As the main power supply, a high fidelity mathematical model of GE T700 turboshaft engine is constructed in MATLAB/Simulink to emulate the technology of today. Selected aero gas turbine’s mathematical model is combined with NASA’s Baseline electrical power distribution architecture which is firstly designed for N-3X turboelectric aircraft. MATLAB/Simulink model is utilized to analyses a single-engine operational scenario of twin-engine aircraft which is a major design consideration due to single-engine failure. Power requirements, distribution percentages, preliminary power assessment for power electronic systems and nominal power capacities of each electrical unit of a turboelectric propulsion system are obtained using GE T700 as the main power supply.

Baseline architecture design for a turboelectric distributed propulsion system using single turboshaft engine operational scenario

Abstract Reducing the carbon footprints of aerial transportation became a major target for both industries and academia. Various solutions have been proposed to develop cleaner alternative methods for green transportation. Full electric, hybrid electric, and turboelectric propulsion system architectures intend to reduce greenhouse gas emissions and fuel consumption of today’s aero gas turbine engines. In this study, a turboelectric propulsion system, which is considered as the most promising technology for future aviation is selected for modelling and simulation. As the main power supply, a high fidelity mathematical model of GE T700 turboshaft engine is constructed in MATLAB/Simulink to emulate the technology of today. Selected aero gas turbine’s mathematical model is combined with NASA’s Baseline electrical power distribution architecture which is firstly designed for N-3X turboelectric aircraft. MATLAB/Simulink model is utilized to analyses a single-engine operational scenario of twin-engine aircraft which is a major design consideration due to single-engine failure. Power requirements, distribution percentages, preliminary power assessment for power electronic systems and nominal power capacities of each electrical unit of a turboelectric propulsion system are obtained using GE T700 as the main power supply.

Single Turboshaft Engine Failure Analysis of an Inner Bus Tie Architecture for Turboelectric Distributed Propulsion System

Single Turboshaft Engine Failure Analysis of an Inner Bus Tie Architecture for Turboelectric Distributed Propulsion System

Flow simulation and optimal shape design of N3-X hybrid wing body configuration using a body force method

System studies show that NASA's N3-X hybrid wing-body aircraft with a turboelectric distributed propulsion system using a mail-slot inlet/nozzle nacelle can meet the environmental and performance goals of N+3 generation transports (three generations beyond the current air transport technology level). In this paper, we present flow calculations and shape optimization of the integrated N3-X configuration, including the mail-slot propulsor, based on an unstructured-mesh Navier–Stokes solver. To simulate the propulsor fans flow, a novel body force model is suggested for a realistic and efficient representation of flow turning, pressure rise and losses resulting from the fan blades and the inlet-fan interactions for distorted inflow conditions. This work is the first of its kind analysis and design study on boundary layer ingestion inlet and fan interaction problems using the body force method. A mail-slot geometry was generated and installed on the N3-X configuration with an efficient CAD-free method. An optimal shape design of the mail-slot nacelle surface with the adjoint method was successfully conducted to reduce the strength of shock waves and flow separations on the cowl surface.

Method to Explore the Design Space of a Turbo-Electric Distributed Propulsion System

AbstractMeeting future goals for aircraft and air traffic system performance will require a fundamental shift in approach to aircraft and engine design. In 2005, the National Aeronautics and Space Administration (NASA) released plans of a next generation commercial airplane for 2030 combining the blended wing body (BWB) and a superconducting distributed propulsion system. The BWB concept adapts NASA’s cruise-efficient short take-off and landing (CESTOL) airframe. The propulsion system employs distributed electric fans, which are embedded on the upper surface of the airframe, driven by superconducting motors with power provided by two wing-tip mounted turboelectric generators. This paper describes a method to design a turboelectric distributed propulsion (TeDP) system on the hybrid wing body airframe, including a way to obtain the propulsor number and its weight, a method to simulate boundary layer ingestion, and a method to calculate electric system performances and its weight. An examination of the syste...

Design point analysis of the turbofan-driven turboelectric distributed propulsion system with boundary layer ingestion

The performance benefits of boundary layer ingestion in the case of air vehicles powered by distributed propulsors have been documented and explored extensively by previous study. However, the increased inlet flow distortion and the system total weight would dramatically reduce the expected benefits. In this paper, a novel turboelectric distributed propulsion module on the N3-X airframe has been developed. It includes two direct-shaft-driven turbofans (each drives a free power turbine) and a propulsors array, and therefore both the direct-shaft-driven turbofan and the propulsors unit produce thrust. Secondly, a parametric and quasi two-dimensional study at component and at system level is carried out so that the effects of these two aerodynamic issues over the system performance can be assessed. The figure of merit in this study is the thrust-specific fuel consumption and the system parameters examined are: the thrust split between propulsors and engines, the capture height and the direct-shaft-driven turbofan parameters. Preliminary results found optimum configurations at around 60–90% thrust split ratio, when installation effects were neglected. The final value depends on the propulsor intake pressure loss and the bypass ratio of the propulsion system.

Turboelectric distributed propulsion benefits on the N3-X vehicle

Purpose – The purpose of this article is to present a summary of recent study results on a turboelectric distributed propulsion vehicle concept named N3-X. Design/methodology/approach – The turboelectric distributed propulsion system uses multiple electric motor-driven propulsors that are distributed on an aircraft. The power to drive these electric propulsors is generated by separately located gas turbine-driven electric generators on the airframe. To estimate the benefits associated with this new propulsion concept, a system analysis was performed on a hybrid-wing-body transport configuration to determine fuel burn (or energy usage), community noise and emissions reductions. Findings – N3-X would be able to reduce energy consumption by 70-72 per cent compared to a reference vehicle, a Boeing 777-200LR, flying the same mission. Predictions for landing and take-off NOX are estimated to be 85 per cent less than the Tier 6-CAEP/6 standard. Two variants of the N3-X vehicle were examined for certification noi...

Turbo-electric distributed propulsion – opportunities, benefits and challenges

Purpose – With the predicted rise in air traffic, a growing need exists to make the aviation industry more environmentally sustainable in the long-term future. Research has shown that the turbo-electric distributed propulsion system (TeDP) could be the next disruptive technology that has the potential to meet the ambitious environmental goals set for the N + 3 time frame. This however will require the use of superconductivity, application of high-temperature superconducting materials and cryogenic liquids. This paper provides a brief overview of the technology and further discusses the benefits, advantages and new opportunities that may arise from the application of the technology. Design/methodology/approach – This paper provides a brief overview of the technology and further discusses the benefits, advantages and new opportunities that may arise from the application of the technology. Findings – Implementation of superconducting technology is currently one of the greater challenges faced and hence this article also reviews some of the key considerations to enable utilisation of cryogenic fuels in the future. Originality/value – This paper provides a viewpoint and reviews some of the work undertaken in the field. It also provides a perspective on some new possibilities and advantages from using TeDP with cryogenic fuels.

Thermal cycle analysis of turboelectric distributed propulsion system with boundary layer ingestion

A fundamental shift in propulsion system design was needed to satisfy future aircraftsʼ strict emission and fuel consumption requirements. The turboelectric distributed propulsion system (TeDP) uses electricity to transmit power from the core turbine to number of fans. This novel concept can dramatically increase bypass ratio to achieve lower fuel consumption and noise. This paper put forward a method to design a TeDP system on hybrid wing body airframe. An examination of the system thermodynamic performance for a range of fan pressure ratio (FPR) was made and FPR 1.3 was chosen for a detailed analysis. Finally, a comparison with results from the NASA N+3 technical reports on TeDP system has been performed. The new model returned similar results but estimated the new system has lower specific fuel consumption at cruise for the same thrust level.