Article

A framework for electrified propulsion architecture and operation analysis

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Abstract

Purpose The purpose of this paper was to create a generic and flexible framework for the exploration, evaluation and side-by-side comparison of novel propulsion architectures. The intent for these evaluations was to account for varying operation strategies and to support architectural design space decisions, at the conceptual design stages, rather than single-point design solutions. Design/methodology/approach To this end, main propulsion subsystems were categorized into energy, power and thrust sources. Two types of matrices, namely, the property and interdependency matrices, were created to describe the relationships and power flows among these sources. These matrices were used to define various electrified propulsion architectures, including, but not limited to, turboelectric, series-parallel and distributed electric propulsion configurations. Findings As a case study, the matrices were used to generate and operate the distributed electric propulsion architecture of NASA’s X-57 Mod IV aircraft concept. The mission performance results were acceptably close to the data obtained from the literature. Finally, the matrices were used to simulate the changes in the operation strategy under two motor failure scenarios to demonstrate the ease of use, rapidness and automation. Originality/value It was seen that this new framework enables rapid and analysis-based comparisons among unconventional propulsion architectures where solutions are driven by requirements.

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... The baseline, advanced, and EAP vehicles were modeled and sized using the multi-disciplinary analysis and optimization environment called Electrified Propulsion Architecture Sizing and Synthesis (E-PASS), developed by Cinar [19,20]. E-PASS is a Matlab-based aircraft sizing and synthesis tool that enables the design and performance evaluation of conventional and advanced aircraft concepts with any type of propulsion system architecture. ...
... This is a powerful approach as it completely removes the need to tailor the performance calculations to a specific architecture. The interested reader is referred to Ref. [20] for the mathematical framework upon which this novel approach is built. This approach is utilized within E-PASS, but the framework is tool-agnostic and can be used with any modeling environment. ...
Conference Paper
View Video Presentation: https://doi.org/10.2514/6.2022-1994.vid This paper explores the design spaces of a thin-haul and a regional aircraft with parallel hybrid electric propulsion architectures and an entry into service date of 2030. Notional technology reference aircraft models were developed for a 19- and a 50-passenger aircraft based on publicly available data on the Beechcraft 1900D and ATR 42-600, respectively. Advanced technology aircraft models were developed by infusing the reference aircraft models with a set of selected airframe and propulsion system technologies projected to reach maturity by2030. Matlab and NPSS-based parametric, physics-based models were created for the charge depleting parallel hybrid electric propulsion system architecture. Different modes of operation were identified and parametrized with a basket of design variables to investigate the feasibility and trade space for peak power shaving, climb power boosting, electric taxi, battery usage schedules, and in-flight battery recharge strategies. A design of experiments with thousands of data points was conducted for the 19- and 50-passenger electrified aircraft propulsion vision systems. The vision systems were sized for the same point and mission performance requirements as their conventional counterpart. Artificial Neural Network models were fit toa set of subsystem, system, and mission level metrics of interest. An extensive trade study was performed to identify the fuel burn, weight, and efficiency trends and sensitivities as a function of different modes of operation as well as the electric powertrain key performance parameters and technology projections for 2030 and onward. The resulting multidisciplinary design space exploration environment was used to identify the optimum vision system designs and modes of operation for the minimum block fuel burn objective. It was found that both vehicle classes with the charge depleting parallel hybrid electric architecture provided fuel burn benefits over their 2030 advanced technology counterparts under certain modes of operation.
... Cinar [12], [13] presented a methodology for sizing of electrified propulsion aircraft, using matrices to depict the connections between energy sources, power sources and thrust sources, as well as the power flows through the powertrain. This allows easy representation of new architectures as well as implementing different power management strategies. ...
... The definitions of how energy and power are split between different components along the powertrain, used in this work are described in detail in [15]. These are based on or are extensions of parameters defined by other authors [9]- [13]. ...
... It has built-in physics-based subsystem models, component-based weight estimation techniques, a power management optimizer and a generic mission analysis module which allows for mission performance evaluations of any propulsion architecture. The interested reader is referred to Ref. [27,28] for more information on this aircraft design tool. ...
... This schedule is an input to the analysis and defines the power flow and splits between the power and energy sources as a function of time. The interested reader can refer to Ref. [28] for a detailed explanations and definitions regarding the power splits between thrust, power and energy sources. In the context of this hybrid turboelectric architecture, power can be split between the energy and power sources in the following scenarios: ...
Conference Paper
Full-text available
Electrified propulsion systems can provide potential environmental and performance benefits for future aircraft. The choice of the right propulsion architecture and the power management strategy depends on a number of factors, the airframe, electrification objectives and metrics of interest being the most critical ones. Therefore, the generic advantages and disadvantages of various electrified propulsion architectures must be quantified to assess feasibility and any possible benefits. Moreover, the objectives and the metrics of interest can be different for military applications than commercial ones. This research investigates the feasibility of turboelectric and hybrid turboelectric propulsion architectures integrated within a medium altitude long endurance surveillance unmanned aerial vehicle. The electrified propulsion system is desired to provide the same endurance and takeoff and landing field length characteristics of the baseline aircraft. This paper presents the results of the first phase of this research where only the electrified propulsion system is sized while the airframe is kept fixed. Physics-based models and a generic mission analysis methodology are used to evaluate the performance of the major subsystems of the propulsion system and to provide a full flight mission history. A state of the art rechargeable battery is employed for the hybrid case. Various power management strategies where the battery is discharged and charged in different flight segments are explored for varying sizes of battery packs. Results indicate that, while none of the architectures can offset the added weight and the efficiency factors of the electrical components as expected, the hybrid turboelectric propulsion architecture can provide fuel burn and performance benefits when sized for, and operated under, a specific set of power management strategies.
... In this study, both the TRA and the ATA models are set up using Electrified Propulsion Architecture Sizing and Synthesis (E-PASS) [2], [3], a MATLAB-based multi-disciplinary analysis and optimization environment which enables the design and performance evaluation of aircraft concepts with any type of propulsion system architecture. ...
... In this design framework, FLight OPtimization Systems (FLOPS) [17,18] is used to perform the aerodynamic analysis and to estimate airframe component weights; Numerical Propulsion System Simulation (NPSS) [19] and Object-oriented Weight Analysis of Turbine Engines (WATE++) [20] are used to model the gas turbine engines and compute their weights; Hamilton Standard propeller maps [21] are used to estimate propeller performance; modules of Electric Propulsion Architecture Sizing and Synthesis (E-PASS) [22,23] are adapted to size the electric components, which include the electric motors and the battery; finally, a custom MATLAB program is created to integrate the above disciplinary analyses, perform mission analysis, and control the aircraft sizing loop. ...
Conference Paper
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View Video Presentation: https://doi.org/10.2514/6.2022-3204.vid The Parallel Electric-Gas Architecture with Synergistic Utilization Scheme (PEGASUS) is a regional aircraft concept developed by NASA’s Aeronautics Systems Analysis Branch to explore the opportunities created by the technology of electric aircraft propulsion. It features a distributed parallel hybrid-electric propulsion architecture with two wingtip-mounted hybrid-electric propulsors, two inboard electric motors, and one aft boundary layer ingestion electric motor. Although PEGASUS has been demonstrated to have advantages in fuel burn and energy consumption over conventional aircraft in preceding studies, it may encounter difficulties in complying with critical-engine-inoperative flight certification rules due to the extreme locations of the wingtip-mounted propulsors. Using a certification-driven design framework, this paper presents a vertical tail sizing and propulsive power split optimization study for the PEGASUS concept incorporating certification requirements. For comparison, a vertical tail retrofit study is also conducted on the ATR 42-500 aircraft, which serves as the conventional baseline of the PEGASUS, using the same design space, to gain insights into the different impacts of certification constraints on the design process between conventional and unconventional aircraft. In each study, a design space exploration is performed by sampling the design space using a Design of Experiments, constructing surrogate models for responses of interests including design objectives and constraints, filtering the design space based on its feasibility with respect to constraint functions, and identifying a set of Pareto optimal candidates through a Monte Carlo simulation. The feasibility test shows that the certification constraints yield a much smaller feasible design space for the PEGASUS aircraft when compared to the ATR 42. The comparison between the unconstrained and constrained optima implies that performance improvements induced by novel technologies are negatively correlated to design constraints. Despite a much smaller feasible design space, the constrained Pareto optima of the PEGASUS still exhibit lower cruise drag coefficient, fuel burn, and operational energy cost when compared to those of the ATR 42.
... There are three main architectures of hybrid propulsion system as shown inFig. 2exist: series, parallel and series-parallel[61][62][63]. ...
Preprint
The excessive depletion of fossil fuels and increasing environmental concerns have lead to a need to explore alternate source of power for aircraft. This has spurred the various stakeholders in the aerospace industry to explore hybrid-electric propulsion technology and fully electric vehicles. Air-ships are aerial platforms based on the lighter-than-air systems technology, and they have several unique features compared to the other vehicles, chiefly being more environment friendly, due to low fuel consumption. Among the airships, the lifting-body dynastats are the most suitable configuration for implementing different levels of hybridization in propulsion systems, due to their large surface-to-volume ratio. The present study deals with the relevance of the hybrid propulsion (conventional engine + electric motor) system and their comparison to the conventional ones. A single-point optimization problem is formulated to achieve a configuration with minimal envelope volume of a tri-lobed dynastat to carry 10 ton of payload over 1530 km, for a specified operating condition. The design space is explored assuming a future battery technology level with specific energies ranging from 400 to 1600 Wh/kg. Three case-studies of hybrid-propulsion are investigated, viz., fuel alone, fuel + batteries, and fuel + batteries + solar array. It is seen that the airship can be fully electric with zero-carbon emission, but at the expense of longer length (+ 53%) and higher envelope volume (+ 272%).
... Next, a series propulsion architecture, pictured in Figure 1 below, was developed in an in-house tool called Electrified Propulsion Architecture Sizing and Synthesis (EPASS), such that the battery could be disconnected resulting in a turboelectric architecture. More information on the sizing and synthesis tool is available in Ref. [3,4] The series architecture allows for a source of power to be carried on the vehicle which does not lapse with altitude like an internal combustion engine and can be recharged and used again during the mission. The turboelectric variant does not provide an additional source of power but allows the turboprop engine to be decoupled from the propeller and thus allows both the engine and propeller to be operated more efficiently. ...
Conference Paper
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View Video Presentation: https://doi.org/10.2514/6.2021-3289.vid Distributed propulsion systems are enabled by electrified aircraft and can provide aero-propulsive benefits. The magnitude and impact of these benefits rely on the location of propulsors on the vehicle, the amount of propulsive force generated by those propulsors, vehicle geometry, and the extent of hybridization of the propulsion system. With an increased number of degrees of freedom over conventionally electrified aircraft, the full extent of the impacts of this technology have not yet been explored, especially for military applications. This study builds on a previous one that implemented a series hybrid and turboeletric propulsion architecture on a turboprop UAV, by introducing a distributed electric propulsion system on the same vehicle. The previous study showed that with a hybrid architecture, the same performance, in terms of range and endurance, could not be achieved for a fixed gross take-off weight. This study investigates the impact of the distributed propulsion system with the goal of identifying the benefits over the previous vehicle and determining the level of technology required to break even with the conventional propulsion UAV. In incorporating the new propulsion system, the engine and main motor are resized, leading edge wing mounted propellers and motors are added to the configuration, and a new battery sizing strategy is implemented. Preliminary results show that, although this new system shows increased range and endurance over the series hybrid vehicle, it still falls short compared to the conventional vehicle with current levels of technology. Although improvements are needed to the electrical system technology to reduce the weight enough to break even with the conventional system, the new vehicle shows increased performance during climb, and has the capability to store energy during the mission. With the proper power management and battery utilization strategies, this system can provide reduction in fuel burn and improved performance during certain phases of the mission which could be beneficial for military applications.
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Exceeding the European Commission Flightpath 2050 goals (zero-emission ground maneuvering, reduction of 90% in NOx and 75% lower CO2 in-flight emissions), the feature of this technical work was to create an Integrated Aircraft Study Platform (IASP) allowing for the future investigation of systems and sub-systems that would serve to produce transport aircraft concepts delivering zero emissions from gate to gate. The assumed Entry-into-Service (EIS) for this study was set as 2035. This ambitious zero-emissions target was achieved through implementation of a Universally-Electric Systems Architecture (UESA), which includes a propulsion solution solely powered through electrical means. The design of UESA outfitted transport aircraft is an extremely inter-disciplinary activity produced by simultaneous consideration of complex, tightly-coupled systems and functions. Here, advanced Li-ion batteries constitute the only source of electrical power. The batteries have been configured as modular packs that fit into suitably modified LD-3 containers in order to facilitate expedient turn-around and aid loadability. With regards to motive power the proposal utilizes ducted fans run by High-Temperature Super-conducting (HTS) electric motors. This technical paper provides details about the generic Aircraft Top-Level Requirements for medium capacity, short-haul operations, and, in accordance with Air Transport Association (ATA) Chapter designations offers design descriptions covering the UESA approach including impact to motive power, Flight Control System, fuselage cross-section and volumetric utilization, low-speed and high-speed integrated performance, and, operating economics.
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The ongoing efforts to reduce aviation related greenhouse gas emissions and fuel burn have led to advancements in power generation and distribution (PG&D) subsystem technology. Due to the absence of historical data, PG&D subsystem models must be created from first-order analysis without compromising crucial information on their characteristics.This paper demonstrates the development of parametric, physics-based subsystem models such as battery, electric motor, power distribution and management system, and propeller speed reduction unit for rapid and low-cost sizing, simulation and analysis at early design stages. A special focus was put on rechargeable battery technology and implementing a dynamic (rather than steady-state) discharge behavior into the propulsion architecture. A methodology to integrate the developed subsystem models was presented. A sample application was also provided to demonstrate the combined capabilities of the models. To this end, the models were applied within a sample parallel hybrid electric architecture using Dornier 328 as a test bed. The subsystem behaviors under varying power requirements were then analyzed. Finally, the importance of having more dimensionality at the subsystem level at early design stages was highlighted by comparing the results of two different architectural choices.
Article
IntroductionBattery ParametersLead Acid BatteriesNickel-based BatteriesSodium-based BatteriesLithium BatteriesMetal Air BatteriesBattery ChargingThe Designer's Choice of BatteryUse of Batteries in Hybrid VehiclesBattery ModellingIn Conclusion References
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