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Daniel Guggenheim School of Aerospace Engineering
Daniel Guggenheim School of Aerospace Engineering
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ItemA Framework for Electrified Propulsion Architecture and Operation Analysis(Georgia Institute of Technology, 2019-07) Cinar, Gokcin ; Garcia, Elena ; Mavris, Dimitri N.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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ItemSizing and Optimization of Novel General Aviation Vehicles and Propulsion System Architectures(Georgia Institute of Technology, 2018) Cinar, Gokcin ; Cai, Yu ; Chakraborty, Imon ; Mavris, Dimitri N.The drive for more efficient flying vehicles in all categories may necessitate a significant departure from the tube-and-wing or rotary-wing norms that have been the mainstay of aviation for many decades. This poses challenges for predicting the aerodynamic characteristics and the weight build-up of such unconventional vehicles in early design phases. Additionally, the design and assessment of advanced/unconventional all-electric or hybrid-electric propulsion system architectures require consideration of degrees-of-freedom and trade-offs that do not arise for conventional purely fuel-powered architectures. Thus, there is a need for a flexible vehicle sizing, trade-off, and optimization capability that is not limited to a single vehicle configuration (e.g., fixed-wing, rotary-wing) or propulsion system architecture. To be suitable for the early design phases, such a framework must evaluate relatively quickly, not require extensive definition of the vehicle, and lend itself to customizable design optimization setups. This paper describes the initial creation of such a capability and demonstrates its application to design trade-offs for a General Aviation vehicle with an advanced propulsion system architecture.
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ItemA Categorical Model for Airport Capacity Estimation Using Hierarchical Clustering(Georgia Institute of Technology, 2017-12) Cinar, Gokcin ; Jimenez, Hernando ; Mavris, Dimitri N.Motivated by the need for very inexpensive, easily updated, first-order-accurate estimates of airport capacity required in system-wide analyses, we propose a novel approach to generate a predictive categorical model. The underlying hypothesis tested in this work is that for the same weather conditions airports with a similar runway configuration and fleet mix will have similar capacities. Accordingly, if airport categories with known capacity are defined a-priori on the basis of similarity in fleet mix and runway configuration, then a membership function to the set of categories essentially constitutes a predictive model. We test this hypothesis by formulating and implementing such a model in order to examine its feasibility and discuss key practical considerations. Verification demonstrates model fit error within 4% with a categorical training set of 35 major United States airports. Validation against European airports for model representation error is limited by data availability but shown to be in the order of 7-10%. Results suggest that elemental runway configurations are the primary driver for categorical definition, and variations within each category can be associated to fleet mix variations. The implementation of the proposed method to generate other such models with different data sets is encouraged.
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ItemSizing, Integration and Performance Evaluation of Hybrid Electric Propulsion Subsystem Architectures(Georgia Institute of Technology, 2017-06) Cinar, Gokcin ; Mavris, Dimitri N. ; Emeneth, Mathias ; Schneegans, Alexander ; Riediger, Carsten ; Fefermann, Yann ; Isikveren, AskinThis paper presents a methodology for the sizing and synthesis of power generation and distribution (PG&D) subsystems. The PG&D subsystem models developed in a previous work done by the authors were applied within a parallel hybrid electric propulsion architecture using the Dornier 328 as the baseline aircraft. The hybridization took place only during the cruise segment. Analyses were performed in Pacelab SysArc, a system architecture design tool, to assess the impact of different hybrid electric propulsion architectures and changing PG&D subsystem characteristics at aircraft and mission levels. To this end, sensitivity analysis was conducted to reveal the sensitivity to the subsystem level characteristics. Moreover, six different architectures were compared in terms of their mission level performance. These architectures included the PG&D subsystems with current state of the art technology, NASA 15-year technology goals and a more advanced battery technology. Although neither the current state of the art PG&D subsystems nor NASA 15-year technology goals were advanced enough to match the design range requirement of the baseline aircraft, some of the competing architectures met the practical range target while enjoying substantial amount of fuel reductions. Finally, it was observed that in order to reach a break-even point in terms of the design mission range, a battery specific energy of 5 kWh/kg was necessary for a 50% level of hybridization during cruise. In this work the Dornier 328 was used as a testbed, however the methodology can be generalized for all parallel hybrid electric propulsion applications.
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ItemDevelopment of Parametric Power Generation and Distribution Subsystem Models at the Conceptual Aircraft Design Stage(Georgia Institute of Technology, 2017-01) Cinar, Gokcin ; Mavris, Dimitri N. ; Emeneth, Mathias ; Schneegans, Alexander ; Fefermann, YannThe 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.