Browsing by Author "van Heerden, Albert S. J."
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Item Open Access Aircraft systems architecting: a functional-logical domain perspective(American Institute of Aeronautics and Astronautics, 2016-06-17) Guenov, Marin D.; Molina-Cristobal, Arturo; Voloshin, V.; Riaz, Atif; van Heerden, Albert S. J.; Sharma, Sanjiv; Cuiller, C.; Giese, TimPresented is a novel framework for early systems architecture design. The framework defines data structures and algorithms that enable the systems architect to operate interactively and simultaneously in both the functional and logical domains. A prototype software tool, called AirCADia Architect, was implemented, which allowed the framework to be evaluated by practicing aircraft systems architects. The evaluation confirmed that, on the whole, the approach enables the architects to effectively express their creative ideas when synthesizing new architectures while still retaining control over the process.Item Open Access Aircraft thermal management: Practices, technology, system architectures, future challenges, and opportunities(Elsevier, 2021-11-12) van Heerden, Albert S. J.; Judt, David M.; Jafari, Soheil; Lawson, Craig P.; Nikolaidis, Theoklis; Bosak, D.The provision of adequate thermal management is becoming increasingly challenging on both military and civil aircraft. This is due to significant growth in the magnitude of onboard heat loads, but also because of their changing nature, such as the presence of more low-grade, high heat flux heat sources and the inability of some waste heat to be expelled as part of engine exhaust gases. The increase in the use of composites presents a further issue to address, as these materials are not as effective as metallic materials in transferring waste heat from the aircraft to the surrounding atmosphere. These thermal management challenges are so severe that they are becoming one of the major impediments to improving aircraft performance and efficiency. In this review, these challenges are expounded upon, along with possible solutions and opportunities from the literature. After introducing relevant factors from the ambient environment, the discussion of the challenges and opportunities is guided by a simple classification of the elements involved in thermal management systems. These elements comprise heat sources, heat acquisition mechanisms, thermal transport systems, heat rejection to sinks, and energy conversion and storage. Heat sources include both those from propulsion and airframe systems. Heat acquisition mechanisms are the means by which thermal energy is acquired from the sources. Thermal transport systems comprise cooling loops and thermodynamic cycles, along with their associated components and fluids, which move the heat from the source to the sinks over potentially large distances. The terminal aircraft heat sinks include atmospheric air, fuel, and the aircraft structure. In addition to the discussions on these different elements of thermal management systems, several topics of particular priority in aircraft thermal management research are deliberated upon in detail. These are thermal management for electrified propulsion aircraft, ultra-high bypass ratio geared turbofans, and high power airborne military systems; environmental control systems; power and thermal management systems; thermal management on supersonic transport aircraft; and novel modelling and simulation processes and tools for thermal management.Item Open Access Computational framework for interactive architecting of complex systems(Wiley, 2020-02-17) Guenov, Marin D.; Riaz, Atif; Bile, Yogesh H.; Molina-Cristobal, Arturo; van Heerden, Albert S. J.Presented is a novel framework for interactive systems architecture definition at early design stages. It incorporates graph‐theoretic data structures, entity relationships, and algorithms that enable the systems architect to operate interactively and simultaneously in different domains. It explicitly captures the “zigzagging” of the functional reasoning process, including not only allocated, but also the derived functions. A prototype software tool, AirCADia Architect, was implemented, which allowed the framework to be demonstrated to and tried hands‐on by practicing aircraft systems architects. The tool enables architects to effectively express their ideas when interactively synthesizing new architectures, while still retaining control over the process. The proposed approach was especially acknowledged as the way forward for rationale capture.Item Open Access Framework for integrated dynamic thermal simulation of future civil transport aircraft(AIAA, 2020-01-05) van Heerden, Albert S. J.; Judt, David M.; Lawson, Craig P.; Jafari, Soheil; Nikolaidis, Theoklis; Bosak, DavidThe development of increasingly more electric systems and ultra high bypass ratio turbofan engines for civil transport aircraft is projected to bring forth critical challenges regarding thermal management. To address these, it is required that the thermal behavior of the complete propulsion-airframe unit is studied in an integrated manner. To this purpose, a simulation framework for performing integrated thermal and performance analyses of the engines, airframe, and airframe systems, is presented. The framework was specifically devised to test novel integrated thermal management solutions for future civil aircraft. In this paper, the discussion focuses mainly on the thermal modeling of the wing and fuel. A highly flexible approach for creating wing thermal models by means of assembling generic thermal compartments is introduced. To demonstrate some of the capabilities, a case study is provided that involves thermal analysis of a single-aisle airplane with ultra high bypass ratio engines. Results are provided for fuel temperatures across flights in standard, hot, and cold days and for different airframe materials. Engine heat sink temperatures and input power to the engine gearboxes, both important parameters needed to design thermal management systems, are also presented.Item Open Access Interactive uncertainty allocation and trade-off at early-stage aircraft computational design(AIAA, 2018-01-13) Molina-Cristobal, Arturo; Guenov, Marin D.; Riaz, Atif; van Heerden, Albert S. J.A common probabilistic approach to uncertainty allocation is to assign acceptable variability in the sources of uncertainty, such that pre-specified probabilities of meeting performance constraints are satisfied. However, the computational cost of obtaining the associated trade-offs increases significantly when more sources of uncertainty and more outputs are considered. Consequently, visualizing and exploring the trade-off space becomes increasingly difficult, which, in turn, makes the decision-making process cumbersome for practicing designers. To tackle this problem, proposed is a parameterization of the input probability distribution functions, to account for several statistical moments. This, combined with efficient uncertainty propagation and inverse computation techniques, results in a computational system which performs order(s) of magnitude faster, compared with a combination of Monte Carlo Simulation and optimization techniques. Also, to aid decision-making regarding the potential combinations of uncertainty allocation, enablers for visualizing the trade space are proposed. The combined approach is demonstrated by means of a representative aircraft thermal system integration example.Item Open Access Interactive uncertainty allocation and tradeoff for early-stage design of complex systems(AIAA, 2019-11-20) Molina-Cristobal, Arturo; Chen, Xin; Guenov, Marin D.; Riaz, Atif; van Heerden, Albert S. J.A common probabilistic approach to perform uncertainty allocation is to assign acceptable variability in the sources of uncertainty, such that prespecified probabilities of meeting performance constraints are satisfied. However, the computational cost of obtaining the associated tradeoffs increases significantly when more sources of uncertainty and more outputs are considered. Consequently, visualizing and exploring the decision (trade) space becomes increasingly difficult, which, in turn, makes the decision-making process cumbersome for practicing designers. To address this problem, proposed is a parameterization of the input probability distribution functions, to account for several statistical moments. This, combined with efficient uncertainty propagation and inverse computation techniques, results in a computational system that performs order(s) of magnitude faster than a state-of-the-art optimization technique. The approach is demonstrated by means of an illustrative example and a representative aircraft thermal system integration example.Item Open Access Managing assumption-driven design change via margin allocation and trade-offs(Taylor and Francis, 2023-10-11) El Fassi, Soufiane; Chen, Xin; Riaz, Atif; Guenov, Marin D.; van Heerden, Albert S. J.; Jimeno Altelarrea, SergioAssumptions are commonly introduced to fill gaps in knowledge during the engineering design process. However, the uncertainty inherent in these assumptions constitutes a risk that ought to be mitigated. That is, assumptions can negatively impact the system if they turn out to be invalid. Adverse effects may include system failure, violation of requirements, or budget and schedule overruns. In this paper, the relationships between assumptions and margins are made explicit, with the purpose of aiding risk mitigation, as well as accommodating future opportunities such as product evolvability. To this end, a novel assumption management framework is proposed, which consists of a taxonomy of margins, an algorithm for change absorber localisation, and an interactive approach for margin trade-off. The proposed framework is demonstrated with a conceptual aircraft design use case, which shows that the most relevant margins can be identified, given a revision of a set of assumptions. It is also demonstrated that the application of the method allowed the margins to be adjusted according to the confidence in the assumptions, while maintaining satisfaction of all design constraints, without unacceptable compromise of system performance.Item Open Access Margin allocation and trade-off in complex systems design and optimization(AIAA, 2018-05-01) Guenov, Marin D.; Chen, Xin; Molina-Cristobal, Arturo; Riaz, Atif; van Heerden, Albert S. J.Presented is an approach for interactive margin management. Existing methods enable a fixed set of allowable margin combinations to be identified, but these have limitations with regard to supporting interactive exploration of the effects of: 1) margins on other margins, 2) margins on performance and 3) margins on the probabilities of constraint satisfaction. To this purpose, the concept of a margin space is introduced. It is bi-directionally linked to the design space, to enable the designer to understand how assigning margins on certain parameters limits the allowable margins that can be assigned to other parameters. Also, a novel framework has been developed. It incorporates the margin space concept as well as enablers, including interactive visualization techniques, which can aide the designer to explore the margin and design spaces dynamically, as well as the effects of margins on the probability of constraint satisfaction and on performance. The framework was implemented into a prototype software tool, AirCADia, which was used for a qualitative evaluation by practicing designers. The evaluation, conducted as part of the EU TOICA project, demonstrated the usefulness of the approach.Item Open Access Performance and economic assessment of mechanically integrated parallel hybrid aircraft(American Society of Mechanical Engineers, 2022-10-28) Carpentier, Thibault; Zhang, Jinning; van Heerden, Albert S. J.; Roumeliotis, IoannisIn this study, a selection of environmental and economic considerations of mechanically integrated parallel hybrid (MIPH) electric propulsion systems for single-aisle civil transport aircraft are assessed. The environmental assessment focuses on the carbon dioxide and nitrogen oxide emissions with different power management strategies and levels of battery technology. In the economic study, the potential subsidies and tax incentives required to make these aircraft financially viable are determined. To capture the performance results, models of the propulsion systems and airframe were constructed using the Siemens Simcenter Amesim systems modelling software. The operating cost was then computed using adapted direct operating cost estimation methods. Battery replacement was incorporated by using a battery cycle aging model. The results showed that using a battery energy density of 300 Wh/kg will not provide any meaningful benefits. For 600 Wh/kg, fuel savings of up to 3% for missions below 650 nm could be obtained for a PMS where the electrical powertrain operates during takeoff, climb, and cruise. However, the NOx emissions were lowest for the takeoff and climb only PMS, implying a trade-off when selecting a PMS. Based on the cost results, it is determined that taxation on carbon emissions would have to increase at least 50-fold from its current levels for the most optimistic scenarios. Alternatively, considerable subsidies, representing large percentages of the purchase price of the aircraft, will be needed.Item Open Access A scalable hydrogen propulsion system for civil transport aircraft(ICAS, 2022-11-28) van Heerden, Albert S. J.; Sasi, Sarath; Ghelani, Raj; Sanders, Drewan S.; Roumeliotis, IoannisThe aim of this research was to explore the application of engineering systems evolvability analysis techniques in devising potential scalable hydrogen propulsion systems for future civil transport aircraft. Baseline and derivative aircraft concepts were generated for a medium-sized long-range aircraft, with the derivative options having different levels of hydrogen incorporated in a dual-fuel arrangement (with separate hydrogen and kerosene turbofans), as well as potential turboelectric propulsion with boundary layer ingestion. Commonality between each baseline-derivative pair was then estimated, which could be used to predict the derivative development cost savings that could potentially be obtained when working from a specific baseline. The performance and cost results enabled different future scenarios to be explored. It was shown that developing the future concepts based on an existing state-of-the aircraft as baseline can offer considerable cost savings, as opposed to designing a clean sheet version. The importance of the baseline configuration selection in reducing the development cost for the different hydrogen configurations was also highlighted.