| 1. |
- Hecken, Tobias, et al.
(författare)
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Conceptual Design Studies of “Boosted Turbofan” Configuration for short range
- 2020
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Ingår i: AIAA 2020-0506 Session: Hybrid Electric Aircraft Design Under Clean Sky 2 (LPA WP1.6.1.4). - Reston, Virginia : American Institute of Aeronautics and Astronautics.
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Konferensbidrag (refereegranskat)abstract
- This paper describes the current activities at the German Aerospace Center (DLR) and an associated consortium related to conceptual design studies of an aircraft configuration with hybrid electric propulsion for a typical short range commercial transport mission. The work is implemented in the scope of the European Clean Sky 2 program in the project “Advanced Engine and Aircraft Configurations” (ADEC) and “Turbo electric Aircraft Design Environment” (TRADE). The configuration analyzed incorporates parallel hybrid architecture consisting of gas turbines, electric machines, and batteries that adds electric power to the fans of the engines. A conceptual aircraft sizing workflow built in the DLR’s “Remote Component Environment” (RCE) incorporating tools of DLR that are based on semi-empirical and low level physics based methods. The TRADE consortium developed a simulation and optimization design platform with analysis models of higher fidelity for an aircraft with hybrid electric propulsion architecture. An implementation of the TRADE simulation and optimization design platform into the DLR’s RCE workflow by replacing the DLR models was carried out. The focus of this paper is on the quantitative evaluation of the “Boosted Turbofan” configuration utilizing the resulting workflow. In order to understand the cooperation between the DLR and TRADE consortium, a brief overview of the activities is given. Then the multi-disciplinary overall aircraft sizing workflow for hybrid electric aircraft built in RCE is shown. Hereafter, the simulation and optimization models of the TRADE design platform are described. Subsequently, an overview of the aircraft configuration considered in the scope of this work is given. The design space studies of the “Boosted Turbofan” configuration are presented. Finally, the deviations of the results between the workflows with and without the TRADE modules are discussed.
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| 2. |
- Lindblad, Daniel, 1989, et al.
(författare)
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Convergence Acceleration of the Harmonic Balance Method using a Time-Level Preconditioner
- 2020
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Ingår i: AIAA Scitech 2020 Forum. - Reston, Virginia : American Institute of Aeronautics and Astronautics. - 9781624105951 ; 3
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Konferensbidrag (refereegranskat)abstract
- The Harmonic Balance method is nowadays widely applied for numerically solving problems that are known to possess time-periodic solutions. Key reasons for its success are its wide range of applicability, relative ease of implementation, and computational efficiency compared to time-accurate approaches. The computational efficiency of the Harmonic Balance method is partly derived from the fact that it searches directly for a periodic solution, instead of integrating the governing equations in time until a periodic solution is reached. Convergence acceleration techniques such as multigrid, implicit residual smoothing and local time stepping may also be used to improve the efficiency of the Harmonic Balance method. This paper considers another option for accelerating convergence, namely a novel time-level preconditioner that can be applied to the Harmonic Balance residual locally in each computational cell. This preconditioner is derived from a rigorous stability analysis of the Harmonic Balance equations and is shown to give a speed-up factor of 2 when applied to simulations of laminar vortex shedding behind a circular cylinder.
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