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Progress in Aerospace Sciences
International Journal of Aerospace Engineering
Benefits of Exergy-Based Analysis for Aerospace Engineering Applications—Part IThis paper compares the analysis of systems from two different perspectives: an energy-based focus and an exergy-based focus. A complex system was simply modeled as interacting thermodynamic systems to illustrate the differences in analysis methodologies and results. The energy-based analysis had combinations of calculated states that are infeasible. On the other hand, the exergy-based analyses only allow feasible states. More importantly, the exergy-based analyses provide clearer insight to the combination of operating conditions for optimum system-level performance. The results strongly suggest changing the analysis/design paradigm used in aerospace engineering from energy-based to exergy-based. This methodology shift is even more critical in exploratory research and development where previous experience may not be available to provide guidance. Although the models used herein may appear simplistic, the message is very powerful and extensible to higher-fidelity models: the 1st Law...
45th AIAA Aerospace Sciences Meeting and Exhibit
Exergy Analysis as a Tool to Decision Making in Aircraft Design2006 •
This paper compares empirical and computational fluid dynamics (CFD) based exergy calculation procedures for modeling the airframe subsystem of aircraft. Calculations were based on the B747-200 aircraft, with the presumption that the empirical methods were valid. They were carried out for a range of values of the angle of attack, assuming transonic flight. Good agreement was observed for one approach, supporting the viability of using CFD for realistic airframe calculations in a system-level analysis and design optimization.
A new exergy-based formulation is derived for the assessment of the aerothermopropulsive performance of civil aircraft. The choice of exergy is motivated by its ability to provide a well-established and consistent framework for the design of aerospace vehicles. The output of the derivation process is an exergy balance between the exergy supplied by a propulsion system or by heat transfer, the mechanical equilibrium of the aircraft, and the exergy outflow and destruction within the control volume. The theoretical formulation is subsequently numerically implemented in a Fortran code named ffx for the post-processing of CFD-RANS flow solutions. Unpowered airframe configurations are examined with grid refinement studies and a turbulence model sensitivity analysis is performed. A numerical correction is introduced and calibrated to obtain an accuracy similar to the near-field drag method. The code is thereby validated against well-tried methods of drag prediction and wind-tunnel tests, when available. The investigation of powered configurations demonstrates the ability of the approach for assessing the performance of configurations with aerothermopropulsive interactions. First, the formulation is validated for the simple case of a turbojet engine for which consistent figures of merit are exhibited. The method is also proved robust for assessing the overall performance of a boundary layer ingesting propulsion system placed on the upper surface of a simplified blended wing-body architecture. Moreover, this configuration enables the investigation of thermopropulsive interactions by the transfer of heat upstream of the propulsion system. Subsequently, the integration of a heat exchanger on a commercial aircraft is examined for which the exergy point of view provides guidelines for an efficient design. The ability of the formulation to consistently assess all these types of subsystems is a clear benefit of this method.
http://arc.aiaa.org/doi/abs/10.2514/1.J053467?journalCode=aiaaj Aircraft have evolved into extremely complex systems that require adapted methodologies and tools for an efficient design process. A theoretical formulation based on exergy management is proposed for assessing the aeropropulsive performance of future aircraft configurations. It consists of the combination of a momentum balance and a fluid flow analysis involving the first and second laws of thermodynamics. The exergy supplied by the propulsion system and its partial destruction within the control volume is associated with the aircraft mechanical equilibrium. Characterization of the recoverable mechanical and thermal outflows is made along with the identification of the irreversible phenomena that destroy their work potential. Restriction of the formulation to unpowered configurations yields connections to some well-known far-field drag expressions and shows that their underlying theory can be related to exergy considerations. Because the exergy balance does not rely on the distinction of thrust and drag, it is especially suitable for the performance evaluation of highly integrated aeropropulsive concepts like boundary-layer ingestion.
2018 •
EXGY-01 Because of increased industrialization and energy demand, energy and exergy studies are becoming increasingly important in all materials that produce and use energy. Supply and demand unbalancing in energy production and consumption necessitates effective usage of energy. Exergy analyzes; has become one of the most important tips and solution partners that engineering practitioners have been mindful of in explaining the availability of energy. In aviation sector; jet engines components are playing a key role for energy production, transmit and distribution. In this critical mini review, exergy analyses of jet engines (gas turbines) used in the air vehicles are given comparatively. The studies that emphasize the importance of energy and exergy analysis and the more effective usage of energy in jet engines are compiled. In this mini but new review approach, the exergy of jet engines are added to the literature with reviewed version.
Paper available upon request! Authors: Aurélien Arntz and David Hue Aircraft have evolved into extremely complex systems that require adapted methodologies and tools for efficient design processes. A theoretical formulation based on exergy management has been recently proposed by Arntz et al. for assessing the aerothermopropulsive performance of future aircraft configurations. The present article focuses on the validation of its numerical implementation in a FORTRAN code for the postprocessing of Reynolds-averaged Navier–Stokes flow solutions. The flow around the wing-body NASA Common Research Model is assessed in terms of anergy destruction. A 2 MW work potential associated with the lift-induced vortices is identified in the wake of the airplane. Subsequently, a six-level grid convergence study enables determining the robustness and accuracy of the exergy postprocessing code. The introduction and calibration of a numerical correction allows to account for the spurious numerical vortex dissipation and to obtain an accuracy similar to the traditional near-field drag method. Finally, the postprocessing code is validated for drag prediction against computational fluid dynamics and experimental wind-tunnel data.
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