Multi-level Modeling Methodology for Aircraft Thermal Architecture Design 2018-01-1910
This paper proposes methodology to conduct thermal analysis in the conceptual phase of the aircraft development process. Traditionally, thermal analysis is conducted after the system architectures have already been defined. The aircraft system thermal environment evaluation may lead to late design changes that can have a significant impact on the development process. To reduce the risk of late design changes, thermal requirements need to be defined and validated in the conceptual design phase. Up until now, several modeling methodologies had been used to conduct thermal analysis during preliminary and detailed design stages, but a significant gap exists for the conceptual design stage. The development of a methodology to assess aircraft thermal architecture during this stage involves several challenges for the expected models:
• They should have the right level of fidelity for conceptual design;
• They should be automated and parametric to cover the desired design space;
• They should represent the proper interfaces with other disciplines (e.g. aerodynamic for flow demand).
This paper introduces a multi-level modeling strategy based on a bottom-up approach (from high to low detailed methods). The proposed novel bottom-up approach introduces three different fidelity levels of models, and their associated sub-levels, to allow the assessment of an aircraft thermal architecture during the conceptual design phase.
This new approach deals with the development of a simplified CFD analysis capability for Preliminary Multi-Disciplinary Optimization (PMDO) and Conceptual Multi-Disciplinary Optimization (CMDO) phases. It also proposes to use surrogate-modeling techniques based on high detailed methods, such as CFD (Computational Fluid Dynamics) analyses, to generate thermal models suitable for preliminary design. Moreover, this approach extends the use of the dimensionless numbers concept to the temperature stratification analysis of aircraft equipment bays for conceptual design phase. These models, with the right level of fidelity, can be used to assess the thermal environment of a specific aircraft zone, predict the temperature stratification level and enable a global aircraft thermal architecture design capability. The application of the proposed multi-level modeling strategy is shown on a simple case study.