Ventilation considerations for an enhanced thermal risk prediction in aircraft conceptual design

Abstract

The capability to assess thermal aspects early in aircraft design is a crucial enabler for unconventional, more-electric, hybrid-electric, or all-electric aircraft configurations. This paper presents an extended version of a so-called thermal risk assessment approach for aircraft conceptual design. The assessment of thermal risk and the definition of a suitable cooling strategy during the conceptual design phase enables the anticipation of changes in the design process within a multidisciplinary design and optimization framework. In a previous paper, the authors propose applying dimensionless numbers to assess the thermal environment of a considered aircraft zone and predict the systems' thermal risk with a limited number of inputs. This research paper investigates the relations between the aircraft systems' locations within an equipment bay and the characteristics of the ventilation sources. The concept of mainstream flow is introduced, and new dimensionless numbers are established. The streamwise and the cross-stream numbers help to assess the closeness of a system to a ventilation source, while the heat removal potential assesses the cooling effectiveness due to the closest ventilation source for a particular system in an equipment bay. Two aircraft equipment bays with different configurations demonstrate the effectiveness of the thermal risk assessment methodology. The results are validated using computational fluid dynamic simulations. The enhanced thermal risk assessment approach will enable a more accurate definition of thermal requirements for aircraft systems within the aircraft conceptual design phase and reduce potential thermal issues later in the design process.