Aerodynamic Effects of a Wing Surface Heat Exchanger

Abstract

One challenge for the design and analysis of hybrid electric aircraft configurations is an increased demand in the rejection of excess waste heat. A wing surface heat exchanger concept, which is explored as part of the IMOTHEP project, foresees transferring heat from the propulsive electrical components to the wing surface of the aircraft. Here, heat is mainly dissipated and transported by forced convection. The present study focuses on the analysis of the impact of heat rejection via the wing surface on the wing’s heat transfer and aerodynamic efficiency characteristics. For this purpose, RANS CFD studies of 2D airfoils and a 3D wing propeller geometry of a regional turboprop configuration in representative flight conditions (take off, cruise, and taxi in) are carried out. For each condition, the influence of defining parameters, such as altitude, freestream velocity, angle of attack, surface temperature, and propeller thrust is explored. It is shown that, when increasing the wing surface temperature compared against the freestream temperature, the aerodynamic efficiency of the wing deteriorates for all flight conditions. In reference cruise conditions for example, the lift-to-drag ratio decreases by 4%, while the average heat transfer coefficient is reduced by almost 20% when increasing the surface temperature by 300 K. Furthermore, the propeller slipstream enhances the wing’s heat transfer capacity significantly.

A Study on Thermal Management Systems for Hybrid–Electric Aircraft

“…These root mean square errors are considerable when comparing to the heat transfer coefficient value (100 W/m 2 K), as expected given the different experimental data used to build these semi-empirical expressions. To determine which of these expressions is more adequate for the aircraft here considered, a computational fluid dynamics (CFD) model would be necessary, as recently carried out by Habermann et al [42]. However, this is outside of the scope of this work as the aircraft is still being studied at its conceptual level.…”

Aerodynamic Drag Study of the Heat Exchange Equipment with Different Fin Geometries

“…Currently, many designs of compact heat exchange surfaces for heat exchangers of the "gas-liquid" system have been developed, which are characterized by a large ratio of heat exchange surface to volume [1]. In industry, convective surfaces from pipes are used with transverse spiral, tapered, round, corrugated, bispiral, wire fins [1][2][3][4][5]. The replacement of typical structures with smooth pipes on fins makes it possible to significantly increase the efficiency of heat exchange equipment and reduce material consumption.…”

Thermal modal analysis of hypersonic composite wing on transient aerodynamic heating

“…Sampaio 6 also used a one-way coupling approach to calculate the thermal flux distribution of a low aspect ratio wing at different altitudes. Anaïs 7 based on the CFD method, studied the impact of wing aerothermal effects on aerodynamic efficiency characteristics, revealing that as the wing surface temperature increases, the aerodynamic characteristics deteriorate under all flight conditions. Zhao 8 pointed out that tightly coupled and adaptive step methods can efficiently solve hypersonic aerothermal problems.…”