Tunnel Development for Heat Transfer Analysis in Compact Heat Exchangers

A high performance compact heat exchanger forms a critical component of the unique hybrid airbreathing and rocket engine cycle, known as SABRE, that is being developed in order to reduce the cost of access to space by enabling the realization of a fully reusable single stage to orbit spaceplane (Skylon). The performance enhancement of this heat exchanger (whose role it is to provide precooling of the airflow into the SABRE engine) via conventional methods i.e. compactness, wall thickness, flow arrangement etc has reached its practical limit. The substantial gains in payload offered, however, by further performance enhancement has lead to a research program (sponsored by Reaction Engines, leaders of the SABRE/Skylon project) to investigate alternative methods for increasing the heat transfer capability of the SABRE’s compact precooler matrix. This has driven the development of an ultra low speed (0-1.5 m/s) wind tunnel with the capability to evaluate with confidence the performance gains of such methods. As demonstrated in this paper, the operating tunnel provides high quality, uniform flow over the required Reynolds number range. This facility has already been used to verify the current precooler design.