Developments in turbomachinery internal air systems

Abstract

Development of turbomachinery technology, including aircraft propulsion, has been an outstanding achievement of the last 50 years and, as illustrated by Ruffles in his paper ‘The future of aircraft propulsion’ (2000), further advances are expected in the future. Here, one particular aspect of turbomachinery technology, the internal air system is considered. An article by Dixon et al., published by the Institution of Mechanical Engineers in 2004, shows how computational modelling has become central to the design process and the importance of the internal air system in engine design. Bayley and Conway's 1964 paper, motivated by shortcomings in industrial design methods and understanding, was one of the first investigations of flow and heat transfer in rotating disc cavities typical of internal air systems. During the study, a theoretical or numerical treatment was considered intractable and so experiments were undertaken. These paved the way for an extensive research in this area. Today, the use of computational fluid dynamics (CFD) in industry for internal air flow prediction is commonplace. In this review, it is shown that the unshrouded disc cavity flow considered by Bayley and Conway is still challenging for modern CFD methods, and so the experimental data remain of interest to researchers in the field.