Abstract
The variable cycle engine (VCE) is of interest for military and supersonic civil platforms due to its improved operational flexibility. However, the increase in design and control degrees-of-freedom results in a more complex engine architecture. Numerous different VCE concepts have been proposed and studied in literature. This paper provides an overview of VCE concepts and technology. A historical outline of important activities, investigated concepts, and technical advancements is given, and the main objectives and use cases of the technology are described. In addition, specific challenges and technical solutions for variable compressors and turbines are discussed in detail. Important VCE concepts are qualitatively evaluated, and their advantages and disadvantages are highlighted.