In this paper performance characteristics for a Ranque-Hilsch vortex tube are presented. The was of divergent design and optimised both size performance, to be used supply cold air turbomachinery experiments with feed in the pressure range 3.0–7.0 bar, overall mass flow rates 0.05–0.14 kg/s. Optimum fixed parameters selected from literature were: ratio cold-exit diameter inlet internal (0.50); ...