Accurately model the wake of launched aircraft to provide a safer working environment.
The UK's future 'Queen Elizabeth Class' carrier is designed to launch and recover aircraft according to mission requirements. However, when a jet aircraft launches from the flight deck, it generates a large volume of high-velocity jet efflux which creates a hazardous working environment for onboard service personnel working on parked aircraft.
Without a safe flight deck, the carrier would not be able to launch enough aircraft to support the desired missions, rendering it unsuitable for its intended purpose. Frazer-Nash was therefore asked to suggest design and layout improvements to overcome this problem.
Understanding and managing the behaviour of this efflux is key to providing a safe working environment for the flight deck personnel. We therefore used Computational Fluid Dynamics (CFD) to model a full aircraft launch run along the flight deck, and predict the time-dependent growth of the efflux wake. We then simulated a number of potential design solutions, and compared the benefits and associated costs of each option.
Not only did this technology help us visualise the flow of the jet efflux during take-off, but it also enabled the design to evolve intelligently and with confidence. This study also made use of related experimental data which provided further confidence in the predictions.
This transient simulation technique allowed us to identify and quantify potential areas of danger and inform operational changes, together with a range of possible layouts to the flight deck to improve safety.
Transient and unsteady flow simulation represents a significant advance in modelling and has only been made possible because of increases in computational power. Real air and fluid flows are typically unsteady and this relatively new capability provides clarity where traditional experimental and steady-state CFD techniques can fall short.