Validation of a numerical strategy to simulate the expansion around a plug nozzle

Rocket engines currently use traditional bell-shaped nozzles that have a fixed area ratio and can only operate at maximum efficiency at a given altitude. Plug nozzles have been proposed as an alternative solution to achieve higher performance over a larger altitude range. Unlike bell nozzles, the flow is free to expand along the plug, as it is no longer surrounded by solid boundaries. Therefore, plug nozzles can adapt to different altitudes by expanding the flow to ambient pressure, resulting in continuous altitude adaptation. Due to the high surface area that needs to be cooled, one of the main challenges of plug nozzle design is thermal management. However, the introduction of aerospike geometry, which is essentially a truncated plug nozzle, has helped mitigate this issue. Simulating an aerospike engine is challenging due to the interaction between the plume and the external flow, which is necessary to accurately predict thrust. In this work, a numerical strategy for predicting the performance of an aerospike engine, during a static fire, was developed and validated.