Numerical study of emergency cold helium relief into tunnel using a simplified 3D model

•A simplified 3D numerical model for mixing 2 gases was introduced and implemented.•Proposed model was validated with experimental results of helium and air mixing flow.•Numerical study of the emergency cold helium relief into the 3D tunnel was performed.

Helium–air mixture formation and its propagation along tunnels is an important issue for the safe operation of cryogenic machines, including superconducting accelerators or free electron lasers. This paper proposes the use of a simplified 3D numerical model for the simulation of mixture parameters, such as temperature and helium content. This model has been validated through experimental results obtained in the laboratory, with a circular tunnel representing the LHC tunnel, scaled at 1:13. The exemplary analysis of helium flow to a rectangular tunnel is presented in this paper. The mixture flow patterns, as well as chosen parameters, are also presented and discussed.