Numerical simulation of two-phase Helium II stratified flow in cryogenic units of TESLA

Numerical simulation has been carried out for two-phase Helium II stratified flow in 12 horizontal or declining cryogenic units each with a length of about 2.5 Km for the proposed 500 GeV TESLA (TeV Superconducting Linear Accelerator). The simulation predicts the He II level, the vapor mass flow rate in the two-phase tube, and the pressure profile through the gas return pipe of all units as well. Based on the numerical results the flow pattern and the stability of He II/vapor two-phase flow are discussed.