In the aeronautical field, CFD simulations, which were previously limited to the external aerodynamic aspects of the aircraft, are taking on an increasingly fundamental role during the development phases of complex systems, in order to have a data driven design optimization tool. The purpose of the thesis is the development of a solid approach to study the behavior of a high temperature PRSOV (Pressure Regulating and Shut Off Valve) part of the anti-ice system of an operating civil aircraft. An increase of efficiency in the anti-ice system reduces the engine air bleeding, ultimately lowering fuel consumption, toward a cleaner aviation. By implementing evolving conditions and dynamic geometries into a CFD simulation of the PRSOV it is possible to evaluate the behavior of significant variables which cannot be measured directly.