I have a turbolent flow with standard air, in Solution Control>Equation Behaviour>Primary variables Equation Status can I swhitch Viscosity in the fluid properties? If I don't swhitch it I have a solution, oterwise it's totally different. I defined constant viscosity , then where is the difference?

If it's turbulent flow, then if you choose Thermophysics Models>Turbulence Models> select ON (choose a model) for example K-E/High Reynolds Number, then in your selected panel, the viscosity should be on automatically. If you switch off viscosity, you are running laminar flow.

All this happens because viscosity consists of two parts - molecular viscosity, wich is set constant in your case and so called "turbulent viscosity" wich is calculated from turbulence parameters (k and epsilon). Turning on viscosity in primary variables tells the code to calculate and account for turbulent viscosity.

Thanks. I solved this problem reading the Userguide, Commands and Methodology Manuals.