TOPFLOW - Transient Two Phase FlowTest Facility

Multipurpose Thermalhydraulic Test Facility

Experimental setup for investigating fluid dynamics during high-pressure contact condensation in the pressure vessel of the TOPFLOW facility.

The multi-purpose thermohydraulic test facility TOPFLOW was constructed between 2001 and 2002 by the Institute of Fluid Dynamics at the Helmholtz-Zentrum Dresden-Rossendorf to investigate steady-state and transient two-phase flows under operational conditions relevant to real-world applications. Since 2003, adiabatic and non-adiabatic experiments have been planned and carried out in close collaboration with the national Computational Fluid Dynamics (CFD) network. The data from these experiments are used for development and validation of thermohydraulic computational codes (thermofluid dynamics of multiphase flows).

Beside these generic activities the facility is applied for various nuclear and procedural projects with industrial founding, e.g. Pressurized Thermal Shock experiments in cooperation with an international consortium as well as for steam condensation tests in a slightly inclined tube.

So TOPFLOW allows flow investigation as in vertical test sections as in horizontal geometries. The facility combines 3 test rigs, a steam generator module and the necessary auxiliary systems.

Scheme with the basic circuitries and technical systems of TOPFLOW

The scheme above shows the basic circuitries and technical systems of the facility. It includes first of all:

• a pressure tank, that allows flow investigation in test sections with thin walls and glass windows for optical observation up to 5 MPa with pressure equilibrium to the tank atmosphere;
• a test section loop, included almost 8 m long vertical pipes with different nominal diameters, on which a X-ray tomograph or wire-mesh sensors were employed for flow pattern detection;
• a tomography laboratory, that currently is used for the investigation of steam condensation phenomena in a slightly inclined tube.

This equipment is completed by an electrical steam generator with a maximal power of 4 MW. It supplies up to 1.4 kg/s saturated steam in a pressure range from 1 to 7 MPa and the required saturated water mass flows. Furthermore a compressed air controlling system delivers dry and filtered air in a wide norm volume flow range from 0.005 to 900 m³/h for gas injection during adiabatic air/water tests. The entire facility is filled with deionized water. So the measured data can be directly used for the validation of thermal hydraulic codes. After the tests the residual steam and water mass flows are injected into the blow-off tank, where the steam is condensed. Thereby the water in the blow-off tank is cooled by dry cooling towers, which release the energy to the environment.