Unsteady flow and fluid-structure interaction in steam turbine control valves

A common method of controlling the power output of steam turbines is the application of a single or a combination of multiple control valves. The control valve separates the steam turbine from the main steam supply and adjusts the pressure drop across the turbine and therefore the mechanical power output.

Due to a shift of the operating points towards increased part load times associated problems come to the fore. The large pressure gradients across the valves at part load lead to unsteady and highly complex flow phenomena. Depending on the operational point and the valve geometry fluid-structure interactions as well as mechanical and acoustic resonances occur and at worst lead to material failure and a forced outage of the turbine.

Using a scaled valve model equipped with an elastic valve support the unsteady flow as well as the fluid-structure interaction will be investigated. The goal of the research project is to improve the understanding of the underlying effects and ensure a safer operation in the future. Along with the experimental setup CFD simulations will be used to extend the experimental results and allow a deep insight into the local flow phenomena. With the experimental validation of the numeric setup, the suitability of different turbulence models as well as coupling methods will be evaluated.