A diverter damper is frequently employed to direct gas to different outlets or to allow gas to enter the system from different inlets. In a combined-cycle power plant, the diverter damper guides the exhaust gas from the gas turbine either into the waste heat recovery boiler or, when operating in open cycle mode, directly to the bypass stack. One of the most commonly used types of diverter dampers is the Flat type, which is numerically modeled based on a valuable reference paper entitled“ COMPUTATIONAL FLUID DYNAMICS SIMULATIONS OF FLOWS AND PRESSURE DISTRIBUTIONS IN A 96 MW COMBINED CYCLE DIVERTER DAMPER”.

Figure 1: Schematic of the damper system, showing the exhaust from the turbine, the damper and the exit paths to the boiler and atmosphere.

Simulation Process

All the necessary dimensions for building the geometry were obtained from the plant’s working drawings and some rough estimates from the actual plant (reference paper). Fluent Meshing software is employed to produce polyhedral elements, leading to 1533378 cells. 404 kg/s mass flow enters the damper system from the exhaust with 830K temperature.

Figure 2: Designed Damper system using Spaceclaim

Post-processing

Based on the CFD simulation results shown in the velocity and pressure contours, we can observe the fluid dynamics around the flat diverter damper. The velocity contour shows higher velocities (red/orange) in the lower right duct, indicating the main flow direction. A low-velocity region (blue) behind the diverter plate suggests flow separation and potential recirculation. The pressure contour reveals higher pressure (yellow/green) on the upstream face of the diverter and lower pressure (blue) downstream, consistent with flow obstruction and acceleration. The simulation calculated forces on the diverter of 4921.9746N in the Y direction and 3008.7593N in the Z direction, likely due to the pressure differential across the plate and the momentum change of the diverted flow. These forces are important for structural design considerations of the damper and its actuating mechanism.