Flow analysis and optimisation

of a trifurcation as a distribution pipeline for a high-pressure hydropower plant

For a new high-pressure hydropower plant with three Pelton turbines (2 x 8.4 MW, 1 x 5.4 MW), the distribution pipeline is to be designed as a trifurcation.

Flow analysis of a trifurcation: challenges in the design

However, the task of designing such pipe junctions, which at first glance appears simple, has often proved problematic in the past. The inevitable deceleration of flow at the junction of a triple branch is highly susceptible to separation, which can lead not only to flow losses but also to pulsations in the individual pipe strands.

CFD-based optimisation of trifurcation geometry to minimise hydraulic losses

On behalf of a turbine manufacturer, we recently carried out a flow analysis and optimisation of the corresponding distribution pipeline. Using the initial design as an example, the following figure shows the velocity distribution at different cross-sectional planes for full-load operation of all three turbines. The unfavourable flow situation identified at the trifurcation junction (see dark blue areas) is clearly evident.

Following several design adjustments, the flow situation was ultimately significantly improved, and a satisfactory result was achieved.