Hydraulic turbomachinery of varying sizes is used for hydro power generation. A clean and renewable form of energy, the power output from these turbines can range from 100kW to 1GW. Given the wide use of these machines, it is important that they are designed to be as efficient and robust as possible.
Improving the design of modern turbomachinery requires highly accurate numerical simulations as they contain complex flow features that affect the performance of the machine. One such phenomena is the vortex rope that occurs at part-load conditions. This flow structure develops in the draft tube and causes large pressure pulsations, leading to structural vibrations and power swings.
In this webinar, we will introduce you to the Cadence® Omnis™ Open Pressure-Based Solver (Omnis Open-PBS) and present the advantages it provides for simulating hydro turbines. Omnis Open-PBS, an easy-to-use multiphysics solver that provides fast and accurate results, is fully integrated in the Omnis platform and now also includes the ability to perform unsteady simulations.
The GAMM Turbine is used as the test case and a steady simulation is performed to analyze the performance at design point. An unsteady simulation is performed at the part-load operating point. The local values of pressure are monitored by inserting probes in the domain and the vortex rope is characterized. The flow field is analyzed using Omnis Post-Pro to fully identify the vortex rope.
Iso-surface of static pressure showing the low-pressure vortex rope in the draft tube
Iso-surface of static pressure indicating the presence of a low-pressure vortex rope in the draft tube which is confirmed by plotting the vortex core lines.