TURBOMACHINERY
NABLA
STEAM
Steam turbine multiphase CFD,
on open-source libraries
WHAT IT IS
A solver for water vapour in steam turbines, built on open-source libraries
CHALLENGE
Commercial CFD licences for steam turbine work are expensive and slow, and the physics is genuinely hard
RESULT
Excellent correlation with cascade experimental data, particularly in predicting condensate formation
01
CHALLENGE
Simulating the change from liquid to steam means modelling thermodynamics, heat transfer and fluid dynamics together and getting all three right. Commercial codes can do it; the licence cost and the run time are what make the work rare rather than routine.
02
SOLUTION
NablaSTEAM is a customised version of OpenFOAM: an open-source solver, extended by us with the physics steam work needs, which simulates water vapour for steam turbines and other applications. The main features developed are:
01
the IAPWS-97 thermophysical model
02
a solver based on compressible, unsteady algorithms
03
a phase-change model
04
the equation for rotalphy
05
mixing-plane and frozen rotor models
03
RESULTS
The tool was validated against cascade experimental data and used to simulate the multiphase behaviour of steam turbines.
It correlates closely with experiment, and closest where such models usually fail: the prediction of condensate phase formation, and of the thermodynamic variables through a rotor-stator stage.