Analysis of Axial Thrust and Flow Characteristics in a Steam Turbine Regulating Stage Under Variable Conditions

A full-scale CFD model of a steam turbine, including the regulating and multiple pressure stages, was developed to quantify the axial thrust—a critical parameter for operational safety. The results under various loads reveal two key findings: (1) The blade root hub is the primary source of the total axial thrust, exhibiting a near-linear relationship with mass flow rate under partial loads—a crucial insight for precise thrust forecasting. (2) Significant circumferential pressure non-uniformity was identified as a primary characteristic of partial-load operation. Furthermore, an optimized mixing chamber geometry is proposed, which reduces regulating stage loss by 0.59% and 0.31% under Valve Wide Open (VWO) and Turbine Heat Acceptance (THA) conditions, respectively. This study provides a concrete strategy for enhancing turbine design and safety.