Augmented heat transfer and dehumidification by in-blade diamond-like structure

Abstract

Steam turbines used in clean energy systems such as solar and nuclear power typically operate at lower inlet temperatures. This leads to high exit humidity and severe erosion of the last-stage blades, thus significantly compromising operational safety and economic efficiency. Advancements in manufacturing technologies, particularly metal 3D printing, enable the incorporation of intricate internal structures within turbine blades to mitigate erosion. We introduced a novel Diamond-Like Structure (DLS) within the hollow stator blade to augment heating dehumidification by reinforcing turbulence and heat transfer. We employed a coupled fluid-structure-thermal numerical simulation to evaluate its efficacy. Our findings reveal that the DLS blades significantly enhance the heating effect compared to a normal blade. Under 100 % rated mass flow operating condition, the DLS blade exhibited a 3.59 K increase in average blade surface temperature and a 9.8 % reduction in water film thickness compared to normal blade operating under identical 370 K heating steam conditions at 4 % flow rate. The effect of incorporating DLS within the blades is comparable to an increase of 27.36 K in the heating steam temperature or to the addition of 0.86 % of the main steam flow as heating steam. Flow visualization analysis indicates that the disruptive effect of the DLS significantly intensifies the heat transfer within the blades. Further investigations employing varied design parameters revealed that a denser DLS configuration resulted in an additional 3.34 K increase in blade surface temperature and a 13.16 % reduction in water film thickness relative to the original DLS blade. The innovative application of DLS in steam turbines demonstrates its potential for widespread use in thermal management across various blade types, including those used in wind turbines and gas turbine stators.