持环、转子、Ni-石墨涂层的全尺寸耦合冲蚀 ① 机制数值研究

In the context of gas turbine technology, the erosion behavior of nickel-graphite sealing coatings on holding rings under service conditions presents significant challenges for experimental measurements. The unique operational environment of gas turbines, characterized by high temperatures, speeds, and pressures, complicates the experimental observation processes, making them time-consuming and labor-intensive. Therefore, computational simulation methods are employed to effectively analyze various operational parameters during service. This study investigates the thermal and mechanical behavior of the nickel-graphite coating system. Full-scale coupled numerical heat transfer calculations are performed, focusing on the entire holding ring, blades, rotor, and coating structure. This study aims to establish a detailed understanding of the thermal stresses and erosion rates associated with different thickness ratios of the coating layers, which involves developing a full-scale thermomechanical coupling model and a complete simulation model for the compressor-holding ring, rotor, and blades. These models are designed to accurately represent complex interactions between components under operational conditions. The numerical simulations are performed using advanced computational techniques, enabling analysis of thermal stress distributions and erosion rates across the coating layers. The results indicate that when the thickness ratio of the nickel-coated graphite surface layer to the NiAl substrate layer was set at 1∶1, the minimum thermal stress was 0.7 MPa, whereas the maximum was 72.96 MPa. Furthermore, when the thickness ratio was adjusted to 2.73∶0.27, with a surface-layer thickness of 2.73 mm, the maximum thermal stress on the coated surface increased to 74.51 MPa. These findings highlight the critical influence of coating thickness on thermal stress distribution, which is essential for understanding the durability and performance of the coatings under high-stress conditions. Additionally, the relationship between the rotational speed of the blades and the erosion rate of the sealing coating was explored. It was found that the erosion rate was negatively correlated with blade rotational speed. Specifically, at a blade rotational speed of 350 m / s, the maximum erosion rate of the sealing coating was calculated to be 2.863 × 10⁻⁵ kg / (s·m²). In this study, from a numerical simulation perspective, the influence of the surface-to-base layer ratio in the seal coating system on the seal coating performance, and the effect of linear velocity on the nickel-graphite coating on the inner wall of a gas turbine casing, were investigated.