Effect of magnetic field on hydrodynamics of MRSTP media flow and material removal modelling of blade tenon

Abstract

In industries like aerospace and energy, where precision is critical, the demand for advanced polishing techniques is growing. Yet, achieving precise polishing in complex components like turbine blades is challenging, especially with irregular features like blade tenons. Ineffective finishing can cause vibration and impact turbine performance. Magnetorheological shear thickening polishing (MRSTP) arises as a promising approach to tackle this challenge. In MRSTP, a magnetic field is utilized to exert a gentle force normally on the surface, while the shear thickening effect amplifies the force tangentially, enhancing material removal efficiency. This research presents a new material removal rate (MRR) model, considering Archard's theory of adhesive wear and Rabinowicz's theory of wear particle, which accounts for sliding-induced wear mechanisms. This model integrates computational simulations and wears principles to predict MRR more accurately in polishing processes. It addresses critical gaps in previous approaches, particularly the inability to simulate sliding contact effects in abrasive polishing, offering improved insights into material removal behaviour for complex geometries of turbine blade tenon. To achieve this, a magnetic field generation device was designed and developed to create the requisite polishing environment. By integrating a magnetic field distribution into a computational fluid dynamics (CFD) module, the behaviour of polishing pressure will be scrutinized by exploring various polishing parameters through CFD simulations. This model will provide valuable insights into the underlying mechanisms governing material removal during the MRSTP process. Subsequently, a series of MRSTP experiments were conducted on Inconel 718-made turbine blades, with a specific focus on measuring and analysing surface topographies to align with the proposed mechanisms. MRSTP of the tenon yielded significant improvement in surface quality, with the tenon protrusions' surface roughness (Ra) decreasing from an initial 0.381 μm to 0.086 μm, marking a 77.4 % enhancement. Similarly, the tenon depressions' surface roughness (Ra) decreased from 0.393 μm to 0.132 μm, representing a 66.4 % improvement after MRSTP. Notably, the polishing process successfully eliminated all scratches from the workpiece surface within 90 min. The theoretical findings demonstrated strong agreement with experimental outcomes. The accuracy and validity of the simulated results and MRR model were confirmed, with an average error of 5.93 % between theoretical and experimental results.