Abstract
In the current design of turbomachines, engine performance is improved by reducing the clearances between the rotating components and the stator, which allows for loss decrease. Due to these clearance reductions, contact events may occur between the rotor and the stator. An abradable coating is deposited along the stator circumference as a sacrificial material to lower the contact severity. However, experiments highlighted the occurrence of rotor/stator interactions with high wear depth on the abradable coating as well as high temperature increases within the abradable coating following contacts. This work focuses on the sensitivity analysis of rotor/stator interactions with respect to the rotor angular speed and the initial clearances between the rotor and the stator, taking into account thermal effects within the abradable coating. Convergence analyses are first conducted to validate the numerical model. Then, after a calibration of the thermal model of the abradable coating based on two experimental test cases, the numerical model is used to investigate the cross effects of the angular speed and the initial clearances on the obtained rotor/stator interactions.
Highlights
To respect increasingly stringent environmental constraints and to lower operating costs, turbomachine manufacturers are focusing on the improvement of engine performance to decrease fuel consumption [1]
In order to reduce the severity of such contact events, an abradable coating is often deposited along the casing contact surface as a sacrificial material [4,5,6]
Previous work of the authors [10] proposed a numerical strategy to model temperature evolution within the abradable coating following contact events and wear. This numerical model is improved focusing on two aspects: (1) the definition of the blade heat flux is refined, the latter is proportional to the friction forces—i.e., proportional to the contact forces—between the blade and the abradable layer, and (2) a dependence of the mechanical properties of the abradable coating on the temperature is included
Summary
To respect increasingly stringent environmental constraints and to lower operating costs, turbomachine manufacturers are focusing on the improvement of engine performance to decrease fuel consumption [1]. A common solution to lower aerodynamic loss and increase overall performance of an engine consists of the reduction of nominal clearances between rotating bladed disks (rotor) and the surrounding casings (stator). The fact that the numerical model—calibrated on the first experiments only— allows similar temperature increases in the second configuration validates the order of magnitude of the predicted heat flux, and of the predicted contact forces. Based on this conclusion, a detailed sensitivity analysis of the dynamical responses of the system with the clearance between the tip of the blade and the casing is conducted. An in-depth analysis of the effect of the initial clearance and of the angular speed on the observed rotor/stator interaction is carried out
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