Preliminary thermal management system design for cycle-integrated parallel hybrid compressors

Cycle-integrated parallel hybrid (CIPH) aero engines are a promising technology for achieving significant reductions in emissions using electric power to operate power-consuming components, such as compressor rotor rows. Permanent magnet synchronous motors (PMSMs) are particularly suitable for this application due to their high specific power and efficiency. However, these motors are sensitive to high temperatures, which can lead to irreversible loss of magnetic remanence in the permanent magnets, resulting in permanent power loss. This presents a significant challenge when the motor is positioned near the gas path of the compressor, as is often the case in CIPH compressors. Effective dissipation of the heat generated within the stator of the electric motor is crucial for maintaining optimal motor performance, in addition to managing the thermal conditions of the rotor. This paper aims to develop a thermal management system for the rotor and stator of PMSMs in CIPH propulsion systems and to investigate how various design parameters affect its performance. The objective is accomplished by creating a thermal resistance model to estimate magnet temperatures in the rotor and designing a cooling flow across the surface of the rotor. The model is further improved with insulation and thermal barrier coatings to enhance thermal resistance. A cooling system model for the stator is also developed, and the impact of design parameters on cooling performance is analysed. The results indicate that air cooling can reduce magnet temperatures by over 70 K, while enhancements in thermal resistance can lower these temperatures by more than 100 K. The design of the stator cooling channels illustrates the need to balance cooling effectiveness with minimising pressure losses, highlighting the importance of optimising the cooling system for overall motor performance.