Abstract: Turbo-electric hybrid propulsion systems for low-altitude aircraft integrate multiple heat sources, thermal zones, and heat sinks, which makes thermal management highly complex. This paper reviews recent advances and key technologies in integrated thermal management for such systems. Typical system configurations and system-level heat-flow characteristics are first introduced. The heat-generation mechanisms, heat-source distributions, and temperature constraints of key components, including gas turbines, generators, propulsion motors, power electronic devices, and propulsion batteries, are then analyzed. Variations in thermal load across typical mission phases, such as ground start-up, take-off, hover, climb, cruise, descent, and landing, are summarized. On this basis, conventional thermal management technologies, including air cooling, liquid cooling, phase-change materials and heat pipes, direct oil cooling, and the use of fuel and lubricating oil as heat sinks, are systematically compared in terms of heat-dissipation capability, engineering penalties, and applicable operating conditions. Representative system-level thermal management schemes are further compared quantitatively in terms of system mass, heat-dissipation capacity per unit mass, and power penalty. The analysis indicates that air cooling is well suited to baseline cooling and final heat rejection, whereas liquid cooling offers high-capacity, continuous heat rejection and temperature regulation. Phase-change materials and heat pipes mainly serve to buffer transient peak thermal loads and localized hot spots. Direct oil cooling enhances near-source heat removal from motors, generators, bearings, and other components, while fuel and lubricating oil used as heat sinks can reduce external heat-rejection requirements, cooling power consumption, and aerodynamic penalties. Thermal management of turbo-electric hybrid propulsion systems should therefore not rely on a single cooling approach. Future work should cover the entire mission profile and focus on system-level cooling-loop architecture design, dynamic thermal-load modeling, localized near-source cooling enhancement, coordinated utilization of onboard heat sinks, and integrated control of thermal and energy management. These developments will support the design of lightweight, highly reliable, and adaptable thermal management systems for low-altitude aircraft.

Key words: Keywords: low-altitude aircraft, turbo-electric hybrid propulsion system, thermal management, mission profile, hybrid cooling, onboard heat sink