Engineers at the Zhukovsky National Research Center have developed a small-sized gas turbine engine with an adaptive starter-generator cooling system that automatically regulates the thermal regime without the use of electronics. The development is registered in the FIPS database.
The design is based on a redesigned starter-generator layout with a "cup-shaped" rotor and a concentric stator located in the central fairing. This solution allowed for a reduction in axial dimensions and a change in the structure of cooling air flows.
Compressed air from the compressor is pre-cooled to a temperature below 100 °C and enters the central cavity through radial body struts.
Further, the flow is divided into two circuits. The first cools the front part of the stator windings through an axial gap with a labyrinth seal. The second is directed to the rear zone, where it passes through annular and radial channels, providing cooling for the magnets and the rotor's magnetic core.
The key feature of the development is self-regulating cooling. When the engine speed changes, the pressure drops and gap geometry automatically change, which redistributes the air flow without external control systems.
This reduces the risk of local overheating and evens out the temperature field along the entire length of the assembly.