Introduction

Rotor support systems based on air bearings are the most common technical solution for distributed generation micro-gas turbines, although their life is limited by the number of start/stop cycles. We have designed an innovative support system that does not have this limit by using two different types of thrust bearings and spline couplings.

Technical features

Under nominal conditions, the turbine axial load is supported by an air bearing, which directly loads the machine frame. Differently, during transients, it is contrasted by an auxiliary bearing (e.g. rolling element or magnetic type) mounted on the shaft. Shaft-impeller couplings are spline pairs. A helical spline ensures that thrust distribution between the two axial bearings is optimal.

Possible Applications

• Application to micro-GT units for distributed generation;
• Retrofit of micro-GT units based on rolling element bearings;
• Use in turbochargers (ACMs) for pressurization of airplane cabins;
• Application to micro-GT systems of suitable dimensions (turbochargers, small turbojet engines).

Advantages

• The foil bearing no longer has any limit of start-stop cycles;
• Auxiliary bearings have higher reliability/performance;
• The machine can operate in optimal fluodynamic conditions;
• The spline pairs allow easy disassembly for overhaul and maintenance.