Compared with the concentric expander which always has very high rotating speed

the centrifugal turbine can achieve higher power output at a lower rotational speed. This article takes a new type of centrifugal expander with small flow rate and low rotating speed which is suitable for organic Rankine cycle(ORC) system as the research object

to study the aerodynamic characteristics. The new centrifugal expander applies R134a as the working fluid

its performance curve at 3 000 r/min is numerically investigated by the CFX software. The velocity distribution

surface pressure distribution

pressure loss coefficient and Mach cloud of internal flow field in the rotor blade are analyzed at the total pressure expansion ratio of 1.7. The results show that

the centrifugal expander can achieve the total pressure expansion ratio of 4.0 at 3 000 r/min while effectively reducing the bearing speed and loading. The choked flow phenomenon occurs in the stator blade flow channels because the blade type is not well designed. The performance of the centrifugal expander is deteriorated by the occurrence of the leakage flow of the rotor. The numerical results can be used to further optimize the centrifugal expander.