Numerical Simulation of Tip Clearance Flow in
a Radial Inflow Turbine for Microturbines
Deng Qinghua,Niu Jiufang,Feng Zhenping
(School of Energy and Power Engineering,Xi'an Jiaotong University,Xi'an 710049, China)
Abstract:Tip clearance flow in a radial inflow turbine rotor for the developed 100 kW
microturbine under the design condition and stage environment was investigated by
3-dimensional viscous numerical simulation with Spalart-Allmaras turbulence model,in which
the mixing plane approach was adopted to transfer the flow interaction information between
rotating and non¡Mrotating mesh blocks.The results indicate that with higher relative
casing motion velocity, secondary flow on rotor blade surface was one of flow impact
factors on rotor tip clearance apart from well-known pressure difference between the
pressure and suction sides and relative casing motion, which have been validated by
experimental investigation.Because of the existence of secondary flow on rotor blade
surface,the flow structure became more complex in rotor tip clearance. Moreover,larger
negative incidence angle at rotor inlet was the primary reason of stronger secondary flow
formed on the rotor blade surface.Thus the factor of incidence angle at rotor inlet should
not be neglected while investigating flow fields of rotor tip clearance in a radial inflow
turbine rotor.
Keywords:microturbine;radial inflow turbine;rotor;tip clearance; numerical simulation