Numerical investigation of 3-D flow phenomena in interblade channel with tie-boss

Authors

Tomáš Radnic - Institute of Thermomechanics of the CAS, v. v. i.
Jindřich Hála - Institute of Thermomechanics of the CAS, v. v. i.
Martin Luxa - Institute of Thermomechanics of the CAS, v. v. i.
Šimurda David - Institute of Thermomechanics of the CAS, v. v. i.

Abstract

The paper is concerned with numerical investigation of 3-D flow field in a last stage rotor blading in a steam turbine of large power output. The mid-span section of 1220 mm long blade is equipped with a stabilization device called tie-boss, two variants of which have been investigated. The tie-boss presents considerable disruption to the flow field and is a reason of loss of efficiency and origin of vortices. The investigation has been conducted in Ansys CFX. Detailed investigation determined origins of vorticial structures and identified separations, which have non-negligible effect on the aerodynamic parameters of the blade cascade. The research allows comparison of the quality of the flow field of both tie-boss variants. The results show that the tie-boss with round trailing edge causes lower loss coefficient increase and higher exit flow angle change than the variant with tailored trailing edge.