Surface roughness impact on secondary flow and losses in a turbine exhaust casing
Paper in proceedings, 2018

This paper experimentally addresses the impact of surface roughness on losses and secondary flow in a Turbine Rear Structure (TRS). Experiments were performed in the Chalmers LPTOGV facility, at an engine representative Reynolds number with a realistic shrouded rotating low-pressure turbine (LPT). Outlet Guide Vanes (OGV) were manufactured to achieve three different surface roughnesses tested at two Reynolds numbers, Re = 235000 and Re = 465000. The experiments were performed at on-design inlet swirl conditions. The inlet and outlet flow of the TRS were measured in 2D planes with a 5-hole probe and 7-hole probe accordingly. The static pressure distributions on the OGVs were measured and boundary layer studies were performed at the OGV midspan on the suction side with a time-resolved total pressure probe. Turbulence decay was measured within the TRS with a single hot-wire. The results showed a surprisingly significant increase in the losses for the high level of surface roughness (25-30 Ra) of the OGVs and Re = 465000. The increased losses were primary revealed as a result of the flow separation on the OGV suction side near the hub. The loss increase was seen but was less substantial for the intermediate roughness case (4-8 Ra). Experimental results presented in this work provide support for the further development of more advanced TRS and data for the validation of new CFD prediction methods for TRS.


Surface roughness




Turbulence intensity and losses


Isak Jonsson

Chalmers, Mechanics and Maritime Sciences, Fluid Dynamics

Valery Chernoray

Chalmers, Mechanics and Maritime Sciences, Fluid Dynamics

Borja Rojo

Chalmers, Mechanics and Maritime Sciences, Fluid Dynamics

Proceedings of the ASME Turbo Expo

Vol. 2B-2018 GT2018-75541

ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition, GT 2018
Oslo, Norway,

Subject Categories

Energy Engineering

Fluid Mechanics and Acoustics



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