Abstract
Abstract This paper presents experimental and numerical CFD studies of the aerodynamics of a turbine rear structure (TRS). The TRS test geometry is an engine-realistic state-of-the-art design with a polygonal outer case, recessed engine mount bumps, and three different vane types: regular vanes, bump vanes in bump sectors, and thick vanes. Using three different sector types simultaneously was found to be crucial for the inlet boundary conditions. Experiments were performed in a modern rotating test facility with a low-pressure turbine (LPT) stage upstream of the TRS. A Reynolds number of 350,000 was used, representative of a TRS in a narrow-body geared turbofan engine. The TRS performance was analyzed both at on- and off-design conditions, and a thorough side-by-side comparison of CFD and experiments was performed. Static-pressure distributions, turning and outlet flow-angles, wakes and losses, and surface-flow visualizations and outlet total pressure contours are presented. The thick vane showed good aerodynamic performance, similar to the regular vane. For the bump vane, the mount bumps were found to generate additional local separations and secondary flows, resulting in extra losses. In the regions with strong secondary flows, CFD over-predicts the wakes, whereas the wakes around midspan, where secondary flows have a smaller influence, are predicted well.
Highlights
In a turbofan engine the rear engine mounts are located in the turbine rear structure (TRS)
The results are used to analyze the flow in the TRS and to validate the CFD simulations
The performance of CFD is evaluated for prediction capabilities of the TRS aerodynamic performance and secondary flows
Summary
In a turbofan engine the rear engine mounts are located in the turbine rear structure (TRS). To the authors’ knowledge the present work is the first publication of both experimental and numerical results for a state-of-the-art TRS with three different vane types and a 3D polygonal shroud with engine mount bumps. EXPERIMENTAL DETAILS In a real aero engine at cruise, the TRS has a Reynolds number, based on channel height and axial velocity, ranging from 105 to 6·105 This entire range can be covered in the test facility at Chalmers University of Technology.
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