Detailed Experimental Study of the Flow in a Turbine Rear Structure at Engine Realistic Flow Conditions

Abstract

A good aerodynamic design of the turbine rear structure (TRS) is crucial for improving efficiency and reducing emissions from aero-engines. This paper presents a detailed experimental evaluation of an engine realistic TRS which was studied in an engine-realistic rig at Chalmers University of Technology, Sweden. The TRS test section was equipped with three types of outlet guide vanes (OGVs) which are typical of modern state-of-the-art TRS: regular vanes, thickened vanes and vanes with an engine mount recess (a shroud bump). Each of the three vane geometries were studied under on-design and off-design conditions at a fixed flow Reynolds number of 235,000. The study shows that the off-design performance of the TRS strongly depends on the presence of the local flow separation on the OGV suction side near the hub, which is greatly affected by the vane pressure distribution and inlet conditions. Similarly, the OGVs with increased thickness and with a vane shroud bump are shown to affect the performance of the TRS by influencing the losses on the OGV suction side near the hub. Furthermore, the presence of the bump is shown to have noticeable upstream influence on the outlet flow from the low-pressure turbine and noticeable downstream influence on the outlet flow from the TRS.

Experimental and Numerical Flow Analysis of an Engine Realistic State-Of-The-Art Turbine Rear Structure

“…The thick vane has some visible upstream effect on total pressure near the hub wall and not influencing the inlet swirl. For all cases the radial gradient of the total pressure is decreasing with increased flow coefficient as shown earlier [13,14]. The inlet profiles illustrate as well that the flow near the shroud is affected by the leakage via the turbine seal and by the presence of the upstream P-flange pocket, shown in Figure 2.…”

“…For the increased vane loading (Fig. 8), the reverse flow region with accumulated particles near the leading edge is seen to grow and is shifted closer to the shroud, similarly to [13], while the diffusive hub corner region becomes larger and the separated zone in this region becomes larger. The CFD simulations capture the increase of the corner region and the increase of the reverse flow zone, however, in CFD the streamlines are more curved, and the reversal zone is larger.…”

“…Figures 7-10 present experimental and numerical flow visualizations on the thick and bump vanes at on-design and high loading off-design conditions. These results are shown on the suction side of OGVs since hub suction side corner is found to be the most sensitive to flow separations and plays a significant role in pressure losses [13,14]. The regular vane case is not shown for the reason that it is very similar to the thick vane case.…”

“…Deshpande et al [11] and Jonsson et al [12] also studied surface roughness and laminar-turbulent transition in this TRS. Vikhorev et al [13] continued to experimentally investigate both thick vanes and engine mount bumps in this circular TRS. In 2019 the TRS component was replaced with a more engine representative geometry, having a polygonal shroud, three types of vanes (regular, thick and bump) and recessed engine mount bumps.…”

Experimental and Numerical Study of Laminar-Turbulent Transition on a Low-Pressure Turbine Outlet Guide Vane

“…Note that streamlines are based on many trials with different mixtures to study different areas of interest. More details of the different load cases can be found in Vikhorev et al [18].…”