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

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 was 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 a noticeable upstream influence on the outlet flow from the low-pressure turbine and a noticeable downstream influence on the outlet flow from the TRS.