FFG - TURANDOT - Turbulence and Optical Measurements for Duct Surface Optimization in Turbofans

pressure to increase efficiency of aircraft forces engine manufacturers to further optimise their engines. One important key component of future aero engines is the intermediate turbine duct between the High Pressure Turbine (HPT) and the Low Pressure Turbine (LPT). Recent developments aim at an integrated intermediate turbine duct solution, the so-called Turbine Vane Frame (TVF) where the function of the following turbine vanes is integrated into the struts of the Turbine Centre Frame (TCF) in order to save length, parts count and thus weight. There are several aerodynamic challenges in designing an efficient and robust TVF. One is the amplification of the flow distortion downstream of the HPT (wakes, swirl angle nonuniformities, secondary flows, and tip leakages) due to flow turning in the TVF duct. Another challenge is the susceptibility of turning vane surface flow to separate if high levels of flow turning are required in the TVF duct, reducing the TVF aerodynamic performance and LPT efficiency. Also, the interaction of a potentially highly non-uniform TVF exit flow with the downstream LPT module must be managed since it may jeopardize LPT performance. The TURANDOT project aims to achieve the following technical objectives: 1. Gain new insight into the intermediate turbine duct flow physics, in particular into the complex three-dimensional flow between two turning vanes to identify further design approaches for performance improvements, 2. Characterize the evolution of turbulence through the duct, determine the importance of unsteadiness in the generation of pressure losses, and use the test results as data-base for the validation and improvement of turbulence modelling tools, and 3. Quantify the potential of drag-reducing surface modifications to improve the aerodynamic performance of an advanced turbine intermediate duct. To reach these project goals an intensive test campaign is planned in a high-speed test turbine rig under engine relevant flow conditions. Optical access into the test setup will be provided to obtain new insight into the flow details of the turbine intermediate duct by means of non-intrusive laser-measurement techniques. Additionally, detailed turbulence measurements are planned to quantify the evolution of turbulence in the HPT exit flow, through the TVF duct and the first LPT rotor. Finally, the same setup with applied surface modifications will be tested and compared to the baseline configuration. All activities proposed in the project (optical access, turbulence measurements, and surface modifications) will be supported by state-of-the-art CFD simulations. Further, these results will increase the knowledge gained in prior projects.