Experimental aero- and thermal investigation for a next generation engine exit module.

Other conference contribution, 2019

Beyond 2020, new efforts are required to improve the engine efficiency and fuel burn to meet the Advisory Council for Aeronautics Research in Europe (ACARE) goals for the year 2035 and 2050. The year 2050 targets aim for a 75% reduction in CO2 emissions, a 90% reduction in NOx emissions and a 65% reduction of the perceived noise relative to engine and aircraft performance of year 2000. It is commonly agreed that the geared turbofan engines have the potential to make a significant step towards the above targets. These engines will have a higher overall pressure ratio which will result in increased operating temperatures. They also have higher by-pass ratios, i.e., larger fan with relatively smaller engine cores, which has consequently a wider operating envelope for the LPT. For the turbine rear structures (TRS) this development implies that designs are needed that: can withstand higher temperatures and temperature variations, and furthermore, can operate under more severe LPT off-design conditions. GKN Aerospace in Trollhättan, with a dominating market position on the TRS for commercial aeroengines, is addressing these challenges in this program.

A unique facility for experimental testing of TRS at engine-realistic flow conditions is currently available at Chalmers' Laboratory of Thermal and Fluids Science and will be used for testing of novel TRS designs for future more efficient aero-engines. The unique design of the facility includes an open test section which permits investigation of the complete TRS assemblies consisting of a TRS and a core exhaust nozzle. The facility is equipped with a 1.5 stage shrouded low-pressure turbine (LPT) providing realistic inflow to the tested TRS.

The main objective at Chalmers is to gain an understanding of the flow mechanism affecting the performance of the LPT-OGV and to validate designs that take advantage of the acquired knowledge. One expected outcome of the project is the most comprehensive aerothermal validation database for TRS designs. For this new measurement methods have been developed and implemented. At the time of writing hotwire and PIV are used to investigate boundary layer development and IR thermography for steady-state heat transfer but further extensive testing is planned within the project. The most up to date results from the test campaign will accompany the already published scientific work in this presentation.