Making good things even better – under the European Clean Sky 2 research program, long-term partners MTU Aero Engines, German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt (DLR)), and GKN Aerospace Engine Systems, Sweden have joined forces to enhance an engine’s compression system and make it lighter. The new technologies could already go into the next generation of geared turbofan engines. At the DLR site in Cologne, the test campaign on the ICD rig has now officially kicked off.
ICD stands for Inter Compressor Duct and is the name of the transition channel be-tween the low- and high-pressure compressors. The goal is to precisely fine-tune the interaction of the low-pressure compressor, ICD and high-pressure compressor to identify and leverage new potential for even more fuel-thrifty engines. An important step in this direction is the systematic mapping of the flow conditions in short, steep transition channels (ICDs). To this aim, an entirely new wind-tunnel test rig was built at DLR Institute of Propulsion Technology in Cologne, MTU’s Center of Competence (CoC) for propulsion systems.
Representatives from the three partners – MTU, DLR, and GKN Aerospace Engine Systems –witnessed the official launch of the test operations. For MTU, being the lead party in the project, Dr. Gerhard Ebenhoch, Director Technology Management, stated: “This cooperation combines the partners’ respective strengths – GKN’s exper-tise in large static components, DLR’s experience in testing, and MTU’s expertise in compressors and systems – in an exemplary manner.”
For the DLR, Prof. Rolf Henke, Executive Board Member responsible for aeronautics research says: “As a national research center, DLR plays a key role in the progres-sive development of the entire air transport system. There have been great advances in propulsion in recent decades. Together with our partners MTU and GKN, we are very proud to introduce it a further large step with this ICD rig.” And for GKN Aero-space Engines Robert Lundberg adds: “To be able to validate our technologies at high TRL in a unique rig is really an opportunity for GKN. We have no chance to do this in Sweden, so it really shows the importance of European collaboration.”
For Clean Sky the Project Officer of the Engine-ITD Jean-Francois Brouckaert acknowledged: “This new test facility allows to perform important EU collaborative research on the next generation of engines. Congratulations to the MTU, DLR and GKN team for achieving this important milestone! It is an excellent example of com-plementarity between experimental and numerical work.”

Measurement technology at the highest level of detail
The ICD rig measures the channel flow in an unprecedented depth of detail: 500 pressure tapping points, probe measurements at three traversal levels, the use of laser technology and turbulence probes allow detailed insights in the flow mechanisms. Dr. Gerhard Kahl, Chief Engineer, Technology Demonstrators and Rigs at MTU is certain: “By conducting these tests, we’ll certainly gain a much better understanding of the flow conditions in the ICD, the aim being to come up with particularly compact designs to further reduce the length, and hence the weight, of the engines in the future.”
In a next step, three different ICD configurations will be tested over the course of next year. Based on the ICD rig test results obtained, a two-shaft test rig will be designed in 2019 and built one year later. From 2021 on, the low- and high-pressure compressors will be tested together as one entity.
Launched in 2014, the Clean Sky 2 technology program is part of the EU’s Horizon 2020 Framework Program for Research and Innovation and is slated to run through 2024. It is the successor to Clean Sky 1, the European Union’s largest-ever aero-nautics research program. The overall objective is to make aviation even cleaner and more efficient. MTU is one of 16 lead partners and is responsible for the ICD test rig that has now begun test operations, plus an engine demonstrator. Core partners are the DLR (Deutsches Zentrum für Luft- und Raumfahrt) and GKN Aerospace Engine Systems.