During the development process as well as the entire lifecycle of aircraft engines extensive testing is required for validation / certification and for maintenance purposes. For this reason various engine test facilities are operated in industry and research institutes. Some of those are indoor test beds which could suffer several deficits concerning the test cell depression or the entrainment ratio. Both are mainly driven by the ejector pump effect that establishes at the detuner inlet of the facility. At the Institute of Jet Propulsion at the University of the German Federal Armed Forces an indoor test bed capable of thrust levels up to 50kN is operated for research as well as academical purposes. Therein engines of different types are operated sometimes even under off design conditions beyond the stability limits. Therefore the knowledge of the flow conditions, which are induced by the facility itself, is of particular importance and they have to be considered in detail. Among stability problems of the gas turbine related to those aerodynamic conditions the test cell depression is a major parameter as it is responsible for the loads onto the facilities statics. Basic research on the field of ejector pump effects in engine test facilities was therefore performed at the institute in the past. But measuring enough data in order to characterize the entire flow conditions inside the test bed or simulating a facility of this kind requires major time and cost efforts and is therefore typically limited to some specific sections. For this reason a scaled model has been build to investigate the basic effects establishing inside the test cell. A jet engine for model aircrafts is operated in the test bed to generate the primary air flow. The scaled model offers the possibility to apply a wider range of measurement techniques than it would be possible inside the large facility. Therefore a large amount of data can be provided for adequate CFD validation purposes. The paper will address the main geometrical parameters of this test bed which take affect on the ejector pump effect. With several changes of the test setup, e.g. variation of detuner location, an insight into the specific flow phenomena during engine testing can be achieved.    «

During the development process as well as the entire lifecycle of aircraft engines extensive testing is required for validation / certification and for maintenance purposes. For this reason various engine test facilities are operated in industry and research institutes. Some of those are indoor test beds which could suffer several deficits concerning the test cell depression or the entrainment ratio. Both are mainly driven by the ejector pump effect that establishes at the detuner...    »