Design and development of a full-scale generic transient heat transfer facility (THTF) for air system validation

This paper describes the design and development of a major new facility capable of reproducing flow conditions for large civil aero engine turbine and compressor segment cavities. The facility reproduces in 3-D, typical secondary air system cruise temperatures, pressures and mass flows. The facility allows better understanding of the circumferential heat transfer effects of air system flows on turbine and compressor casings, as these have a significant influence on both steady-state and transient blade tip clearance behavior. Different air system architectural solutions are considered and 1-D transient air system modelling is used to design architecture to ensure that they meet tight performance requirements in terms of allowable pressure and temperature ripples when subject to fast switching of flows. An explanation of the design of the double-skin pressure vessel using 2-D axisymmetric thermo-mechanical analysis to understand the life-limiting features of the design is discussed. Finally we conclude the paper with some experimental results from rig commissioning and the use of these results in the determination of engine casing transients is discussed