The Transient Heat Transfer Facility was developed to test fullscalehigh pressure compressor and turbine casing air systems usinggas turbine engine representative secondary air system conditions.Transient casing response together with blade and disc responsesgoverns achievable tip clearances in both compressors andturbines. This paper investigates the use of air impingement as ameans to speed up the casing response. The thermal growth ofthe casing was characterised by surface temperature rise over agiven period to assess achievable dynamic response. The experimentalset-up resembles a typical aircraft engine with features thatcan lead to circumferential temperature non-uniformities, as evidentfrom the experimental results. The experimental data was comparedagainst numerical predictions from a conjugate heat transfermodel. The studies show the significance of analysing the full annulus,at engine representative conditions and the benefit of an impingementarray to potentially speed up casing response for futureengines.
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