Experimental and Numerical Investigation of Annular Casing Impingement Arrays for Faster Casing Response

The transient heat transfer facility (THTF) was developed to test full-scale high pressure compressor and turbine casing air systems using gas turbine engine representative secondary air system conditions. Transient casing response together with blade and disk responses governs achievable tip clearances in both compressors and turbines. This paper investigates the use of air impingement as a means to speed up the casing response. The thermal growth of the casing was characterized by surface temperature rise over a given period to assess achievable dynamic response. The experimental setup resembles a typical aircraft engine with features that can lead to circumferential temperature nonuniformities, as evident from the experimental results. The experimental data were compared against numerical predictions from a conjugate heat transfer (CHT) model. The studies show the significance of analyzing the full annulus, at engine representative conditions and the benefit of an impingement array to potentially speed up casing response for future engines.