Transient Performance Analysis of an Aero Gas Turbine Cooled Cooling Air Heat Exchanger

Abstract

Aviation faces several challenges to maintain growth while adapting to an environmentally viable footprint. Increasing efficiency, which in the past induced a steady rise in the turbine entry temperatures, requires successful cooling of critical components to relieve the combined effects of higher temperatures and pressures. Starting with a conceptual design that alters the flow path of the secondary air system to divert bled air into a heat exchanger, this research focuses on assessing the effects of actual flight conditions on a cooled cooling air (CCA) system. In particular, the study undertakes a transient analysis of the CCA heat exchanger under a stressful temperature increase. The performance of the unit from idle to max take off (MTO) conditions required a unique facility for experimental testing, also capable of reaching and sustaining the necessary specifications. The novelty of the concept compelled the development of numerical models to aid the design and evaluation of the experiment. These models use one- and three-dimensional techniques to perform preemptive analysis of the test range, to ensure safety during the actual test, and to provide valuable information about the facility system and the inner flow structure of the heat exchanger. The study completed successful experiments using numerically generated procedures. A back-to-back configuration, representative of multiple installations, offers evidence about the cross-influence of each heat exchanger. The research also examined the dynamic effects to provide the bases for further studies focusing on this topic.