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DEVELOPMENT OF EXPERIMENTAL CAPABILITIES FOR THE AEROTHERMAL CHARACTERIZATION OF SURFACE AIR-COOLED HEAT EXCHANGERS
thesisposted on 23.06.2021, 16:55 by Antonio Castillo SaucaAntonio Castillo Sauca
To perform high spatial resolution measurements on the characterization of a Surface Air-Cooled heat exchanger a suitable empirical procedure and a novel wide range traverse system have been defined.
The characterization through transient measurements involves a proper-sized test article with an array of electric resistances. These provide an accurate and controlled adjustment of the heat provided to the fin array and a fast interruption of the power delivered. A series of numerical simulations were performed on this warm-up state to ensure a homogeneous temperature field throughout the model, and results indicate a mutual constraint from adjacent fins in their respective ability to dissipate heat. Additionally, a large number of pressure taps, with a time response of 0.28 seconds, were distributed throughout the study array to capture and validate the pressure regions provided by numerical simulations that correspond to flow expansions and growth of horseshoe vortices. The test section was also supplemented with accurate RTD sensors to validate the simulated temperature fields, as well as other optical techniques to capture aerodynamic and thermal effects during the test campaigns.
To supplement the high-spatial-resolution measurements, a novel traverse system has been designed. This one combines the independent motions of a rotating disk and the translation of the plate containing such disk to locate a probe all over an unprecedented wide area in an uninterrupted way. A proper sealing was achieved through standard O-ring seals and the introduction of two custom chambers at the test section sides. The action of these seals led to the proper power selection for this mechanism. Finally, a series of Finite Element Analyses assessed the structural integrity of the proposed traversing system and defined its pressure performance map from vacuum to 6 [bar] in the test section.