Research on performance and spatial improvement for precooled ducts: parametric analysis and novel layout of parallel precoolers

To meet requirements such as heat exchange capability and spatial compatibility, multiple sub-precoolers are integrated within a precooled engine. However, no effective solutions have been proposed to address the spatial issue of excessive axial dimensions in precoolers, and there is a notable absence of parametric study for parallel precoolers. In this study, the mechanisms underlying the performance degradation of a single precooler (baseline precooler) under non-uniform airflow conditions, as well as the performance advantages of parallel precoolers, were revealed. Meanwhile, a simplified simulation method was utilized to evaluate the performance of the precooled ducts based on the baseline precooler and the dual-parallel precoolers. The research demonstrated that, with rational central diameters design and coolant allocation of the sub-precoolers, parallel precoolers can almost entirely eliminate the adverse performance impacts caused by non-uniform airflow under the most ideal conditions. Furthermore, compared to the precooled duct based on the baseline precooler, the variable-diameter dual-parallel precoolers featuring a novel axially staggered layout achieves notable spatial contraction and total pressure benefits while maintaining comparable heat transfer performance. With a minor sacrifice of heat transfer power reduction below 0.39 %, it saves the axial space by 20 %–40 % and lowers the total pressure loss by 0.98 %–3.72 %.