Staged impingement arrays for novel heat exchanger designs

Abstract

To expand options for lightweight and compact Heat Exchangers (HEX) in modern electric aviation, a novel HEX design inspired by gas turbine applications is introduced. The new design utilizes opposed and staged impingement arrays to achieve efficient heat transfer. Staging, where the spent air from one array feeds subsequent ones, critically enables the design of impingement heat exchangers (iHEX) for a broader range of operating points and provides multiple design solutions for specific applications, which is not feasible with conventional single-stage configurations.\\ To leverage this potential, accurate design tools are paramount. Therefore, this study numerically investigates the effect of staging on pressure loss and heat transfer using Computational Fluid Dynamics (CFD). A variety of staged impingement array topologies are simulated over a range of Jet Reynolds numbers from 1500 up to 10000 using the RANS k-Omega SST model in Ansys Fluent. The method is validated with experimental data for a single-stage impingement configuration and a Grid Convergence study. The results for Nusselt number and pressure loss of multistage impingement arrays are benchmarked against established correlations, evaluating their applicability to staged configurations. This data is crucial to evaluate the proposed correlations for Nusselt number and pressure loss of impingement arrays for the implementation in pre-design tools of staged impingement heat exchangers.