Development of New Heat Exchanger Design

This study deals with a new heat exchanger design developed by DGA Essais propulseurs [inventor: A. Foata - patents 1–4] which should improve heat transfer compared with standard gas to liquid exchangers tube banks, present better compactness without weighing down the drop loss and ensure the behaviour under drastic operating conditions (1600°C and Mach 2). This new design is based on a bundle composed of nine pairs of spiral tubes which are one to one angular drifted. The predictions of the thermal performances are so fussy whatsoever by using experimental test rig or CFD computations. On one hand, the test rig doesn’t allow to fulfil the entire range of operating conditions. And yet the standard operating conditions can shade the influence of temperature gradients on the aero thermal behaviour of the spiral bundles. On the other hand, in order to obtain reliable numerical predictions of heat transfers, the spiral bundle meshing refinement is crucial to simulate accurately the flow structure and the temperature gradients close to the inner walls. Moreover, if the grooves are explicitly taken into account in the numerical model, the computational grids required will be too fine to guarantee realistic computational time. So firstly, experimental and numerical approaches are used jointly in order to show the new heat exchanger design is sustainable. Optimization of the heat exchanger will be performed in the next phase of this study.