Aeroacoustic impact of heat exchanger installation in an industrial engine cooling module

Engine cooling fan noise becomes even more difficult to predict when considering the presence of the heat exchanger upstream. This paper investigates the impact of different heat exchanger installations on the noise sources of an industrial engine cooling fan using high-fidelity lattice-Boltzmann simulations. The heat exchanger is simulated using an equivalent porous medium upstream of the fan. Four configurations are analyzed at free discharge: full cooling module (i) without and (ii) with a gap between the heat exchanger and its casing, (iii) Fan+Frame, and (iv) Fan. For the sake of comparison, configurations (iii) and (iv) are simulated by imposing a pressure difference that matches the one across the heat exchanger, to ensure that the same operating point is maintained. Results show negligible differences in the overall aerodynamic performance since the same average pressure rise is achieved. The presence of the porous medium affects the spatial distribution of the pressure field upstream of the fan, thus causing a higher tonal content compared to the configurations (iii) and (iv). Further subharmonic humps are caused by the interaction of the blades with vortex structures generated by flow separation at the tip and the casing’s support structures. The presence of a geometry transition from square to round in the casing causes inflow distortions, increasing low-frequency broadband noise.