Pressure drop mechanisms in a cooling system enclosure

Abstract

A potential way to reduce the noise generated by construction machinery cooling systems is to satisfy the flow rate required for cooling at lower fan speeds, and a promising approach to achieving this goal involves finding ways to reduce the pressure drop that occurs in the cooling system ventilation passages. Towards that end, approaches using computational fluid dynamics (CFD) have proven effective for estimating three-dimensional (3D) spatial pressure drops, but there have been few reports on actual loss mechanisms. In this study, the mechanisms of pressure drops that occur inside a cooling system enclosure and around exhaust port vents were investigated by capturing the flow discharged by the axial fan within the enclosure into the atmosphere via the exhaust port. We found that portions of the fan outlet flow divert significantly inside the enclosure and are exhausted at exhaust port outlets located some distance away from the fan. We also found that the pressure drops in such locations are larger than experienced by flow discharged via the shortest path. Since flows within the enclosure collide with each other and become unsettled around the exhaust port, turbulent kinetic energy increases, thus intensifying the pressure drop. Hence, by expelling the flow at the exhaust port via the shortest path without allowing it to mix chaotically inside the enclosure, the flow rate can be increased using the same fan speed.