Conference Year



ductwork, CFD, pressure fluctuations, openFoam


The design of vertical ducting systems is a critical component of indoor climate control with the necessity of striking a balance between the dimensions of the duct and optimal ventilation. ASHRAE RP-1743 specifially adresses the length and geometry of inlet ductwork for equipment performance tests, and this paper is part of that project. In this study, we assess the effect of vertical clearance for a rectangular duct utilized for a uniform flow rate suction of ambient air. Our goal is ascertain the effect of reducing clearances and their effect on flow velocity profiles within the duct. Our computational framework is given by an unsteady Reynolds-averaged Navier-Stokes (RANS) simulation to simulate a medium intensity turbulence framework. Through this framework, we observe the formation of a stagnation point at the floor of our simulated room which is perturbed increasingly with reducing heights eventually leading to limit-cycle instabilities being triggered in the flow through the duct. Our conclusions indicate that the clearance plays an important role in optimizing steady flow patterns through the duct.