CFD simulation of leak in residential HVAC ducts

A three-dimensional computational fluid dynamics model was used to simulate fluid flow in a duct and its simulated leaks with six different air leak geometries placed respectively on its periphery. The k–ɛ turbulence model for high Reynolds numbers flows was used for that purpose and the Reynolds numbers were varied to simulate a variety of flow conditions between 27,000 and 82,000. The computer code was used to produce pressure drop data and leak flow rates across the holes necessary to compute the pressure loss coefficients, as well as to produce flow field and static pressure plots that offer insight into the physics of the flow field. The flow coefficient and pressure exponent (C and n) were found for different leak geometries by curve fitting the pressure and leak flow data derived from CFD simulations and were compared to available data in the literature.

► A CFD model simulates air leaks in duct systems well for simulated leak geometries.
► The CFD results compare well to the power law model.
► New k-factor results were obtained as a function of Re and aspect ratio.
► This new information can provide a basis for improving duct leakage calculations.