Analytical determination of duct fitting loss-coefficients

Loss-coefficient data for 9 ductwork fittings were generated utilizing a commercially-available Computational Fluid Dynamics (CFD) code. A total of 159 unique coefficients were generated for the various flow and geometry conditions. The computer code was used to produce pressure field data necessary to compute the loss coefficients, as well as to produce flow field and static pressure plots that offer insight into the physics of the flow field. The agreements between the published experimental and representative computational results were generally within the ±15% error bounds, with 2 notable exceptions. The exceptions were for the round die-stamped smooth radius and the round 5-gore radius elbows, where the loss coefficients obtained computationally were insensitive to diameter change with r/D constant at 1.5. The reason for the differences between the computational and published results are thought to be due to absolute roughness differences. The agreement in the other cases has led to the conclusion that computational techniques could be accurately utilized to verify and expand duct fitting databases.