Numerical Models for Prediction of Energy Performance and Noise Emissions of Building Roof Fan

Centrifugal roof fans can be categorized as low-power fans. Nevertheless, they make approximately 30% of fans used in nonresidential ventilation. On a mass scale this makes them large energy consumers. In this chapter, enhanced CFD models for the prediction of fan energy performance and noise emissions are evaluated. First, the RANS-based models with the frozen rotor approach and k−e/k−ω turbulence models were reviewed. Secondly, more advanced models of frozen rotor RANS, URANS, and LES models are investigated. The CFD predictions are compared to experimental data from a previous study. The results show that improved prediction of energy efficiency is obtained with LES-based CFD models for the off-design flow regimes. RANS and URANS models can also provide satisfactory results. A good fan noise emission prediction can be obtained using LES data. This allows for the investigation of wide-spectra noise in comparison with RANS-based models.