Flow Pattern and Efficiency Changes of Squirrel Cage Fans due to Inlet Diffuser Diameter Changes - Using CFD Method and Experimental Validation

Inlet is one the basic elements of squirrel cage fans that has a significant effect on fan performance and efficiency. Recently using the CFD calculation methods with sufficient related tools for finding the flow pattern and related parameters, applying modifications and representing proper solutions, has being increased. In the present case study to study the effect of inlet diffuser diameter on the fan efficiency and flow pattern, using numerical simulations and experimental validations, three different inlet diffuser diameters are used as inlet instead of inlet nozzle. To simulate these cases some geometries with special additional element, proper mesh pattern and size and proper turbulence model was chosen.It is observed performance and efficiency curves of fans with respect to use of inlet nozzle are more flattened with higher magnitude. So fan operation around the best performance point is more stable without significant fluctuation of head pressure and efficiency.