Study of the Hydrodynamic Unsteady Flow Inside a Centrifugal Fan and Its Downstream Pipe Using Detached Eddy Simulation

Abstract

The detailed unsteady turbulent flow inside a centrifugal fan and its downstream pipe was studied using detached eddy simulation (DES) at three flowrates, namely, the best efficiency point (BEP), 0.75BEP, and 1.49BEP. Both the mean and fluctuating flow fields were analyzed on the basis of the root-mean-square value as the indication of fluctuating intensity. Results showed that the pressure fluctuation had the minimum value at BEP, but the velocity fluctuation increased with the flowrate. Most regions inside the centrifugal fan underwent large pressure fluctuation with the magnitude of about 10~20% of pref = 0.5 ρu22, where u2 is the blade velocity at the impeller outlet. The pressure fluctuation had a maximum value at the impeller side of the tongue tip rather than the stagnation point, and it decreased rapidly along the outlet pipe with magnitude about 1% of pref after distance of five pipe diameters. The spectra of hydrodynamic pressure showed conspicuous spikes at the blade passing frequency (BPF) in the volute but not in the downstream pipe. At the downstream pipe entrance, pressure fluctuation spectra agreed with experimental results, showing that hydrodynamic pressure fluctuations were dominant; however, the experimental data showed a much slower decreasing rate due to the acoustic fluctuations.

Investigation into Dynamic Pressure Pulsation Characteristics in a Centrifugal Pump with Staggered Impeller

“…Based on the same turbulence model, Wang et al [14] successfully captured the axial vortex in a centrifugal pump as a turbine with an S-Blade impeller. From the research by Cai et al [15], the DES method could accurately predict pressure pulsations Energies 2023, 16, 3848 2 of 14 in centrifugal fans and their downstream pipe, which agreed well with the experimental results. Considering that the DES method is more resource-intensive, Posa and Zhang et al [16,17] predicted the complex flow structure in the pump based on the LES calculation method.…”

Transient Numerical Simulation of a Large-Sized Cement-Mill Fan for Performance Prediction

“…Pritz B. et al [11] studied the unsteadiness of the flow through a centrifugal fan, two turbulence models namely scale adaptive simulation (SAS-SST) and shear stress transport (SST) have been considered and compared in the study. Delayed detached eddy simulation was employed to study the evolution of the unsteady flow structure in turbomachinery [12][13][14]. The impact of the unsteady internal flow field induced by the relative motion of the rotating blade with the volute on the aeroacoustics behavior of centrifugal fans was investigated using CFD [15,16].The influence of the pump geometry parameters, such as the blade outlet angle and the clearance between the impeller and its volute on the pump performance was investigated by means of numerical approach have been also conducted [17,18].…”

A Comparative Study on Numerical Flow Simulations of a Centrifugal Electronic Cooling Fan Using Four Different Turbulence Models

“…Several studies investigated centrifugal fans using Scale-Resolving Simulations (SRSs), often in combination with or even focusing on aerodynamic noise predictions. Liu et al [38], Lu et al [39] and Cai et al [40] investigated the same fan model with 12 forward-curved blades. In [38] Large Eddy Simulations (LESs) were performed on a relatively coarse mesh of 2.2 million cells for the fan's design point.…”

“…Based on these results, the authors optimized the thickness of the volute walls to reduce vibrations and validated the results using vibroacoustic simulations. In [40] a Detached Eddy Simulation (DES) study for this fan model including a downstream pipe was performed. The authors compared the mean flow field as well as the pressure and velocity fluctuations for three different operating points.…”