Courtesy of Matsushita Electric Industrial Co., Ltd.

FLUENT/UNS predictions of flow distribution and pressure drop in an air heater are being used by Matsushita Electric Industrial Co. in Japan to cut the time and expense of the design process. Using the new sliding mesh model in FLUENT/UNS, Matsushita engineers have validated the use of CFD for their application and gained valuable design insight.

The flow through the air heater is driven by a tangential fan that draws cold air from the environment through a radiator region where the air is heated by two staggered arrays of heated tubes and separated by thin plates (see figure). The filtered and heated air then passes through the blade region and is discharged back to the environment. Key design objectives are to minimize the overall pressure drop and any potential recirculation zones.

Quantified Performance and Design Insight

The accuracy of the predictions was assessed, in part, by comparing the computed pressure drop to experimental data. The results showed good agreement between the computations and the data with respect to the overall slope of the pressure vs. flow rate performance curve and the absolute magnitudes of the pressure differences.

In addition to quantitative information on the fan curve, designers were able to identify local pressure extremes, pressure losses due to filter material, and the extent of overall pressure recovery in the downstream section of the device. The calculation also revealed the presence of an undesirable recirculation zone along the wall in the diffuser region, which contributes to losses and reduces the system performance.

FLUENT/UNS predictions matched the measured pressure drop through the system very closely.

Full Suite of Tools

FLUENT/UNS now offers a wide choice of modeling techniques for fans and turbomachines, ranging from the sliding mesh model for time-accurate prediction of rotor-stator interactions, to a mixing-plane model that is good for quasi-steady rotor-stator interactions and the moving-reference-frame model for quasi-steady flows with minimal rotor-stator interactions. Matsushita's work provides important benchmarking on the usefulness of the sliding mesh approach for practical problem solving.

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