Courtesy of Innomatec S.c.r.l.

Engineers at Innomatec S.c.r.l. (ERGOM Group), based in Melfi, Italy, recently used FLUENT along with an experimental study to carry out a series of validations of automotive fuel tank sloshing. The confidence they gained from the exercise encouraged them to evaluate sloshing in the fuel tank of a new version of the popular FIAT Punto European compact car.

Working with the staff from Fluent Italia, Innomatec engineers began with a 2D validation to quickly check the feasibility of the approach itself and the accuracy that might be expected. A 2D simulation of a shape similar to a fuel tank cross-section was performed, and the predicted liquid levels were compared with experimental measurements. The fuel tank was 75% full of dyed water, and was oscillated between the angles of +/- 27 degrees at a frequency of between 3 and 7 cycles per minute for a period of one minute. Good agreement between the 2D simulation and experiment gave the Innomatec engineers confidence in the CFD modeling technique, so the more difficult 3D fuel tank validation was initiated.

2D experimental (left) and CFD simulation (right) of the 2D fuel tank shape showing the free surface at an angle of +27°

The 3D CFD simulation of the FIAT Punto automotive fuel tank included four liquid level monitoring stations (capacitive transducer probes) that were used in the experimental apparatus. This meant that the CFD model was identical to the physical tank geometry. These capacitive probes were used to measure the local liquid level in the tank as it went through a fixed oscillatory cycle similar to that used in the 2D experiment. The overall trends in the 3D simulation were good and the predictions were found to be accurate to within +/- 9%.

3D CFD simulation showing the four stations

Station four liquid depth measurements versus time predicted by FLUENT (red) are compared with experiment (blue)

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