1503 Three-dimensional velocity-field measurement of inflow phenomenon in buoyant jet at low Froude number

A ventilated cavity was investigated using three-dimensional numerical simulation and cavitation water tunnel experiments under the condition of low Froude number. A two-fluid multiphase flow model was adopted in numerical predictions. The drag between the different phases and gravitational effect, as well as the compressibility of gas, was considered in the numerical simulations. By comparing the ventilated coefficient computational results of three different turbulence models with the Epshtein formula, the shear-stress-transport turbulence model was finally employed. The phenomenon of double-vortex tube gas-leakage was observed in both numerical simulations and experiments. Based on the validity of the numerical method, the change law of the lift coefficient on the afterbody was given by numerical predictions and accorded well with experimental results. The cause for the appearance of an abrupt increase in lift was difficult to get from experiments for the hard measurement, whereas the numerical simulations provided some supplements to analyze the reasons. The distribution of lift coefficient on the afterbody had important significance to the design of underwater vehicles.

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Velocity Field Measurement and Flow Visualization of Rectangular Jet with Tapered Triangular Tubes at Nozzle Four Corners

The Proceedings of Mechanical Engineering Congress Japan ◽

10.1299/jsmemecj.2020.s05119 ◽

2020 ◽

Vol 2020 (0) ◽

pp. S05119

Author(s):

Naoki KAJITANI ◽

Takahiro KIWATA ◽

Takaaki KONO ◽

Nobuyoshi KOMATSU ◽

Riku OUCHI

Keyword(s):

Velocity Field ◽

Flow Visualization ◽

Field Measurement ◽

Rectangular Jet ◽

Four Corners ◽

Velocity Field Measurement

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On the Inflow Phenomenon in Near Field of Buoyant Jet at Low Froude Number

Volume 5: Fusion Engineering; Student Paper Competition; Design Basis and Beyond Design Basis Events; Simple and Combined Cycles ◽

10.1115/icone20-power2012-55245 ◽

2012 ◽

Author(s):

Atsushi Maeda ◽

Takayuki Yamagata ◽

Nobuyuki Fujisawa

Keyword(s):

Reynolds Number ◽

Froude Number ◽

Near Field ◽

Quantitative Information ◽

Experimental Result ◽

Inflow Rate ◽

Buoyant Jet ◽

Square Duct ◽

Wide Range ◽

Low Froude Number

In the present paper, the inflow phenomenon in the near-field of a buoyant jet issuing from a square duct is studied by using scanning LIF and scanning PIV measurements. The scanning LIF visualization allows an insight into the critical condition of the inflow phenomenon in a wide range of Froude number and Reynolds number. While, the scanning PIV allows the quantitative information on the inflow rate through the duct exit. The experimental result shows that the critical Froude number increases with an increase in Reynolds number in the duct exit up to Reynolds number 2,000, though it is weakened at higher Reynolds number. The examination of the inflow rate indicates that the large magnitude of the inflow rate occurs in the lower Froude number and Reynolds number.

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