| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 105 === This research uses an experimental arrangement to measure the penetrative entrainment flow rate due to a turbulent fountain at a density interface in the steady state. The salt-bath technique is employed to conduct the experiments in an acrylic model. Experiments start with two layers of fluids initially, i.e. fresh water as the top and salt water as the bottom. Two sources, a fresh water source and a salt water source, are located at different heights in the acrylic model. A fresh water source is placed at the top of the acrylic model, and there is a stainless steel mesh placed at the outlet of the fresh water nozzle to make the outflow become turbulent. A salt water source is placed at 2 cm above the bottom of the acrylic model by using an acrylic pipe to supply salt water to the bottom layer. Dye attenuation technique is used to analyze the light intensity data derived from the recorded images of experiments. According to the density of salt water and the volume flow rate of fresh water, there are eight experiments in this research. The experimental results show that the interface height is highly related to the density of salt water and the volume flow rate of fresh water in the steady state. For the experiments having the same density of salt water, the distance between the density interface and the fresh water source increases with the increasing volume flow rate of fresh water. For the experiments having the same flow rate of fresh water, when the density of salt water increases, the distance between the density interface and the fresh water sources decreases. The theoretical model gives three equations to estimate the penetrative entrainment flow rate in the steady state. The theoretical turbulent fountain model gives the turbulent fountain radius, the vertical velocity and the volume flow rate at the density interface to estimate the penetrative entrainment rate, the Richardson number, and the densimetric Froude number. The research results show the Richardson number at the density interface between 0.030 and 4.261, and the penetrative entrainment rate in the range of 0.13 to 2.32.
Keywords: Density interface, turbulent fountain, penetrative entrainment, steady-state experimental arrangement.
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