Fluid Boundary Layer Resistance Testing And Flow Visualization

The thesis describes the experimental study on water channel. It designs fluid dragmeasurement system for floating wall and flow visualization system using hydrogenbubble theory.The thesis designs the system of measuring fluid velocity which composed by pitot,difference pressure gauge and figure display instrument basing on the pitot principle ofmeasurement velocity. It gets the relation curvesof transducer frequency with velocityand experiment measures the distribution of the flow velocity at different section of thewater channel when transducer frequency is changed in the water channel. So it knowsthe real-conformation of fluid in water channel.Basing on peruseing the interrelatedoverseas articles and according to the needs of water channel and fluid drag reductioncontrol on subject, it designs fluid drag measurement system. By designing,manufacturing, installation, debugging, it accomplishes experiment part and floating wall.It manufactures resistance sensor based on the semiconductor strain gauge and theworking principle of Wheatstone bridge. The performance of semiconductor strain gaugeis obtained by experiment measurement. By debugging the system, measuring anddisposing the experiment data, it obtains the basic parament on boundary layer drag atdifferent velocity of flow.Using the principium that water is electrolysed to hydrogen andoxygen., it designs hydrogen bubble generator, electrical source, relay, platinum threadand camera composing a hydrogen bubble display system.The experiments includesthose that platinum thread parallels the floating wall meanwhile uprights the direction offlow velocity and that platinum thread uprights the floating wall meanwhile uprights thedirection of flow velocity. It screens pictures about the interior structure on fluidboundary layer in the water channel.This research on drag measurement system for floating wall and flow visualizationsystem gets the basic parameter of fluid flow in the water channel. It provides theexperiment method of drag measurement and the technology of flow visualization to theresearch of fluid drag reduction.