On the Flow Speed Measuring Devices of Model Experiment in a Circulating Water Tank

摘要

It is considered indispensable to measure the flow speed in the course of experiment of fishing gear models in the circulating water tank. Especially, it is considered necessary to measure it with a high accuracy because the resistance of fishing gear models against stream is in direct proportion to the square of flow speed. Moreover the stream must not be disturbed by the setting of measuring apparatus, and therefore it is considered that the apparatus must be as small as possible. Hereupon, the authors manufactured on trial basis a small and handy but hypersensitive flow measuring device using strain gauge. Four resistors that are different in shape each other were manufactured as the flow measuring devices of strain gauge type, and their drag coefficient was also obtained. It was confirmed that they are readily reproducible and are accurate enough for practical usage with the accuracy within ±2cm/sec in the flow speed range of 5-60cm/sec.