A Study on the Flow Visualization by the Hydrogen-Bubble Method.

Abstract

In the investigations of both the steady and unsteady flow in turbomachines, it has been found to be highly successful to visualize the flow in ducts and around the bodies. Recently W. Clutter and O. Smith have presented a suitable technique for flow visualization using small hydrogen-bubbles produced by electrolysis of the working water itself. According to their experiments, unfortunately the method was not applied to the flow with higher velocity than about 0.6m/sec. In order to observe the stream lines flowing at about 5∼8m/sec in an axial-flow type testing water compressor, the authors improved the electric source and the working liquid in the hydrogen-bubble method, and developed several new probes which are inserted into the stream as cathodes for the electrolysis process and which consist of a straight or kinked platinum wire and fork-type brass stem. In a small water tunnel having a test section 60×200 mm and two observation windows on each side, direct current of high tension (2000volts) was charged between the probe and the tunnel duct and thereby the lines of hydrogen-bubbles generated from the probe wire were visible fairly well even in the higher velocity stream of about 7m/sec. Further, using the above mentioned method, some photographs of the rotating stalls occurring in the testing water compressor were taken successfuly as was expected.