Standing Room Only

so that the water will be smooth and even again when it completes its circuit and re-enters the working cham-ber. The resorber system is built into an 85-foot shaft, dug straight down into the ground under the Labor-atory. Thus, behind the tiny model in its small working chamber are literally tons of equipment filling up a good part of the large building. on, the water starts When it gets to the it is made to rush past the model, and pressure changes pressure is lowered to the water's boiling point, and bubble or cavity formed is then pushed by the water along the model until it runs into an There the bubble collapses as water in areas of higher pressure pushes into the there is a battery of recording instruments for keep- ing track of the forces that act on the model during this boiling process. It is when the water smacks against itself, rushing into the cavities, that the forces are set free which are responsible for cavitation damage. But at the same time something else happens that is a mixed blessing for the hydrodynamics engineer. The water slapping against itself makes a great deal of noise-just as air does when it rushes in to fill the cavity caused by a lightning discharge. The smacking air is thunder, and the thunder of while it warns engineers when something is beginning pumps objectionably noisy, and causes vibration that annoys the passengers on all, however, fact that cavitation flow, or increases resistance to flow. And this, in turn, means that pumps maximum efficiency, andropellers that objects running with heavy cavitation are difficult to control. These are some of the problems hydraulics engineers tace, and the problems the California ot lechnology researchers have set out to solve. The tools of their investigation- the water tunnel, the special high-speed movies, the models-have been developed to the point where the engineers know how to control pressure and velocity in order to make any good shape cavitate or any bad shape stop cavi And recently, through studying their photo- way. Now Institute researchers have identified several kinds of bubbles which behave in several ways. Engineering advances The fruits of this research, made possible through the support of the Bureau of Ordnance, with the helf of the Office of Naval Research, are being made avail able to industry and to other researchers. Already about a dozen firms and several universities have obtained copies of the Institute's moving picture. An he Institute research team has moved ahead into newer fields, toward more fundamental problems. Located in a building next to the Guggenheim Aeronautical Laboratory of the California Institute of Technology, the Hydrodynamics Laboratory is an ideal spot to study the widest ramifications of its field. For the flow of water and the flow of air are related, and the research being done by these two laboratories gives promise of ever-widening discoveries and devel-opments, which in turn give promise of more efficient pumps and turbines, better underwater shapes, even bet ter fluid transmission for automobiles-and engineering advances that may affect every one of the millions of parts that operate in fluids in American industries. This review of cavitation studies in Caltech's Hydrodynamics Laboratory is the first of a series of reports on research in progress at the Institute. Page 16 Standing room only Most popular of Caltech's Friday Evening Demonstration Lector the general public throughout the school year, is the one on high voltage, delivered by Prof. R. W. Sorensen. l'he demonstration in the High Voltage Laboratory which follow: Prof. Sorensen's talk is still, after 25 years, one of the best show: on the campus. It proved to have its usual strong draw this year when, on a rainy Friday evening, almost 1,000 people stormed East Prof. Sorensen obligingly gave his lecture twice, and the lab ran off three demonstrations, while a special police detail coped Specially designed for conducting researches requiring high-voltage electrical energy, the High Voltage Laboratory was built in 1924, with tunds supplied by the Southern Calitornia Edison Co. The first laboratory in the country to have a reliable 1,000,000 volt power trequency, provided by a chain system of transformers designed by Prof. Sorensen, its facilities are available for research or for industrial tests. These facilities have been used to aid Southern California Edison in the development of high-voltage transmission lines, to furnish lightning protection of oil storage tanks for the oil industry, to test insulators for numerous utility companies. ENGINEERING AND SCIENCE MONTHLY