Cavitation phenomena in cylindrical long orifices are studied experimentally in this paper and especially, possible influences of the inlet configuration of orifice and oil temperature changes are examined.
The conclusion obtained is as follows.
(1) In the case of a sharp edged long orifice, cavitation occurs at the inlet portion there of and the sound noise level does not so much vary with oil temperatue changes.
(2) In the case of a round edged one, cavitation occurs around the jet at the down stream therein. And it begins to occur with an increase in oil temperature.
(3) In the case of a conical edged one, cavitation phenomena in the range of low oil temperatures are similar to those occurring in the round edged one. However, at a specific point of high temperature range, cavitation suddenly occurs at the inlet portion of orifice in addition to that already having occurred around the jet at the down stream therein.

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Oil hammer generates for an instant much greater pressure than that supplied to the pipe line, and this is important, indeed, in terms of the safety of oil hydraulic equipments.
If you can take advantage of this phenomenon to pick up only the high pressure for a very short period of time, you will be able to make such a hydraulic pressure intensifier as can convert the oil pressure, produced by a low pressure pump, into several times higher one.
In the case of water, a hydraulic ram utilizing this idea by means of waterhammer has been long investigated. However, its discharge pressure is several tenths MPa at most.
For the oil hydraulics, to the author's knowledge, no report is available on an intensifier by means of oil hammer. Then, you would need a quite different structure because about one hundred times higher pressure will usually be needed.
In the present research, an intensifier on a new principle was developed with a view to convert an oil pressure of several MPa into several times higher one and, moreover, to make more easily than a traditional intensifier consisting of oil cylinders.
The discharge volume of the intensifier and the pressure fluctuation in the pipe line are theoretically predictable with a good accuracy.

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