Abstract: A rotary vortex separator for heterogeneous liquids, e.g. water with a small oil content on an offshore oil platform, includes injection channels (30) which inject water to be de-oiled at an axial speed relative to the periphery of the separator at the upstream end (4) of a cylindrical separation chamber (2) rotating about its axis (8). Purified water leaves from the other end (6) of said chamber via an annular outlet opening (26) of smaller radius to constitute a free vortex type of flow. The oil is removed by an axial tube (28).

Abstract: In hydrodynamic testing, in particular in laboratory testing of propellers, it is necessary to measure the concentration of cavitation nulcei in a liquid. The measurement is performed by counting bubbles of vapor formed by the cavitation nuclei in a zone (C) having minimum cross-section and pressure (Pt) in a forced flow along a duct. A deflector core (18) is disposed on the axis of a diverging downstream portion (C) of said duct in order to avoid the liquid streamlines from becoming detached and to facilitate bubble counting.

Abstract: In a microbubble injector usable to separate materials of different density by flotation, a deflector wall deflects radially a flow of water exiting under pressure from an injector hole and containing dissolved air at the saturation concentration. This procures cavitation which is localized at the edges of the hole and which generates the required microbubbles of air downflow thereof.

Abstract: The concentration of air in water is rapidly reduced by 80% in a separation enclosure (28) at reduced pressure by virtue of prior injection of microbubbles of air into the enclosure (26). Degassed water is useful for scaling cavitation effects in a hydraulic test tunnel.

Abstract: A method of producing bubbles for treating a suspension by flotation, wherein in which the suspension enriched with dissolved gas is caused to flow into a flotation vat via a pipe the flow in the pipe is rapidly interrupted at a predetermined frequency by a shutter unit which is suddenly closed and produces, in the downstream portion of the pipe, a periodic wave of low pressure such that cavitation bubbles are produced in the flow in said downstream portion, the low pressure wave propagating in the pipe up to the flotation vat where it is reflected as a wave of high pressure which produces the collapse of the cavitation bubbles and forms micro-bubbles which become fixed to the particles to be floated, the conditions in the pipe being such that the micro-bubbles are in a super-saturated medium in relation to the local pressure conditions and tend to be enlarged during their flow up to the flotation vat.

Abstract: A method for simulating cavitation on models by hydraulic testing with seate micro-bubbles which produce effects similar to those of a prototype operating at the same cavitation number wherein the micro-bubble content of the test liquid around at least a predetermined part of the model is adjustable in number per unit volume and the bubbles are homogeneously distributed thereabout and have dimensions of less than 200 microns.