Abstract This invention relates to percussive liquid jets which consist of a sequence of liquid bunches, instead of a free stream of substantially uniform diameter. The percussive jets impinge on a target as a sequence of impulses rather than as a steady force, or as a cyclical sine-wave type force. The method for creating percussive jets from a continuous discharge of liquid consists of producing a relatively small cyclic variation of the discharge velocity, such that the resulting velocity variation along the free jet of liquid compels the jet stream to bunch at regular intervals. The invention includes apparatus for producing percussive liquid jets by said method. Percussive jets are applicable as controlled sources of liquid bunches, which may be separate drops, for cyclic impact or for where transformation of a jet discharge from a steady to a percussive impact is beneficial. One application of the method and apparatus for percussive jets is in the cutting or the excavation of rock and other materials.
A method for creating a percussive liquid jet from a continuous jet discharge consisting of producing a relatively small cyclic variation of the discharge velocity about its time average, whereby the free jet is given a lengthwise variation in forward velocity compelling the free jet to become a bunched stream with a change in lateral diameter occurring periodically along the length of the stream.
Claim 2
Independent Claim
64 words
A method for creating a percussive liquid jet from a continuous jet discharge consisting of producing a relatively small cyclic variation of the discharge velocity about its time average, whereby the free jet is given a lengthwise variation in forward velocity compelling the free jet to become a bunched stream with a change in lateral diameter occurring periodically along the length of the stream.
Claim 3
Dependent Claim
33 words
The method according to claim 1 in which said cyclic variation of the discharge velocity is obtained by producing a cyclic variation of the liquid pressure at the inlet to a discharge nozzle.
Claim 4
Dependent Claim
40 words
The method according to claim 2 in which said cyclic variation of the liquid pressure at the inlet to the discharge nozzle is obtained by producing a cyclic variation of flow resistance in the flow of liquid to the nozzle.
Claim 5
Independent Claim
92 words
A method for cutting the surface of a body of material comprising impinging on said surface a modulated stream of water, said stream issuing from a nozzle as a coherent uninterrupted bunching stream having different internal axial velocities from point to point along its direction of axial flow, whereby beyond a bunching distance the laterial diameter of the stream varies periodically along the length of the stream without substantial deterioration until after the stream passes a deterioration distance, and maintaining the surface of the material to be cut between the said distances.
Claim 6
Independent Claim
92 words
A method for cutting the surface of a body of material comprising impinging on said surface a modulated stream of water, said stream issuing from a nozzle as a coherent uninterrupted bunching stream having different internal axial velocities from point to point along its direction of axial flow, whereby beyond a bunching distance the laterial diameter of the stream varies periodically along the length of the stream without substantial deterioration until after the stream passes a deterioration distance, and maintaining the surface of the material to be cut between the said distances.
Claim 7
Dependent Claim
20 words
The method according to claim 4 in which bunches are formed at the rate of at least 1000 per second.