Sonic water jet nozzle

A nozzle body has an elongated, conical passage with the smaller end opening facing in the direction it is desired the jet to travel. At right angles thereto, a fitting in the nozzle body interconnects with a supply of pressurized water. The pressurized water enters into a manifold or plenum surrounding a chamber in which a sonic transducer is located. The manifold wall has a plurality of openings arranged in a circle for directing pressurized water into the conical chamber along each of the openings. Water from the manifold serves to fill the enclosure containing the sonic transducer to provide full fluid coupling throughout the entire interior of the jet nozzle construction. A set of fins are arranged about the walls defining the conical passage to stabilize water moving therethrough and reduce any tendency to rotate on emission.

The present invention relates generally to a sonic water jet nozzle and, 
more particularly, to an improved nozzle for emitting a laminar column of 
water substantially free from surface irregularities over an extended 
length and along which sonic energy passes. 
BACKGROUND OF THE INVENTION 
Sonic and especially ultrasonic energy is being increasingly utilized in 
the nondestructive testing or inspection of parts for defects. In a 
typical form of such apparatus a quantity of water on the part to be 
tested serves as a coupling means for sonic energy generated by a 
relatively remotely located transducer. It has been found that even the 
presence of a very small amount of surface irregularity in the column 
causes sonic reflections which substantially impair operation of the 
apparatus by impeding flow of the sonic energy through the water to the 
test piece. It is therefore a desideratum to provide water coupling 
between the sonic transducer and the surface to be inspected which is as 
free from surface irregularities as possible. 
In a frequently encountered testing apparatus particularly for use in the 
scanning inspection of large sheetlike surfaces by sonic means, a jet-like 
stream of water is emitted toward the surface to be tested and along which 
jet the sonic energy passes. U.S. Pat. No. 4,004,736 granted Jan. 25, 1977 
discloses an ultrasonic water jet for use in this general type of 
apparatus and which is stated as providing a 4 to 6 inch stream of water 
which is unbroken and free of bubbles. 
Both the patented device as well as other known devices for producing water 
jets in the art have not been found capable of producing a jet or stream 
free from surface irregularities extending for more than about 6 inches, 
and this fact sets an inherent restriction on present sonic nondestructive 
test equipment. That is, either the jet nozzles have to be located close 
enough to the test piece so that the stream will be in its pure 
homogeneous state, which is not always possible, or the degradation in the 
water stream associated with greater lengths of the stream must be 
compensated for in some manner. 
SUMMARY OF THE INVENTION 
There is provided in the practice of the present invention a nozzle 
construction including a nozzle body with an elongated, conical opening 
having the smaller end opening facing in the direction it is desired the 
jet to travel. At right angles thereto, a fitting in the nozzle body 
interconnects with a supply of pressurized water. The pressurized water 
enters into a manifold or plenum surrounding a chamber in which a sonic 
transducer is located. The manifold wall has a plurality of openings 
arranged in a circle for directing pressurized water into the conical 
chamber along each of the openings. Water from the manifold serves to fill 
the enclosure containing the sonic transducer to provide full fluid 
coupling throughout the entire interior of the jet nozzle construction. A 
set of thin metal fins are arranged about the conical walls defining the 
conical chamber which serves to stabilize water moving therethrough and 
reduce any tendency to rotate on emission which has been found to cause 
surface irregularities.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference now to the drawings and particularly FIGS. 1 and 2, the 
water jet nozzle of this invention is identified generally as at 10 and is 
seen to include a generally cylindrical tubular housing 11 having an open 
end 12 and a partially closed end 13 with an opening 14 therein for a use 
to be described. A suitable fitting 15 is threadedly received within the 
side wall of the housing 11 and interconnected by a pipe or tube 16 to a 
suitable supply of pressurized water. 
The inner wall of the housing 11 spaced slightly inwardly from its open end 
12 has been removed to form an enlarged opening that terminates inwardly 
at an annular shoulder 17. A plurality of equally spaced passages 18 
arranged in a circle about the longitudinal axis of the tube 11 are formed 
in the annular shoulder 17 and are in open communication with incoming 
water from 16 through the fitting 15, allowing it to exit free from 
rotation in the direction of the arrow toward the tube open end 12. 
An elongated cylindrical nozzle body 19 has an external diameter such as to 
enable fitting receipt of an end portion within the open end 12 in housing 
11 at which time the nozzle body end abuts against the annular shoulder 
17. A conical passage 20 extends longitudinally within the nozzle body 
with its large end opening at the end of the nozzle body 19 received 
within housing 11 and its small end opening at the opposite end. It is to 
be noted that the large end of the passage 20 has a sufficient diameter to 
provide ready communication between each of the openings 18 and the 
conical passage 20 such that incoming water from the tube 16 will make its 
way along the direction of the arrow through the fitting 15, along the 
passages 18 into the conical passage 20 and thence outwardly from the 
nozzle body as a stream of water 21. 
With reference now particularly to FIGS. 2 and 4, it is seen that 
substantially midway along the longitudinal dimension of the conical 
passage 20 there is located a thin metal sheet 22 which conforms closely 
to the walls of the passage 20 and includes a plurality of finlike members 
23 extending from the wall towards the center of the opening. More 
particularly, the metal sheet is a strip laid out with two edges curved so 
that when the other strip edges are brought together the peripheral 
surface of the hollow tube so formed will match the curvature of the cone 
of passage 20. The finlike tabs are stamped from the metal and bent 
inwardly so as to extend radially partway towards the central axis of the 
conical opening but having their inner ends spaced from each other. Each 
of the fins is radially located within the passage and terminates at an 
inner edge that is substantially parallel to the wall surface defining 
passage 20. 
A sonic transducer 24 has a generally cylindrical construction with an 
enlarged mounting ring 25 extending circumferentially thereabout. One end 
26 includes energizing wires 27 and the opposite end 28 is the active or 
vibrating surface. A hollow mounting tube 29 has an internal diameter 
sufficient to receive the transducer main body in a loosely fitting 
arrangement and an enlarged hub 30 against which the mounting ring 25 
abuts. Typically, the transducer is secured to the mounting tube by a pipe 
and nut arrangement 31. The tube 29 has an outer diameter which snugly 
fits within the opening 14 of housing 11, and the tube inner end abuts 
against a shoulder 32 both for securement and to fixedly locate the 
transducer. 
In operation of the described apparatus, first pressurized water is added 
via the fixture 15 which fills a first chamber 22 in housing 11, the 
passage 20 in the nozzle body as well as the interior of mounting tube 29. 
Accordingly, on the transducer being energized there is full and complete 
fluid coupling of the sonic energy produced by the transducer and the 
emitted water stream 21. 
As a result of adding pressurized water to the conical opening or passage 
20 via the circular set of passages 18 and stabilizing fluid flow by the 
fins 23, a completely bubble free stream or smooth water column 21 is 
obtained having a length substantially greater than that provided by any 
known nozzle means. For example, in actual comparative tests of a 
practical construction of the invention with available nozzles established 
a clear superiority in performance. Thus, whereas one known nozzle 
produced a bubble-free column of water for 4 inches from the end of the 
nozzle and a second known nozzle produced such a column 6 inches from the 
nozzle end, the present invention provided a column that showed no 
tendency to break until after 10 inches from the nozzle end. 
A most important factor in the production of a smooth water column (i.e., 
no surface irregularities) is the prevention or substantial reduction of 
column water rotation. That is, it has been found that if the stream or 
column emitted from the nozzle rotates, it will break down quicker and 
form surface irregularities that attenuate sonic energy. The passages 18 
and fins 23 are believed to be responsible for preventing any tendency for 
the emitted water stream 21 to rotate. 
A second adverse aspect of known prior nozzles for this general purpose has 
been the attenuation of sonic energy within the nozzle itself. In this 
invention, a gentle slope of the nozzle interior such that the sonic 
energy reflects from, rather than refracts into the surface 20, is 
believed of critical effect in maintaining the transmission of sonic 
energy relatively unimpaired through the nozzle.