US2435605A - Spray nozzle - Google Patents

Description

Feb. 10, 1948. ROWELL 1 2,435,605

S PRAY NOZ ZLE Filed March 31, 1944 ilwuc H101, HERMAN L. Rom/ELL #44 W ill-mm) Patented Feb. 10, 1948 FFICE SPRAY NOZZLE Herman'L. Rowell, United States Army Application March 31, 1944, Serial No. 528,914 a 2 Claims. (01. 299-120) (Granted under the act of March3, 1883, as

amended April 30, 1928; 370 G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a type of spray nozzle particularly useful for extinguishing fires of materials such as magnesium bombs and liquid fuels which burn stubbornly at high temperatures.

Numerous spray nozzles are known to have been developed for fire fighting and other applications, and many of these have been perfected for particular purposes. Yet, when the problem of quickly extinguishing burning magnesium bombs seriously arose, it was difiicult to find any effective spray nozzle for this purpose.

Nozzles which do not fully atomize a stream of water but emit a jet of water in the midst of a fine spray are not suitable because the let will make a burning magnesium incendiary react with explosive violence. On the other hand, nozzles known to be designed for complete atomization have had various drawbacks in being expensively constructed, large, requiring inflowing feed streams of very high velocity, having small orifices which become clogged, and in forming hollow sprays difiicuit to focus and concentrate on a burning incendiary.

An object of the present invention is to provide a spray nozzle which avoids the drawbacks noted and which has a simplified construction so it can be made economically by mass production for wide distribution and use.

In general, the nozzle of the present invention has a conical-shaped body tapering from an upstream inlet to a downstream outlet or discharge orifice and includes within the body a means for separating an axially'fiowing solid stream of liquid into a plurality of spiral streams changed in velocity and forced to impinge on converging inner walls of the nozzle so that the liquid becomes fully atomized with low resistance. The nozzle is adapted for attachment to pipe or hose installations of various sizes and supplying liquid under various pressure and velocity heads.

The fog-producing or atomizing action of the nozzle is mainly dependent upon the shape of the structure within the nozzle and its relationship to inner walls of the nozzle body converging toward an outlet orifice.

Preferably, the inner structure comprises a solid plug tapered toward the inlet and centrally disposed near the inlet of the nozzle with a series of curved vanes or blades adjoined. The blades are disposed to divide the solid stream from the inlet into a plurality of spiral streams curved toward the inner wall of the nozzle converging toward the outlet orifice of the nozzle. Each blade has a concave surface which is nearly parallel for a, substantial portion to a plane along the longitudinal axis of the nozzle beginning at the up stream edge of the blade, then curves more toward the upstream direction. The blades have agradually increased thickness from both end tips or edges toward the center. The reverse side of each blade is convex and faces toward a concave surface of an adjacent or neighboring blade.

At the discharge end of the nozzle, it is preferred to have an orifice outlined by the thin edge of an inward projection triangular in crossv section.

A spiral stream of liquid fiowing between two of the fixed blades is given an increased velocity by contraction'in cross section and is diverted at a suitable angle from the axis of the nozzle toward the nozzle wall for impingement and. deflection toward the orifice, thus avoiding excessive resistance.

The principles of the nozzle will be explained in more detail with reference to the drawing which illustrates a practical embodiment of the type of nozzle suited for extinguishing magnesium incendiary fires.

In the drawing:

Figure 1 is a sectioned, longitudinal side view of the nozzle body and holder assembly with a side full view of means within the nozzle for separating a solid stream of liquid entering the nozzle into a plurality of curved streams;

Figure 2 is a sectional view of the nozzle body along the longitudinal axis of the nozzle;

Figure 3 is a perspective side view of the tapered plug and blade means; and

Figure 4 is a cross-section view taken along the line A-A in Figure 1 and in the direction of the arrows.

Referring to the drawing. and in particular to Figure 1. the holder comprises'a tubular body I threaded internally at the inlet end 2 and externally at the outlet end 3. Gaskets 4 are seated against a retaining ring 5 within the body I adjacent to the internal thread 2 for making a tight 3 discharge end II, but internally for a portion of the distance beginning at the inlet, the walls may be substantially cylindrical, as, for example, up to a point l2, and thence be tapered to form an angle of about to 25 with the longitudinal axis of the nozzle as they converge to the outlet orifice I3.

Close to the discharge end of the nozzle the gradual converging or arching of the inner wall, preferably ogival in contour, abruptly ends; and at this point, or slightly beyond, the inner wall slants sharply toward the longitudinal axis, making an angle of close to 70 therewith and ending in the sharp tip l3, triangular in cross-section. The thin edge of this sharp tip is the perimeter of the outlet orifice. It defines the shape of the issuing mist stream. The orifice piece having the tip l3 may be in the form of a replaceable insert secured to the discharge end of the nozzle or integral therewith. This piece may have a cylindrical surface section which meets the end of the ogival surface and leads to the tip I 3.

The structure shown in Figure 3 is the means inserted within the nozzle close to the inlet for separating the entering solid stream of liquid into a plurality of curved streams. It is set into the nozzle as shown in Figure 4 with the tapered solid plug it centrally disposed and with the adjoining curved vanes or blades l5 extending from the plug to the surrounding inner wall of the nozzle. Four of these blades make a suitable number; and with four blades, each blade is radially positioned at 90 from an adjacent blade.

The blades are identically shaped with a concave surface l6 beginning at the upstream edge approximately parallel to a plane through the longitudinal axis of the nozzlea'nd then curving at a suitable angle toward a side of the nozzle and with a convex surface I! facing and converging with the concave surface of an adjacent blade. It is also preferred to have the cross section of the blades gradually increase from both edges toward the centers.

With the blades thus shaped and positioned, a stream of liquid entering the nozzle is divided into four separate spiral streams, and each of these separate spiral streams first flows axially between a pair of adjacent blades, then becomes curved and constricted in the narrowed passageway between a concave surface and a convex surface near the downstream ends of adjacent blades.

The center structure of plug and blades, conveniently made by casting as one piece, is readily inserted into the nozzle through the inlet opening, and may be fixed in place by a set screw fastened into the depression iii of a blade through threaded opening l9 in the nozzle wall and by which then are directed out through the orifice on rebounding. The mass of droplet ejected from the orifice is substantially homogeneous and bulb-like in form.

Spray nozzles of the type illustrated were made for fitting average small-size hoses, such as might be found installed commonly in buildings with 4 about 1% inch inside diameter and ordinary water pressures, and were found to perform satisfactorily. They were also used in successful airraid defense demonstrations of exemplary methods for extinguishing magnesium incendiary bombs. It is considered that they are very effec-' tive for this purpose by virtue of the localized high-cooling action by the quickly vaporizing fog they lay down surrounding a bomb.

An advantageous feature of the described nozzle is that the divided liquid at all times has a substantially forward moving vector so that at no place is the flow completely obstructed. Another feature resides in the shaping and positioning of the blades to impart increased velocity at the place in the nozzle where th impingement is to effect the atomization. With spiralling relatively high velocity, the liquid is subjected to several atomizing forces simultaneously, such as a centrifugal force, an impact force, and a forward velocity force.

With high efiiciency for completely atomizing a stream of liquid, spray nozzles embodying the features of thi invention are adapted to many uses, as, for example, for precipitating dust, air washing, cooling ponds, humidifying air, spraying liquids in condensers, atomizing liquids in vaporizers, reactors, dryers, absorbers,and the like. The nozzles may be varied in size to suit the needs.

While, for the sake of simplicity, one type of nozzle has been illustrated, it is to be understood that modifications may be made which come within the spirit of the invention.

I claim:

1. A spray nozzle for ejecting a homogeneous mass of liquid droplets comprising a tubular conduit converging for at least a portion of its length from an inlet to an outlet, a centrally spaced solid plug tapered toward the inlet and spaced from inner surfaces of said conduit, a serie of blades disposed around said plug said blades having concave curved surfaces and convex curved surfaces, each of said blades having a gradually increased thickness from the end tips toward their centers, and the distance separating the concave surface of one blade from the convex surface of an adjacent blade becoming gradually smaller in a downstream direction.

2. In a spray nozzle for fully atomizing a solid stream of liquid, at set of radially spaced curved blades, each :blade having a relatively wide edge pointing substantially into an entering solid stream of liquid and a relatively narrow edge pointing downstream toward impingement wall surfaces in said nozzle, and each blade having gradually increased thickness from both said edges toward the center of the blade.

HERMAN L. ROWELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,282,176 Binks Oct. 22, 1918 1,367,769 Coffey Feb. 8, 1921 1,381,734 Parker et a1 June 14, 1921 1,442,356 Parker Jan, 16, 1923 1,496,924 Day June 10, 1924 1,506,722 Yunker Aug, 26, 1924 2,047,716 Thompson July 14, 1936

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