US2834146A

US2834146A - Apparatus for projecting substances in a divided state

Info

Publication number: US2834146A
Application number: US572695A
Authority: US
Inventors: Jean H Bertin; Francois G Paris; Pain Maurice
Original assignee: SNECMA SAS
Current assignee: Safran Aircraft Engines SAS
Priority date: 1955-03-22
Filing date: 1956-03-20
Publication date: 1958-05-13
Anticipated expiration: 1975-05-13

Description

y 3, .1953 J. H. BERTIN ET m. 2,834,146

APPARATUS FOR PROJECTING SUBSTANCES IN A DIVIDED STATE Filed March 20, 1956 INVENTORS JEAN H-BERTIN Fnmcms 6. pARlS Mnumcs PAIN Wm, M,Mwmw

ATTORNEYS APPARATUS FOR PROJECTING SUBSTANCES IN A DIVIDED STATE Jean H. Ber-tin, Neuilly-sur-Seine, Francois G. Paris, Garches, and Maurice Pain, Paris, France, assignors to Societe Nationale dEtn-dc et de Construction dc Moteurs dAviation, Paris, France, a French company Application March 20, 1956, Serial N 0. 572,695 Claims priority, application France March 22, 1955 4 Claims. (Cl. 43-147) Apparatus is already known which is used for the projection of various substances, for example insecticides or flaming particles (flame-throwers).

For projecting insecticides, the idea has already been put forward of utilising the energy contained in puffs of gas at high speed which are discharged from a resonant pulsatory combustion chamber of the type used in pulsejet units, chambers of this kind being, in fact, of very simple construction and very simple in use.

The applicants have found that the range of the projection could be increased by arranging an ejector, or a pipe open at its two extremities, after the exhaust discharge nozzle of the pulsatory chamber, the successive puffs of gas being discharged into the said ejector, the air which fills the ejector in the intervals between the puffs of gas being thus pushed out, and the substance to be projected being introduced on the upstream side of the said ejector.

At first sight, it might not have been expected that an ejector of this kind would enable the range to be increased, since the speed of flow therein is less than the speed of the gases at the outlet of the discharge nozzle of the pulsatory chamber, the reduction in speed being due to the fact that each puff of gas transfers a part of its kinetic energy to the mass of air which fills the ejector. The increase observed in the range is no doubt explained by the increase of the mass of gas set into motion, and especially by the increase of its cross-section, the ejector discharging a jet which is wider and more uniform than that which is discharged from the nozzle, and thus resist longer against the effects of its disintegration by the resistance of the surrounding air.

The increase in range is also due to the fact that, although the gases have a high speed at the outlet of the exhaust nozzle, they have however at that point also a low specific mass by reason of their very high temperature, whilst the presence of the ejector reduces the temperature of the gases by mixing them with fresh air, so that the mixture of air and gas passing out of the ejector has a higher specific mass which is more favourable to the penetration of the jet into the air.

In addition, in the case in which the substance to be protected has properties which are liable to be altered by heating to a high temperature, as is the case with powder or liquid insecticides which it is desired to spread over the ground or over crops, the presence of the ejector and the introduction of the substance between the outlet of the discharge nozzle and the ejector gives the further favourable result of treating the substance to be projected with care, by virtue of the cooling of the gases discharged from the discharge nozzle. On the other hand, in the absence of an ejector, it would be necessary either to introduce the substance into the exhaust nozzle before its outlet, thereby running the risk of decomposing it by excessive heating, or to introduce the substance at the outlet of the exhaust nozzle, which would produce a bad projecting efiiect by insufficient guiding and a small effective range.

The suction effect created by the ejector may also be States Patent O used with advantage to facilitate the injection of the substance into the flow of gas in motion.

In the case of a flame-thrower, the ejector enables the contact between the exterior air and the inflammable substance to be improved and prolonged, thus increasing the efficiency of the combustion. in addition, it enables the flame to be directed in the desired direction. Without an ejector, the heating effect would in fact produce an expansion of the flame in all directions, whilst with an ejector, this expansion is directed only along the axis, which results in an increase in range.

The description which follows below with reference to the attached drawings (which are given by way of example only and not in any sense by way of limitation) will make it quite clear how the invention may be carried into effect, the special features which are brought out, either in the drawings or in the text, being understood to form a part of the said invention.

Figs. 1 and 2 are diagrammatic views in vertical crosssection of two forms of embodiment of the invention as applied to the projection of a substance.

In Fig. 1 there is shown at 1 a pulsatory combustion chamber provided with an air-admission tube 2, with a fuel injector device 3 and with its exhaust nozzle 4 through which are discharged the hot gases generated in the chamber 1 at each combustion. The pulsatory chamber is of the resonance type, the combustion being effected successively by self-ignition and being inherently maintained at the frequency of the sounding tube constituted by the combustion chamber and its exhaust nozzle. Pulsatory combustion chambers of this kind are moreover well known and have been particularly employed in pulse-jet units.

The exhaust nozzle 4 discharges into an ejector fixed to this nozzle by one or a number of supporting arms 4a. This ejector comprises a convergent intake 5 placed at a certain distance from the outlet of the exhaust nozzle, and a divergent portion 6 which discharges to the atmosphere. The ejector fills with air through the convergent intake 5 following each puff of gas and the air thus introduced is thrust out by the next puff following, with an excellent energy efficiency. I

The substance to be projected, which may be liquid or powder, is contained in a reservoir 7 and a pipe 8 which opens at 9 into the upper part of the space which separates the outlet of the exhaust nozzle 4 from the intake of the ejector and allows the said substance to flow into the said space. This substance is thus sucked into the ejector and is carried away. It is carried along by the jet of air and gas which is discharged from the ejector, and is thus projected a long way so as to come into contact with the desired objects or fall simply on the ground. In this way, there are obtained the advantages indicated in the preamble to the present description. It may also be noted that in the case of a powdered substance, the flow of this substance towards the outlet 9 of the pipe 8, starting from the header tank 7, is facilitated by the powerful vibrations which result from the actualoperation of the pulsatory combustion chamber.

In the form of embodiment shown, it has been assumed that the intake pipe 2 was of the aerodynamic valveless non-return type, the said tube being freely open but having a profile such that its resistance to flow in the direction of the chamber is greater than its resistance to a flow in the opposite direction. Tubes of this kind are well known per se. As, however, it is inevitable that a certain proportion of the gases will escape through the tube at each combustion, this phenomenon may be used to project a part of the substance, by folding the whole unit constituted by the chamber 1 and its exhaust nozzle 4 through an angle of so that the tube 2 and the exhaust nozzle 4 open towards the same direction, and by placing a Patented May 13, 1958.

second ejector list as an extension of the tube 2. The tube .8 is then provided with a second orifice 9a opposite the space between the pipe 2 and the ejector 6a, so that a part of the substance to be projected may be sucked-in by the ejector 6a. The latter has, of course, a smaller volume than the ejector 6 with respect to the volumes of gas discharged at 2 and 4 respectively.

The apparatus thus constituted is simple and robust. It can be readily transported and installed at the place of utilisation or again it may be mounted on wheels, or even on an automobile vehicle so as to facilitate its dis placement. It is particularly effective and gives a large range of projection without any risk of changing substances having delicate properties.

The form of embodiment shown in Fig. 2 comprises a special device for bringing the substance to be projected into the suction of the ejector 6 which follows the exhaust nozzle 4 of the pulsatory chamber 1. A tube or pipe 10 channels the puffs of gas generated by the efiect of periodic combustion in the chamber '1, into the closed reservoir 11 which contains the powder to be projected. This blowing eiiect produces a continuous agitation in the reservoir 11 and the powder is put into a thick suspension in the atmosphere inside this reservoir. As the upper part of the reservoir communicates through a tube 12-13 with a ring 14 provided with a slot 15 or with orifices level with the intake of the ejector 6, this ejector sucks in the suspension of gas powder coming from the reservoir 11.

In the example shown, the pulis of gas are produced in the tube 10 by the gases escaping at each combustion from the aerodynamic non-return valve 2. To this end, the pipe 10 is coupled to a small convergent-divergent member 16, the orifice of which is opposite the aerodynamic valve 2. Each puff of gas passing out of the latter thus pushes out the air inside the convergent-divergent device 16 into the pipe 10. The convergent-divergent member is not necessary to the functioning of the device described but it enables its efiectiveness to be improved.

If the material to be projected is very sensitive to heat, a cooling efiect may be effected, for example by injecting a vaporisable liquid which has no adverse action on the material to be projected, into the exhaust nozzle of the pulsatory chamber. water. An embodiment of this kind has been shown in Fig. 2 in which there is shown at 17 a tube which leads a certain quantity of water to an orifice 18 provided in all) This liquid may for example be '4 the exhaust nozzle 4. The cooling obtained is proportional to the rate of flow of this liquid within very wide limits.

The arrangements described are also applicable to the projection of flaming material (flame-throwers). In a case of this kind, the combustible material (liquid, powder or gas) may be injected into the exhaust nozzle 4 of the pulsatory chamber in such manner as to be ignited by the gases of high temperature passing out of the pulsatory chamber.

A special conventional ignition device may also be provided.

It will of course be understood that modifications may be made to the form of embodiment which has just been described, in particular by the substitution of equivalent technical means, without thereby departing from the spirit or from the scope of the present invention.

What we claim is:

1. An apparatus for projecting substances in a divided state comprising a pulse jet unit having a valveless airintake duct and an exhaust pipe facing substantially in the same direction, said pulse jet unit being in the form of a U-shaped duct, an ejector tube extending opposite said intake duct and substantially coaxial therewith to collect the leak gas issuing therefrom, a further ejector tube extending opposite said exhaust pipe and substan tially coaxial therewith to collect the exhaust gas issuing therefrom, and means for introducing thesubstance to be projected into each of the gaseous streams through said ejector tubes.

2. Apparatus as claimed in claim 1 wherein the ejector tubes have inlets spaced downstream from the ends of the intake duct and exhaust pipe associated therewith whereby gaps are formed between said ejector tubes and said duct and pipe.

3. Apparatus as claimed in claim 2 wherein the substance introducing means open into each gap.

4. Apparatus as claimed in claim 3 wherein the substance introducing means comprise a supply line and two branches thereof having discharge ends positioned within each gap.

References Cited in the file of this patent Karcher (German Publication), June 11, 1948.