US2990686A - Combustor apparatus - Google Patents

Description

July 4, 1961 J. P. LONGWELL COMBUSTOR APPARATUS Filed Sept. 29, 1955 III FIG. I

m u m JOHN. P. LONG WE LL 2,990,686 COMBUSTOR APPARATUS John P. Longwell, Scotch Plains, NJ., assignor, by'mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Sept. 29, 1955, Ser. No. 537,611

Claims. ('01. 6039.65)

This invention relates to a combustion apparatus and more particularly to an improved combustion chamber structure.

The present invention, although not limited thereto, is particularly adapted for use with a can type pilot or combustor of a ram jet power plant.

The recirculation of hot gases into the upstream end of a can type pilot or combustor is exceedingly important since it serves to act as the primary source of ignition for the remainder of the fuel and air mixture. In the initiation and propagation of fuel combustion in a high velocity air stream, it has been found that a sheltered volume, closed on all but the downstream side, offers a very effective device for anchoring and piloting burning. The sheltered volume functions as a mixing chamber to continuously burn a quantity of fuel and release the burning gases to the downstream end, where burning may be propagated to an additional fuel supply if desired.

Since the sheltered volume is open at only one end, unburned air-fuel mixture must enter and burned'gases must exit through the same area, thereby providing very effective heat exchange. Because of this heat exchange characteristic the sheltered volume is usually called 'the recirculation zone. The efiiciency of combustion within the sheltered volume or the amount of fuel that can be burned therein is largely dependent upon the quantity of air-fuel mixture fed into the zone and the mixing pattern between the burned and unburned gases. In gen eral it may be said that the amount of material burned increases as the flow intothe recirculation zone increases. Thus, the ideal combustor arrangement is one which 'allows for substantially unimpeded intake and exhaust through the same area thus offering maximum effective burning of the gases and subsequent distribution thereof.

Accordingly, it is an object of the present invention to provide an improved combustor structure wherein'the' circulation of unburned air-fuel material is increased, thereby obtaining better overall combustor performance.

It is a further object to provide means for controlling and directing the flow of gases into and out of the forward part of a combustor to eliminate undesired interference between the incoming air streams thereby increasing the eifectiveness of the combustor. 1

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a side view of a portion of a ram jet power unit with parts broken away to show a conventional combustor, the flow lines illustrating the existing problems inherent in such devices;

FIG. 2 is a cross-sectional view taken along line 2--2 of FIG. 1 looking downstream;

FIG. 3 is a top elevational view of a portion of a ram jet power plant with parts broken away illustrating a rectangular combustor incorporating a preferred embodiment of the present invention;

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3 looking downstream;

FIG. 5 is a side elevational view of a portion of a ram jet power plant with parts broken away illustrating an annular combustor in which the present invention is utilized; and

7 provided in combustors of this type, but such illustration of FIG. 5 looking downstream.

In order to facilitate a clear understanding of the "ice function of the present invention FIGS. 1 and 2 illus trate a portion of a ram jet power plant employing the. usual combustor apparatus. In the portion shown a generally rectangular shaped combustor 10 is centrally mounted within the cylindrical housing or duct 11 in the normal manner. The flow arrows 12 show that the airfuel mixture passes through the housing from the left or upstream end 13 to the right or downstream end 14 where combustion of the mixture subsequently takes place. i

In actual practice the plant structure is designed such that some of the mixture is allowed to bypass the combustor, while some is admitted into the combustor 10 by means of a plurality of opposed registering ports or openings 15. The upstream end of the combustor is closed at 16 thereby providing. for the recirculation or sheltered zone 17 between the closed end 16 and the row or groups of ports shown.

Additional ports extending downstream are generally has been omitted for purposes of simplicity. Ignition means such as spark plug 9 is provided in the sheltered zone for igniting the combustible mixture.

It is well known that combustor performance is predicated upon efficient circulation of the mixture into andout of this zone. As shown by the fiow arrow 12 in" FIG. 1 the combustible mixture passes along the-o'ut-' side surfaces 18 of "the combustor 10 and enters thecombustor through the opposed ports 15. The mixture enters from opposite sides of the combustor in the form of jets which impinge to form axial cores which flow to the recirculation zone and downstream (FIG. 1). i It can be readily seen (FIG. 2) that in addition to sending the mixture up and downstream the impinging jets also create:

side movement of the gases, that is, flow normal to the longitudinal axis of the combustor. I'hese gases moving to the sides partially block the spaces between the opposed pairs of jets, thus presenting substantial interference to the return flow of burning gases from the recircula-. tion zone since such gases must exhaust through these spaces. This blocking characteristic greatly reduces the circulation and accordingly combustor performance.

The present invention consists of flow control means positioned within the combustor to eliminate this undesirable side action of impinging jets and increased combustor efficiency.

In FIG. 3 a portion of a power plant is shown having a combustor which utilizes one form of the present in vention to prevent interference and loss of energy due to impinging jet side action. 7 A combustor 19 having a closed upstream end 20 and an open downstream end 21 is centrally positioned within the housing 22 in the manner similar to that of FIG. 1. Spaced downstream from the closed end 20 are a plurality of ports 23 formed in the top and bottom walls 24 and 25 respectively, of the combustor 19. The space between the closed end 20 and the row of ports form the recirculation zone generally designated by the numeral 26. Spark plugs 27 may be disposed within the forward part of the combustor for igniting the combustible mixture. The ports 23 are arranged in opposed parallel rows wherein each port is in substantial alignment with its corresponding port in the opposite wall of combustor 19. Each port has associated therewith flow control means which as shown comprises spaced baffie or deflector members 28, the terminal portions of each baffle being in medial contiguous relationship with its adjacent port. The baffles 28 are substantially parallel with the longitudinal center line of the combustor 19 and are shown as having a length along the combustor walls equal to the diameter of the ports 23. The length of the battles may, however, be extended up or downstrea'rns or in both directions should it' be found desirable'to do so under certain operating conditions. It has been-determined-that the cooling; effect provided by the inlet jets: offsets to some extent the heat generated by the hot exhaust gases such that a thin metal sheeting ofapproximately 'to A3 inch thickproves adequate for use as the deflector or baffle means.

' due to the unrestricted exit or exhaust passage for the burned gases.

While FIGS. 3 and 4 disclose the-invention incorporated in a rectangular shaped combustor, the invention is not limited to any particular shaped combustor structure. FIGS. 5 and 6 show the utilization of the invention in an annular type combustor or burner 29 mounted w thin the housing or duct 30. A series of opposed ports 31 are formed in the upstream end 32 of the combustor 29 substantially removed from the closed cone-shaped end 33 to form the recirculation zone 34. Each pair of opposed ports located in the outer Wall 35 and the inner wall 36 of the combustor 29 are joined by baffle or deflector members 37 inthe-manner previously described in regard to the device of FIGS. 3 and 4. Here again, in the operation of the plant the control-ling and directing members 37 prevent interference and loss to the sides of the intake ports thereby eliminating the blocking action between the jets and providing for greater flow of air-fuel mixture through the recirculation zone 34'.

Obviously many modifications and variations of the presentinvention are possible in the light of the above teachings. It is therefore to be understood that within the" scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is' claimed is:

1. In combustion apparatus, a pair of mutually spaced walls closed at one end and defining a combustion chamber therebetween, said walls having a plurality of openings in registration with respect to each other for admission of combustible gas to the combustion chamber, baffle means disposed within the combustion chamber and extending between said pair of spaced walls and bordering on said openings, said baflie means connecting said pair of spaced walls and enclosing said openings at least on two sides thereof.

2. The apparatus defined in claim 1 wherein the baffle means are in substantial parallel relationship with the longitudinal center line of the combustion chamber.

3. The apparatus defined in claim 1 wherein the batile means comprises elongated plate members, the short sides ofs'aid -plat'e'membersbeing in medial contiguous relationship with its respective adjacent opening and having a length at least equal to the diameter of the opening.

4. A combustion-apparatus comprising a first Wall and a second wall, additional walls connected to said first and second wallsto form a combustion chamber therebetween, said first and second wall being in opposed spaced relationship to one another, a first row of ports in the first wall, a second row ofports in the second wall, the

ports in said first and second rows being in substantial registry, and battle members connecting said first andsaid second walls at points on opposite sides of registering ports.

5. A combustion apparatus comprising an annular inner wall and an annular outer wall, said walls being in spaced concentric relationship to form an annular combustion chamber having a closed forward end and an opened rear end for the escape of gases therefrom, said inner wall having a plurality of circumferentially spaced gas receiving ports therein, said outer wall having a plurality of circumferentially spaced gas receiving ports therein, each of said ports in the outer wall being in substantial registry with one of said ports in said inner wall to form a pair of opposed registering cooperating ports, said ports being spaced from the closed'end of the combustion chamber to define a gas recirculation zone therebetween, gas flow control means associated with each pair of opposed cooperating ports, said gas flow control means including a pair of spaced parallel baflle members extending between said inner and said outer walls adjacent each pair of opposed ports, the baffie members of each pair being spaced to position the members on opposite sides, and in close proximity to their associated port, said baffle members being parallel to the longitudinal axis of the combustion charn ber, theterminal portions of the battle members extending along the inner and the outer walls at least as far as each extremity of the associated port in the direction parallel to the axis of said combustion chamber, thereby providing a combustion chamber which prohibits interfiow of gases between adjacent pairs of opposed cooperating ports thus'permitting maximum circulation of gases into and out of the recirculation zone with resulting greater combustor performance.

References Cited in the file of this patent UNITED STATES PATENTS

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