US2942672A - Ram jet propeller - Google Patents

Description

June 28, 1960 c. A. SERRIADES RAM JET PROPELLER 2 Sheets-Sheet 1 iZYVEHfUF CdlldfA/Vf/IVE A 5520,4256

Filed Nov. 28, 1955 June 28, 1960 c. A. SERRIADES 2,942,672

RAM JET PROPELLER United States Patent RAM JET PROPELLER Constantine A. Serriades, 732 Bittersweet Place, Chicago, 11].

Filed Nov. 28, 1955, Ser. No. 549,360

Claims. (Cl. 170-1354) This invention relates to an improved type of jet propelled propeller structure. Specifically this invention relates to a jet propelled propeller structure having a twostage centrifugal flow compressor integral with the propeller hub as a means for supplying an additional velocity increment to air passing through the hollow blade portions of the propeller structure.

In conventional propeller driven aircraft, the propeller and engine are separate components in the thrust producing system for the aircraft. This independent unit type of construction has necessarily resulted in a power package of considerably great weight and bulk as compared to the weight of the propeller structure itself. The additional weight of accessories, control system, and a suitable gear reduction device between the propeller structure and engine, accounted for a very substantial part of the non-pay load weight of the aircraft. It thus becomes readily apparent that any proposed power system which could integrate the propeller and engine as a single structure would produce substantial weight savings due to the elimination of many of the separate drive and control components, necessary for the separate propeller-engine type of construction.

Various integrated propeller-jet propulsion systems have been proposed from time to time as a solution to the problems above mentioned,- but for the most part these systems have only been a combination of a conventional propeller and some form of separate jet propulsion device. A common example of this is the application of the ram jet engine to the tip of a propeller blade or rotor, such as is used in some experimental helicopters. Actually, most of the propeller-engine combinations currently in use are only a combination of a conventional propeller and jet engine, each unit retaining its individual form and function.

The present invention discloses an entirely novel form of integrated propeller-jet propulsion system in which the propeller structure itself becomes part of a jet engine. By thus integrating the component parts and functions of the formerly separate jet engine and propeller, substantial advantages result in the form of a great reduction in weight of the combination structure, simplicity of construction and maintenance, and an overall improvement in efliciency and control.

Briefly described, the present invention contemplates a generally conventional propeller structure having two or more hollow blades having an air inlet or series of inlets in the leading edge of one or more of the blade elements, substantially near the blade tip, and a jet exhaust outlet or nozzle in the trailing edge of one or more of the blade elements, serving to direct a jet exhaust out of the blade nozzle tangential to the blade path, as a rotative power source for the propeller.

The hollow hub portion of the propeller, in addition to retaining the blades in proper aerodynamic relationship and housing a pitch control device, also includes a twostage centrifugal flow compressor, receiving air from the inlet, or inlets, in one or more of the blades, thereby supplying an additional velocity increment to the air moving out of the second stage compressor toward the jet exhaust outlet in the rotative thrust producing blade. The compressor elements of the two-stage centrifugal flow com; pressor are preferably of the double-entry, back-to-back type, the outlet of the first stage compressor element feeding the inlet or eye of the second stage compressor element, though a single sided compressor blade cascade might be used in some particular installations. Air passing through the inlet and down the hollow blade toward the hub, will thus receive an additional pressure and velocity increment before passing through the jet exhaust outlet nozzle.

Provision is also made in the thrust producing blade element for the addition, mixing and ignition of fuel, as an additional means of augmenting the jet velocity out of the jet nozzle in the thrust blade element. Furthermore, a substantial velocity increment is added to the air in the thrust producing blade element as it moves toward the jet exhaust outlet nozzle, due to the centrifugal force effects from the rotation of the propeller assembly.

The provision for a two-stage centrifugal flow compressor in the hub of the propeller assembly also greatly extends the operating range and applications of the present invention, in that a much lower propeller speed can be maintained without danger of failure of the integral jet propulsion system, due to the large velocity increment imparted to the air as it passes through the two-stage centrifugal flow compressor in the hub of the propeller.

Thus it will be appreciated that the present invention discloses a novel type of combined propeller and integrated jet propulsion system which overcomes the disadvantages of excessive weight, bulk, control, and maintenance problems, usually attributed to a separate component type of construction, and at the same time presents an extremely versatile power package for conventional propeller driven aircraft. I

In addition, the present invention is easily adaptable or usable, as a supplementary or secondary power source with a conventional engine, where a wide range of operatingspeeds and flight conditions are expected. Use of the present invention in conjunction with a conventional engine would make possible a much smaller primary engine unit, the integral jet propulsion system of the present invention being adequate to maintain normal flight and cruising speed once a desired altitude is reached. Substantial fuel savings could be expected when using the instant invention in conjunction with a conventional engine, particularly at high altitudes, where the jet propulsion system becomes substantially more ellicient than a reciprocating engine.

The present invention will thusservefto increase the useful operating range, cruising speed, ceiling and generally add to the utility of -a conventional propeller driven aircraft when used as'a primary power source or in conjunctionwith a conventional engine.

lt is an object then of the present invention to provide an improved type of propeller utilizing an integrated jet propulsion system as a rotative power source,

Another object of the present invention is to provide an improved jet-propelled propeller structure, in which a rotary type compressor is utilized to additionally pressurize air moving through the internal passages of the propeller structure which form a jet flow passage thercthrough.

A further object of the present invention is to provide a method of imparting an increased velocity increment to air moving through the hollow internal portions of a propeller blade, which forms a jet propulsion flow passage, in addition to the velocity increase resulting from the centrifugal force of the blade rotation as the air moves toward a jet exhaust outlet in the blade tip.

a V 3 Anothefobject of the present invention is to'redu ce the'weight of the power=package of propeller "driven aircraft. 7 7

Yet another object of the present inventionis to provide'd anfimproved type of jetgpropelled propeller which overcomes the deficiencies*of the prior art where the-cen- ,g'inetype ofconstruction.

7 Many other obj ets and advantages of the present .in-

ventionwill Q become manifest te those '-versed in the art upon mal'ring reference :to the detailed description which follows and the accompanying sheets of drawings. thedrawings: v a

Figure l a somewhat broken elevational view, par-r tiallysectionaland diagrammatigwithsome parts omitted 'toshowjunderlyingparts; a

. Figure 2. is an enlarged fragmentaryview, partially sectional and diagrammatic, illustrating the compressor assembly in the hub; and

Figure Bis-1a cross-sectional view, with parts in elevation, palong theilineflIII-llL-of Figure 1.

As'shown on the drawings:

E'Intheembodiment "of the invention illustratedin' Figure :3

11, a 'threejbladedpropeller assembly is-shown, designated generallyby the, reference letter-P. V

* 'Thepropeller assembly P is comprised of-a hollowhub member 10, which receives a plurality of blades A, Band C. Theiblades A,B and C are'rotatablysecured itoithe hub'loso. as to permit a limited amount of angular C. A series of baflies or agitators 23 are positioned in the aceeleratingexhaust passage l'lc-immediately-downstream of the main fuel injector 21 to insure an adequate mixing of the fuel-air mixture entering the combustion chamber 18. 7

It will thus be appreciated, that the blades A and B form the inlets, and that the blade C for-ms the exhaust outlet, for an integrated jet=propulsion system in the propeller assemblysl. 7

It should further be appreciated thatt while a three bladed propeller assembly-shown=in Figurel having two inlet blades and asin glie'exhaust blade, many variations in the number:and, .arrangen enttof inletrand exhaust outlets are possible depending on the application of the principal invention. 1

Referring now to Figure 2 in conjunction with Figure 1, a two-stage centrifugal flow compressor assembly D a is enclosed in the hollow central portion of the hub memtheirfhub end withja centrifugalflow compressor-'assemblyi D in the'hub 10, and at'their' blade tipjend with a pair-Voftangential,airihletSQ OpslZa andILZb'and a tang'entialijet exhaust out1eti13c, respectively.

7 QThe blades A, B and C ,also include1leading edge portionsi14a-c and trailingedge portions 16a-,c. 'iThe air inlet 'scoopslza and 12b "are positioned in the outer ,peripheryof itheblades A an'djB, in the leading edge portionsll4a' and ,14b, respectively and serve-to turn ahigh velocity stream oftairlinto the radial, flow passageslla and 11b. A- plurality ofv fguide vanes 17a and 17b in the air"inlet's"12a and 12b, reduce the turbulence andienergy losses of theflh igh velocity air entering the.radial 'fiow passage 111a and 11b.

'jltrshouldbe appreciated that the radialfiow passages 'Iltz and 11b .are,soformed ;as tosminimize ductzlosses and the centrifugal forceefiects .on air in the passages .rr1oving .towardithe hub 10, due. to. therrotation of the ,ipropellertassembly-P.

"The" bladeQincludes theqietexhaust outlet13c in the Afflametholder :19, and spark gap, 20,-immediately up- ,stream of theicombustionrchaanberirm servewas a starting ,anfd mainfuelignitionmeans ion the jetcombustionproc essthe'eombustion chamberolii. .--A fuelinjectoror spray 12, 1, substantially: upstream oftthe flame, holder 19 her 10. The twostage centrifugal flowieompressor assembly -D is comprised of a pairof centrifugal rotors 26a and 26b, which-are in registry with the decelerating radial flow passages 11a and 11b, respectively, and receive 'initia'llypressurized'air therefrom. r

The'firs't-stage compressors 26a andi-26b =are*enclosed by a-pair'of volutes-27a and '27b,*the' compressors being preferably of the double entry type, 'but:it-should'-be understood that any other-type of compressor might be used depending on=the-particular--application of theprincipal'invention. A pairpf difiuser rings ZSa and 25b surround the compressors 26a and 26b respectively, and serve to initially impart a vortex flowto high'velocity air leaving the-vanes of-the-compressors 26a and 26b. The volutes 27a-and 27b' -are-so formed as to divide thejair fiow moving-down thepassages-Jla and 11b toward'the hub '10, so as to permit an axial entry into 'theifirst-stage compressor rotors 26a and-26b. Internal guide'vanes, notshown, arealso provided in thevolutes 27a and 27b *to minimize any losses around 'the compressor rotors 26a and 26b. t 7 The volutes 27a and-27bhave dilfuser' horns 28a and -28bzto providea pressurerecovery for high velocityair leaving the compressors which alternately communicate -with either eye of a a second-stagecompressor rotor 29,

so as to form a two-stage compressor assembly.

The second stage compressor rotor 29 similar tothe first-stage compressors 16a and-26b but is slightly. larger to accommodate .the discharge offboth of the ljrst-stage -compressors when-'soperating at fulloutput. A diffuser ring '30 similar to the diffuser ringsigsiz andjZSb, surrounds the -second stage compressor129 and also serves 'to initially channel the fiowfr'romlthe coruprefifiotfi into a r unding-wi ter 31. .Arl ra ityp intern r ui vanes in the volume"31,-riot shown, also serve'to any duct losses. around the. compressor rotorjfl;

V diffuser m'3 ommun c te withth t ese sra ns *flo pa age c i t eb adei tan tprov de a pr ssur recovery for i elo y ai d scharg n t r t It .will thus be appreciated that ,the twostage com- 'p bly."Dimthe;hub mipr vidc ia su s an ia velocity increase to air at jtheh ublil in the.decelerating flow passagesdla and'llb, aboutto enterlhe accelerattseryes as the.niainQfuelsupplysource, and-receives,fuel' "connecting conduits'gzlin thesolidgportion f .theblade ing flow passage 1 1c. 7

It will further;beappreciate rtha lthspr vi q tc th rstag comp s semblylDis .only h w byw y ofrpre rr d ampl wh r th p qpe n meturej P wil ;.be operated at comparatively; slow ,speeds. or under high 1 load conditions,oan d that a propellerlstructure incorporating more, or less than ,a two-stage, three-compressor .ar- Ians ment, r sam other combi io th r of m ht 'prove more advantageous for a particular installation depending on the 7 application and ,operating conditions tconffimplated. a r j a ,,Aneathe pressur dth h vi 1Q ty-..ai haszenteredvth iac eleratingflcmpa as tl ai tth lbladekkarredetwquantity of fuel will be metered into the flow from the fuel injector or spray 21. As the air continues to advance toward the blade tip, it will receive an additional velocity increase and mixing action due to the centrifugal force effects of the blade rotation. The baffles or agitators 23 will further mix the fuel-air mixture until it is ignited by the spark gap 20. A flame front, established by the ignition from the spark gap will then ignite bleed fuel in the flame holder 19, which then acts as a continuous primary ignition source for the fuel-air mixture entering the combustion chamber 18.

A plurality of cooling ducts or bleeds may be provided around the combustion chamber 18, in the leading edge portion 14c in the event conduction cooling to the atmosphere does not prove adequate.

Referring now to Figure 3, an enlarged cross-sectional view of the hub and second-stage compressor is illustrated, in conjunction with the propeller assembly accessorres.

In Figure 3, the second-stage compressor 29 is shown fastened to a shaft 33 which is journalled for rotation at one end by a bushing 34 in the volute chamber 28b and hub 10, and by a bearing assembly 36 at the other end of the hub member 10. A planetary gear 37c is secured to the shaft 33 and engages an internal sun gear 38 in the face of an accessory support member E, adjac'ent the hub 10. As the internal sun gear 38 is rigidly fastened to the accessory support member E, rotation of the propeller structure P will induce a relative difierential rotation of the compressor rotor 29, thereby increasing the velocity increment of air received from the volute chambers 28:: and 28b.

The first-stage compressors 26a and 26b, are similarly splined or keyed to a shaft and planetary gear which also engages the internal sun gear 38 to provide a firststage compression for air entering the hub from the decelerating passages 11a and 11b.

It will be appreciated that an optimum gear ratio is provided between the internal sun gear 38 and planetary gears 37a-c so as to obtain the optimum interstage compression ratio for a particular propeller assembly and application.

The propeller assembly P is secured to a main shaft 39 by a series of fasteners 40 and is rotatably journalled in the accessory support member E by a plurality of bearing assemblies 41.

The main shaft 39 has a flanged portion 42 at its propeller hub end which includes an external ring gear 43. The ring gear 43 is in toothed engagement with a spur gear 44 which connects to a starter or accumulator S,

through a shaft 46, to initially rotate the propeller structure P until the jet propulsion system becomes operable. Suitable clutch means, not shown, disengage the starter S when rotation of the propeller assembly becomes selfsustaining.

An accessory drive gear 47 is secured to the main shaft 39 at its end opposite the hub member 10, by a plurality of fasteners 48. A fuel pump F engages the accessory drive gear 47 through a shaft 49 and spur gear 50. A generator or magneto G also engages the accessory drive gear 47 through a shaft 51 and spur gear 52, to provide a high potential spark to bridge the spark gap 20 in the blade C when starting the propeller assembly P.

The main shaft 39 is hollow and encloses a main fuel conduit 53, which communicates fuel from the fuel pump F through the hub member 10 and blade C to the fuel injector or spray 21 and flameholder 19.

A high potential spark conduit 54 is concentrically positioned within the main fuel conduit 53 and communicates a high potential current from the generator G through the hub member 10 and blade C to the spark gap 20.

It will thus be appreciated that the accessory support member E compactly houses the necessary accessories for the operation of the integral jet propulsion system in the propeller assembly B so as to permit ease of maintenance, servicing or replacement, and at the same time allowing greater space for a useful pay load.

It should further be appreciated that if the present invention were utilized in conjunction with a conventional engine, as a supplementary or stand-by power source, many of the accessories and controls shown in Fig. 3 could be eliminated as they would be present in the primary powersupply, thus making possible even greater weight savings and compactness.

It will be understood that many other modifications and variations may be efiected without departing from the scope of the novel concepts of the present invention.

1 claim as my invention:

l. A jet propelled propeller structure comprised of at least two hollow radial blades extending from a central hollow hub member and circumferentially spaced with respect to one another, leading and trailing edge portions on said blades, an air inlet in the leading edge of at least one of said blades remote from said hub, a jet exhaust outlet in the trailing edge of at least one other of said blades, a combustion chamber also in said trailing edge communicating with said exhaust outlet, a radial flow inlet passage in the hollow internal portion of at least one of the blades registering with the inlet in said blade, a radial flow outlet passage in the hollow internal portion of at least one other of the blades registering with the jet exhaust outlet in said blade, said radial flow inlet and outlet passages communicating with the hollow hub member, at least one first stage centrifugal flow compressor in said hub member having an inlet and an outlet, at least one second stage centrifugal flow oompressor in said hub memberhaving an inlet and an outlet in series with said first stage centrifugal flow oompressor, means communicating the inlet of said first stage centrifugal flow compressorwith a radial flow inlet passage, means communicating the outlet of said second stage centrifugal flow compressor with a radial flow outlet passage,. means communicating the outlet of said first stage centrifugal flow compressor with the inlet of 'said second stage centrifugal flow compressor, means in said hub member for supplying fuel to air flowing through said radial flow outlet passage, and means for igniting said fuel to'produce a propulsion reaction in the combustion chamber and a jet exhaust out of said jet exhaust outlet thereby causing said propeller structure to rotate.

2. A jet propelled propeller structure comprised of a hollow central hub portion, a plurality of hollow radial blades extending from said central hub portion having at least one tangential air inlet remote from said hub portion and at least one tangential jet exhaust outlet in one of said blades and forming a jet flow passage in another of said blades, said hollow blades forming a flow passage for air moving axially through each of said blades toward the jet exhaust outlet and subjecting the air to the acceleration effects of the centrifugal force induced by the rotation of said propeller structure, said central hub portion enclosing a two-stage centrifugal flow compressor system, at least one first stage centrifugal flow compressor registering with a radial flow passage in one of the blades and receiving air therefrom, at least one second-stage, centrifugal flow compressor registering with a radial flow passage and receiving initially compressed air from said first stage centrifugal flow compressor, and fuel addition, mixing, means supplying fuel to air flowing through said blades, and means for igniting said fuel to increase the jet velocity of air moving tengentially out of said jet exhaust outlet causing the propeller structure to rotate.

3. A jet propelled propeller structure comprising a plurality of hollow radial blade members extending from a central hub member and forming a radial jet flow passage therethrough spaced inwardly of the leading and trailing edges of each of the blades, leading and

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