US2836063A - Apparatus for generating fluid at hypersonic speed - Google Patents

Description

y 7, 1958 Y. A. YOLER ETAL 2,836,063 APPARATUS FOR GENERATING FLUI D AT HYPEiRSONIC SPEED Filed Feb. 28, 1956 2 Sheets-Sheet 1 [r5 ver? tor: Yusu Vo/er' 7/7/r' tit-own e y.

ay 27, 1958 Y. A. YOLER ETAL 2,336,063

APPARATUS FOR GENERATING FLUID AT HYPERSONIC SPEED Filed Feb. 28, 1956 2 Sheets-Sheet 2 [r7 ven for:

and

The/P Attorne APPARATUS FOR GENERATING FLUID AT HYPERSONIC SPEED Yusnf A. Yoler and Henry T. Nagamatsu, Schenectady,

N. Y., assignors to General Electric Company, a corporation of New York Application February 28, 1956, Serial No. 568,947

16 Claims. (Cl. 73-147) This invention generally relates to improvements in hypersonic flow generators and more particularly to an improved apparatus for propelling fluids at extremely high velocity for the purpose of studying their behav1or under these conditions and their interaction with bodies moving through them.

Hypersonic flow generators, which may be defined as devices employing shock waves to propel fluids at hypersonic speeds (at mach numbers greatly in excess of 1), have been heretofore employed to study the behavior and properties of such fluids at these speeds and their interaction with bodies, such as flight vehicles, traveling through such fluids. Known devices of this type have been of the single nozzle variety employing an explosion for generating a shock wave in such a manner as to propel a fluid, such as gas, through a single nozzle or the like at high speed over a stationary flight vehicle model. However, with such devices, it is diflicult and time consuming to study difierent models or the same model with different fluid speeds, since the generator must be shut down to insert the new model or to change the nozzle for obtaining different flow speeds. Furthermore, it is difficult to reproduce the same conditions in succeeding tests using different model shapes or to simulate different controllable conditions of flow with the same model since each test requires the generation of a separate shock Wave by an explosion whose characteristics may vary.

To overcome many of these' disadvantages in accordance with the present invention, there is provided a unique apparatus that employs a shock wave in a new and different manner to impart great compression and heat to an essentially stagnant fluid. The energy thus imparted to the stagnant fluid is thereupon transformed into the desired high speed flow through a plurality of separate nozzles rather than through one nozzle as in the prior arrangements. By this unique process and apparatus, it is evident that the difiiculty of simulating the same or different conditions in succeeding tests is obviated, since a number of models can be tested simultaneously under the same conditions with each explosion or different flow speeds can be obtained using like models and employing different nozzles. This is accomplished by utilizing a shock wave to store energy in an essentially stagnant fluid and employing means to thereafter convert this stored energy to energy in the form of high speed flow, rather than directly employing a shock wave to propel the fluid as is the present practice.

It is accordingly one object of the present invention to provide an improved apparatus for propagating fluid at hypersonic speeds for a relatively long time duration.

A still further object of the present invention is to provide a less expensive and more accurate apparatus for simulating the movementof an object through a fluid medium at hypersonic speed.

Still another object of the present invention is to provide an improved apparatus for simultaneously simuice lating the movement of a plurality of like or unlike objects through a fluid medium at like or unlike hypersonic speeds.

Other objects and many attendant advantages of this invention will be more readily comprehended to those skilled in this art upon a detailed consideration of the following detailed specification taken with the accompanying drawings wherein:

Fig. 1 is a perspective view illustrating one preferred apparatus in accordance with the present invention, partially in disassembled relation,

Fig. 2 is a sectional view illustrating the preferred structure for the nozzle and tube arrangement of Fig. 1,

Fig. 3 is a perspective view illustrating one preferred coupling arrangement of Fig. 1, partially in section,

Fig. 4 is an enlarged view similar to Fig. 2, partially in section, and

Fig. 5 is an elevational view of portions of the preferred structure of Fig. 1, partially in section.

Referring now to Fig. 2 for a detailed consideration of one preferred process and apparatus for performing this process, in the first step a combustible material, such as any one of a number of gases, within a suitable container 10 is introduced into a sealed driver tube 11 through suitable piping 12 and valves (not shown). An

oxidizing agent, such as oxygen, within a companion con tainer 13, is also introduced into this tube 11 through piping 14 to provide the desired explosive mixture within the sealed driver tube 11. The sealed driver tube 11, as shown, may preferably be comprised of a hollow cylindrical tube, of relatively thick wall construction, having a diaphragm member 15 sealing one end thereof and a second diaphragm 16 sealing the opposite end thereof.

In the second step, this mixture is ignited by firing'a spark plug 17 or the like causing this combustible mixture to explode. This explosion ruptures diaphragm 16 and propagates a strong incident shock wave down the length of an elongate hollow driven tube 18. This shock wave, traveling at high velocity, compresses and heats the fluid, such as air, initially within the driven tube 18 and sets this gas in motion. Continuing down the tube this shock wave then ruptures a third sealing diaphragm 19 at the opposite end of the driven tube 18 and enters a nozzle chamber, generally designated 20.

After entering the nozzle chamber 20, the incident shock wave is reflected from the walls of this chamber and back into the driven tube 18 further compressing and heating the gas in the driven tube and stopping its forward movement. In this step, the compressed and heated gas moving down the driven tube meets the returning shock Wave moving in the opposite direction; and

as this shock wave travels through this gas it stops the forward movement of the gas and further compresses and heats the gas. As a result this gas within the nozzle chamber is highly compressed and heated to temperatures in the order of 20,000 degrees C., but is substantially stagnant in condition.

In the following step, the considerable energy imparted to this gas by compression and heat is transformed into a high velocity flow at hypersonic speed by means of the expansion of this highly heated and compressed gas through a plurality of Venturi type nozzles 21, 22 and 23 opening from the nozzle chamber 20. Since this gas is for all practical purposes at stagnant condition within the nozzles may be positioned either axially or radially with,

respect to the driven tube 13 and chamber 20 permitting the use of a number of the same or different nozzles and the simultaneous study of the same or diflerent hypersonic flow speed over a number of the same or differently Patented May 27, s

shaped aerodynamic models 24, 25 and 26. Each of these models 24, 25, and 26, as shown, may be suitably mounted on a removable prod 27', 28, and 29 to be removably positioned within an expansion chamber 30, 31, and 32, respectively.

In the finalstep, the arrival of cold .rarefaction waves:

I back into the driven tube 18 frornrthe nozzle walls of chamber 20, the total nozzle throat area, or the openings of the nozzles 21, 22- and 23 leading into thetnozzle chamber 20, are made su fliciently small referenced to the cross sectional area, of the driven tube 18 such that the flow velocity of gas behind the reflected shockvwave can be kept at a very low value relative to the local speed of sound. This enables the compressed and heated gases within the nozzle chamber20 contained behind'the reflected shock Wave to be maintained at practically stagnationconditions, as desired.

The'available testing time of the hypersonic flow of fluid over the models is dependent uponthe length of the driven tube 18 and the loss of time resulting before the compressed and heated stagnation gases are converted to hypersonic speeds through the nozzles. This latter time which may be termedthe flow starting process time is controlled by the mass of gasinitially in' the Venturi' type nozzles which must be removed before flow can be established. Consequently this time can bereduced by suita bly evacuating the chambers 30, 31, and 32 to a relatively' low vacuum prior to operation.

To reduce disturbances in the flow of fluid through the driven tube 18 and into chamber-20, the diaphragm 19 is preferably chosen to rupture easily.

To-further control the hypersonic fluid flow to be gen-' erated-into the chambers-30, '31, and 32', thepressure of the combustible mixture in the driver tube 1! and the initial gas pressure in'the' driven tube 18 are adjusted and controlledso as to produce'the desired free Tflighttype stagnation conditions;

and associated equipment in accordance with the present invention. As shown, the driver tube 11 is supplied with a combustible mixture from tanks 10 and 13 through suitable piping. This driver tube 11 is connected to an elongate driven tube18 but separated therefrom by a diaphragm, generally shown as 16, within a coupling 39. The far end of the elongate driven tube 18 is connected to a nozzle chamber 20 but separated therefrom by the diaphragm generally designated 19 within a coupling 40. Extending outwardly from the nozzle chamber 20 are the three nozzles 21, 22 and 23, which in turn lead into the chambers 30, 31, and 32.

To eliminate or to minimize any loss of time incurred in the flow starting process from the nozzle chamber into the nozzles, it is desired to evacuate the initial air within the nozzles 21, 22 and 23 to as low a vacuum as practically feasible prior to operation of the generator. For this purpose, each of the chambers 36, 31 and 32 is connected to an evacuation tank 41, 42 and 43, respectively. For ease of replacing or servicing the nozzles, chambers, piping and the like, each of these nozzles, together with their chambers and evacuation tanks are mounted upon a slidable platform 44, 45 and 46,, respectively, adapted to reciprocally slide over pairs of fixed,

rails 76, 47, and 48, respectively. Each of these tanks 41, 42, and 43, are connected by means of suitable evacuation pipes 49 to avvacuurn pump or other suitable evacuation means 50 driven by motor 51. By this arrangement it is observed that not 'only can the nozzle throat section be removed without movement of the complete platform, but that the complete nozzle, chamber, and evacuation tank may all be disconnected and removed from' the nozzlechamber 20 for servicing, repair or' changeover of parts as desired.

, The Venturi typenozzles- 21, 22, and- 23' maybe at tached directly to-the far end-of thedriven tube 18,ior

as shown may be attached to a separate'nozzle chamber 20., use of three nozzles, it is believed-evidentthat many more nozzlesmay be fastened to the end of the driver tube.

The hypersonic speed of fluid flow over the models 24',

throat; sections to the mainnoz-zleat'one'end and to the nozzle chamber 20 at the otherend, it is observed that these throat pieces may be slipped in and out of place .without removing or moving either the nozzlechamber 20 or the main nozzle structure itself, thereby permitting the substitution of different throat. diameter sections in all or anyone of the nozzles and enabling, the generation Although the -preferred embodiment discloses the of'difierent hypersonic fluid-flow speeds 'overthe models as desired. Although any of the known .t'ypes'of' two sand/or three dimensional nozzles and contoursgrnay -be' employed in accordance with the present'inventiom'it is preferred to usethesirnplecone type 'of'nozzle construction, as shown;

Referring now to Fig. 1, there is shown an overall perspective view. illustrating onepreferred fiowgenerator.

, forces generated For materials testing purposes and'for the use of this generator for studyingcertain chemical reactions, it is desirable-to produce a 'square wave change in the temperature after the'explosion. The incident or the reflected shock provides afvery sharp jump for the beginning of such'aisquare wave changezin the explosive temperature but in the usual generationof a shock, the. tail of the 'squarewave is usuallyformed by the reflection of rarefaction waves-from the closed end of the driver tube, and

hence the cooling takes place gradually. The tail of this wave can besteepenedconsiderably by causing a strong 7 expansion Wave to form at some point in the driver tube.

For this purpose, a quenching generator generally desig-.

nated' 52 is provided to send out a strong quenching wave to'end the hot flow at the model after a predetermined time interval, .As discussed above in connection with Fig. 2, this quenching generator is separated from the driver tube 11 by means of the diaphragm 15. Consequently when it -'is desired to generate this quenching expansion wave, the'explosion ruptures this diaphragm 1 5' propagating an expansion wave down the tube and forcing 'gase'sinto the quenchingtank. This quenching generator may also serve as a safety enclosure for dissipating-excessive pressures which may develop upon the ex-. plosion taking place 7 For thepurpose of. observing and recording the behavior ofthe'compressed, andv heated gases within the nozzle chamber 20,, this chamber (Fig. 4) may bepreferably formed with suitable window opening 53 comprised of a suitable. frame54 housing a transparent window of-iglas sfquartzior other suitable material properly made to withstandthe: temperatures,rpressures and shock As also may berobservedifrom-iFig the second diaphragmfmember '19 separatingthe: driven tube 18 from the nozzlelchamber 20 may be separately inserted between interlocking sections 55 and 56 which'are housed between the connectionofethe drivenitube '18 and the nozzle; chamber 20. By this arrangement; the, second'diaphragm 7 19f rnaybe installedbetweeri'these two sections 55 and 56 outside of the tube while an additional diaphragm assembly is installed in the tube ready for test. a

In known generators for propagating fluid flow at supersonic and greater speeds, the flight models are usually mounted directly upon some member which is an integral part of the construction, such as a nozzle wall. One of the serious difiiculties encountered with this arrangement has been the parasitic noise and errors introduced into measurements by strong vibrations and transmitted to the model through its connecting support. In accordance with the preferred structure of the present invention, this difliculty is eliminated by mounting the model upon a prod 27, which, in turn, is supported upon a suitable strong frame member 59, located outside of the evacuation tanks. This prod projects inside the tanks and expansion chamber through an expandable and contractible soft bellows 6i suitably sealed to prevent the entry or escape of the gases into the evacuation chamber. By means of a suitable window 53 in the nozzle test section the model may be observed from outside and any detected eifect taking place during hypersonic fluid flow over the model can be recorded and/ or measured.

This support and bellows arrangement additionally enables insertion or removal of the model as may be necessary for making changes in the model, changes in the instrumentation, wiring and the like and for positioning the various portions of an elongate aerodynamic model in line with the test section window 58. Additionally, the electrical wiring associated with anymeasuring instruments on the model may be removed from the tank through a suitable opening in the prod 27 (not shown), if desired.

As best shown by Fig. 5, this elongate prod 27 may be slidably mounted within upright openings of a frame 59, having a U-shaped cross section, and positively engaged at one end by a clamping member 61 whose opposite end is connected to a threaded nut 62. This threaded nut is rotatably engaged by a threaded shaft 63 driven by a motor 64 or the like whereby upon rotation of the motor and corresponding rotation of the threaded shaft 63, the nut and clamping member ride back and forth reciprocally along the threaded rod moving prod 27 and the aerodynamic model further into or out of the generator, as desired. By this arrangement, the aerodynamic model may be positioned, inserted, or removed from the generator as desired without moving either the nozzle, expansion chamber, or the evacuation tank.

To enable the ready insertion and removal of the main diaphragm 16 in accordance with the preferred structure of the present invention, this diaphragm is preferably held in place by means of a floating collar arrangement, generally designated 39, adapted to slide over the driven tube. Both the driven tube 18 and the driver tube 11 are preferably fixed upon rigid foundations. The end of the driver tube 11 has an outstanding flange 65 suitably notched at 66 and 67 as shown to receive bolts from the floating collar assembly. Connected to these bolts, peripherally mounted around the outstanding flange or collar, are a plurality of hydraulic cylinders 68 whose piston rods are connected to these bolts engaging the collar. Upon actuation of these hydraulic cylinders, the rods 69 connected thereto are withdrawn into these hydraulic cylinders or moved out of these hydraulic cylinders thereby sliding this movable collar arrangement 39 away from or against the end of the driver tube 11 thereby sealing or unsealing these units. As is now evident, the diaphragm 16 is preferably inserted at the end of the driver tube 11 whereby movement of this collar 39 to seal the members together sandwiches the outer periphery of this diaphragm between the end of the driver tube 11 and the collar shoulder 39'.

Thus it is observed by means of the process and preferred apparatus of the present invention, there is generated by means of a unique reflection technique a mass of stagnant fluid under high compression and at extremely disconnecting said first and high temperature. Utilizing this stagnant gas, studies can therefore be made of transientphenomena and relaxation effect caused by strong shocks, effects of dissociation of gas, ionization and recombination, other chemical reactions in air, spectroscopic studies of atomic and molecular structure and heat transfer and radiation from hot gases and the like. All of such studies would be made principally in the stagnation region behind the reflected shock at the end of the driven tube.

In addition, it is evident that investigations and studies may be made simultaneously of fluid flows about a plurality of models under conditions simulating those encountered by high speed vehicles in free flight at hyper sonic speeds at various altitudes. Measurements and investigations can also be made of overall forces such as drag, lift, moments, and pressure and heat transfer distributions at various flight attitudes and simulated flight altitudes. Qualitative investigations may be additionally made to yield information on shock wave shape and location, luminosity around the flight model, boundary-layer transition, separation, boundary layer-shock wave interactions and the like. In addition to these studies, the generation of gases at high temperatures, pressures and speeds permits the testing of electromagnetic wave propagation through mediums under these conditions including such studies as measuring certain properties of ionized gases and gas discharges by microwave techniques.

Although one preferred process and preferred apparatus for carrying out this process have been illustrated and described in detail as required by the patent laws, it is evident that those skilled in the art may make many changes and variations without departing from the spirit and scope of this invention. Accordingly, this invention is to be considered as being limited onlyin accordance with the following claims appended hereto.

What is claimed is:

1. In a device for generating fluid over a plurality of paths at hypersonic speed, a first container having an inlet and outlet, a second container having an inlet and outlet, the inlet of the second container being connected to the outlet of said first container, connected, rupturable means sealing the contents of the first container from the second container, second rupture means sealing the outlet of the second container, said second container being filled with air at predetermined temperature and pressure, means for generating a shock wave within said first container to move down the length of the first container and burst said rupturable means and pass down said second container, thereby compressing and heating the air within said second container and moving this air down the length of the second container as it passes therethrough, a plurality of energy converting nozzles opening from the outlet of the second container, said second container including means proximate the outlet thereof for reflecting the shock wave therefrom to further heat and compress said fluid and render said fluid non-moving as the reflected shock wave again passes therethrough, whereby the energy contained in the compressed and heated non-moving fluid is converted into flow of said fluid at hypersonic speeds along a plurality of separate paths through said nozzles.

2. In the device of claim 1, a plurality of moveable supporting members, one for each of said nozzles, with each member adapted to support a flight model, and

means including a flexible bellows associated with each moveable supporting member for enabling each of said supporting members to be inserted into or removed from its associated nozzle while sealing said nozzle against the escape of said air.

3. In the device of claim 2, means for evacuating the air within said nozzles prior to saidexplosion to a predetermined condition. 7

4. In the device of claim 3, means for connecting and second container in 'a fluid tight manner, said means including a joining member rupture to seal said containers from one another and its 1 ready replacement after rupture. V

5. In a device of the class described an elongate housing for containing a fluid and having plurality of openings at one end thereof with the total opening area being considerably smaller than the cross sectional area of said incl'osure, a plurality of energy converting nozzles, each nozzle being connected to said housing with its opening in alignment with adiflerent one of said openings in said housing, means for propagating a shock wave within said housing to travel down the length of said housing toward said nozzles and thereafter be reflected from the end of said' housing, said shock wave highly compressing and heating. fluid'within' said housing and rendering said fluid non movin'g in the vicinity of said nozzles, thereby enabling the generation of said fluid at hypersonic speed through each one of said plurality of nozzles;

6'. In a generator for producing airflow at hypersonic speed, means'for compressing and heating the air-to extremely high temperatures and at substantially stagnant conditions, said" means including a means for generating a shock wave, means for confining said shock waveto travelthrough said air in a direct path andagain travel through said air ina reflected path, and a plurality of meansfor venting saidhighly heated and compressed stagnant air in a plurality of separate paths, each said means comprising-.an-- energy converting nozzle having a mouth opening in contact with said compressed and heated air.

7. In the apparatus of claim 6, each of said nozzles including'a removablethroat section for receiving said stagnant air and a nozzle body connected thereto, said throat, section being constructed to control the rate of expansion of. the air therethrough and the corresponding speed offlow-of this air through the nozzle body, whereby the flow speed of any one of said paths may be'readily varied by the substitution of a differently constructed throatisection.

8.: Inia device for generating fluid along a plurality of paths at hypersonic speeds, a first hollow tubular member, a secondhollow'elongatemember having an open inlet anda substantially closed-end wall, a removable coupling interconnecting said first member with the inlet of the second memberand providing a fluid tight seal therebetween, rupturable means associated with said removable coupling for providinga fluid tight seal between said first and second members, a plurality of energy converting nozzles openingirom the end'wall of said second tubular member, and means-for generating a shock wave within said first member: to travel down the length of'said first and second members and be reflected from the end wall of said second member.

9. In a device for generating fluid along a plurality of paths. at hypersonic speeds, a first hollow member, a second elongate hollow member having a plurality of openingsat one end thereof, disengageable coupling'means interconnecting said meinbersin'a fluid tight joint,first rupturablezmeanls engaged by said couplingin its'sealed positionlfor providinga flu'id 'tightseal bet-ween said'first' andsecond; members, second rupturable means positioned withlrespect to'saidsecondhollow member to 'piovidea fluidi tiglitseallbetweenthecontents of theisec'ond member and the openings at the end thereof, a plurality of energy converting: nozzles opening from the unconnected end ofixsaidmecond member, each nozzle being'aligned witha difierent one of said openings, and means for generatingm shoclcwave within said-first member to travel .9%? the length; of said-"first" and second members after connected thereto, said throat section being constructed bursting said first and second rupturable means and being reflected from the end or said second member.

10. In a device for generatin fluid along a plurality of paths at hypersonic speeds, a first hollow member, a second hollow member, said second member including an elongate hollow body and a substantially enclosed end section connected thereto having a plurality of openings therein, a first disengageable coupling interconnecting said members, a first rupturable means engaged by said first coupling for providing'a fluid tight seal between said members, a second rupturable means separating said hollow member and end section for providing a fluid tight seal therebetween, a plurality of energy converting nozzles opening from the end section, each nozzle being in alignment with a difierent one of said openings, and means for generating a shock wave within said first member to travel down the length of said first member, body and end sectionand be reflected by said end section backwardly into said body and first member.

1l. In the device of claim 10, a plurality of movable supporting members, one for each of said nozzles, with each member adapted to support a flight model, and means for inserting or removing each of said supporting members into or out of its associated nozzle while'pro viding'a fluid tight seal between said movable supporting members and said nozzles. I

12. In the device of claim 11 means for evacuating said nozzles prior to'the generation of said shock wave.

'13: In the" device of claim 12, each of said nozzles including a removable throat section and a nozzle body toicontrol the rate of expansion of fluid therethrough and the corresponding speed of flow of this fluid throngli'the nozzle body, whereby the flow speed through any one of said nozzles m'ay'be readily varied by the substitution of a differently constructed throat section.

14; In adevice for generating fluid flow at hypersonicsp'e'ed; an elongate chamber containing a fluid, means generatin a strong shock wave down the length of the chamber to initially heat and compress the fluid therein, said chamber including means for reflecting the shock wave from the opposite end thereof to again heat and Compress said fluid duringits reflected travel and render said fluid substantiallyv non-moving, said chamber being,

provided with a plurality of openings in the vicinity of the reflecting means thereby enabling the expansion of' said compressed and heated fluid through said plurality of openings to transform the extreme energy contained in said non-moving fluid into flow of said fluid at hypersonic speeds, the total area of said openings being considerably smaller than the cross-sectional area of said chamber.

15 In an apparatus for generating fluid flow at hyper sonic speed, an elongate container containing a fluid; means propagating a shock Wave to pass down the con tainer'toheat and compress the fluid and set this fluid-in motion as it passes therethrough, said container including means at the opposite end thereof to reflect such shockwave in adirection opposite to said moving fluid to again heat and compress said fluid while rendering the fluidsubstantially non-moving as it again passes 'therethrough,

said containeriforming a plurality of openings at the opposite end thereof for enabling the expansion of said compressed and heated fluid through said plurality of tube containing air and having inletancl outlet ends there: of, means propagating a shock wave to travel down said;

tube toward saicl outlet and to heat and compress the air 'thereina'n'dpropel thisair down the length of the tube,-

saidtube including imeans at the outlet end thereofifor 1 reflecting sfaid' shockw'av'e to move in-a direction oppcy site to the propelled air to again heat and compress the air as it repasses therethrough, thereby stopping move ment of the air in the vicinEty of the reflecting means thereof to provide a mass of stagnant air under great compression and high temperature, said tube being formed with a plurality of openings in the vicinity of the reflecting means to enable the expansion of said compressed and heated air therethrough at hypersonic speed.

References Cited in the file of this patent UNITED STATES PATENTS Bodine Mar. 6, 1951 Anderson Apr. 24, 1951 Whitener June 11, 1957

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