Патент USA US3099152код для вставки
July 30, 1963 H. GARTEN ETAL 3,099,141 SHAFT FOR USE IN NUCLEAR RADIATION ENVIRONMENT Filed Nov. so, 1961 ' P _ Ill [lll Illl lll/Ä 'f Y' -. f ' 'Y fr Y ` l Í -- Illl lll lill/[IIIA ?' WMM/_MM United States Patent O ” 1 3,099,141 SHAFT FOR USE IN NUCLEAR ‘RADIATHÜN ENVIBGNMENT Herbert Garten and Robert Herman Schaffer, Cincinnati, Ohio, assignors to General Electric Company, a corpo ration of New York Filed Nov. 30, 1961, Ser. No. 156,189 S Claims. (Cl. 64-1) ßßgìldl Patented July 30, i963 2 fins) integral therewith, the tin being in the form of a helix having a predetermined angle and direction, the ratio of the total fin mass to the total mass of the member, excluding the iin, »also having a predetermined value, wherein the fin acts as a load-transmitting member itself, thus pr-oviding maximum load carrying capability with minimum total shaft weight and heat generation in the nuclear radiation environment. >FIGURE l is a longitudinal view of the shaft, partially in cross section, in combination with a nuclear radiation This invention relates to a torque-transmitting member, 10 source; and, more particularly, to a shaft for use in a nuclear FlGURE 2 is a yview taken along line 2--2 of FIG radiation environment wherein heat induced in the mem URE `l; ber by radiation is substantially proportional to the mass FEGURE 3 is a segment o-f a helical lin in cross section of the member. taken along line 3--3 in FIGURE 1 showing the relation Recent studies have proven that nuclear flight at sub 15 ship of the depth and pitch of the tin; and sonic, and possible supersonic speeds is feasible. These FIGURES 4, 5, 6, 7, and 8 are 4graphical representations studies have primarily been concerned with two different of -certain parameters governing the design of the inven avenues of approach for a nuclear powered aircraft jet tion. engine, namely, an “indirect” cycle and “direct” cycle con Referring now more specifically to FIGURES l and 2, 20 figuration. In an. “indirect” cycle nuclear .turbojet air indicated generally by -numeral il@ is a tubular member, or craft engine the nuclear radiation source, or reactor is shaft. The tubular member, or shaft is preferably of one placed off to one side «of the engine and the conventional piece construction and is adapted to transmit rotational chemical combustion chamber heat source is replaced by a force, or torque between a driving component and a driven large radiator. The radiator is kept hot by a closed-loop component (not shown). For example, in >aircraft ap 25 heat transfer system in which a flu-id is circulated through plications the shaft may find use in a nuclear turbojet the reactor and into the radiator and back to the reactor. engine wherein in the usual manner one or more com On the other hand, in the “direct” cycle configuration the pressors are driven by one or more turbines downstream reactor replaces the normal chemical `fuel combustion of the compressor. As seen in the drawing, the shaft ex chamber of the turbojet engine and the engine airiiow and tends through a nuclear radiation field, in this instance, a the compressor power shaft pass through the reactor. 30 reactor. The shaft is a hollow, preferably cylindrical, Thus, a direct cycle nuclear turbojet engine may be de seamless member, and includes a shell portion Ztl and a scribed as an “in-line” engine, with the coupling shaft be plurality of iin portions 5b. The shaft wall, or shell thick tween the compressor section and the turbine section of ness tS is preferably relatively small so that the shaft, for the engine passing through the center of the reactor, or a given diameter and length, can be more easily cooled. 35 nuclear radiation source. As pointed out, when a metallic member, in particular, As in the conventional chemically fueled turbojet air is used in la nuclear environment Iit will be subject to craft engine, the shaft must transmit both a torque load nuclear radiation such that heat is lgenerated in the mem and an axial -load. However, contrary to the situation in ber, in this case the shaft lili. The heat so generated the conventional engine where a nuclear heat or radiation will be substantially proportional to the mass of the metal 40 source is not present, heat is lgenerated in -the shaft as it in the member. While the mass MS of the shaft 10 has passes through the reactor, the amount of which is sub been significantly reduced by the descri‘oedV thin-walled stantially proportional to the mass of the shaft. While configuration, it will be apparent that with a given power cooling air may be directed against the shaft in any one transmission requirement a certain degree of structural of a number of known ways, this may not be enough to strength in the shaft will still be required. Thus, the ofi-set the increased heating effect of the nuclear radia 45 problem, as stated, is to provide sufficient power, or load tion. Thus, contrary to the normal application where transmission capability (in the case of a turbojet engine, there is no limitation against strengthening of the shaft by torque load and axial load) with minimum weight in the simply increasing its mass, or weight, in a direct cycle nuclear radiation environment. Since a heavier shaft will nuclear engine a heavier shaft will run hotter. This is run hotter and since metallic materials, especially, lose unacceptable because of fthe fact that the metallic mate their `strength with increasing temperature, the wall thick rials of which such shafts are usually constructed normal ness fs cannot merely be increased. ly lose their strength with increasing temperature. While As is well known, while a smooth shaft generally is it would -appear that the shaft could be strengthened mere most efficient in carrying a load, a finned shaftv of an ly by increasing its diameter, for a nuclear turbojet ap equivalent tot-al mass will run cooler, thus raising the al plica-tion this will be undesirable since any increase in shaft 55 lowable stress in the shaft. However, the actual stress in diameter will be `accompanied by a significant increase in commonly used finned shafts will be increased because the reactor overall diameter. This, in turn, affects reactor fins carry only an insignificant part of the load. This then shielding requirements adversely, so that the net result is raises the stress in the shell portion of the shaft as a result an intolerable overall weight increase. The problem, of the reduced masspthereof, since part of the original, or therefore, becomes one of providing, in a nuclear environ 60 equivalent mass has been converted to tins. However, if ment, a shaft capable of maximum torque, or power trans the increase in the ‘allowable stress exceeds this increase mission, the shaft being of `minimum diameter and weight, in actual stress, the use of such lins may be justified. But since increasing weight becomes self-limiting in the shaft, fins can only be justified in an airborne application if they it being clear that in any successful airborne application do useful work, i.e., if they aid in power transmission. 65 the total system weight is of critical importance. In other words, if lthe fins can be made to function as la Therefore, an object of this invention is to provide a shaft of minimum diameter and weight «for use with a nuclear radiation source, which shaft has a configuration `structural portion of the shaft and not merely as a means for cooling the shaft, they will justify their use. Thus, while it was known to provide a shaft with fins for the minimizing nuclear heat generation and temperature in the purpose of cooling, it was not, prior to the present inven shaft, the shaft providing maximum power transmission. 70 tion, readily apparent that the addition of fins to a shaft, 'In one embodiment, the shaft of the present invention which would seem at best a grossly inefficient way of in comprises a hollow, cylindrical member having a iin (or 3 3,099,141 creasing shaft strength, could solve the problem of increas ing the torque or load transmitting ability of a shaft in a nuclear enviroment, without unduly increasing shaft di ameter or weight. Therefore, with a fixed shaft `diameter and length, fixed flow rates and properties of the cooling ñuid utilized, if any, and a fixed internal heat generation rate for the nuclear radiation source through which the shaft must 4 design of the heat generation rise lbeing proportional to mass increase will be examined. FIGURE 5, as Well as IFIGURE 4, indicates that the iins can increase the «tern perature margin (a corollary «of load-carrying capacity in a nuclear radiation environment) significantly with predetermined increases in the MF/MS ratio within a certain range of values. Thus, by selecting an optimum value for the shaft weight, a maximum temperature mar pass, the inventors have devised preferred embodiments -gin may be obtained. In the example given for a shaft of the shaft determined by such parameters as the shape of the iin, or fins, 3€), the angle of the helix formed by 10 weight of 3 units, chosen as an optimum Ifor a smooth (unfinned) shaft, the best value of MF/MS is .5 since it‘ï each iin as it spirals internally of the shaft along the provides the greatest temperature margin (140°). It will shaft length, the direction of the helix, the :total shaft be noted that increasing the fin mass beyond a certain mass Ms, and the total iin mass MF. The relationships point will not raise the load-carrying capacity significant yof these parameters are utilized to attain maximum shaft ly, even when the shaft Weight is increased, since with power transmission capability and minimum weight in a too large a fin the resultant increase in shaft shell stress nuclear environment. Briefly, the inventors have `opti necessitates “beeiing-up” the shaft to the point where, in mized the iin helix angle 0 and the ydirection of the helix 'in order that the iin carries as much of the loads as pos sible, thus minimizing the effective stress on the shell. a nuclear radiation Íiel'd, the resultant temperature rise so weakens the material strength as to overcome the effect Also optimized is the thickness of the shell so that too 20 of the added weight. This, as pointed out, is not a prob lem in a non-nuclear environment. Also, as seen in the small a thickness is avoided, since stresses would be too graph in FIGURE 5, the increase in MF/MS from .5 to high, and to‘o great a thickness is avoided, since with the high temperatures of a nuclear heating environment, an undue increase in the thickness would cause such a de 1.0 accomplishes something less than the increase from 0 to .5. This indicates that for very large values of the eline in the material properties as would over-balance the 25 ratio MF/MS, the full cooling effectiveness will not be attained, and, further, stress concentrations may become reduction in stress and, although “beefed-up,” the shaft a limiting factor. Therefore, optimization of the finned would actually «be less safe. Moreover, the shape and shaft load-carrying capability for a desired minimum vangle of the ñns is chosen so as to minimize or eliminate may be accomplished by use of the graphs in FIG the effects of manufacturing tolerance variations in the 30 »weight URES 4 and 5. By choosing a desired torque load-carry nuclear environment, i.e., uneven heating which may cause ing capacity (or temperature margin) and representing shaft bowing, or arcing. _, it as the ordinate of the graph, the abscissa may then In describing how the shaft is designed to achieve lthe represent the desired range of values -for shaft weight. desired load-carrying capability with any given shaft di ameter in an application requiring minimum weight, par* 35 Curves for various ratios of t-he total fin mass to the total shell mass -MF/MS-can then be plotted. The first ticular reference is made to FIGURES 4 through 8. FIG URE 4 illustrates a parameter affecting the l-oad-carrying capability of the member 1G. In the graph, the torque curve intersected by a horizontal line drawn at the de~ (MF/M520). In this instance the torque load-carrying is a mechanical rather than a thermal parameter, i.e., since the ratio is the total amount of fin material to the total amount of shell material, it deals only with the load sired torque load (or temperature margin) specifies the lightest shaft for the `given conditions. The inventors have load~carrying capacity is plotted as a function of the shaft weight Áfor several values of the ratio of the total 40 determined that the preferred value for the ratio MF/MS -will lbe greater than .2 but :less than 1.5 for aircraft nuclear of ñn mass MF to the total shaft mass Ms. To turbojet engine applications. understand the significance of the curves, first consider It should -be understood that the iin ratio just discussed the curve Where the shaft is smooth, =i.e., there are no ñns capacity is low in the nuclear environment for either a light or heavy shaft, altho-ugh somewhat greater for some intermediate Weight. The reason for this is that an ex tremely lightweight shaft is is easily cooled because the shaft wall is relatively thin. However, depending on the »carrying capacity of the fin member. On the other hand, the best thermal iin ratio, which is defined here as the ratio of the total surface area of the ñn and shell portion combined, to that of the surface area of a comparable extent of the thinness there may not be enough shell ma 50 smooth surfaced cylinder of equal diameter, obviously terial to carry the torque load for a particular applica will 4depend somewhat upon the amount and properties tion so that the shaft thickness, and the Weight, may nec of the cooling fluid utilized, if any, in the particular ap~ plication. In a nuclear radiation environment, larger cline comparatively slowly. Thus, additional material in 55 thermal fin ratio values will reduce shaft iinv temperature very effectively. However, the shell temperature will be creases the load~carrying capacity and the curve in FIG essarily have to be increased. At ñrst, `cooling will still be reasonably effective and the material strength will `de reduced yonly slightly, so »that the reduction in shell tem URE 4 will rise. As the shaft thickness is increased still perature is more than offset by an attendant increase in further in a nuclear radiation environment, however, «the shell stress. The increase in thermal fin ratio virtually cooling becomes less effective and the shaft operating tem necessitates a simultaneous increase in MF/MS which perature rises rapidly. This ydrastically reduces the ma terial strength the result being that the shaft is weakened 60 causes the attendant increase in shell stress. Thus, with the present invention, where »the ñns are provided with Ifaster than the additional material can make up the a load or torque carrying capability, it has been found strength, causing the load-carrying capacity to fall again. that the optimum thermal ratio, as defined, which results 'Dh-us, for a given application (or temperature margin, in is preferably on the order of approximately two to one. a nuclear radiation environment) one particular shaft Refenring now to FIGURE 6 shown therein is one thickness will produce the strongest shaft. The curves 65 effect of differences in the value of the fin helix angle 0 in FIGURE 4 are therefore characterized by a downward on the shaft load-carrying capacity. It will be noted that concavity. If the shaft is then provided with fins, for the for pure torque loads Ian tangle of appnoximlately 45° is reasons'given above, the curves for different values at MF/MS will still be characterized by a `downward con 70 best, although it is not critical. For a shaft which carries la «combination of axial and torque loads, suc-h as in an cavity. aircraft tumbojet, the `curves in [the FIGURE 6 indicate Considering next the relationship between the curves, that the .angle is optimum ‘between 30° and 55°. How since, as stated above, the problem is one of obtaining ever, it was ldetermined that to avoid the effects of un the greatest load-carrying capacity in the peculiar en balance due to thermal bow of the shaft in the nuclear -vironment of a nuclear radiation source, the effect on shaft 75 radiation environment, which causes one surface of the 3,099,141 shaft to experience a greater temperature rise than the other, thus causing the shalt centerline to arc longitudi nally, each lin should spiral at least one complete revolu tio-n. Thus, the angle of the helix is also dependent on the relationship of the diameter to the length of the shaft. The optimum value of the angle 0 was therefore deter 6 the member is substantially proportional to its mass, said member comprising: a hollow, cylindrical shell portion, said shell portion mined to depend primarily on two parameters. One of these is the ratio of the diameter D times the axial load F to the torque load T, Ior D ><F/ T. For values of D XF/ T less than 3, the optimum value «of 6 is between 30° and 10 transmitting a part of ysaid load and having a total mass MS; a lin integral with said s‘hell portion, said iin comprising .a helix extending the length of the shell portion and having a total mass MF, wherein the ratio of `the iin mass to the shell mass M F/MS-is greater than .2 but less than 1.5, so as to enable said lin to transmit the remaining part of said load at la minimum total weight lof said mem 55°; tor values of DXF / T greater than 3, the optimum value of 0 is from 0° to 30°. This is shown graphically in ber in said nuclear radiation environment. ` FIGURE 7. However, the value of 0 must also be such 2. A load transmitting member tor use in a nuclear as to insure that the relationship of the shaft diameter D radiation environment wherein the »temperature rise in to its length s permits each iin, `or helix to make approxi 15 the member is substantially proportional to its mass, said mately ione complete revolution. Thus, changes in D, in member comprising: DXF / T, will «also aiîect the relationship of D to s. la hollow, cylindrical shell portion, said shell portion Further, «the direction ot a fin, or helix in a shaft will transmitting «a part of said load; be found to coincide gene-rally with :the direction of the a -tin integral with said shell portion, said iin compris 20 maximum torque load. Tor maximum torque load-car ing ‘a helix extending the length of the shell portion rying capacity in the nuclear environment it has been rand having a height d »and a pitch p, found that, additionally, the ‘direction of the helix should wherein the ratio of the liin height to the tin pitch be such that the torque load tends to tighten the spiral, thus d/ p-is greater than .1 but less than 2.0, putting the tins in tension, and increasing the load-carry 25 ing capacity of the shaft. Finally, the :graph in FIGURE 8 illustrates the rfact that the tin shape must also be taken into consideration when optimizing the sha-ft and Íin torque load-carrying capacity. so 4as to enable said lin to transmit the remaining part of lsaid load at a minimum total weight ot said mem ber in said nuclear radiation environment. 3. A load transmitting member for use in a nuclear radiation environment wherein the temperature rise in In >FIGURE". 3 the conñguration of the llin is depicted in the member is substantially proportional to its mass, said terms of the relationship of the height, or depth of the 30 member comp-rising: 1in d to the pitch of the helix p. With a lin «ilank angle la hollow cylindrical shell portion, said shell portion «of approximately 15°, or in the range `from 5° to 30°, transmitting a part of said loading and having a total and a substantial ñllet approximately equal to the shell mass MS, thickness at the base of the lin, to reduce stresses, the la fin integral with said shell portion, sai-d fin comprising iin shape which combines the best heat transfer 0r cool 35 a helix extending the length of the shell portion and ing properties with mechanical strength tor load-carrying having `a height d and a pitch p, capabilities will have a configuration substantially as »that wherein the ratio lof the lin height to the iin pitch show-n in FIGURE 3. In the embodiment shown the lin d/p-is greater than .l Ibutless than 2.0, slenderness ratio land wherein »the ratio «off the lin mass to the shell mass 40 MF/MS--is greater than .2. but less than 1.5, for maximum load-carrying capacity is approm'rnately .3; so ‘as to enable said lin to transmit the remaining part «of said load at a minimum total weight of said mem ber in said nuclear radiation environment. 4. A torque load transmitting member tor use in a but, in any event, in the range from .1 to '2.0. This ran-ge 45 nuclear radiation environment wherein `the temperature will also give the greatest íin cooling effectiveness with a rise in the member is substantially proportional to its maximum strength and minimum weight in the nuclear mass, said member comprising: environ-ment. a hollow, cylindrical shell portion, said shell portion Thus, the inventors have provided a new land useful torque and axial load-transmitting member `ior use in a 50 transmitting a part of said load; nuclear radiation iield wherein the heat Vgenerated in the member, as a result of nuclear heating, will be substan tially proportional to the mass thereof. The member has a hollow shell yand helical ñns integral with either the outer surface of the shell, or lthe inner surface of fthe shell, or 55 both. Further, the helix direction is to be determined by vthe direction ‘of the torque load, ‘and the preferred value of .the ratio MF/MS is greater than .2. but less than 1.5, the preferred angle of the helix is greater than 30° 60 but less than 55°, the value of the ratio d P a fin integral with said shell portion, said lin comprising «a helix extending the length of the shell portion -and having a height d and a pitch p land an angle 0; wherein lthe natio of the tin height to the iin pitch d/p--is greater than .l but less than 2.0, and wherein the direction fof the helix is such that twisting in said member due to the torque load will tend to tighten said -an-gle 0 of the helix, so las to enable said tin to transmit the remaining part of said load lat a minimum total weight of said mem ber in said nuclear radiation environment. 5. A torque and axial load transmitting member for use in a nuclear radiation environment wherein tempera ture rise in the member is substantially proportional to (as lmeasured perpendicul-uar to the lin helix angle) is 65 its mass, said `member comprising: a hollow, cylindrical shell portion, said shell portion preferably greater .than .1, but less than 2.0, with the lin proportioned in la manner so that its flank angle is greater than 5° but lless than 30°, and the thermal iin ratio is approximately 2 to l, in order that the shaft will provide maximum power transmission with minimum ‘overall 70 weight in the nuclear radiation lield. What we claim and desire to secure by Letters Patent 1s: 1. A load transmitting member -for use in a nuclear radiation environment wherein the temperature rise in 75 transmitting a part of the axial load F and the torque load T, said shell portion having a ldiameter D; a tin integral with said shell portion, said iin compris ing a helix extending the length of the shell portion; wherein the angle of said helix is such that when the value of the ratio DXF/T is less than 3, the op timum helix angle will be -greater than 30°, but less than 55°, and 'when the yvalue of the ratio is greater than 3, the optimum helix angle will be less than 30°, 3,099,141 so as to enable said iin to transmit the remainder of said loads F and T at a total minimum weight of said wherein the angle 9 of said helix is such that said iin makes at least one complete revolution of said cylin member in said nuclear radiation environment. 6. A torque and axial load transmitting member for drical shell portion along said length s, use in a nuclear radiation environment wherein tempera ture rise in the member is substantially proportional to 5 its mass, said member comprising: a hollow, cylindrical shell portion, said shell portion transmitting a part of the axial load »F and the torque so as to enable said ñn to transmit the remainder of load T, said shell portion having a diameter D and a mass MS; and wherein the angle 0 of said helix is such that when the value of the ratio DXF/ T is less than 3, the op timum helix angle will be greater than 30°, but less than 55°, and when the value of the ratio is greater than 3, the optimum helix will be less than 30°, 10 said loads F and T at a minimum total weight of said . . . . member I1n said nuclear radiaiton environment. a iin integral with said shell portion, said iin comprising a helix extending the length of the shell portion and 8. A torque and axial load transmitting member 'for' use in a nuclear radiation environment wherein tempera having a -mass MF; ' ture rise in the member is substantially proportional to wherein the angle of said helix is such that when the 15 its mass, said member comprising: value of the ratio D XF/ T is less than 3, the optimum a hollow, cyl-indrical shell portion, said shell portion helix angle will be greater than 30", but less than 55 °, and when the value of the ratio is greater than 3, the optimum helix angle will be less than 30°, transmitting a part of the axial load F and the torque load T, said shell portion having a diameter D; a iin integral with said shell portion, said fin compris- and wherein the ratio of the `iin mass to the shell mass-MF/MS--is greater than .2 but less than 1.5, so as to enable said lin to transmit the remainder of said loads F and T to a total minimum weight of said member in said nuclear radiation environment. 7. A torque and axial load transmitting member ‘for use in a nuclear radiation environment wherein tempera 25. area of an unfinned load transmitting member of ture rise in the member is substantially proportional to its mass, said member comprising: equal diameter D, is approximately 2, e so as to enable said 1in to transmit the remaining part of said loads F and T at a minimum total weightv a hollow, cylindrical shell portion, said shell portion transmitting a part of the axial load F .and the torque load T, said shell portion having a diameter D; a iin integral with said shell portion, said iin compris ing a helix extendingr the length s of the shell por tion and having an angle 0; ing a helix extending the length s of the shell portion and having a height d and a pitch p; wherein the ratio of the iin height to the tin pitch d/p-is greater than .1 and less than 2.0, and wherein the ratio of the total surface area of the iin and shell portion combined to that of the surface 30 of said member in said nuclear radiation environ ment. No references cited.