US 2700530 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Jan. 25, 1955 s. B. WILLIAMS HIGH TEMPERATURE ELAsTTc FLUID APPARATUS 2 Sheets-Sheet l Filed Aug. 27, 1948 Jan. 25, 1955 I s. B. WILLIAMS 2,700,530
HIGH TEMPERATURE ELASTIC FLUID APPARATUS Filed Aug. 27, 1948 2 Sheets-Sheet 2 INVENTOR.
E )www United States Patent() HIGH TEMPERATURE ELASTIC FLU APPARATUS i Samuel B. Williams, Detroit, Mich., assignor to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Application August 27, 1948, Serial No. 46,463
3 Claims. (Cl. 253-39.1)
cation forms a continuation-in-part of my hereinafter referred to copending application Serial No. 777,310, now U. S. Patent No. 2,641,439.
It is an additional object to produce turbine blading traversed internally by a multitude of cooling pores d1- recting the discharged coolant so that it has a substantial velocity component in the line of flow with the driving fluids in transit through the machine.
Turbine development has progressed to a point where machines of conventional designs may be divided into more or less standardized groups. In what may be called the rst type, the blades are solid articles which operate at relatively low temperature and they require no cooling. One disadvantage of this iirst type is that the heat which is transmitted to the blade from the hot gases coursing through the machine is absorbed and conducted away through the buckets to the rotating parts of the machinery or else conducted away through the vanes to the scroll and stationary parts of the machine. This heat lost by the fluid represents a loss to the system and the fluid actually is unnecessarily cooled as it progresses in its circuit. The blades, inasmuch as they are not cooled, are more subject to an eroding effect and soon tend to warp out of shape or otherwise deteriorate such that their replacement is soon necessary. It is another object of this invention to produce blading wherein means are provided for utilizing the heat normally conducted away from the motive uid through the surface of the blades to heat the coolant for the blades and tend to eliminate thereby one of these primary losses. This heat imparts to the coolant what may be considered a velocity head; this velocity head may be used to impart a jet effect or reaction boost to the rotating machinery to increase their speed. Moreover, in cooling these blades, the invention makes possible a longer life blade since it is maintained at a considerably reduced temperature and is thereby essd subject to eroding and other wear eifects as are solid la es.
Another type of turbine blade construction includes a vane portion having an internal cavity or having two or more longitudinal passages therein. Consequently, the coolant may be discharged directly from the tip of the blade into the motive uids used to drive the machine. The pressure maintained to expel the coolant is of practically negligible order and fairly little -air may be handled. However, some positive pump work must be provided and a pump of fairly substantial proportions is necessary. Moreover, the air or other coolant which forces through these blades is introduced directly into the driving fluids and tends to reduce their temperature somewhat.
It is a further object of the present invention to provide blading which is cooled so that the blade temperature will remain the same as that of the second type machine and which also requires negligible operating pressure to force the coolant through the blade. Within contemplation of the present invention, in the place of a hollow blade or a partitioned hollow blade which has large cooling passages, is the use of a blade traversed by minute passages of a large number such that, with the same negligible pressure to operate against, only a minute amount of air is handled. Thus a first saving will be made possible as the amount of air handled. With small ICC passages the temperature of the coolant passing through the blade will have a more intimate scrubbing action on the unit and will tend to increase its temperature to a marked degree. As a consequence, its velocity pressure will build up somewhat even though the inlet pressure to the blade for the coolant is effectively as low as for the second type of conventional machinery. The coolant will not leave the blade at a speed as high as that of the hot motive fluid; yet, with the discharge passages for the coolant being in the trailing edge of the blading, the hot driving fluid will tend to have an eductor effect on this coolant and may draw it from the blade. Accordingly a relatively small amount of pump work is necessary for the coolant since the driving uid tends to aspirate the coolant from the blade. The coolant may thereby be introduced into the driving fluid with no turbulence and what is a loss as to the conventional engine is thereby eliminated. Since the temperature of the coolant which is discharged according to the present invention is appreciably higher-in fact it approaches that of the hot driving fluid-the coolant does not tend to cool the driving fluid as much as was noted previously and another saving is afforded. Thus less air is handled, a good portion of the positive pump work is dispensed with, turbulence is eliminated, and cooling of the hot gases is tended to be lessened.
Let it be supposed that for identical installations the same air in quantity is to be handled for the conventional second type engine and the improvement as herein offered; the same relatively little amount of air will be handled in both cases. About the same size pump will be employed to drive the coolant. Although the improved design may operate against a small pressure as contrasted with the negligible pressure of the second type engine this f' seeming disadvantage may be offset by advantage of nonturbulent flow as contrasted with the turbulent ow and its attendant losses. Since the same amount of air is handled the discharge Velocity of gases leaving the improved design will be greater than that of the hot motive iluid and accordingly a jet elfect will be imparted to the rotating blades and a boost in velocity will be imparted to the motive fluid by the stationary blades. Hence, as contrasted to the heat loss to the blades being a total loss, the heat will be recovered in the improved design to yield positive work. Inasmuch as the same amount of air may be handled in both cases, the air going through the small passages will tend to maintain a cooler blade whereas'the air passing through only one or two large passages will allow the blades to operate at a higher temperature. Blade life accordingly will be markedly different. Moreover, as the coolant passes through these small channels its temperature tends more closely on a heat exchanger principle, to come to the heat of the driving fluid before being discharged from the blades. Then as the coolant is introduced into the driving iluid, there will be less tendency toward a chilling effect.
Let the discussion proceed upon a reasonable assumption that there is a third type of machine which operates at even a higher gas temperature than the second type and in which it is desirable to maintain even a cooler blade temperature. To accomplish this end with a hollow blade, it will be necessary that the rate of air flow is stepped up. Also, instead of allowing the coolant to discharge directly into the driving lluid and to create an excess of turbulence due to its increased flow, the coolant will have to be discharged from a peripheral takeoff from the rotor blades so that it does not come in direct contact with the driving fluid. The pump for the coolant will operate against some intermediate pressure and a moderate amount of air will be handled. Greater pump work will be necessitated and cosiderably more heat will be lost to the blades by being transmitted to the coolant passing through them. It is yet a further object of the present invention to accomplish these same purposes yet, by handling less air, to decrease the pump work to a moderate amount; a first gain then is evident in the amount of air handled. By the improved means of providing small air passages the heat absorbed by the air or coolant which normally would be lost is available to impart a reaction eifect to the rotating blades and to increase the torque energy available. If by the improved design the same amount of pump work happens to be available as in the third type of conventional machine considered, still another object then is to keep the blades even cooler according to the present invention under these operating conditions and afford a life gain as concerns the blades. Since more air tends to be handled by the conventional form, albeit supplied at a relatively lower intermediate pressure, the work input to the pump amounts to about the same in either case. The heat imparted to the blades though, may be recovered by the jet air reaction effect inherent in the present invention and a second gain is made possible.
In what may be called a fourth type of turbine, the blades of the turbine wheels operate at excessively high gas temperatures and require an extreme cooling effect. If hollow blades are used, a somewhat standardized practice, the coolant driven through them gains but a few degrees in temperature. A considerable amount of air must be delivered by the coolant pump; the heat absorbed by the blades and transmitted to the air is entirely lost to the system. With the extreme cooling effect available with the improved design, however, the temperature rise of the coolant is considerable and a substantial velocity head may be given to the coolant. Upon being discharged at the trailing edge of the blades this jet effect may be appreciable. The scrubbing action is marked and consequently the blade temperature is maintained at a considerably lower value. Blade life may be thus increased. Moreover, since the passages are small and cannot accommodate a large amount of air ow, relatively speaking, there is` less air forced through the machine and less pump work required. This fact has appreciable significance when it is borne in mind that in order to maintain the overall efficiency of any such high temperature machines, relatively meager amounts of coolant are desirably handled; that is, the smaller the quantity of air necessary for the operator to cool the blading properly, the better the arrangement is.
An additional object of the invention is to maintain this overall efficiency for the machine and keep the operating losses either at a minimum by recovering as work the heat involved in these would-be losses.
Still an additional object is to produce an article of manufacture, of the type previously described, which is relatively easy and simple to fabricate, which is of sturdy design, which is inexpensive to make, and which has long wearing qualities.
Further `an additional object is to produce a turbine element which, although an innovation, does not require appreciable departure from conventional overall turbine designs.
These and other objects will become clear from the detailed description to follow read in conjunction with the accompanying drawings in which:
p Fig. l is a longitudinal sectional view of a turbine incorporating the present invention;
Fig. 2 is a transverse section of one of the rotor blades;
Fig. 3 is a full face view of the rotor blade, parts be ing broken away; while Fig. 4 is a face View of a stator blade, parts being broken away.
With reference to Fig. l of the drawing, indicates a turbine shown in longitudinal section. This machine incorporates a casing or scroll 12 adapted to remain stationary during operation. Within this scroll may be a central core member comprising sections 14, 16, and 18 in which the rotating members are supported. One rotating member is a turbine disc or wheel 20 mounted on a central shaft, not shown, and behind it a similar wheel 22 which may be mounted on the same shaft and designed to rotate with the first wheel. At the far left of the machine may be seen an inlet duct 24 which is constructed and arranged to provide the turbine with hot driving uid. This uid may be a hot gas, may be steam, but it is preferably at an advanced temper ature. At the other end of the machine may be seen a discharge duct 26 designed to conduct the hot motive uid away from the turbine. As to the particulars of one of the turbine wheels say 22, for example, radial passages 28 may be provided which open radially into a chamber as at 30. These passages may be drilled or otherwise formed in the wheel so as to` conduct the coolant for the blades therethrough. Along the periphe ery of the wheel are transverse shoulders 32 and 34 by which the blading may be locked to the wheel. These shoulders tend to resist any centrifugal forces which may act on the rotating blades. Turbine buckets, one of which is shown at 40 may be placed circumferentially in rows around the wheel and may operate under the influence of the driving gases to impart turning couples or moments to the wheel and torque to the rotor shaft. Each bucket may have a flange at its inner end such as at 42 supported by ribs 44, 46, and 4S. This frange rnay take the form of a shelf supported as it is and may fit on the concave side of the blade integral therewith so as to abut the convex side of the next succeeding blade. The shelf 42 happens to be mounted on the blade preceding the blade 40 shown, and for that reason is illustrated in section. This ange 42 may abut the convex face then of blade 40 and thus operate to help form an annular ring about the turbine wheel. The continuous ange presents a gas conducting face to the hot motive iluid and directs its travel as desired, weaving in and out of the labyrinth of the machine. At the outer end of the blade may be a shroud segment 50 which cooperates with the ange 42 to confine the gases. This shroud may be made into segments of lengths as suitable and may be adapted to be tted by means of its key 52 into the scroll of the turbine. A bolt or other fastening means such as shown at 54 may lock this shroud to the stationary part of the machine. The face 56 of the shroud opposes the gas conducting surface of flange 42.
Corresponding to the bucket just described may be another bucket 60 mounted on the turbine wheel 28. 1f a multi-stage machine is the apparatus desired, this bucket 60 may be of the same proportions as the bucket 40 yet of relatively smaller size if it is to constitute a first stage for example. Bucket 60 is served by hollow passage 62 in the turbine wheel which conducts the coolant into the chamber 64 and on up through the hollow anchoring portion of the blade 66.
As to Fig. 2, an enlarged view of the bucket such as under consideration is presented. There is a blade portion shown at which is delined by a concave face 102 and a convex face 104. The concave face 162 is adapted to be the working surface of the blade and rcceives the impact of the hot gases playing along the face thereof. The convex face 104 may be made up of small or relatively thin coatings 106, 16S which may be plated onto the blade or otherwise affixed thereto. At the ends of the blade there may be a thickened leading edge 112 and a tapered and relatively thinner trailing edge 114. These edges are of conventional airfoil type and configuration and are adapted to present the streamline section to any flow into which they are set. Defined by the blade portion proper 100 and the coating 104 of the convex face may be seen small passages 120 and 130. There are a plurality of these capillary passages dispersed along the face of the blade and they conform generally to its concavo-convex form. These passages may make the bucket pervious to air or such coolant as employed and may run to a number upwards of 20 as desired.
In regard to Fig. 3, a face view of the bucket is shown; as meets the eye of the observer the convex face appears. The bucket may comprise longitudinally a root portion 140. Projecting shoulders 142 and 144 may be formed on this root portion and may be adapted to engage the shoulders of the disc for positive affixation thereto. The lower edge or face of the root shown at 146 may be provided with an aperture therein which communicates with an internal passage 148. Integral with the root portion may be seen a neck portion 150 which contains a small chamber 152 connecting with the aforementioned passage 148. At the upper end of chamber 152 may be provided lands 154 which tend to block off the end of the chamber. Between these raised lands 154 may be located alternating grooves 156 which are in direct communication with the chamber 152. Thus when the plating or coating is applied to the convex face of the blade the lands and grooves and plating define the minute passages desired. In' the upper reaches of the neck may be seen additional lands 158 which further ramify the passages 156 in the blade. The last longitudinal segment of the bucket may be seen at 160. This may be the blade portion which may consistof a tip edge 162 and side edges which are defined more or less' by the blading at 164 and 166. In the lower reachesof the blade portion there may beprovided additional lands 168 which have' the effect of further increasing the number Vof the cooling passages. For
purposes of analysis these passages may be roughly divided into two classes. Those such as indicated at 120 have supply portions 122 which run longitudinally of the blade and are localized more or less in the leading edge portion. The terminals of passages 120 incline as at 124 toward the trailing edge, of the blade more or less and discharge through apertures or orifices 126. The balance of these capillaries shown at 130 have shorter supply portions 132 which develop into terminals 134 leading toward the trailing edge. These terminal portions 134 enter the trailing edge through foraminations or orifices 136 disposed along the trailing edge. All of the pores just described may contribute to a jet or reaction effect more or less on the blade. The leading edge passages 120 may be inclined only slightly to the longitudinal axis of the blade yet they expel the coolant at an angle such as will impart a reaction effect to the tip. The passages 130 may centralize in the trailing edge, may direct the coolant in more or less a normal direction to the longitudinal axis of the blade, and may provide likewise a reaction effect tending t'o speed the blade in its rotary motion.
A turn of attention again to Fig. 1 will reveal that outside of the scroll 12 may be located a shell or outer casing 70. Since the fixed blades do not have to have the special consideration of being cooled while in motion they may be supplied through the stationary casing in a relatively simple fashion. Casing 70 may be supplied with coolant by a passage means 72 at its one end and the coolant may be led into the annular plenum or chamber defined by the outer casing 70 and the scroll 12. This annular chamber may be divided by a filter screen 74 into an outer compartment 76 and an inner compartment 78. This inner compartment 78 may be used to maintain an ambient atmosphere for the scroll under a considerable pressure. The only means of escape for this atmosphere will be through the hollow root portion of the nozzle vanes, one of which is indicated at 80. This nozzle vane may be locked into place on the scroll by suitable fasteners as at 82. A fiange may be provided for this vane at 84 and a corresponding deecting baille may be provided at 86. These two shelves define a toroidal passage in keeping with the general annular passage presented to the driving gases by the machine. The vane S0 may have a flange 88 of annular configuration and another 90 at the tip which may be adapted to be received by the inlet duct 24 and anchor the two members together. Radially extended ribs, as at 92 and 94, provided for the vane 80 may be used to hold the vanes securely affixed to the inner core member. These vanes may be disposed in rows which are situated circumferentially to the inner core member and are anchored firmly in the scroll. If a multi-stage machine is contemplated7 another set of vanes may be provided, one of which is indicated at 90. This vane may be firmly affixed to the scroll by suitable fastening means 92 and may be provided along the top face by a ramp 94 and by a flange at the other extremity at 96.` This ramp and fiange when considered in conjunction with the mating ramps and flanges of the other vanes in row therewith present a toroidal passage for the driving gases. By virtue of the taper to the upper ramp, the gases from the rst stage may be expanded by pressure reduction and to them imparted a low stage velocity of larger value. This vane 90 may have a corresponding rib 97 and 98 to mount its tip end securely to the inner core member.
As respects Fig. 4, an enlarged view of one of these vanes is presented. This vane may comprise a root portion 200 which may be, for example suitably threaded as at 202 for anchoring in the scroll. An inner passage 204 originating in an aperture of the root edge or face 206, may be provided with means by which the coolant may enter from the annular or plenum chambers of the machine. The neck portion 210 of this vane may be provided with an internal passage 214 connecting with the passage 204 in the root portion 200 to form one continuous passage. This passage 214 in turn admits the coolant to the blade portion proper 220 of the vane. This blade portion proper may comprise a leading edge 222 and a trailing edge 224 through which the coolant may be expelled. A small distributing chamber 226 cornmunicating with the passage 214 may be used in conjunction with the passages shown at 228 by means of observer.
which thecoolant is conducted through the blade to the trailing edge 224.
The passages 228 comprise longitudinally extending sections 230 which carry into transverse capillaries 232 communicating with the orifices along the trailing edge 224. These orifices are best seen in original Fig. 1 inasmuch as in that particular view the vane is set at its operating angle with respect to the machine. In Fig. 4, the vane is shown in full face view rather than at an oblique angle for better purposes of illustration.
y-As to operation of such a turbine as shown in Fig. 1, the hot motive gases may weave through the various stages of the machine driving the wheels 20 and 22 such that they may be conceivably rotated toward the The coolant which passes through thevanes of the blades may be heated in its passage therethrough and enters into the stream of the hot gases at much their same temperatures. The velocity can be gauged as desirable such that it may be slower than the velocity of the hot fluid. In that case less pump work will be required for the coolant and the hot fluid will tend to educt or draw the coolant from the blades.
If the pressure is increased as regards the plenum chamber 78 the coolant may be discharged at the very same velocity as the driving gases. Still if the pressure is again increased a positive accelerating or boosting jet effect will be imparted to the hot gases. By virtue of the operating angle for the blade proper of the vane as shown in Fig. l the orifices along the trailing edge for the cooling pores are displayed to advantage.
Next in succession for the path of the gases is the passage-producing means of the blade 60 and its shelf and shroud. The cooling capillaries in this blade react differently to different coolant pressures such that at a reduced pressure the driving fluids tend to educt the coolant. ,At an even higher pressure the coolant may be introduced into the gas stream in non-turbulent fiow and without adding or detracting from the gas velocity. Then if the pressure is again increased, a positive reaction or jet thrust will be imparted to the blade and the velocity of the driving fiuid may even be increased.
As to the carrier for such a blade as 60, the hollow passages and chambers therein together with the mounting means for the blade are fully described in copending application Serial No. 786,679, now Patent No. 2,- 641,440, led November 18, 1947 under the name of Williams. As regards the minuteness of size of these cooling passages in the buckets or the vanes, either drilling or casting means may be employed. Still if a plating method is to be accomplished as over grooves or recesses formed in the blade blank, reference as to the procedure to be followed may be found disclosed in detail in copending application Serial No. 777,310, now Patent No. 2,641,439, filed in the name of Williams on October 1, 1947. Still and all this process of manufacture forms no per se part of the present invention, and is fully described in said copending application.
The size of these passages may be a critical factor in the functioning of the blading of the present invention. They serve to afford an intimate scrubbing action by the coolant and cause an appreciable rise in its temperature before it is discharged from the edge or edges of the blading. These small passages give a high velocity for relatively small quantities of coolant that may be handled. Hence, as described at the outset, in order to preserve and maintain an overall eiciency for the power plant, use of small quantities of fiuid is advantageous and the desired end is accomplished.
The next set of blading to be encountered by the hot gases may consist of such a blade as at which by virtue of its ramp 94 may expand the passing gases; although it causes their temperature and pressure to drop, the sacrifice is in the cause of increasing their depleted velocity so as to make up for the slowing effect encountered in preceding stages. The trailing edge of this vane 90 may present its foraminations to the turbine at about the same angle as the preceding vane. The coolant may permeate this blade also and pass out through the trailing edge to produce what may be a jet acceleration upon the hot gases. The rate of flow of the coolant and the relative speed at which it is introduced to the driving gases will largely depend on the size chosen for the cooling pores and may be proportioned to the coolant discharge ow for the preceding vane 80 by the relative sizes selected.
A nal row of blades may be of the typev which appears at 40, somewhat of larger dimensions than 60 but answering to the same general construction. From this bucket the coolant may be educted by the hot iuid, may be expelled at the same velocity as that of the uid, or forced out at a relatively higher velocity than at which the iiuid is traveling. In the latter case a reaction effect may be experienced by blade 40 adding to its eective moment.
Having described the method of operation of my invention together with the apparatus which I now consider to represent the best embodiments thereof, 'l wish it to be understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.
What i claim as new and desire to secure by Letters Patent of the United States is:
1. For use with a turbine providing coolant for the blading, a nozzle vane comprising a root portion, a neck portion joined thereto, and a blade portion extending from said neck portion; said blade portion being partially defined by a leading edge and a trailing edge; a distributing chamber formed within said blade portion; said trailing edge having a series of openings therein; a plurality of small passages radiating from said chamber and communicating with said trailing edge; said root and neck portions being formed with a passage therethrough communicating with said chamber thereby providing a continuous path for the transfer of coolant from said root portion through said neck portion and said plurality of passages to saidk series of openings in said trailing edge.
2. In a turbine having an annular casing within which hot working fluids are caused to pass in an axial direction, said casing having a series of apertures therein, an annular row of nozzle vanes interposed in the tluid path within the Ecasing; each vane comprising a blade portion, a neck portion secured to said blade portion and a threaded root portion joined to said neck portion; said blade portion having a distributing chamber therein; said neck and root portions being formed with a passage therethrough communicating with said chamber; the threaded root portion of each vane protruding outwardly through one of said apertures in the casing andv having a nut threadably received thereon to hold the vane in place with the end of the root portion outside the casing, said blade portion having a trailing edge remote from the distributing chamber and provided with spaced orificesY therealong, and an internal passage means interconnecting each oritice and the distributing chamber.
3. In a turbine having an annular casing within which hot velocity fluids pass axially laccording to a generally toroidal path, said casing having a series of apertures therein, an annular row of nozzle vanes interposed in the uid path within the casing each comprising lengthwise a threaded root portion, a neck portion, and a blade portion, the blade portion having an internal distributing chamber therein, the root portion being open at an` end, said neck and root portions being hollow thereby providing communication between the open end of the root portion and the distributing chamber, the threaded root portion of each said vane protruding outwardly through one of said apertures in the casing and having a nut threadably received, thereon to hold the blade in place with the open end of the root portion outside the casing, said blade portion having a trailing edge remote from the distributing chamber and provided with spaced orices therealong and further having internal passages communicating with said distributing chamber, each of said passaggs being connected to a different one of said spaced ori ces.
References Cited in the tile of this patent UNITED STATES PATENTS 741,776 Dodge Oct. 20, 1903 2,220,420 Meyer Nov. 5, 1940 2,364,189 Buchi Dec. 5, 1944 2,408,788 Ludington Oct. 8, 1946 2,410,259 Birmann Oct. 29, 1946 2,489,683 Stalker Nov. 29, 1949 FOREIGN PATENTS 184,879 Great Britain Aug. 21, 1922 319,622 Great Britain Dec. 18, 1930 346,599 Germany Ian. 5, 1922 491,738 Germany Feb. 12, 1930 544,940 Germany Feb. 26, 1932 594,931 Germany Mar. 23, 1934 600,057 Great Britain Mar. 30, 1948 705,976 Germany May 15, 1941 878,999 France Nov. 2, 1942