US2316813A - Bearer for the stationary vanes of rotary motors - Google Patents

Description

April 20, 1943. G. SCHAPER BEARER FOR THE STATIONARY VANES OF ROTARY MOTORS Filed July .17, 194C) 2 Sheets-Sheet 1 INVENTOR Y e. SCH/\PER ATTORNEYS April 20, 1943. G. SCHAPER 2,316,813

BEARER FOR THE STATIONARY VANES OF ROTARY MQ'IIORS I Filed July 17,1940 2 Sheet s-Sheet 2 INVENTOR Y 6. SCH/\PER ATTRNES Patented Apr. 20, 1943 BEARER FOR THE STATIONARY VANES OF ROTARY MOTORS Georg Schaper, Mulheim-Ruhr, Germany, as-

signor to Holzwarth Gas Turbine 00.. San

Francisco, Calif.

Application July 17, 1940, Serial No. 345,990 In Germany July 22, 1939 Claims.

The stationary vanes of rotary motors propelled by fluids of high temperature are very often subjected to a maximum of stress by heat. This is especially the case if the whole rim of the wheels is not impinged by the motive fluid continuously and at a uniform rate but only a partial contact takes place. In this case there is sufilcient time and opportunity for the moving vanes which rotate with the wheel or drum to be cooled down at the part of the circumference which does not get into contact with the motive fluid. This accounts for the fact that the average temperature of the moving vanes is considerably below that of the stationary vanes. This permits certain conclusions to be drawn with reference to the stress caused by heat. The stationary vanes. however, cannot change their position in relation to the nozzles conducting the motive fluid. They are therefore continuously and without a pause subjected to the stress exercised by the flow of the motive fluid as long as the motive fluid flows through the nozzles.

Due attention has been paid to this discovery, and the stationary vanes of older types of turbines have already been provided with an effective system of cooling or have been made of material capable of overcoming without any difliculties the increased stress caused by the heat. But it is likewise a fact that not only are the stationaryvanes proper subjected to this increased stress, but also the walls into which the vane.

bases are inserted, in particular the surface which is touched by the motive fluid.

Attempts have been made to meet this stress by securing the cooled stationary vanes to a cooled bearer having as thin walls as possible and attached, preferably by means of welding, to the wheel casing. By this method it has been possible to diminish considerably the strain exercised by heat on the walls. However, this arrangement was responsible for an inevitable accumulation of material at the point where the vane feet are secured to such a type of bearer. This accumulation of material renders it diflicult for the heat to leave the motive fluid in order to be absorbed by the cooling liquid. This is especially true if the gases of explosion turbines are the motive fluid.

The present invention is based on the observation that for the purpose of smooth and continuous operation, it will be necessary to overcome also this insufliciency. According to the invention, the problem is solved by the application of a bearer for the stationary vanes which consists of two separate thin-walled rings or ringshaped parts arranged on both sides of the row or rows of vanes. These rings or ring-shaped parts are connected with one another only by means of the vanes which they carry, apart from their connection via the wheel casing in which they are placed. This method permits of the (CL Gil-41) construction of a bearer for the vanes with a minimum of mass and, consequently, eliminates any accumulation of material. This bearer thus makes it possible for the cooling liquid to get freely and in every direction into contact with the feet of the vanes. It is thereby also possible to bring the cooling liquid and the material of which the vanes are made into as close proximity as possible to the part of the vanes taking on the heat. This is important because a satisfactory dissipation of the heat depends on as short a distance as possible between the part of the vane taking on the heat and the part releasing it in order that the temperature drop which is required to lead away the heat may be as small as possible. The temperature drop de termines the degree by which the temperature of the vanes must be higher than the temperature of the cooling liquid. In this way it is possible to improve the cooling effect on the feet of the vanes with the aim of decreasing the temperature of that part of the vanes which is in the center of the flow of the motive fluid. As a result, the invention contributes toward greater safety in operation not only of the bearer proper but also the vanes.

The invention will be further described and in greater detail by reference to the accompanylng drawings, in which- Fig. 1 shows the practical application of the invention -o a bearer of a stationary vane of an explosion turbine. The bearer is illustrated in cross-section.

Figures 2 to 5 demonstrate, also on the basis of cross section, the individual stages of construction of the bearer.

Fig. 6 illustrates anexplosion turbine plant in which certain features of my improved bearer or carrier for the stationary turbine blades as shown in Fig. 1 are embodied.

In Fig. 1, the reference character I indicates the wheel of the type of a Curtis wheel, with the two rims 2 and 3, while 4 designates the nozzle piece which conducts the motive fluid from an explosion chamber and a nozzle valve (which are shown in Fig. 6) to the vanes.

The system of vanes consists of two rows of vanes 2 and 3 and the wheel I, as well as of a segment with one row of stationary vanes 5. This segment has at least the length of the nozzle arch 4.

According to the invention, the bearer of the stationary vanes is constructed as follows:

It consists of two separate thin-walled rings or arcuate parts 6 and I which are arranged on both sides of the row of vanes 5 and which, aside from being connected with one another via the wheel casing in which they are placed, have connection with one another only by means of the vanes which they carry. I prefer to make this connection by means of welded cross-ties I the head ends of which coincide with the two arcuate sections 8 and 8" of welding material peripherally arranged. For the purpose of holding these arcuate sections 8 and 9 the arcuate parts I, I have arcuate excavations at l 1 respectively. The feet I of the vanes project slightly beyond the bordering surface I" and 1 of the cooling liquid canal II. This arrangement accounts for the formation of arcuate niches having angle-shaped cross-section i I, which are filled by means of rings I! of welding material. In this way the arcuate parts 6 and I having varehor angle-shaped cross sections, respectively, are connected with one another in addition to their connection via the turbine casing; the welding seams are marked it and i4.

The feet of the vanes should also have a slot-shaped excavation l5, which may be obtained by milling in a peripheral direction and which opens into the cooling liquid canal III. This excavation permits the cooling liquid conducted through the cooling liquid canal to be brought as close as possible to the part 5 of the stationary vanes taking on the heat. The dissipation of heat is furthermore faciltiated by placing (in a manner which in itself is known, see, for instance, the patent to Holzwarth, No. 2,256,479) cores Ii of such heat-conducting material as copper or the like, in a longitudinal grooveof the vanes 5.

These cores join a base plate l6.

Owing to the fact that the excavation ll extends into both the foot of the vane and the core and core base, the cooling liquid has full access to all heat conducting parts. The flow of heat is facilitated by insuring metallic continuity between the core and the core base on the one hand, and the vane and the foot of the vane on the other. a

Figures 2 to 5 illustrate the steps of building up such a type of bearer for the stationary vanes.

Figure 2 is a cross section of an arcuate block of material and contains in itself the cross sections of parts 6 and l. The groove ll with the arcuate excavations 6 and l which serve to hold the welded sections 9 and 9 has already been cut into the block. The total excavation l1, l8 extends beyond part ll which forms the groove proper to a space which is subsequently occupied by the cooling liquid canal.

Figure 3 shows a ring shaped part which has been worked upon according to Figure 2, but after having inserted the vanes I and constructed the cross-ties 9 and the welded sections 9 and 9". It will be observed that the cross-ties are made of relatively thin stock, and hence no dangerous accumulation of material at the base of the vanes occurs; and further, that they increase the rigidity of the connection of the rings or arcuate sections 6 and I and the vanes each with the other. The whole unit is now rigid enough to be slotted, as shown in Figure 4, whereby it will be possible to connect the ends of the vane feet 5 and 5" projecting beyond the bordering surfaces 6 and-l with the block by filling the niches II with rings of welding or soldering material. By this construction the surface contacted by the cooling liquid is increased, the filling also insuring a solid, tight and heat-conducting connection between the feet of the vanes and the bearer.

The slot-shaped excavations l5 may now be cut in the direction of the cooling liquid canal between the flanks of the vane feet and make it possible to bring the parts contacted by the cooling agent still closer to the parts of the vanes which receive heat.

According to Figure 5 the lateral arcuate parts 6 and I are thereupon completed, except for ma- I ment shown in Figure 1.

Fig. 6 shows a known type of constant volume explosion turbine assembly in which my improved construction is incorporated. The explosion turbine plant includes one or more constant volume explosion chambers II in which a combustible charge of fuel and air is periodically exmoded and the combustion gases under high temperature and pressure are discharged into a nozzle piece or channel 4 upon opening of the male valve ii, the nozzle itself being'shown at 22. The gases flow through the blades of the rotor i, being intermediately reversed in the stationary blades I,

and then flow through the channel 28 to theblading of the rotor I, being finally discharged at 24. An auxiliary nozzle valve 25 conducts the explosion gases of lower temperature and pressure, for example, the gases displaced by the scavenging air, directly to turbine I by way of the conduit 26. The explosion chambers are fed in known manner by a fuel valve 2'! and an air valve 2., all of the valves being hydraulically controlled by a pressure oil distributor 28, driven by a motor 30 which also drives a pump II,

which feet; oil under pressure to the distributor.

I claim:

1. In a rotary motor operated by a medium of high temperature and including a casing and a rotary wheel carrying a plurality of rows of vanes thereon, the combination of stationary vanes between two rows of rotary vanes, and a bearer for the stationary vanes comprising two arcuate sections, arranged one on each side oi the stationary row of vanes, said sections beinl anchored within the wheel casing and being additionally connected with each other by way of the stationary vanes which they carry.

2. A bearer construction as set forth in claim 1 wherein the arcuate sections are connected with the vanes by way of peripherally extending welding seams, and are additionally connected with each other only by way of cross-ties filling gaps between the vanes and connected with the arcuate sections.

3. Abearer construction as set forth in claim 1, wherein the feet of the stationary vanes project beyond the sections, the angular space between such sections and the projecting vane feet being filled with metal so as to establish a solid, tight and heat conducting connection between the vanes and the bearer.

4. A construction as set forth in claim 1, wherein the vane feet are provided with slot-shaped peripheral excavations between the flanks of said feet which are connected with the arcuate sections, said sections constituting part of the wall of a cooling canal and said excavations extending This results in the arrange

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