Abstract:
The invention relates to a method and apparatus for improving the performance of back-to-back turbocompressor or turbopump systems, or, more generally, of internal-separation energy separators. A helicoidal or spiral baffle is used to impart simultaneously a positive prerotation to the flow which is to be de-energized and a negative prerotation to the flow which is to be energized.

Description:
The invention herein described was made in the course of or under a contract or subcontract thereunder with the Department of the Navy. 
    
    
     SUMMARY OF THE INVENTION 
     This invention relates to a method and apparatus for imparting opposite prerotations to the two sub-flows into which the input flow is divided in back-to-back turbocompressor or turbopump systems, or, more generally, in internal-separation energy separators as described in my U.S. Pat. No. 3,361,336, the subject matter of which is incorporated herein by reference. 
     Theory and experiment have shown that significant improvements in the performance of energy separators, at any given rotor peripheral speed, are obtained when, prior to entering the rotor discharge passage, the subflow which is to be de-energized (hereinafter to be referred to as the &#34;cold&#34; flow) is imparted a positive prerotation, i.e., an angular momentum of the same sign as the angular velocity of the rotor, while the subflow which is to be energized (hereinafter to be referred to as the &#34;hot&#34; flow) is imparted a negative prerotation, i.e., an angular momentum of the sign opposite to that of the angular velocity of the rotor. I have found a method for imparting both prerotations simultaneously in a single step, with lower flow losses than are generated by conventional guidevanes. 
     It is, therefore, a principal object of this invention to provide a means for improving the performance of apparatus for pumping, lifting, or compressing of fluids of all kinds, and for heating, cooling, refrigerating, air conditioning and related purposes. 
     Further objects and advantages of this invention will be apparent from the following description. 
    
    
     THE DRAWINGS 
     FIG. 1 is a side elevational view, partially in section, of an apparatus constructed in accordance with the present invention; 
     FIG. 2 is a sectional view along the lines of 2--2 of FIG. 1, looking in the direction of the arrows; 
     FIG. 3 shows, in diagrammatic form, another illustration of apparatus for energy separation with dual prerotation in accordance with the present invention; 
     FIGS. 4 and 5 are side elevational views, partially in section and broken away for convenience, of other embodiments of apparatus for carrying out the present invention; 
     FIG. 6 is a side elevational view, partially in section, of yet another embodiment of apparatus suitable for carrying out the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now in detail to FIGS. 1 and 2 of the drawings, 1 is a stationary cylindrical body coaxially positioned with respect to a bearing-mounted rotatable shaft 2, which supports and rigidly connects hot-output disc 3 and cold-output disc 4 of the energy separator rotor for rotation with respect to surrounding stationary housing 5. In the configuration shown, body 1 houses the bearings which support shaft 2, but, as one alternative, the bearings could be placed elsewhere (for example, on shaft extensions beyond discs 3 and 4), or, as another alternative, fluid-film support of the rotor could be provided in the clearance gaps between housing 5 and discs 3 and 4. These clearance gaps are exaggerated in the figure for the sake of clarity, but in fact leakage through them is to be minimized. 
     6 is the input fluid supply duct, and 7 is the input port. 8 and 9 are rotor discharge passages extending through discs 3 and 4, respectively, for discharging fluids in the direction of arrows A and B, respectively. The total discharge area of passages 9 is greater than that of passages 8, and the ratio of the two areas is so proportioned that under the combined action of the issuing jets the rotor periphery moves at a predetermined velocity in the direction of arrows C. Thus, in a coordinate system fixed to housing 5, the total specific energy of the jets issuing through passages 8 is higher, and that of the jets issuing through passages 9 is lower, than that of the input flow, in accordance with the theory set forth in my U.S. Pat. No. 3,361,336. 10 is a substantially helicoidal baffle, extending radially from the outer surface of body 1 to the inner surface of housing 5, and of pitch almost equal to the distance between discs 3 and 4. The edges 11 and 12 of baffle 10 are welded or otherwise secured to body 1 and to housing 5, respectively. Baffle 10 divides the space between body 1 and housing 5 into two tapered conduits 13 and 14, and the input flow, on being fed into this space through port 7, is divided by body 1 into two flows, one of which is constrained to acquire a negative prerotation as it enters conduit 13, which leads it to the hot-discharge disc, while the other is imparted a positive prerotation as it enters conduit 14, which leads it to the cold-discharge disc. The tapering of the conduits tends to compensate for the fact that the mass flow rate decreases in each in the direction of the flow, and contributes, therefore, to the maintenance of a constant rate of flow through the discharge orifices on each side and to the reduction of fluctuations and losses in both flows. 
     The characterization of baffle 10 as &#34;substantially helicoidal&#34; is intended to describe a configuration similar to a helix but with such departures from an exact helix and with such variations of thickness along its length as may be deemed desirable to produce a better flow on each side. Baffle 10 may also perform the structural function of supporting body 1, whether or not this body houses the bearing assembly which supports shaft 2. 
     FIG. 3 shows an arrangement in which the centerline of the prerotation channel follows a path which is a modified helix or spiral. Components shown in FIG. 3 corresponding to similar components in FIGS. 1 and 2 have been given the same reference numbers with the subscript b. 
     In the arrangement shown in FIG. 4, enshrouding wall 15 corresponds to enshrouding wall 5 of the arrangement shown in FIG. 1 but is part of the rotor 16 and connects the two rotor discharge ends 3c and 4c. Therefore, baffle 10 c  is not attached along its edge 12 a  to wall 15, but its inner edge 11 c  is attached to stationary member 1 c . The fluid supply duct 6 c  extends through the interior of body 1 c  and feeds the input flow radially outwardly, through port 7 c , into conduits 13 c  and 14 c . 
     In FIG. 5, there is shown an arrangement similar to that shown in FIG. 4, in which, however, the hot and cold flows discharge through nozzles 8 d  and 9 d  in the enshrouding portion 15 d  of the rotor. Nozzles 8 d  and 9 d  have substantially opposite orientations and are placed in two different planes of rotation, on opposite sides of port 7 d , thus making possible the separate collection of the two issuing flows, through separate collectors. Baffle 10 d  is attached along its inner edge to stationary body 1 d . 
     FIG. 6 shows the central portion of an arrangement similar to those shown in FIGS. 4 and 5, in which, however, two helicoidal channels 13 e  and 14 e  are formed by two helicoidal baffles 20 and 22 positioned with respect to one another in the manner of the threads of a multi-threaded screw. Each of the two channels is fed through one of the two ports 7 e  discharging radially outwardly from the interior of member 1 e  at diametrically opposite sides. It is clear that the two channels could, alternatively, be fed inwardly from ports in the enshrouding wall, as in the arrangement shown in FIG. 1. It is also clear that three ports could discharge into three helical conduits in a similar multi-threaded screw arrangement, and so on. 
     It is to be understood that in all of the above-described embodiments of apparatus for carrying out this invention each group of nozzles or openings may be replaced by a cascade. The two groups may differ from one another in the size, number, radial position, and orientation of the discharge openings. It is also obvious that various modifications of the embodiments described are possible within the scope of the invention claimed. 
     In the following, the designations &#34;helicoidal&#34; and &#34;spiral&#34; will be used interchangeable, in accordance with common usage and with the definitions of these words given, e.g., in the Random House Dictionary of the English language.