US1964731A - Nozzle construction for turbines - Google Patents

Description

2 Sheets-sheet 1 IN1/Enron /ws Mouw/Pr# mom/frs July 3, 1934. H. HOLZWARTH NOZZLE CONSTRUCTION -FORTURBINES Filed April 2s, i927 U WIT/V588 y WMM/M July 3, 1934. H. HoLzwARTH NOZZLE CONSTRUCTION FOR TURBINES Filed April 23, 1927 2 Sheets-Sheet 2 A TTOHNEYS Patented July 3, 1934 UNITED STATES Nozzm ooNs'rnUc'rIoN ron 'ruminvrzsV ,l

' Hans Holzwarth, Dusseldorf, Germany, assignor to Holzwarth Gas Turbine Co., San Francisco, Calif., a corporation of Delaware Application April k23, 1927, Serial No. 186,095

3 Claims. (Cl. (S0-4 1) In turbines using combustion gases, according to constructions of a type developed by me, it has been the practice heretofore to pass the combustion gases from the valved outlet of a combustion chamber to an intermediate chamber or conduit and from the latter to a plurality of nozzles discharging a plurality of jets from such chamber against the blades of the turbine rotor. These nozzles were separated by partitions, the latter cooled or uncooled. The walls of this interme- 'diate chamber were cooled, as by means of a water jacket, and it was found that the amount of heat thus abstracted from the-'combustion gases was quite considerable, and that the veiiiciency of the turbine was materially reduced thereby.

In view of this difliculty, it has been my aim to reduce the transfer of heat from the combustion gases on their way from the combustion chamber to the nozzles, and my present invention relates to a very simple and efficient type of con'- struction for accomplishing this' result. A fea.- ture of my invention consists in the substitution for the plurality of nozzles, which in prior constructions have been connected with each intermediate chamber or channel, of a single nozzle for conducting to the turbine rotor all of the combustion gases generated in a combustion chamber,

l the said nozzle converging from its inlet to a point of minimum cross-section only slightly removed from said inlet, and increasing in crosssectional area from such point to a point near the outlet end of the nozzle, the outlet end itself being fitted in segment-like fashion to the rotor circumference. This arrangement reduces the size of the intermediate channel between the outlet valve located at the mouth of the combustion chamber and the nozzle itself, that is, the narrowest section of the latter, to the smallest possible magnitude with a corresponding decrease in the amount of heat lost by the combustion gases before they reach such narrowest section of the nozzle. Another feature of my present invention relates to the shape of the chamber or conduit through which the gases pass from the outlet valve of the combustion chamber tothe nozzle proper. According to my invention, this chamber or conduit is made as small as possible, and is contracted after the fashion of a funnel converging toward the narrowest portion of the nozzle. I ,prefer to make the walls of this intermediate chamber or conduit follow straight lines from the immediate vicinity of the nozzle or exhaust valve of the explosion chamber to the inlet end of the nozzle, the volume of such conduit being thereby made a minimum consistent with the absence of throttling. Due to such construction, the gas ,pressure builds up more rapidly in the nozzle conduit or channel to that prevailing in the explosion chamber, and with a lower drop in pressure from themaximum explosion pressure, than in the larger nozzle conduits heretofore employed. In this manner I minimize the expansion and whirling motion of the gases in such tapering or funnel-shaped portions, and this again reduces the losses due to abstraction of heat, investigations having shown that such whirling motion is responsible for a considerable proportion of the heat losses occurring between the combustion chambers and the nozzles, in constructions prior to my present invention.

. I am aware that my United States Patents Nos. 853,925 and 877,194 show constructions in which a single nozzle is associated with each combustion chamber. In both of these patents, however, the nozzle conduits are large, as were the conduits in a number of explosion turbines built by me subsequently to these patents, in which turbines the heat losses in the nozzle conduits were enormous; these patents, moreover, fail'to show other constructional features described hereinbelow and defined in the claims.

Without desiring to restrict myself to the particular details illustrated, I will now describe a preferred and satisfactory embodiment of my present invention, with reference to the accompanying drawings, in which Fig. 1 is a partial longitudinal section through a turbine provided with my improved nozzle and nozzle conduit; Fig. 1a is a horizontal section or a reduced scale taken through the conduit and valve shown in Fig. 1; Fig. Z'is a section along the axis of the nozzle, substantially on line 2-2 of Fig. 1; and Fig. 3 is a face view, looking lengthwise ofthe turbine shaft, against the outlets of the nozzles, with parts omitted.

The apparatus shown comprises a plurality of combustion chambers 10 provided with suitable devices for the admission of air and fuel and for the ignition of the combustible mixture. As these devices form no feature of my present invention, and may be of any well-known or approved construction, I have not shown or described them in detail in the present application. The combustion gases pass out from the chambers 10 into conduits 11, there being one such conduit for each chamber4 10, andthe connection to each conduit is controlled by an outlet valve 12, the several valves being actuated by the turbine in any approved 'manner (not shown). As illustrated by Fig. 1, the conduit 11 vmay be jacketed for the circulation of water or other cooling medium, and the Jacket may be extended to cool that -portion of the combustion chamber .10 which is adjacent to its outlet. I The conduit 11 is widest in the neighborhood of the valve 12, the outletof the explosion chamber being of considerablylarger diameter than the inlet-of the nozzle as shown in Fig. 1a. As the walls of the nozzle conduit or channel run along 1o substantially straight lines from the region of the nozzle valve to the inlet of the nozzle, the cross-section of the conduit 11 constantly diminishes from the nozzle valve to the nozzle, so that the volume of such conduit is made a minimum 15 without causing throttling ofthe gases. There is but a single nozzle for each combustion chamber 10 and its conduit 11, said nozzle being of the De Laval type. The outlets of such nozzles are close to the plane of rotation of the blades 14 2o on the rotor 15, or of the first set of rotor blades, when (as illustrated) the rotor has more than one set of blades, in which case a set of stationary bladesr 16 is interposed between the adjoining sets A of rotor blades. As shown, the explosion chambers are arranged with their longitudinal axes parallel to the turbine shaft, whereby a large number of chambers may be associated with the turbine rotor. As' more clearly shown in Fig. 3, the outlets of the nozzles are curved in the form of segments so as to conform to the arrangement of the rotor blades, and as each combustion chamber has only one nozzle, each segment-like outlet is made long enough to discharge the gases against a plurality of blades which it spans.

' The conduit 1l is relatively short, and the narrowest portion or throat 13 of the nozzle is relatively close to said conduit, the major portion of the nozzles length lying between said throat 13 and the nozzle outlet. From said throat the noz.- 40 zle passage aresboth toward the nozzle inlet in funnel-like fashion and toward the nozzle outlet, as indicated at 13a and 13b respectively. The general direction of the nozzle is oblique both when viewed in an axial plane (Fig. 1) and when looking along the turbine axis (Fig. 3); that is,

the nozzle inlet is farther away from the turbine axis than the nozzle outlet, and furthermore, the

inlet and the outlet are in different axial planes,

the outlet being in advance of the inlet, in the direction of the rotation. The nozzles 13 may also be jacketed, as indicated at f13, for the circulation of water or other cooling fluid. A

The nozzle 13 diverges from the constricted section 13 to a point nearthe outlet end thereof at which the gases have expanded to an extent determined by the expansion ratio of the nozzle.

Fromthis point to the outlet end of the nozzle the walls of the nozzle no longer diverge but are parallel to the nozzle axis through this outlet section, as shown in Fig. 2.

By adapting the nozzle outlets in segment-like fashion to the rotor circumference in accordance withA the present invention, wherein the nozzles are so constructed that the walls of the outlet portion thereof run parallel to the nozzle axis fromthe point at which the necessary expansion relation is attained to the nozzle outlet, it is possible to` retain the necessary expansion relation with the smallest possible circumferential extent of the nozzle outlet. In this manner a sumcient number of nozzle outlets and consequently of combustion chambers maybe arranged about the rotor circumference t permit an economical operation of the turbine. In other words, my invention actually makes practicable the utilizalet, a single De Laval nozzle, and a conduit leadtion of a single nozzle for each combustion chamber. This single nozzle is of the greatest importance because it makes possible a reduction by fully one-third of the heat losses suffered by the gases on their way to the rotor.

It will befclear from Figs. 1 and 1a that the walls of the connecting conduit 11 extend along straight lines from the 'outlet of the combustion chamber to the inlet of the nozzle valve 11. The conduit is therefore free of enlargements and has a minimum volume consistent with the absence of throttling, so that the pressure in such conduit, upon opening of the nozzle valve 12, Y rapidly builds up and becomes equal to that prevailing in the explosion chamber after only a very short drop from the maximumA explosionpressure of the gases.

For the reasons explained in the introductory part of this specification, an arrangement such as described with reference to the accompanying drawings reduces to afsvery considerable extent the losses due to abstraction of heat from the .combustion gases on their way from the valvecontrolled outlets of the combustion chambers 10 to the throats or narrowest portions of the 100 nozzles, such throats 13' being much nearer to the outlet valves 12 than in previous constructions, and the area of heat-abstracting surfaces being much smaller. Another reason for the reduction of the heat losses is found in the funnel shape of the conduit 11 and of the nozzle portion 13, whereby whirling motion of the gases is minimized. The eciency of the turbine is inwhich not only is relatively short, as stated above, 1 5

but includes no enlargements and is throughout asnearly equal as possible in cross-sectional area tothe minimum necessary to convey all the gases to the nozzle within the small period of time allowed by each explosion cycle.

Various modifications may be-made without departing from the nature of my invention as set forth in the appended claims;

I claim:

1. In an apparatus for driving turbines by means of combustion gases under pressure, a turbine rotorfan explosion chamber supported with its longitudinal axis parallel to the shaft of the rotor and having a valve-controlled out- 13o ing from said outlet to the inlet portion of the nozzle, the said outlet being of considerably larger cross-section than the inlet of the nozzle, the walls of said conduit extending' along straight lines from said outlet'to the inlet of said nozzle and diminishing in cross-section gradually from such outlet in the nozzle inlet, whereby the vollume of said conduit is kept at a minimum with absence of throttling, said nozzle being adapted to conduct to the rotor of the turbine all the gases discharged by said combustion chamber through said conduit, and being constricted near its upper portion, said upper portion being directly connected to said conduit and of funnel u shapeand converging from the inlet opening to the constricted section of said nozzle, the nozzle increasing in cross-section from said constricted section to a point near the outlet thereof, said latter outlet being in the form of a segment corresponding to the curvature of the Vperiphery of the rotor and spanning a plurality of blades of said rotor.

2. In an apparatus for driving turbines byV means of combustion gases under pressure, a turbine rotor, an explosion chamber supported with its longitudinal axis parallel to the shaft of the rotor and having a valve-controlled out- Y let, a single De Laval nozzle, and a conduit dening an intermediate channel between said outlet and said nozzle, the said outlet being of considerably larger cross-section than the inlet of the nozzle, the walls of said conduit extending along straight lines from said outlet to the inlet of said nozzle, whereby the volume ot said conduit is kept at a minimum with absence of throttling, the nozzle being adapted to conduct to the rotor of the turbine all of the combustion gases generated in said chamber and converging from its inlet to a point of minimum cross-section adjacent to its inlet and diverging from such point to a point near the outlet end thereof, the walls of the outer section of the nozzle from said latter point to the discharge outlet being parallel to the axis or the nozzle and fitted in the form of a segment to the r'otor circumference so as to maintain the expansion.

3. In an apparatus for driving turbines by means of combustion gases, the combination of a turbine rotor, an explosion chamber supported with its longitudinal axis parallel to the shaft of the rotor and having a valve-controlled outlet, a single De Laval nozzle arranged to discharge against said rotor all of the gases generated insaid chamber, and a conduit dening an intermediate channel between said outlet and said nozzle, the said outlet .being of considerably larger cross-section than the inlet of the nozzle, the walls of said conduit extending along straight lines from said outlet to the inlet of said nozzle, whereby the volume of said conduit is kept at a minimum with absence of throttling and pressure consequently rapidly built up therein upon opening of said valve-controlled outlet, so that whirling of the gases and loss of heat in said channel are reduced to a minimum.

HANS HOLZWARTH.

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