GB2035459A - An intermittent combustion gas turbine plant - Google Patents

Abstract

A gas turbine plant comprises a shaft 1 which extends through and is rotatably mounted in a stationary block 5 containing combustion chambers 6 each having an inlet valve arrangement 10, 17 and an exhaust valve arrangement 11, 18 operated by cams 15, 16 on the shaft. A turbine disc 3 is secured on the shaft and has a peripheral ring of blades 4 extending perpendicular to the plane of the disc and profiled for both impulse and reaction centrifugal radial operation. A compressor 2 supplies carburetted air to the combustion chambers via a passage 8 and a duct 9. Combustion gas leaving a chamber 6 passes through a discharge chamber 12 and is directed onto blades 4 through nozzle 13. <IMAGE>

Description

SPECIFICATION A gas turbine set This invention relates to a gas turbine and engine set of the kind in which the motive gases are generated by explosive burning and in which the pressure rise of the motive fluid is produced partly by a compressor and partly by combustion at constant volume.

A gas turbine set of this kind comprises a series of combustion chambers provided with controlled inlet and exhaust valves, each chamber feeding a respective exhaust nozzle of the turbine. Compared with conventional gas turbines it has the advantage of requiring only a moderate pressure rise from the compressor. Sets of this type have not been developed very far hitherto, because they give rise to very considerable difficulties in respect of the production of the combustion chambers, the valve distribution system, and the turbine.

An object of this invention is to simplify the construction of a set of this kind while improving its performance.

Accordingly, the invention provides a gas turbine set in which the motive gases are generated by explosive burning, which turbine set comprises: a stationary cylinder block formed with a series of constant volume combustion chambers each having an inlet valve and an outlet valve; a shaft extending through and rotatably mounted in said cylinder block, the combustion chambers of said cylinder block being distributed around the shaft with the inlet and exhaust valves extending radially of the shaft; cams mounted directly on the shaft for actuating the inlet and exhaust valves of the combustion chambers; a compressor having an outlet arranged to supply the combustion chambers of the cylinder block via their inlet valves; a turbine mounted on the shaft and comprising a disc bearing at its periphery a ring of blades extending perpendicular to the plane of the disc, the ring of blades enclosing the cylinder block; and an exhaust nozzle for each combustion chamber of the cylinder block, the nozzle communicat ing with the combustion chamber via its ex haust valve and being oriented tangentially of the ring to act directly on the blades, each blade of the turbine being profiled for both impulse and reaction cent.,-lugal radial operation.

Fuel for combustion in the combustion chambers is delivered by a carburettor or by a fuel injection arrangement disposed in the compressor intake, or by an arrangement for directly injecting fuel into the combustion chambers.

The turbine may comprise two concentri cally disposed independent stages, one stage driving the said shaft and the other stage driving the compressor directly.

In order that the invention may be readily understood, an embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an axial section of a turbine set embodying the invention on the line I-I in Fig. 2; and Figure 2 is a cross-section on the line ll-ll in Fig. 1.

An air compressor 2 of any type, radial or centrifugal, is mounted on a drive shaft 1, which also bears a rotor disc 3 of a gas turbine, the periphery of the disc 3 having a cylindrical ring of blades 4 cantilevered from the disc 3 at right angles thereto and with a section profiled as shown in Fig. 2.

A stationay cylinder block 5 is disposed inside the space formed by the rings of blades 4. The shaft 1 extends through and is mounted rotatably in the block 5, which comprises a number of regularly distributed combustion chambers 6 (e.g. six such chambers in the Figure). The compressor 2 has a highpressure outlet 7 connected via a passage 8 to a circular duct 9 in the block 5. Carburetted air under pressure is supplied from the duct 9 to the various chambers 6 through respective inlet valves 10 (Fig. 1) disposed radially of the shaft 1.

Each chamber also has an exhaust valve 11, which is visible in Figs. 1 and 2, and which feeds an exhaust chamber 1 2 followed by a tangential ejection nozzle 1 3. There are therefore as many nozzles 1 3 as there are combustion chambers 6. Also, referring to Fig. 2, each combustion chamber 6 has a spark plug 14 projecting into the interior of the chamber. Cams 1 5 and 1 6 fixed on the drive shaft 1 control valve push rods 1 7 and 1 8 fixed on the stems of the valves 10 and 11 and biassed by springs (no reference), said cams being designed to open the valves one or more times per revolution in a regular rotating or star sequence.

The operation of the chambers 6 comprises an intake phase corresponding to the opening of the inlet valve 10, and during this phase the compressor 2 supplied compressed carburetted air to the corresponding combustion chamber. After the valve 10 has closed, an appropriate electrical distributor produces a spark at the plug 14 of the corresponding chamber and ignites the mixture, the pressure of which rises rapidly. Almost simultaneously, the valve 11 then opens to exhaust from the chamber the gases, the pressure of which, greatly increased by the explosive burning, results in very high velocity ejection into the corresponding nozzle 1 3. These gases act on the turbine blades 4, each of which (see Fig.

2) has parts with opposite slopes, the radially innermost part being equivalent to impulse operation, i.e., the gases ejected from the nozzle 1 3 are progressively decelerated and curved outwardly while their pressure increases, whereas the radially outer part is equivalent to reaction operation, i.e. the gases expand therein and their pressure is converted into velocity which is transmitted to the turbine by the blades, the gases finally being ejected centrifugally through apertures 1 9 at the periphery of a casing 20 which closely surrounds the turbine and is connected to the stationary block 5.

Fuel to be burnt in the combustion chambers is delivered to a conventional carburettor or an injection system disposed in an intake 21 of the compressor 2, which is consequently supplied with carburetted air. In that case, the final pressure at the outlet 7 of the compressor must not exceed the auto-ignition pressure of the fuel used, which is equivalent to the conventional pressure at the end of compression in the combustion chamber of conventional internal combustion engines. The fuel can also be supplied by an arrrangement for directly injecting fuel into the combustion chambers after the style of a diesel engine. In that case the foregoing limitation on compressor output pressure does not apply.

Of course, the combustion chambers 6, which have no piston nor any moving parts internally, may be of any shape whatsoever and require no high accuracy.

The actual turbine 3, 4 may be in two separate stages, one of which directly drives the compressor and the other of which delivers the drive power. In that case, the two stages are advantageously disposed concentri caily, for example the radially inner stage driving the compressor while the radially outer stage delivers the drive power relatively independently of the engine speed, so that if the set is applied to a landgoing vehicle it is possible to reduce or avoid expensive gearboxes.

Of course the block 5 containing the combustion chambers and their valves may have any suitable water or air cooling system (not shown).

In addition to simplification of the compressor, which now has to provide only a relatively moderate pressure, the invention enables a gas turbine set to be made more simply and compactly than conventional sets.

By comparison with a conventional internal combustion engine, the simplification is also important in that pistons and connecting-rod bearings are eliminated and the valve arrangement is greatly simplified.

Of course a turbo-engine embodying the invention can be adapted to operate in accordance with the features of a known diesel engine. In that case atmospheric air (which may or may not be mixed with partially burnt gases from the exhaust) is delivered by the compressor at a very high pressure to the combustion chambers, and injectors introduce the fuel into the combustion chambers where auto-ignition takes place, all the features of the engine being adapted accordingly.

Claims (7)

1. A gas turbine set in which the motive gases are generated by explosive burning, which turbine set comprises: a stationary cylinder block formed with a series of constant volume combustion chambers each having an inlet valve and an outlet valve; a shaft extending through and rotatably mounted in said cylinder block, the combustion chambers of said cylinder block being distributed around the shaft with the inlet and exhaust valves extending radially of the shaft; cams mounted directly on the shaft for actuating the inlet and exhaust valves of the combustion chambers; a compressor having an outlet arranged to supply the combustion chambers of the cylinder block via their inlet valves; a turbine mounted on the shaft and comprising a disc bearing at its periphery a ring of blades extending perpendicular to the plane of the disc, the ring of blades enclosing the cylinder block; and an exhaust nozzle for each combustion chamber of the cylinder block, the nozzle communicating with the combustion chamber via its exhaust valve and being oriented tangentially of the ring to act directly on the blades, each blade of the turbine being profiled for both impulse and reaction centrifugal radial operation.

2. A gas turbine according to claim 1 comprising a carburettor for supplying carburetted air to the compressor.

3. A gas turbine set according to claim 1 comprising a fuel injection arrangement for injecting fuel into air drawn into the compressor.

4. A gas turbine set according to claim 1, comprising a fuel injection arrangement for injecting fuel directly into the combustion chambers of said cylinder block.

5. A gas turbine set according to any preceding claim, wherein the turbine comprises two concentrically disposed independent stages, one stage driving the said shaft and the other stage driving the compressor directly.

6. A gas turbine set substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.

7. Any novel feature or combination of features herein described.