JPS5939648B2 - Gas turbine combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion device for a gas turbine engine, which normally supplies air from a swirler to a combustion chamber.

In general, a gas turbine engine consists of a compressor, a combustion device, a turbine, etc. l)ζ Normally, small gas turbine engines often use a type of combustion device called a reverse flow can type for design reasons.

As shown in FIGS. 9 and 10, this type of combustion device is provided with a turbine T disposed on the downstream side of the compressor C on the same axis P as the compressor C, protruding from the outer side of the turbine T, and a surrounding wall portion. A combustion chamber 3 having a secondary air inflow hole 1 and a dilution air inflow hole 2, an air supply passage 4 formed around the outer periphery of the combustion chamber 3, a combustion injection nozzle 5 provided in the combustion chamber head, and a nozzle 5. The compressed air 8 to be supplied to the combustion chamber 3 is supplied to the air supply passage 4 in the opposite direction to the outflow direction of the exhaust gas 9. Inflow. In this type of combustion device, due to the protruding arrangement relative to the turbine scroll S and the rotation of the compressor plate, the compressed air 8 has a velocity component in the direction O relative to the turbine scroll S. As a result, the compressed air 8 flows into the annular air supply passage 4 while rotating as shown by the arrow 10 due to the circumferential force of the combustion chamber. If the swirling speed component of the compressed air 8 is strong, even when the compressed air 8 reaches the swirler 6, the swirling motion remains, and this swirling motion forms a free vortex at the inlet of the swirler 6. The static pressure at the inlet of the swirler 6 decreases. When the free vortex is strong,
The static pressure at the inlet of the swirler 6 becomes much lower than the static pressure in the combustion chamber 3, causing a backflow of combustion gas and flame from the combustion chamber 3 to the input of the swirler 6, which not only prevents normal combustion, but also This also causes burnout of the surrounding area of the swirler 6. This invention improves the static pressure at the swirler inlet by providing a vane in the air supply passage that reduces the circulation velocity component of the compressed air, or converts a part of the velocity head of the compressed air into a static pressure head. It is an object of the present invention to provide a combustion device that can perform optimal combustion by preventing a drop in pressure and supplying a set amount of air from a swirler. Embodiments of the present invention will be described below based on the drawings.

In FIGS. 1 and 2, reference numeral 11 denotes a combustion chamber formed by an inner cylinder 12; a combustion chamber head; a fuel injection nozzle 13 on the upper end wall of the inner cylinder 12, into which primary air flows in from around it; A swirler 14 and an ignition flag 15 are provided, and a secondary air inflow hole 16 and a dilution air inflow hole 11 are provided in the peripheral wall of the combustion chamber. The swirler 14 has a large number of blades 20 arranged radially between an inner ring 18 and an outer ring 19. Further, since the inner cylinder 12 has a single layer structure and is not a double structure with a combustion gas circulation passage provided therein as described in U.S. Pat. No. 3,754,393, the swirler 14 From there, only the primary air is supplied into the combustion chamber 11. 2
Reference numeral 1 denotes an annular air supply passage formed between the inner cylinder 12 and the outer cylinder 22, and extends from the exhaust end side of the combustion chamber 11 to the combustion chamber head.

As described above, the compressed air 24 flows into the air supply passage 21 from around the exhaust side of the combustion chamber 11 with a tangential velocity component in a direction opposite to the outflow direction of the exhaust gas 25. It flows while swirling as shown. 2
A vane 3 reduces the swirling velocity component of the swirling flow 26, and is disposed downstream (above) the secondary air inflow hole 16 in the air supply passage 21, around the circumferential force of the combustion chamber.

FIG. 4 shows the shape of the rotation suppressing blade 23.
The upstream side (lower side) 23a of 3 is inclined in the direction of the swirling flow 26,
The downstream side (upper) 23b faces in the axial direction, and the blade 23
By passing through, one swirl flow 26 is converted into an axial flow 26a. Even when such an axially directed flow reaches the vicinity of the inlet of the swirler 14, there is little or no tangential velocity component, and therefore, no free vortices are formed near the inlet of the swirler 14. As a result, the static pressure at the inlet of the swirler 14 is higher than if the blades 23 were not provided. Looking at this from another perspective, the axial speed of air is determined by the amount of air flowing into the combustion chamber 11 from the swirler 14, and in the speed range where the influence of air compressibility can be ignored, the speed of the swirl flow 26 is determined by the amount of air flowing into the combustion chamber 11 from the swirler 14. Axial component U1 of U and axial flow 2
Since the velocity V of the swirling flow 26 is equal to the velocity V of the swirling flow 26, the latter velocity V is smaller than the former velocity U by an amount corresponding to its swirling direction component U2VC1.Therefore, among the velocity heads of the velocity U of the swirling flow 26, It can also be said that the velocity head of the rotation speed component U2 is converted into a static pressure head by the blade 23. In this way, compressed air 24 (swirling flow 26)
Reducing the rotation speed component U2 of the speed U of is equivalent to decreasing the speed U of the compressed air 24. b1 To decrease the speed U, the rotation speed component U2 must be decreased, and the rotation speed If the component U2 decreases, the speed U will inevitably decrease. In the embodiment shown in FIGS. 1 and 2, the rotation suppressing blades 23 are provided on the outer peripheral surface of the inner cylinder 12, but they may also be provided on the inner peripheral surface of the outer cylinder 22. In addition, in FIG. 1, since the swirl suppressing blade 23 is provided downstream of the secondary air inflow hole 16, the compressed air 24 remains swirling around the secondary air inflow 16, so that the secondary air Since the secondary air flows into the combustion chamber 11 from the inflow hole 16 while swirling, there is an advantage that the air and fuel are sufficiently mixed and agitated within the combustion chamber 11 and the combustion condition is improved.
On the other hand, as shown in FIG. 3, if the swirl suppressing blade 23 is provided on the downstream side of the secondary air inflow hole 16, the secondary air whose swirl is suppressed will flow from the secondary air inflow hole 16 to the combustion chamber 11. This is disadvantageous because the above advantages are lost. Furthermore, in FIG. 4, the lower part 23a of the swirl suppressing blade 23 may be directed in the opposite direction to the direction of the swirl flow 26. Until now, compressed air 2
4 flows into the air supply passage 21 with a tangential velocity component.
As mentioned above, 1. Because the combustion device is arranged to protrude from the turbine scroll S, the flow velocity distribution of the compressed air around the passage circumference at the entrance of the air supply passage 21 becomes extremely uneven, which becomes a problem. There is. In such a case, in order to eliminate unevenness in the flow velocity distribution, as shown in Fig. 5, the inner cylinder 1
A guide vane 28 may be provided on the lower circumference of 2. These guide vanes 28 are attached to the outer peripheral surface of the inner cylinder 12 or the outer cylinder 22.
The compressed air 24 is attached to the inner circumferential surface of the compressed air 24 and gives swirl to the compressed air 24.
The compressed air 24 flowing into the air supply passage 21 with a non-uniform flow velocity distribution passes through the guide vanes 28 to form a swirling flow 26, thereby effectively eliminating non-uniform flow velocity distribution. Also in this case, the rotation suppressing blade 23 is provided at the upper part of the inner cylinder 12.
If provided, the swirl flow 26 is converted into an axial flow by passing through the swirl suppression vanes 23. Therefore, no drop in static pressure occurs on the swirler 14. 6 and 7 show a modification of the combustion device shown in FIG. 5. In this example, the swirl suppression blades 23A are arranged radially on the upper end wall of the inner cylinder 12, and one swirling flow 26 is suppressed from swirling by the blades 23A. If the compressed air 24 is swirling from the beginning, the guide vane 28 at the entrance of the air supply passage 21 is unnecessary. In this modification, the rotation suppressing blade 23A is a flat blade, but may be a curved blade if necessary. In either case, swirling is suppressed by the vanes 23A, and a significant drop in static pressure at the inlet of the swirler 14 does not occur, allowing optimal combustion in the combustion chamber 11. FIG. 8 shows yet another modification, in which the rotation suppressing blade 23B is
Inner cylinder 1 is tilted at a certain angle with respect to the radial direction of 2.
2 is located on the upper end wall. In this case as well, the blade 23B
is a flat blade.If necessary, it may be a curved blade. As described above, even if the compressed air swirls and flows through the air supply passage of the combustion device, the swirl can be suppressed by the vanes provided in this passage, thereby preventing a drop in the static pressure at the swirler inlet. Since air can be normally supplied into the combustion chamber from the swirler and optimal combustion can be performed, the combustion performance and durability of the combustion device are improved. Further, since the swirl suppressing blade 23 is located downstream of the secondary air inlet hole 16, the secondary air having a swirl component flows from the secondary air particle inlet hole 16 into the combustion chamber 11.
Since the air and fuel flow into the combustion chamber 11, the air and fuel are sufficiently mixed and stirred, which has the advantage of improving the combustion state.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view showing an embodiment of the present invention, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, and Fig. 3 is a partially broken front view showing a configuration not included in the present invention. Figure 4 is a diagram showing the shape of the swirl suppression vane shown in Figures 1 and 2 and the speed of compressed air passing through this vane, and Figure 5 is a diagram showing the shape of the swirl suppression vane and guide vane used together. FIG. 6 is a partially broken front view showing another modified example, FIG. 7 is a sectional view taken along line B-B in FIG. 6, and FIG. FIG. 9 is a partially cutaway plan view showing still another modification, FIG. 9 is a schematic longitudinal view of a small gas turbine having a conventional combustion device, and FIG. 10 is a perspective view of the conventional combustion device. 11... Combustion chamber, 12... Inner cylinder, 13
...Fuel injection nozzle, 14...Swirler, 16...Secondary air inflow 17...
- Dilution air inflow {Lh2l...Air supply passage, 22...Outer cylinder, 23, 23A, 23B...
...Swirl suppression vane, 24...Compressed air 6...
...exhaust gas, 26...swirling flow, 28...
... Guide vane, U ... Speed of compressed air, U2
・・・・・・Turning direction component of speed U.

Claims (1)

[Claims] 1 A ring is provided between the inner cylinder 12 and the outer cylinder 22 that form the combustion chamber 11, through which the compressed air 24 to be supplied to the combustion chamber 11 flows from around the exhaust side of the combustion chamber 11 in a direction opposite to the outflow direction of the exhaust gas 25. A fresh air supply passage 21 is formed in the upper end wall of the inner cylinder 12, and compressed air 24 that has passed through the air supply passage 21 is formed on the upper end wall of the inner cylinder 12.
A swirler 14 is provided in the peripheral wall of the inner cylinder 12 to allow a part of the compressed air 24 to flow into the combustion chamber 11 as primary air, and a secondary air inflow hole 16 is provided in the peripheral wall of the inner cylinder 12 to allow the other part of the compressed air 24 to flow into the combustion chamber 11 as secondary air. In a combustion apparatus for a gas turbine in which only the primary air is supplied from the swirler 14 into the combustion chamber 11, the air supply passage 21 is provided downstream of the secondary air inflow hole 16 in the air supply passage 21. A combustion device for a gas turbine, characterized in that swirl suppression vanes 23, 23A, and 23B are provided to reduce the swirl direction component U_2 of the speed U of compressed air 24 and prevent a drop in static pressure at the inlet of the swirler 14. .