JPH1019737A - Jet engine test cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a facility itself compact, by setting a shielding plate at the side of an engine chamber of an exhaust duct which shields a peripheral edge of the duct and rotates. SOLUTION: A shielding plate 7 is rotatably set at the side of an engine chamber 3 of an exhaust duct 4. A cross section of the exhaust duct 4 is shielded to a nearly semi-circular shape. A central part of the exhaust duct 4 is notched in the shape of an arc. The shielding plate 7 is rotated by a rotary ring 11 via a transmission shaft 9 by a turbine 8 in an exhaust chamber 6. Since the shielding plate 7 shuts only a peripheral edge of the exhaust duct 4, a high temperature exhaust gas at the central part is allowed to pass directly without being hindered by the shielding plate 7. A low temperature air in the periphery is shielded by the shielding plate 7 and enters only from an opening part to the exhaust duct 4. The high temperature exhaust gas is pressed by the low temperature air and flows to deflect to the back side of the shielding plate 7. Therefore, a position of the exhaust gas is always changed by the rotation of the shielding plate 7. Accordingly, a face in the exhaust duct 4 exposed partially to the high temperature gas for a long time is eliminated, the exhaust duct can be shortened, and the facility itself becomes compact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jet engine test cell, and more particularly to a jet engine test cell capable of reducing the length of an exhaust duct and reducing the installation area.

[0002]

2. Description of the Related Art In general, a jet engine test cell is a test facility for measuring and evaluating the performance and functions of a new jet engine after maintenance or by operating a new jet engine. When operating a jet engine, noise is a problem, so the test cell is always a building equipped with soundproofing equipment. More specifically, as disclosed in Japanese Patent Application Laid-Open No. 58-218633, a test cell includes a cell body partitioned by partition walls to form an intake chamber on the upstream side and an exhaust chamber on the downstream side, and a cell. An intake muffler is provided on the intake chamber side of the main unit, an engine room for accommodating the test jet engine is provided downstream of the intake muffler, an exhaust duct is provided downstream of the engine room, and an exhaust muffler is provided on the exhaust chamber side. ing.

[0003] In the test cell having such a structure, in addition to the noise countermeasures, treatment of high-temperature engine exhaust gas becomes a problem from the viewpoint of protection of the cell itself and pollution prevention. If the hot engine exhaust gas directly hits the exhaust chamber wall before it is diluted (cooled), the wall itself will be damaged. This tendency is greater for a high-power engine, for example, the temperature of exhaust gas is 1800 ° C. or higher, whereas the limit is 200 ° C. for a normal concrete wall, and when it exceeds this, moisture in the concrete evaporates and becomes brittle. Would.

For this reason, conventionally, there are two methods of treating high-temperature exhaust gas: a water-cooled method and an air-cooled method. The water-cooled type cools the exhaust gas by injecting water into the exhaust gas in the exhaust duct or exhaust chamber.However, the equipment and operating costs are increased due to the large amount of cooling water used and the need to process the used cooling water. It is expensive and uneconomical. In this regard, in the air-cooled type, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 58-218633, cooling air can be automatically sucked from the intake chamber by the effect of sucking the exhaust gas of the jet engine. If mixed with exhaust gas in a duct, a cooling effect can be obtained, so that this method is economically superior to a water-cooled type.

[0005]

However, in order to obtain a cooling effect of mixing the suction cooling air with the exhaust gas and keeping the exhaust gas at a uniform temperature, the air cooling system requires the exhaust The duct must be long enough. In the case of the air-cooling type, generally, the ratio of the duct diameter D to the duct length L of the exhaust duct is set to be sufficiently long with L / D being about 30 as a guide. For this reason, in some cases, there is a problem that the installation area itself becomes larger and the construction cost of the test cell itself becomes higher than that of the water-cooled type.

[0006] The present inventors have investigated this technical field, and found that in order to shorten the length of the above-mentioned exhaust duct,
No technology that improved the air-cooling system was found. This is presumably because there was no case where the installation area of the test cell itself was limited. However, in recent years, test cells have tended to increase in size due to the increase in the size of jet engines and the increase in output due to the installation of afterburners and the like. This is because, as described above, the exhaust gas temperature becomes higher than 1800 ° C. with the increase in the size and the output of the engine. Therefore, the heat-resistant structure of the partition wall of the test cell is formed as a laminated structure of heat-resistant bricks. This is because the exhaust system equipment including the exhaust duct has been increased in size in order to cope with the change in the system. Therefore, the installation area of the test cell itself has been limited due to the relationship with the area of the site such as an airport or a factory where the test cell equipment is installed.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a jet engine test cell that can reduce the length of an exhaust duct and reduce the size of equipment itself even if exhaust gas processing is performed by air cooling. It is assumed that.

[0008]

In order to achieve this, the present invention provides an intake chamber having an intake silencer on the upstream side of a cell body and an exhaust chamber having an exhaust silencer on the downstream side. In a jet engine test cell in which an engine room accommodating a test jet engine and an exhaust duct are sequentially provided from the intake chamber side in the main body, a shield for rotating and rotating the periphery of the exhaust duct is provided on the engine room side of the exhaust duct. That is, a plate was provided.

In the present invention, when the exhaust duct is circular,
It is preferable that the shape of the shielding plate be such that the cross section of the exhaust duct is shielded in a substantially semicircular shape so that the suction cooling air is more efficiently mixed with the exhaust gas.

[0010] In addition, as the structure of the shielding plate when the exhaust duct is elliptical, it is preferable to provide a rotating belt having a large number of shielding plates arranged along the periphery of the exhaust duct.

Further, as a means for driving the shielding plate, it is efficient to provide a turbine in the exhaust chamber, drive the turbine with the exhaust gas, and rotate the shielding plate by driving the turbine.

In the present invention, by providing a shielding plate on the engine room side of the exhaust duct, which shields a part of the exhaust duct space and is rotatable around the inner periphery of the duct, the efficiency of the suction cooling air to the exhaust gas is improved. It is possible to obtain a cooling effect of mixing well and keeping the exhaust gas at a uniform temperature.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of the present invention will be described below with reference to FIGS. 1 (a) to 1 (c). FIG.
FIG. 1A is an overall front sectional view of a jet engine test cell of the present invention, and FIG. 1B is a view taken along a line AA in FIG.
FIG. 1C is a view taken in the direction of arrows BB in FIG. The basic structure of the test cell of the present embodiment is the same as that of the prior art. That is, the cell body Q divided and formed by the partition wall M so as to form the intake chamber 1 on the upstream side and the exhaust chamber 6 on the downstream side.
And an intake muffler 2 on the intake chamber 1 side of the cell body, an engine chamber 3 for accommodating the test jet engine 10 downstream of the intake muffle chamber 2, an exhaust duct 4 downstream of the engine chamber 3, and an exhaust chamber 6 on the exhaust chamber 6 side. The exhaust silencer 5 is provided.

The shield plate 7 of the present invention is provided on the engine room side of the exhaust duct 4 and is rotatably supported in the peripheral direction of the duct so as to shield a part of the peripheral edge of the exhaust duct.
As shown in FIG. 1B, the shielding plate 7 has a shape in which a cross section of the exhaust duct space is substantially semicircular and a portion corresponding to the center of the exhaust duct is cut out in an arc shape.

The shield plate 7 is driven by a turbine 8 provided in the exhaust chamber 6 to rotate the rotary ring 1 via a transmission shaft 9.
Rotated by one. The turbine 8 has an exhaust chamber 6
It is driven and rotated by the energy of the exhaust gas passing through it. In the case of a normal engine test, the exhaust gas flow passing through the exhaust chamber 6 has sufficient energy to rotate the turbine 8, and no special power is required to rotate the shielding plate 7. . The rotation of the shielding plate 7 may be performed by a power source such as a motor, but the method of the present embodiment is excellent in that no special power is required, and it is not necessary to simply discharge a large energy of the exhaust gas flow. It is also excellent in power recovery.

The shielding plate in the present invention is, as described later,
It is necessary to intermittently shield the periphery of the exhaust duct in order to shield the flow path of the suction air flow passing through the periphery of the exhaust duct and deflect the intake air flow toward the engine exhaust gas flow. is there. For this reason, it is necessary to rotate the periphery of the exhaust duct instead of fixing the shielding plate to the periphery of the exhaust duct. Further, in order to secure a flow path of the engine exhaust gas flow passing through the center of the exhaust duct, it is necessary that the shielding plate does not extend to the center of the exhaust duct. As described above, the shape of the shielding plate for achieving this is preferably a shape in which the periphery of the exhaust duct is shielded in a substantially semicircular shape, and a portion corresponding to the center of the exhaust duct is cut out.

In the above configuration, the function of the shielding plate will be described with reference to FIG. 2 showing the flow of air in the exhaust duct.
First, air a that has flowed into the engine room 3 through the intake muffler chamber 2 on the side of the intake chamber 1 becomes exhaust gas b after a part of the air a has been used as combustion air for the jet engine 10. It is ejected toward the exhaust duct 4. On the other hand, the other air c passes around the jet engine 10 and flows into the exhaust duct 4 together with the engine exhaust gas b. At this point, the mixture of the high-temperature engine exhaust gas b and the low-temperature air c passing around the engine is not sufficiently mixed, and the exhaust gas b at the center of the exhaust duct remains at a considerably high temperature.

As described above, since the shielding plate 7 has a shape that shields only the periphery of the exhaust duct, the high-temperature engine exhaust gas b at the center is not interfered or hindered by the shielding plate 7.
The low-temperature air c that passes through the place where the shielding plate 7 of the exhaust duct 7 is installed (opening X) as it is and is blocked by the shielding plate 7 around the exhaust gas b is directly discharged into the exhaust duct 4. And flows into the exhaust duct only from the opening X of the shielding plate 7. At this time, the high-temperature exhaust gas b flowing through the center portion is pushed by the air c (the lower air in FIG. 2) flowing only from the opening X of the shielding plate 7, and the exhaust gas b of the shielding plate 7 without the inflowing gas is pushed. The flow is biased toward the back side Y.

In the present invention, since the shielding plate 7 is constantly rotating, the opening X of the shielding plate 7 is rotated with the rotation of the shielding plate 7.
Constantly changes its position, and the hot exhaust gas b
(The portion where the high-temperature exhaust gas flows in the exhaust duct 4) always changes its position. Therefore, by constantly changing the position of the flowing portion of the high-temperature exhaust gas, mixing of the high-temperature gas and the low-temperature gas is promoted, and the wall surface which is locally exposed to the high-temperature gas for a long time in the exhaust duct 4 is formed. Disappears.

If the shielding plate 7 does not rotate, the flow of the high-temperature exhaust gas flowing unevenly is fixed, and the mixing of the high-temperature and low-temperature gases is not promoted.
Since the same wall portion is locally exposed to the high-temperature gas for a long period of time, damage to the wall surface is hastened, which has an adverse effect. According to the present invention, the turbulence diffusion coefficient increases due to the rotation of the shield plate, compared with the mere turbulence diffusion of the exhaust gas in the conventional exhaust duct, and the averaging of the exhaust gas temperature = the cooling rate is much higher. early.

The results of simulating the temperature distribution in the exhaust duct by the finite volume method and confirming the effect of the shielding plate of the present invention are shown below. FIG. 3 shows a calculation grid of the exhaust duct by the finite volume method,
This figure shows how the space inside the exhaust duct is divided into a number of cells (grids). The assumption is that the diameter D of the exhaust duct 4 is
= 5500 [mm], length L = 40000 [mm], L
/D=7.27, exhaust gas temperature of engine 10 = 170
The temperature was set to 0 ° C., and the calculation was performed using a モ デ ル model. In FIG. 3, the constricted part on the left side is the engine, the black painted part in front of the engine is the shielding plate 7, and the upper half of the exhaust duct 4 has the same substantially semi-circular shielding as in FIG. I put a board.

First, FIG. 4 shows a temperature distribution of the exhaust gas in the exhaust duct 4 (longitudinal direction) in a state where the shielding plate is not rotated and is stationary. In FIG. Is the engine 10, and a vertical line portion in front of the engine is the shielding plate 7. The high temperature exhaust gas ejected from the engine is mixed with the cooling air, so that the maximum temperature 1703K (immediately after the engine is ejected) in the exhaust duct. (Kelvin) to the temperature range of the minimum temperature of 291.9 K, the temperature decreases toward the downstream side of the duct. A to F in FIG.
Indicates a boundary temperature region of the exhaust gas in the duct, and respective temperatures (K) are A: 1502, B: 1300, and C: 10
98, D: 896.8, E: 695.2, F: 493.
5 Due to the shielding effect of the shielding plate 7, compared with low-temperature exhaust gas (the lowest-temperature gas in the lower half of the exhaust duct 4),
A relatively high temperature exhaust gas portion G (shaded portion, 494-695)
K) is biased toward the upper half of the exhaust duct 4, and this bias also tends to be more pronounced downstream of the exhaust duct.

Next, FIG. 5 shows the exhaust gas temperature distribution in the exhaust duct (radial cross section) immediately after the shield plate when the shield plate is stationary without rotating. In the figure, the maximum temperature 1703 at the center of the exhaust duct (engine ejection section)
From K to a temperature range of 293.2K, which is the minimum temperature of the peripheral portion of the exhaust duct, the temperature is concentrically higher toward the center of the engine exhaust port, and the exhaust gas is hardly cooled. In the figure, the respective temperatures (K) of A to F indicating the exhaust gas boundary temperature region in the duct are A: 1502, B: 1
300, C: 1099, D: 897.5, E: 696.
1, F: 494.6.

On the other hand, FIG. 6 shows the temperature distribution at the outlet of the exhaust duct, which is far away from the shield plate, when the shield plate is stationary without rotating. Here, the high-temperature exhaust gas is biased while passing through the exhaust duct and mixed with the low-temperature air, so that the maximum temperature of the exhaust gas is about 564K (291%).
° C), the minimum temperature is about 300K, which is considerably lower than the exhaust gas temperature of the engine 10 of 1700K,
Still, the mixing of exhaust gas with cold air is not yet sufficient. The respective temperatures (K) of A to M indicating the exhaust gas boundary temperature region in the duct in the same drawing are A: 544.9, B:
526.1, C: 507.4, D: 488.6, E: 4
69.8, F: 451.0, G: 432.2, H: 41
3.4, I: 394.6, J: 375.9, K: 35
7.1, L: 338.3, M: 319.5.

Therefore, the temperature distribution of the exhaust gas at the outlet of the exhaust duct when the shield plate is rotated is calculated. Since the temperature distribution of the exhaust gas also rotates according to the rotation of the shielding plate, the average temperature of the exhaust gas in the exhaust duct space is calculated at each point in the exhaust duct (points at different distances from the center of the exhaust duct = radii) ) Temporal change of temperature = determined by taking the temperature distribution in the circumferential direction of the exhaust duct at each point. FIG. 7 shows the relationship between the distance from the center of the exhaust duct to the outer edge and the average temperature of the exhaust gas. From this figure, it can be seen that the maximum temperature has dropped to about 453 K (180 ° C.). As a result, the exhaust gas temperature at the outlet of the exhaust duct can be remarkably reduced as compared with the related art in which the shield plate is not provided and the case of FIG. 6 in which the shield plate is not rotated.

In the present invention, it is preferable that the area of the shielding plate is variable so that the function of the shielding plate can be adjusted according to the situation, for example, according to the output scale of the engine. If you inhale too much cooling air, increase the area of the shielding plate,
It is necessary to reduce the amount of suction by reducing the opening of the exhaust duct. This is because the negative pressure from the atmospheric pressure in the engine room is severely restricted for the performance test of the engine, and it is necessary to prevent an excessive intake amount of air. As a specific mechanism, as shown in FIG.
0 is stacked on the fixed frame 11 so as to be slidable. With this structure, the ratio of the shielding portion (2θ) can be changed from θ in which the shielding plates are completely overlapped to 2θ in which the shielding plates are maximized.

Further, the exhaust duct of the jet engine cell may be not only a perfect circle but also an elliptical shape having a wide cross section. When the jet engine cell stores the entire aircraft and performs tests with the engine mounted on the aircraft, the engines are installed side by side, as in the case of twin-engines, etc., so the wide elliptical shape Exhaust duct is required. In such a case, it is necessary to rotate the shielding plate in an elliptical shape that matches the cross-sectional shape of the exhaust duct, instead of the circular movement structure of the shielding plate described above. In FIG.
In this case, a specific example is shown. In FIGS. 12A and 12B, reference numeral 12 denotes a rotating belt provided along the periphery of the exhaust duct, and a number of sliding shield plates 13 are provided inward. Is provided. The ratio of the shielding portion can be adjusted by the number of shielding plates provided. In this example, the shielding plate 13
Has a shape in which the periphery of the exhaust duct is shielded by a plurality of sheets, and the driving of the rotating belt is performed via the transmission shaft 9 by the driving of the turbine 8 provided in the exhaust chamber 6 as in the case of FIG.
Rotated.

[0028]

As described above, according to the present invention, the exhaust gas temperature can be remarkably reduced as compared with the prior art, and the length of the exhaust duct can be shortened even if the exhaust gas is processed by air cooling. The industrial value in this field is great, for example, it is possible to provide a jet engine test cell capable of making the equipment itself compact.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention, in which “a” shows an entire normal cross section of a jet engine test cell, “b” is a view of an AA arrow, and “c” is a a BB arrow view. It is.

FIG. 2 is an explanatory diagram showing a flow of air in an exhaust duct provided with a shielding plate of the present invention.

FIG. 3 is an explanatory diagram showing a calculation grid for exhaust duct temperature distribution simulation by the finite volume method.

FIG. 4 is an explanatory diagram showing a temperature distribution of exhaust gas in a longitudinal direction of an exhaust duct.

FIG. 5 is an explanatory diagram showing a temperature distribution of exhaust gas in a portion where a shielding plate is provided in a radial direction of the exhaust duct.

FIG. 6 is an explanatory diagram showing a temperature distribution of exhaust gas at an outlet portion in a radial direction of an exhaust duct.

FIG. 7 is an explanatory diagram showing an average temperature at an outlet portion in a radial direction of an exhaust duct when a shielding plate is rotated.

FIG. 8 is an explanatory view showing another embodiment of the shielding plate of the present invention.

9 shows another embodiment of the shielding plate of the present invention, wherein a is an explanatory view of the shielding plate, and b is an enlarged view of a portion X in FIG.

[Explanation of symbols]

 1: Intake chamber, 2: Intake muffler, 3: Engine room, 4: Exhaust duct, 5: Exhaust muffler, 6: Exhaust room, 7, 13: Shielding plate, 8: Turbine, 9: Transmission shaft, 10: Engine, 11: rotating ring, 12: rotating belt, Q: jet engine cell body, M: partition

Claims (4)

[Claims] An intake chamber having an intake silencer is provided on the upstream side of the cell body, and an exhaust chamber having an exhaust silencer is provided on the downstream side, and a test jet engine is housed from the intake chamber side in the cell body. A jet engine test cell provided with an engine room and an exhaust duct sequentially, wherein a shield plate that shields and rotates the periphery of the exhaust duct is provided on the engine room side of the exhaust duct. 2. The jet engine test cell according to claim 1, wherein the shielding plate has a shape that shields a cross section of the exhaust duct in a substantially semicircular shape. 3. The jet engine test cell according to claim 1, wherein a large number of shielding plates are arranged on a rotating belt provided along the periphery of the exhaust duct. 4. A turbine is provided in an exhaust chamber, and the shield plate is rotated by driving the turbine.
The jet engine test cell according to any one of the above.