Gas turbine test bench

Abstract

The invention relates to a test bench (1) comprising a casing (10) that extends along a first axis (B) and has an inner diameter equal to a first diameter D1, and a shaft (20) that extends along a second axis (A) and is intended to rotate a turbine engine (90) about the second axis (A), the diameter of the turbine engine (90) being equal to a second diameter D2, the casing (10) comprising an angular damage sector (80) around the second axis (A) and a damage mechanism (81) intended to damage a blade (95) of the turbine engine (90) in this angular damage sector (80). The second axis (A) is offset parallel to the first axis (B) by an offset distance (H) in the direction opposite the angular damage sector (80) relative to the second axis (A).

Description

Description Title: Gas Turbine Test Bench

[0001] The present invention relates to a gas turbine test bench. More specifically, the invention relates to a turbomachine test bench.

[0002] Prior to commissioning a turbomachine, it is necessary to perform mechanical tests on it. Specifically, tests are conducted to assess the turbomachine's behavior after projectile ingestion, potentially resulting in the loss of one or more blades and the emission of blade fragments. To perform these tests, the turbomachine is mounted on a rotating shaft, driven by a motor. The turbomachine is housed in a cylindrical enclosure, and the shaft's axis of rotation is coaxial with the enclosure's longitudinal axis. Blade damage or loss is simulated using a damage mechanism that damages a blade when it is located within a specific angular sector, known as the angular damage sector.

[0003] Thus, we know of a turbomachine test bench with longitudinal axis X, which includes a box extending along a first axis B and whose internal diameter is equal to a first diameter D1, and a shaft extending along a second axis A and which is intended to drive the turbomachine in rotation around the second axis A which is coincident with the longitudinal axis X, the maximum diameter of the turbomachine 90 being equal to a second diameter D2, the box including an angular sector of damage around the second axis A and a damage mechanism which is intended to damage a blade of the turbomachine in this angular sector of damage.

[0004] During blade loss tests, the focus is on debris ejected radially outwards, which could potentially strike and damage the aircraft's airframe surrounding the turbomachine. This debris (size) and its trajectories (speed, kinematics) are studied. For this purpose, it is advantageous to have as large a space as possible around the turbomachine. Therefore, the wall of the test chamber must be at least equal to the radius of the turbomachine when it is at the radial end of a blade. This condition This implies having a casing with a diameter at least twice that of the turbomachine. However, larger casings are more expensive to manufacture, and the testing phases also generate higher costs due to the increased volume of the casing. This additional cost is further increased when it is necessary to create a vacuum within the casing. Moreover, this issue is likely to become even more relevant with the evolution of turbomachinery towards models with larger diameters and unfaired propellers. Description of the invention

[0005] The present invention aims to remedy these drawbacks.

[0006] The invention aims to provide a test bench with a box that allows, in an economical way, the testing of turbomachines in cases of blade loss, including larger turbomachines.

[0007] This goal is achieved thanks to the fact that the second axis A is parallel to the first axis B and offset from the first axis B by an offset distance H along a first radial direction which is opposite to the angular sector of damage with respect to the second axis A.

[0008] Thanks to these features, the test bench is capable of testing turbomachines with a diameter greater than half the internal diameter of the casing. Indeed, in the angular damage sector, which is the region of the casing where blade fragments, or even a blade itself, will be most frequently projected, the distance between the turbomachine and the casing wall is increased (compared to the case where there is no offset of the second axis A).

[0009] Advantageously, the offset distance H satisfies the conditions {H < Vi (D1 - D2)} and {H > (D2 - Vi D1)}. Thus, the test bench is suitable for testing turbomachinery with a diameter up to 2 / 3 of the internal diameter of the casing. Therefore, a test bench with a casing 8.5 meters (28 feet) in diameter will be able to test any existing turbomachine, as well as future turbomachinery with unfaired propellers 5.2 meters (17 feet) in diameter. It will therefore not be necessary to construct casings 10.4 meters in diameter. (34 feet) which would be much more expensive to design, manufacture, and operate than caissons 8.5 meters in diameter.

[0010] For example, the first radial direction is vertical downwards

[0011] For example, the first axis B is horizontal

[0012] For example, the inside of the box is suitable for being vacuum-sealed.

[0013] For example, the damage mechanism is a projectile projector on the turbomachine.

[0014] For example, the damage mechanism includes an explosive located on one of the blades.

[0015] The invention also relates to an assembly consisting of a test bench according to the invention and a turbomachine.

[0016] The invention will be better understood and its advantages will become more apparent upon reading the following detailed description of embodiments shown by way of non-limiting examples. The description refers to the accompanying drawings in which:

[0017] [Fig. 1] Figure 1 is a longitudinal view of a test bench according to the invention.

[0018] [Fig. 2] Figure 2 is a cross-sectional view of the test bench of Figure 1 along line ll-ll.

[0019] [Fig. 3] Figure 3 is a mathematical drawing which serves as a basis for calculating the distance between the distal end of a blade and the wall of the box. Detailed description of the invention

[0020] Consider a turbomachine test bench 1 with a longitudinal axis X, which is the axis of rotation of this turbomachine. The term "radial" designates a position or direction in a transverse plane perpendicular to the axis of rotation X.

[0021] By way of example, the invention is described in the case where the turbomachine 90 is a turbomachine with unfaired propellers ("Ultra Single Fan" or USF). However, the invention applies to any turbomachine, including one with a External fairing. Figure 1 illustrates a turbomachine test bench 1 in longitudinal view. The test bench 1 comprises a casing 10 extending along a first axis B. This casing 10 is substantially cylindrical with an internal diameter equal to a first diameter D1. For example, the first axis B is horizontal. For clarity, the interior of the casing 10 is shown. The test bench 1 also includes a shaft 20 extending along a second axis A. The turbomachine 90 is mounted on the shaft 20 such that the longitudinal axis X (axis of rotation) of the turbomachine 90 coincides with the second axis A, as illustrated in Figure 1. The turbomachine 90 is located inside the casing 10. The test bench 1 also includes a motor (not shown) that drives the shaft 20 in rotation. The test bench 1 includes a support 30 on which the stator of the turbomachine 90 is fixed and which supports the turbomachine 90. The support 30 is fixed on the box 10 and / or mounted on the floor.For example, as illustrated in Figure 1, the support 30 is mounted on pillars 31 that rest on the ground. The turbomachine 90 is thus able to be driven in rotation about the second axis A. The maximum diameter of the turbomachine 90 is equal to a second diameter D2, and in this case corresponds to the diameter of the propellers including the blades 95. The second diameter D2 is strictly smaller than the first diameter D1 so that the turbomachine 90 fits within the casing 10. The second axis A is parallel to the first axis B. The casing 10 is mounted on the ground. For example, the casing 10 rests on feet 11 that rest on the ground. For example, these pillars 31 and / or these feet 11 are fixed in the ground, for example in a concrete slab.

[0022] In order to simulate an ingestion test in the test bench 1 when the turbomachine 90 is rotating, one or more blades are damaged using a damage mechanism 81 which will damage this blade in an angular damage sector 80 around the second axis A.

[0023] In one embodiment of this damage mechanism 81, the damage mechanism 81 is a projector that launches a projectile 85 towards the turbomachine 90 along a trajectory (for example, parallel to the second axis A), within this angular damage sector 80. The collision of the projectile 85 with a blade 95 generates blade debris that is ejected at high speed radially outwardly essentially in the angular damage sector 80. This embodiment is illustrated in Figure 1.

[0024] In another embodiment of this damage mechanism 81, the damage mechanism 81 comprises an explosive 82 which is placed on a blade 95, for example at its base (proximal end). The explosion of the explosive 82 is triggered when the blade 95 is in the angular damage sector 80, or just before entering this angular damage sector 80. This explosion causes the detachment of blade debris or of a blade 95, which is ejected at high speed radially outwards essentially into the angular damage sector 80. Such an explosive 82 at the base of a blade 95 is illustrated in Figure 1.

[0025] In order for the trajectories of these debris to be validly studied, these trajectories must be sufficiently long. Therefore, the wall of the caisson 10 must be sufficiently far from the distal end of a blade 95. For this reason, in caissons designed according to the prior art, the first diameter D1 is at least twice the second diameter D2. In other words, the distal end of a blade 95 is at least half the distance of the second diameter D2 from the wall of the caisson 10.

[0026] The inventors' tests showed that it was possible to validly study debris trajectories when the distal end of a blade 95 was as far from the wall of the casing 10 as possible (a distance g) over the angular damage sector 80 only. The distance g is measured along a radial direction of the turbomachine 90. Thus, it is not necessary for the radial end of a blade 95 to be the distance g from the wall of the casing 10 over the entire circumference of the turbomachine 90. In other words, the distal end of a blade 95 can be radially (i.e., along its radial direction) from the wall of the casing 10 by a distance less than g outside the angular damage sector 80.

[0027] Consequently, according to the invention, the second axis A is offset along a first radial direction 50 relative to the first axis B by a non-zero offset distance H. This first radial direction 50 is the direction diametrically opposite to the firing angular sector 80 relative to the second axis. A. In other words, the first radial direction 50 is opposite, with respect to the second axis A, to the median radial direction of the firing sector 80. The median radial direction of an angular sector is defined as the direction of the ray that bisects this angular sector. Advantageously, and for reasons of cost and ease of implementation, as shown in the figures, the firing sector 80 is vertically upward (with a median radial direction that is vertically upward) and the first radial direction 50 is vertically downward. In this case, the second axis A is offset vertically downward with respect to the first axis B. Alternatively, the second axis A is offset in another direction with respect to the first axis B.

[0028] Advantageously, the offset distance H is such that the turbomachine 90 does not touch the wall of the casing 10. Consequently, the offset distance H is less than the difference between the internal radius of the casing 10 and the radius of the turbomachine 90. This first condition is expressed by the following equation (1):

[0029] [Math 1] H < 1 / 2(D1 - D2)

[0030] For optimal test efficiency, as demonstrated by the inventors, it is advantageous that, in the direction opposite to the first radial direction 50, the distance g between the turbomachine 90 and the wall of the casing 10 be greater than the radius D2 of the turbomachine 90 (the distance g is shown in Figures 1 and 2). This second condition is expressed by the following equation (2):

[0031] [Math 2] g > 1 / 2D2 <=> { 1 / 2D1 - ( 1 / 2D2 - H)} > 1 / 2D2 <=> H > (D2 - 1 / 2D1 )

[0032] By combining equations (1) and (2) and eliminating the offset H, we obtain a condition on the first diameter D1 and on the second diameter D2, which is expressed by the following equation (3):

[0033] [Math 3] (D2 - 1 / 2D1) < 1 / 2(D1 - D2) <=> 3 D2 < 2 D1

[0034] Thus, for a box with a first diameter D1, the maximum diameter D2 ma x of turbomachine D2 that can advantageously be tested in this chamber is equal to % D1. The offset H ma x, for which it is ideal to offset such a turbomachine of diameter D2 max relative to the first axis B is calculated in replacing D2 with D2 ma x in equation (1) and in equation (2). We thus obtain H max — (D1 ) / 6.

[0035] Advantageously, on the firing angular sector 80 with an angle of 2-0, the radial distance t between the distal end of a blade 95 and the wall of the casing 10 is greater than, equal to, or slightly less than the distance (guard) g. The radial distance t between the distal end of a blade 95 and the wall of the casing 10 decreases as one moves circumferentially away from the median radial direction of the firing angular sector 80. The radial distance between the distal end of a blade 95 and the wall of the casing 10 on the firing angular sector 80 is therefore less than the distance g. However, the radial distance t is only slightly less than the distance g for a firing angular sector 80 with a small angle, i.e., less than TT / 3 (i.e., 0 less than TT / 6). A distance slightly less than g is meant to be less than g by g / 10 or less, that is, greater than (0.9) g.Indeed, with reference to Figure 3, which geometrically illustrates a circle of diameter D2 offset inside a circle of diameter D1 by a distance H along an axis of offset, calculations show that the radial distance t between the distal end of a blade 95 and the wall of the box 10 along a direction making an angle 0 with respect to the axis of offset (vertical in Figure 3) is given by equation (4) in the case where g = 14 D2 (that is, H = D2 - 14 D1 according to equation (2)):.

[0037] For example, in the case where D2 = D2 ma x = % D1, equation (4) becomes equation (5):

[0038] [Math 5] (cos 0 — 2 + cos 2 0 + 8) <=> (cos 0 — 2 + lcos 2 (0 + 8)

[0039] For an angle 0 = TT / 6 (that is, an angular sector of 80° with an angle TT / 3), we obtain t = 0.91 g. For an angle 0 = TT / 8, we obtain t = 0.95 g.

[0040] Advantageously, during an ingestion test in test bench 1, the interior of the chamber 10 is evacuated. Thus, the turbomachine 90 is not subjected to air friction on the rotating blades 95 during this test.

[0041] The invention also relates to an assembly consisting of a test bench 1 according to the invention and a turbomachine tested in this test bench 1.

Claims

Demands

1. Test bench (1) of turbomachine (90) with longitudinal axis (X), comprising a casing (10) extending along a first axis (B) and having an internal diameter equal to a first diameter (D1), and a shaft (20) extending along a second axis (A) intended to drive said turbomachine (90) in rotation about said second axis (A) which coincides with said longitudinal axis (X), the maximum diameter of said turbomachine (90) being equal to a second diameter (D2), said casing (10) comprising an angular damage sector (80) about said second axis (A) and a damage mechanism (81) intended to damage a blade (95) of said turbomachine (90) in said angular damage sector (80),said test bench (1) being characterized in that said second axis (A) is parallel to said first axis (B) and offset from said first axis (B) by an offset distance (H) along a first radial direction (50) which is opposite said angular damage sector (80) with respect to said second axis (A).

2. Turbomachine (90) test bench (1) according to claim 1 such that said offset distance (H) satisfies the conditions {H < 14 (D1 - D2)} and {H > (D2 - 1 / 2D1 )}.

3. Turbomachine (90) test bench (1) according to claim 1 or 2 such that said first radial direction (50) is vertical downwards.

4. Turbomachine (90) test bench (1) according to any one of claims 1 to 3 such that said first axis (B) is horizontal.

5. Test bench (1) of turbomachine (90) according to any one of claims 1 to 3 such that the interior of said chamber (10) is suitable for being placed under vacuum.

6. Turbomachine (90) test bench (1) according to any one of claims 1 to 5 such that said damage mechanism (81) is a projectile projector (85) on said turbomachine (90).

7. Turbomachine (90) test bench (1) according to any one of claims 1 to 5 wherein said damage mechanism (81) comprises an explosive (82) located on one of said blades (95).

8. Assembly consisting of a test bench (1) according to any one of the preceding claims and said turbomachine (90).

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