Gas turbine test bench
The offset shaft axis design in the turbomachine test bench enables efficient and cost-effective testing of larger turbomachines by using smaller casings, addressing the inefficiencies and high costs of traditional test benches.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- SAFRAN AIRCRAFT ENGINES SAS
- Filing Date
- 2024-07-12
- Publication Date
- 2026-06-05
AI Technical Summary
Existing turbomachine test benches with large casings are costly and inefficient due to the need for larger volumes and vacuum creation, especially with larger diameter turbomachines and unfaired propellers, which increase manufacturing and operational expenses.
The test bench design includes a shaft axis offset from the casing axis by a distance H, allowing a turbomachine to be tested within a smaller casing, enabling testing of turbomachines up to 2/3 the internal diameter of the casing, reducing the need for larger, more expensive casings.
This design allows economical testing of larger turbomachines with reduced casing size and cost, while maintaining sufficient space for debris trajectory analysis, thus lowering manufacturing and operational costs.
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Abstract
Description
Title of the invention: 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 this turbomachine. In particular, tests are carried out on the turbomachine's behavior after projectile ingestion, possibly 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 placed in a cylindrical enclosure, and the axis of rotation of the shaft is coaxial with the longitudinal axis of the enclosure. Damage or loss of blades is simulated using a damage mechanism that damages a blade when it is located within an angular sector called 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, attention is paid to debris ejected radially outwards that could strike and damage the aircraft 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 casing must be at least equal to the radius of the turbomachine's radial end from the blade. This condition implies 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 larger volume of the casing. This additional cost is further increased when it is necessary to create a vacuum within the casing.Furthermore, this issue is likely to become more relevant with the evolution of turbomachinery towards larger diameter models and with 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 which 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 arrangements, the test bench is suitable for testing turbomachines whose diameter is greater than half the internal diameter of the casing. Indeed, in the angular damage sector, which is the region of the casing where the blade fragments, or even a blade, will be predominantly projected, the distance between the turbomachine and the casing wall is then 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 < μ₂(DI - D₂)} and {H > (D₂ - μ₂D₁)}. Thus, the test bench is suitable for testing turbomachines 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 capable of testing any existing turbomachine, as well as future turbomachines with unfaired propellers 5.2 meters (17 feet) in diameter. It will therefore not be necessary to construct casings 10.4 meters (34 feet) in diameter, which would be much more expensive to design, manufacture, and operate than casings 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 placed under vacuum.
[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] Fig.1 is a longitudinal view of a test bench according to the invention.
[0018] [Fig.2] Fig.2 is a cross-sectional view of the test bench of Fig.1 according to line ILII.
[0019] [Fig.3] The [Fig.3] is a mathematical drawing which serves as a basis for the calculation of the distance between the distal end of a blade and the wall of the casing. Detailed description of the invention
[0020] Consider a test bench 1 of a turbomachine 90 with 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 those with external fairings. [Fig. 1] illustrates a turbomachine test stand 1 in longitudinal view. The test stand 1 comprises a box 10 extending along a first axis B. This box 10 is substantially cylindrical with an internal diameter equal to a first diameter DI. For example, the first axis B is horizontal. For clarity, the interior of the box 10 is shown. The test stand 1 also comprises 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 [Fig. 1]. Turbomachine 90 is located inside 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 to the housing 10 and / or mounted on the ground. For example, as illustrated in [Fig. 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 DI so that the turbomachine 90 fits within the housing 10. The second axis A is parallel to the first axis B. The housing 10 is mounted on the ground. For example, the cabinet 10 rests on feet 11 which 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), in this sector angular damage 80. The collision of the projectile 85 with a blade 95 generates blade debris which is ejected at high speed radially outwards essentially in the angular damage sector 80. This embodiment is illustrated in [Fig. 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 are 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 [Fig. 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 housing 10 must be sufficiently far from the distal end of a blade 95. For this reason, in housings according to the prior art, the first diameter DI 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 housing 10.
[0026] Tests carried out by the inventors have shown that it is possible to validly study the trajectories of debris when the distal end of a blade 95 is located at the greatest possible distance (called the clearance) g from the wall of the casing 10, but only within the angular damage sector 80. 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 at 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 located 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 with respect 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 angular 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 angular sector 80 is vertical. upwards (with a median radial direction that is vertical upwards) and the first radial direction 50 is vertical downwards. In this case, the second axis A is offset vertically downwards relative to the first axis B. Alternatively, the second axis A is offset in another direction relative 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 < ' / 2 (DI - 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 λ / 2D² 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 > L2 D2 <=> (½ DI - (½ D2 - H)} > L2 D2 <=> H > (D2 - L2 Dl)
[0032] By combining equations (1) and (2) and eliminating the shift H, we obtain a condition on the first diameter Dl and on the second diameter D2, which is expressed by the following equation (3):
[0033] [Math 3] (D2 - L2 Dl) < L2 (Dl - D2) <=> 3D2 < 2 D1
[0034] Thus, for a box with a first diameter Dl, the maximum diameter D2max of The turbomachine D2 that can advantageously be tested in this chamber is equal to % Dl. The offset Hmax by which such a turbomachine of diameter D2max is ideally offset from the first axis B is calculated by replacing D2 with D2max in equation (1) and in equation (2). This gives Hmax = (Dl) / 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 ir / 3 (i.e., 0 less than ir / 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 [Fig.3] which geometrically illustrates a circle of diameter D2 offset inside a circle of diameter Dl by a distance H along an axis of offset, the calculations show that .
[0036]
[0037]
[0038]
[0039]
[0040]
[0041] the radial distance t between the distal end of a blade 95 and the wall of the box 10 in a direction making an angle 0 with respect to the offset axis (vertical on the [Fig.3]) is given by equation (4) in the case where g = D2 (i.e. H = D2 - ^2 DI according to equation (2)): t = (D2-^c^d- ™ For example, in the case where D2 = D2max = % Dl, equation (4) becomes equation (5): [Math 5] t _ ( cos^ _ 2 + ^cûs23 + 8 ) <=> t = ( cos# - 2 + \ / cos23+8 ) For an angle θ = ir / 6 (that is, an angular sector of 80° with an angle ir / 3), we obtain t = (0.91)-g. For an angle θ = ir / 8, we obtain t = (0.95)-g. 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. 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 a turbomachine (90) with a 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 the rotation of said turbomachine (90) 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 < (Dl -D2)} and {H > (02-^2 01)}.
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. Turbomachine (90) test bench (1) 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).