Test bench for turbomachine

Abstract

A test bench (2) for a turbomachine (4), the test bench comprising: an upstream sensor (34) measuring an amount of particles in the air upstream of a mounting area (16) of the turbomachine (4); a downstream sensor (36) that measures an amount of particles in the air downstream of the mounting area (16); and a calculation unit (38) that calculates a difference between the downstream particle amount and the upstream particle amount.

Description

Technical Field

[0001] The present invention relates to the field of turbomachines and more particularly to a test bench for aircraft turbojet engines. Background Art

[0002] Certification operations in the aviation field are often complex due to the nature of the equipment to be certified and the standards that must be followed.

[0003] Therefore, the certification of new turbine models requires that the turbine be arranged on a test bench and that standardized operating cycles be carried out, during which various measurements are taken. The International Civil Aviation Organization specifically requires (Annex 16, Volume II of "Standards and Recommended Practices") the measurement of pollutant emissions (NOx, CO2, CO, fine particles (nvPM), HC, SOx, etc.) and the creation of emission profiles in a plane perpendicular to the axis of rotation of the turbine. Figure 1a to Figure 1d An example of such a profile is shown. The profile is obtained using a probe located downstream of the exhaust nozzle of a turbine. The probe samples an air flow which is subdivided into a plurality of streams, each of which reaches a different sensor and / or filter. Different pollutants can thus be measured in a non-invasive manner. The probe is continuously moved to measure emissions at different locations.

[0004] The air flow at the outlet of the turbine is at high speed and high temperature. The implementation of such an instrument is complex and expensive. Therefore, not all test benches are equipped with such an instrument.

[0005] However, it may be attractive to measure the pollutant emissions of the turbine during operation of the turbine and thus after certification of the turbine. Since the constraints related to certification no longer apply during the periodic maintenance inspection phase, it is conceivable to use simpler systems and provide a lower level of detail during the periodic maintenance inspection phase.

[0006] Therefore, in order to regularly monitor pollutant emissions from turbines, a simpler and cheaper instrument design needs to be developed. Summary of the invention

[0007] The present invention aims to propose an instrument which makes it possible to measure the emissions of a turbomachine during its life cycle in a simple and inexpensive manner. The invention also aims to propose a corresponding measurement method.

[0008] The invention relates to a test bench comprising a mounting area of ​​a turbine, wherein the bench comprises an upstream sensor which measures the particle amount in the air upstream of the mounting area, a downstream sensor which measures the particle amount in the air downstream of the mounting area, and a calculation unit which calculates the difference between the downstream particle amount and the upstream particle amount.

[0009] This equipment makes it possible to measure the emissions generated by a turbine in a simple way. Since the high level of detail required for certification is no longer necessary for routine inspections, it is no problem to measure the emissions in their entirety without creating a detailed profile.

[0010] According to an advantageous embodiment of the invention, the stage comprises an air inlet chimney and an air outlet chimney, the mounting area being arranged in a gallery arranged between the chimneys. According to an advantageous embodiment, an upstream sensor is arranged in the inlet chimney and / or a downstream sensor is arranged in the outlet chimney. This enables an overall measurement of the flow at a good distance from the turbine.

[0011] According to an advantageous embodiment of the invention, the particles measured by the sensor are: fine particles, NOx, CO, and / or CO2. Fine particles can be non-volatile particulate matter (nvPM). It should be understood that other particles (whether polluting or not) such as HC, SOx, etc. can also be detected according to the same principle.

[0012] The measured emissions can be expressed as a quantity of particles per unit of air flow (m3, kg, m3 / s, etc.) and / or per unit of time (number, rate, mass, etc.).

[0013] The invention also relates to a method for measuring the emission level of a turbine, characterised in that the method comprises a step of arranging the turbine in the installation area of ​​a table according to any of the above embodiments, and a step of operating the turbine, during which a calculation unit monitors the difference between the downstream particle amount and the upstream particle amount.

[0014] According to an advantageous embodiment of the invention, the operating step consists of applying operating cycles with different engine speeds to the turbomachine and establishing, via the calculation unit, a correlation between the engine speed and the amount of emitted particles.

[0015] The turbine is preferably used at different speeds for sufficient duration to eliminate the effects due to transient phases between speeds.

[0016] According to an advantageous embodiment of the invention, the calculation unit determines an average emission amount during the operating step.

[0017] The invention also relates to a method for monitoring the condition of a turbomachine, characterised in that the method comprises repeating the method according to one of the above embodiments at different times during the life of the turbomachine.

[0018] According to an advantageous embodiment of the invention, the method comprises repeating the above method for a plurality of similar turbomachines and recording the data of all turbomachines in a common database.

[0019] “Similar turbines” means turbines of the same type or sufficiently similar design that they are expected to have similar pollutant emission behavior throughout their useful life.

[0020] According to an advantageous embodiment of the invention, the method comprises a step of interpolating the emissions measured during the lifetime of the turbine to determine the correlation between any given moment in the lifetime of the turbine and the average emissions of pollutants produced at that given moment.

[0021] By monitoring a number of turbines, it is indeed possible to establish a pattern that correlates the number of operating hours of the turbines with the pollutant emissions. During the life of the turbine, it is observed that the pollutant emissions can increase regularly. Abnormally high increases may be a sign of abnormal degradation.

[0022] According to an advantageous embodiment of the invention, the turbine is overhauled, scrapped or inspected for degradation when it exhibits measured emissions exceeding 20% ​​of the relevant average emissions at that point in the turbine's service life.

[0023] The present invention also relates to a method for monitoring the condition of a turbine, characterized in that the method comprises a method according to one of the embodiments listed above, and a step of analyzing, diagnosing or identifying / controlling a turbine whose pollutant emissions are above a regulatory threshold or above a threshold established by a correlation between pollutant emissions and degradation of the turbine.

[0024] A regulatory threshold may be a threshold specified in regulation.

[0025] Measures to be taken may include inspection, repair, and suspension of use.

[0026] After sufficient data has been collected, correlations can be established to establish a causal link between increased emissions and actual degradation of, for example, a component or engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1a to Figure 1d Products of the known method are shown: examples of profiles obtained by a movable detector;

[0028] Figure 2 A test bench according to the invention is shown;

[0029] Figure 3 An example of the results obtained by the station of the invention is shown;

[0030] Figure 4 A method according to the invention is shown. DETAILED DESCRIPTION

[0031] Figure 1a to Figure 1d A diagram showing the distribution diagrams of various types of emissions used for turbine certification. These distribution diagrams are obtained by a probe which is continuously moved to the axis of the turbine (at Figure 2 Different points of a plane perpendicular to the plane are indicated as 19) and point measurements are performed at these points.

[0032] These figures illustrate well the complexity of the process to be implemented. The level of detail required enables verification of the engine architecture. The different positions used for the measurements enable measurement errors that could be associated with a single inappropriate position of the probe to be avoided.

[0033] While it may be useful to know the extent of contamination in a turbine during routine maintenance, a similar level of detail is unnecessary and such a procedure would unnecessarily prolong turbine downtime and incur expense.

[0034] Therefore, the present invention proposes Figure 2 The figure shows in a simplified manner an engine test bench 2, more particularly a test bench 2 for an aircraft turbojet engine 4. The test bench 2 can receive a complete aircraft or at least a part of an aircraft.

[0035] The test bench 2 forms a structure with infrastructure. The test bench comprises an air passage 6 with an inlet 8 and an outlet 10. The passage 6 comprises a generally elongated corridor 12. The length of the corridor may be greater than or equal to 60 meters. The length of the corridor 12 enables a laminar air flow 14 to circulate.

[0036] In order to limit the resistance to the flow through the gallery 12, in particular the resistance to the air flow 14 entering the turbine 4, the gallery 12 may have a width greater than or equal to 50 m. 2 The air flow 14 passing through the test bench 2 can be driven by the turbine 4 itself during the testing phase of the turbine. A mounting area 16 for the turbine 4 is provided. The mounting area 16 can be provided with a fixing system 18 to which the turbine 4 is fixed during its testing. The system 18 can extend vertically from the ceiling of the gallery 12 in the manner of columns or piles. The system 18 makes it possible to mount the turbine 4 in an offset manner and to center the turbine relative to the middle of the gallery 12, in particular relative to the central axis 19 of the gallery 12.

[0037] The corridor 12 may be defined by vertical chimneys 20, 22 at the inlet 8 and outlet 10. The chimneys enable air intake and exhaust vertically and elevated relative to the corridor 12. To reduce noise pollution, the chimneys may include sound baffles 24 or acoustic vanes 24 to enable passive absorption of sound waves.

[0038] Figure 2 The "U" shaped configuration shown in FIG. 5 is a non-limiting example of an overall shape of a test stand.

[0039] There may be additional devices 26 at the inlet 8 and outlet 10 to avoid flow reversals, which would disrupt the test conditions. The device 26 at the stage outlet may also be equipped with purification devices (such as those described in document WO 2021 / 009226A1).

[0040] At the junction between the upstream chimney and the gallery 12, the table 2 is equipped with a series of deflection vanes 28. The deflection vanes enable the air descending from the inlet chimney 20 to be returned in a horizontal direction. At the inlet of the channel 12, the table 2 optionally has a grid 30 to enable the interception of debris that could interfere with the test and damage the turbine 4.

[0041] In order to deflect the discharged flow, a cone 32 may be arranged on the right side of the outlet chimney 22 and fixed to the vertical wall at the end of the gallery 12. The tip of the cone may coincide with the central axis 19.

[0042] In order to determine the pollutant emissions of the turbine 4 , the station 2 comprises an upstream sensor 34 , which is arranged in the passage 6 upstream of the turbine, and a downstream sensor 36 , which is arranged downstream of the turbine.

[0043] Sensors 34, 36 measure the level of particles (e.g., fine particles nvPM, NOx, CO, CO2, HC, SOx, etc.). Sensors 34 and 36 may be identical. It should be understood that the term "sensor" should be understood in its broad sense: sensors 34 and 36 may be measurement units that return signals representing the amount of one or more of the above components; each sensor 34, 36 may also be composed of multiple detectors arranged at multiple locations on the stage to locally and / or independently measure one or more particle amounts.

[0044] The upstream sensor 34 measures the contamination rate in the air flow before the air flow flows into the turbine 4. The downstream sensor 36 measures the contamination rate in the air flow after the air flow has flowed into the turbine 4.

[0045] The sensors 34, 36 are connected to a calculation unit 38 by a wired or wireless connection. The calculation unit 38 thus senses signals corresponding to the amount of particles upstream of the turbine (Pam) and the amount of particles downstream of the turbine (Pav). The calculation unit 38 operates on the difference D (D=Pav-Pam) of the measurements of the two sensors in order to infer therefrom the contribution of the turbine to the pollution of the air leaving the turbine.

[0046] exist Figure 2 Sensors 34, 36 are schematically shown in FIG. 1 at preferred but non-limiting locations.

[0047] In order to limit the measurement uncertainty inherent to improper positioning of the sensors and to provide an overall measurement of the phenomenon in question, the sensors 34, 36 may be arranged at a sufficient axial distance (along the axis 19) from the turbine 4. This distance may be at least 10 meters or at least three times the length of the turbine.

[0048] Although the discussion focuses on two sensors, upstream and downstream, it will be appreciated that the invention may also relate to only one sensor located downstream of the turbine. Thus, in order to assess the degree of pollution caused by the turbine, it would be possible to: (1) assume that the upstream air contains no polluting particles and infer that all particles detected by sensor 36 are caused by the turbine, or (2) perform a reference measurement of the quality of the ambient air before the turbine is put into operation.

[0049] Figure 3 An example of the results that can be obtained by means of the test bench of the invention is shown. By varying the engine speed and measuring the amount of a specific pollutant, it is possible to record the measurement points. The crosses represent the measurements of a turbine obtained at one point in the useful life of the turbine, the squares represent the measurements of the same turbine obtained at a later point in the useful life of the same turbine. Thus, for each of the particles measured and at each stage of the useful life of the turbine, it is possible to formulate laws L1 and L2 of the relationship between the engine speed and the expected degree of pollutants.

[0050] If a similar turbine is measured at time L2 of its service life (circle on the graph) and the recorded value differs greatly from the expected curve L2, it can be concluded that the turbine in question has deteriorated abnormally. The threshold deviation for scrapping or repair or inspection action can be determined, for example, at 20% of the expected value on the L2 curve.

[0051] The test bench of the invention makes it possible to obtain a set of curves for different pollutants as a function of the engine speed and as a function of the age of the turbine. Thus, by interpolating the curves L1 and L2 (and Ln, n>2), we obtain a surface in a three-dimensional coordinate system. Thus, for any engine speed and any age of the turbine it is possible to know the pollutants that are normal for the test.

[0052] The station can also calculate the average pollution of the normalized period, which can be used as a reference instead of or in addition to the engine speed curve.

[0053] Figure 4 A method according to the invention is shown.

[0054] The method starts with the installation 100 of the turbomachine 4 in the test bench 2. In step 200, the turbomachine follows an operating cycle which may consist of different phases at different engine speeds and different accelerations or decelerations. In step 300, the calculation unit 38 determines the correlation between each pollutant and the engine speed ( Figure 3 curve of the type shown).

[0055] These three steps are repeated many times during the life of the turbine to monitor any deviations from the normal course of pollutant emissions and / or to establish behavioral patterns.

[0056] The three steps 100 to 300 are also repeated for other similar turbomachines (ie turbomachines of the same type or turbomachines having a similar behavior with respect to pollutant emissions).

[0057] In step 400, different curves are recorded in a common database.

[0058] Multiple test benches can form a test bench network, and each test bench can access this common database.

[0059] A composite average value for a plurality of similar turbines can be determined in step 500. Interpolation thus enables the determination of the expected value for each pollutant at any time during the service life of the turbine. Thus, the expected average pollution level and the expected pollution level for each of the particles can be defined at each age and each engine speed of the turbine.

[0060] The result obtained in step 300 can be compared with the expected result formulated in step 500. If a too large deviation is detected in step 600 (e.g. Figure 3 ), the machine in question is scrapped or inspected in step 700 to detect one or more components of the turbine that require repair action.

Claims

1. A test bench (2) comprising a mounting area (16) for a turbine (4), the bench (2) being characterized in that the test bench comprises: an upstream sensor (34) that measures a particle amount (Pam) in the air upstream of the mounting area (16); A downstream sensor (36) that measures the amount of particles (Pav) in the air downstream of the mounting area (16); and a calculation unit (38) that calculates the difference (D) between the downstream amount of particles (Pav) and the upstream amount of particles (Pam).

2. The table (2) according to claim 1, characterized in that The station comprises an air inlet chimney (20) and an air outlet chimney (22), the mounting area (16) being arranged in a corridor (12), the corridor being arranged between the chimneys (20, 22), the upstream sensor (34) being arranged in the inlet chimney (20) and / or the downstream sensor (36) being arranged in the outlet chimney (22).

3. The table (2) according to claim 1 or 2, characterized in that The particles measured by the sensor are: fine particles, NOx, CO, and / or CO2.

4. A method for measuring the emission level of a turbine (4), characterized in that The method comprises a step (100) of arranging the turbine (4) in a mounting area (16) of a station (2) according to any one of claims 1 to 3, and a step (200) of operating the turbine (4), during which the calculation unit (38) monitors the difference (D) between the downstream particle amount (Pav) and the upstream particle amount (Pam).

5. The method according to claim 4, characterized in that The operating step (200) consists of applying operating cycles with different engine speeds to the turbine (4) and establishing (300) a correlation between the engine speed and the amount of emitted particles via the calculation unit (38).

6. The method according to claim 4 or 5, characterized in that: The calculation unit (38) determines an average emission amount during the operating step.

7. A method for monitoring the condition of a turbine (4), characterized in that The method comprises repeating the method according to any one of claims 4 to 6 at different times during the life of the turbine (4).

8. A method according to claim 7, comprising repeating the method according to any one of claims 4 to 6 for a plurality of similar turbines (4) and recording (400) the data of all turbines (4) in a common database.

9. The method according to claim 8, characterized in that The method comprises the step of interpolating (500) the emissions measured during the life of the turbine (4) to determine a correlation between any given moment in the life of the turbine (4) and the average emissions of pollutants produced at that given moment.

10. The method according to claim 9, characterized in that When the measured emissions (D) of a turbine (4) exceed 20% of the relevant average emissions at that time in the life of the turbine, the turbine (4) is overhauled, scrapped or inspected for degradation.

11. A method for monitoring the condition of a turbomachine (4), characterized in that The method comprises a method according to any one of claims 4 to 6, and a step of analyzing, diagnosing or identifying / controlling a turbine whose pollutant emissions are above a regulatory threshold or above a threshold established by a correlation between the pollutant emissions and degradation of the turbine.

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