Avionics method and device for monitoring a turbomachine at startup

1. A method of characterizing a turbine engine, the method comprising:

measuring, using an accelerometer monitoring the turbine engine during starting, data to detect energy detected by any contact during said starting between a rotor and a stator of the turbine engine;

measuring, using sensors, thermodynamic data on the turbine engine;

creating a database associating detection of contact with the measured thermodynamic data;

determining a thermal unbalance value based on the measured vibrations; and

determining, based on a model and the database, a presence of a rotor thermal unbalance by associating the thermal unbalance value with the thermodynamic data, in order to avoid contacts between the rotor and the stator on starting.

2. A characterization method according to claim 1 , further comprising inspecting the turbine engine when stopped to determine information about contact, if any, during said starting, which information is then associated with the thermodynamic data for the determining.

3. A characterization method according to claim 1 , further comprising using simulated data concerning the behavior of the turbine engine for the determining.

4. A characterization method according to claim 1 , performed on a particular given turbine engine.

5. A characterization method according to claim 1 , performed for a fleet of turbine engines of the same model.

6. A characterization method according to claim 1 , wherein the thermodynamic data comprises temperatures, pressures, or temperature gradients.

7. A characterization method according to claim 1 , wherein detecting energy released by a contact, if any, comprises calculating a root mean square of the measurements of the accelerometer, or performing a Fourier transform on the measurements of the accelerometer.

8. An avionics device for a turbine engine for an aircraft, the device comprising:

a controller configured to

receive data from accelerometers monitoring the turbine engine during starting and to detect therefrom the energy generated during said starting by contact between the rotor and the stator, if any,

receive, from sensors, thermodynamic data on the turbine engine, and

determine, based on a model and a database associating detection of contact with the measured thermodynamic data, a presence of a rotor thermal unbalance that needs to be taken into account for a starting process,

wherein the controller is configured to determine the thermal unbalance of the rotor from the accelerometer data and to associate the thermal unbalance of the rotor with said information about contact, if any, for the determining of the presence of the rotor thermal unbalance.

9. An avionics device according to claim 8 , wherein the controller is configured to recognize at least one condition for thermal unbalance being present on a rotor of the turbine engine after the engine has been stopped, for use in a possible restarting process.

10. An avionics device according to claim 9 , wherein the controller informs the pilot and that controls the starting process.

11. An avionics device according to claim 9 , wherein the controller is configured to estimate a time period during which the rotor thermal unbalance is present.

12. An avionics device according to claim 9 , wherein the rotor thermal unbalance is estimated by using at least one measured temperature.

13. An avionics device according to claim 9 , wherein the rotor thermal unbalance is estimated by using a measured pressure.

14. An avionics device according to claim 9 , wherein the rotor thermal unbalance is estimated by using a statistical model.

15. An avionics device according to claim 9 , wherein the statistical model comprises a regression tree or a neural network.

16. A characterization method according to claim 1 , further comprising calculating a time interval during which starting is recommended.