Process for the detection of damage to components of an engine
First Claim
1. A process for early detection of an appearance of a fault in a component of a first engine, said process comprising:
- a preliminary phase of investigation using a second engine with a same design as said first to identify, for at least one operating speed of the engine, frequency spectral lines present during operation of the second engine without a fault and then with the fault so as to identify specific spectral lines for the fault and a detection phase during which t he following steps are carried out in an iterative manner in the course of operation of the second engine;
acquiring a string of digital samples representative of a vibratory acceleration signal in the course of an acquisition sequence;
checking that the speed of the second engine has remained stable during said acquisition sequence;
and applying to stable sequences acquired the following processing operations in real time during operation of the second engine or in delayed time;
transforming the signal acquired by temporal sampling into a frequency signal, while eliminating fundamental frequencies of the second engine and harmonic characteristics thereof, performing at least one normed coherence calculation between said frequency signal and the same frequency signal shifted by a frequency value corresponding to a value of one of the frequency spectral lines of the fault detected during said preliminary phase, comparing a value of a coherence peak obtained by the coherence calculation with a first threshold and storing a 1 detection value if said peak is greater than said first threshold and a 0 value if said peak is not greater than said first threshold, summing P stored detection values a and dividing the sum obtained by P to provide a detection ratio, and deeming a fault to be present if said detection ratio is greater than or equal to a second predetermined threshold.
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Abstract
A process for the early detection of a possible fault in a rotary component of an engine wherein a signal representing an acceleration is stored in a sequential manner; the stored signal is transformed into a frequency signal a spectral coherence calculation is performed between said frequency signal and the same frequency signal shifted by frequency values predetermined as a function of the speed of the engine; the sequences are counted for which a correlation peak appears for one of the predetermined frequencies and a fault is deemed to be present if for a number P of consecutive sequences the number of sequences with a correlation peak is greater than a predetermined threshold.
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Citations
10 Claims
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1. A process for early detection of an appearance of a fault in a component of a first engine, said process comprising:
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a preliminary phase of investigation using a second engine with a same design as said first to identify, for at least one operating speed of the engine, frequency spectral lines present during operation of the second engine without a fault and then with the fault so as to identify specific spectral lines for the fault and a detection phase during which t he following steps are carried out in an iterative manner in the course of operation of the second engine;
acquiring a string of digital samples representative of a vibratory acceleration signal in the course of an acquisition sequence;
checking that the speed of the second engine has remained stable during said acquisition sequence;
and applying to stable sequences acquired the following processing operations in real time during operation of the second engine or in delayed time;
transforming the signal acquired by temporal sampling into a frequency signal, while eliminating fundamental frequencies of the second engine and harmonic characteristics thereof, performing at least one normed coherence calculation between said frequency signal and the same frequency signal shifted by a frequency value corresponding to a value of one of the frequency spectral lines of the fault detected during said preliminary phase, comparing a value of a coherence peak obtained by the coherence calculation with a first threshold and storing a 1 detection value if said peak is greater than said first threshold and a 0 value if said peak is not greater than said first threshold, summing P stored detection values a and dividing the sum obtained by P to provide a detection ratio, and deeming a fault to be present if said detection ratio is greater than or equal to a second predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A process for early detection of an appearance of a fault in a rotary component of an engine, said process comprising:
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a preliminary phase of identifying frequency spectral lines present during operation of said engine without a fault in order to form an engine signature, for at least one operating speed of the engine; and
a detection phase during which, in the course of operation of the engine, the following steps are carried out in an iterative manner for the same engine speeds as those for which an engine signature has been established and stored;
acquiring a digital string of samples representative of a vibratory acceleration signal in the course of an acquisition sequence, verifying that during said acquisition sequence, engine speed has remained stable, and applying the following processing steps to stable acquisition sequences;
transforming the signal acquired by temporal sampling into a frequency signal, performing a sliding normed coherence calculation between said frequency signal and the same frequency signal shifted step by step by a sliding frequency value, storing the frequency values V for which a coherence peak greater than a predetermined threshold is obtained, thus constituting a signature of the speed at which a sequence was carried out, comparing said signature with a prior signature stored for the same engine speed, counting the sequences for which there is a significant deviation between the current signature and a stored signature, and deeming there to be an abnormality if for a number Q of consecutive sequences, the number p of sequences deviating from the stored signature is greater than a predetermined threshold.
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Specification