Aerospace Technic and Technology

The method considered in the article consists in the analysis of the vibroacoustic signal generated by the compressor of the gas turbocharger during the operation of the diesel engine under load. Spectral analysis shows that the compressor blades generate vibrations that are always present in the spectrum of the general vibration of a gas turbocharger, regardless of its technical condition. The "blade" harmonic in the spectrum corresponding to these oscillations is determined using the method of limitations. The then calculated instantaneous rotor speed of the turbocharger makes it possible to analyze the amplitude of the fundamental harmonic in the spectrum. For numerical analysis of the amplitude of the fundamental harmonic, the power leakage of the discrete spectrum is eliminated. Further analysis of the amplitude of the fundamental harmonic makes it possible to quickly assess the level of vibration of the rotor during operation. The first part of the experiment was carried out on a ship's main diesel engine 5S60MC at a crankshaft speed of 85 min-1. The recording and analysis of vibroacoustic signals from the TCA 66-20072 turbocharger was carried out. The analysis showed the possibility of highly accurate determination of the rotational speed and the relative amplitude of the turbocharger shaft oscillations. The second part of the experiment was carried out on an experimental stand, which is based on a KamAZ-740.10 engine with an original pressurization system. A turbocharger of the TKR-11 type is used as a pressurization unit. As a result of the experiment, it was shown that the method of diagnosing the operation of a turbocharger, which is based on the analysis of a vibroacoustic signal, can be extended not only to turbochargers of low-speed engines, but also to turbochargers of high-speed diesel engines. In this case, the spectrum of the measured signal contains harmonics, the frequencies of which make it possible to determine the crankshaft rotation frequency. It is also shown that measuring the signal outside the compressor, close to its casing, makes it possible to obtain all the necessary diagnostic parameters as accurately as when measuring the signal directly at the inlet to the compressor wheel. The method can be used in practice. To implement it, a smartphone and a computer with special software are enough. The proposed method can be used as the basis for a system for continuous monitoring of the frequency and vibration level of a marine diesel engine turbocharger.

turbocharger diagnostics; marine diesel engine; vibroacoustic spectral analysis

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