Although direct measurements of the fuel injection pressure and the travel of the injector needle in conjunction with measurements of the valve train mechanism timing can provide complete diagnostic information about the technical conditions of the fuel injection and valve train systems, this requires the installation of sensors and other equipment directly into the systems, which is possible within research laboratories but is generally forbidden during operation of the ship. Malfunctions in the fuel injection and valve train systems can also be identified from the indicator diagrams of an engine operating cycle, expressed as P(V) and P(deg) diagrams. The basic parameters of the engine operating cycle, such as the maximum combustion pressure Pmax, compression pressure Pcompr, and indicated mean effective pressure IMEP, can also be used to indicate deviations from proper engine operation. Using a combination of a vibration sensor with an in-cylinder gas pressure sensor widens the capabilities of diagnostics for marine diesel engines under operational conditions. A vibration sensor with a magnetic base can help in determining the timings of the lifting and landing of the injector needle, fuel delivery by the fuel injection pump, opening and closing of the circulation of heated heavy fuel oil, and opening and closing of the gas distribution valves. This also offers a promising solution for diagnostics of the cylinder lubrication oil injectors. The proposed approach allows valuable information to be received during engine operation in accordance with the principle of non-destructive control, and can help in early detection of possible engine malfunctions.

The application of Digital Twins is a promising solution for enhancing the efficiency of marine power plant operation, particularly their important components – marine internal combustion engines (ICE). This work presents the concept of applying a Performance Digital Twin for monitoring the technical condition and diagnosing malfunctions of marine ICE, along with its implementation on an experimental test-bench, based on a marine diesel-generator. The main principles of implementing this concept involve data transmission technologies, from the sensors installed on the engine to a server. The Digital Twin, also operating on the server, is used to automatically process the acquired experimental data, accumulate statistics, determine the current technical state of the engine, identify possible malfunctions, and make decisions regarding changes in operating programs. The core element of the Digital Twin is a mathematical model of the marine diesel engine’s operating cycle. In its development, significant attention was devoted to refining the fuel combustion model, as the combustion processes significantly impact both the engine’s fuel efficiency and the level of toxic emissions of exhaust gases. The enhanced model differs from the base model, by considering the variable value of the average droplets’ diameter during fuel injection. This influence on fuel vapourisation, combustion, and the formation of toxic components is substantial, as shown. Using the example of calibrating the model to the test results of a diesel engine under 27 operating modes, it is demonstrated that the application of the improved combustion model allows better adjustment of the Digital Twin to experimental data, thus achieving a more accurate correspondence to a real engine.

Efficient oil filtration is crucial for maintaining optimal engine performance and preventing damage, wear, and potential malfunctions in marine diesel engines. Contaminants present in fuel and lubricants can adversely affect combustion and engine operation. This article explores the significance of fuel and oil purification in marine diesel engines, focusing on techniques such as sedimentation, filtration, and centrifugation.The study highlights the substantial consumption of lubricants by marine diesel engines and their vulnerability to contamination. Increased lubricant consumption can result in wear and decreased efficiency. Thus, effective oil purification methods play a pivotal role in extending engine lifespan, reducing wear, and ensuring environmentally responsible operation.  Three primary methods of oil purification are discussed: sedimentation, filtration, and centrifugation. Sedimentation allows particles to settle due to gravity, filtration employs filters to capture solid impurities, and centrifugation utilizes centrifugal force to separate impurities based on density differences. To assess filtration efficiency, a practical scenario is presented, comparing full-flow, partial-flow, and combined filters. The article emphasizes the need for real-world data to make informed decisions about oil filtration methods. Furthermore, it highlights the importance of mathematical models, such as the Darcy-Brinkman equation, for understanding fluid movement and contamination distribution. Effective oil purification is essential for marine diesel engines to ensure optimal performance, reduce wear, and minimize environmental impact. By employing efficient filtration methods and leveraging mathematical models, marine industries can enhance their maintenance practices and contribute to the longevity and sustainability of their engines.

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.