Current practices of condition assessment in large marine engines are largely based on the measurement of cylinder pressure using external kits, which poses challenges due to sensors synchronisation and durability issues, as well as the inability to perform continuous monitoring. For addressing these challenges, this study aims at developing a novel method to solve the inverse problem of predicting the pressure variations in all engine cylinders, by using the Instantaneous Crankshaft Torque (ICT) measurement for large internal combustion engines. This method is developed by considering the Initial Value Problem (IVP) technique along with the integration of a direct crankshaft dynamics model incorporating the sensitivity parameters and stability criteria calculation based on the Lyapunov Exponent (LE) as well as a state-of-the-art Nonmonotone Self-Adaptive Levenberg-Marquardt (NSALMN) optimisation algorithm. The method is tested for a number of case studies using different combustion models based on the Weibe and sigmoid functions, as well as for healthy, degraded and faulty engine conditions. The derived results demonstrate adequate accuracy exhibiting a maximum error of 0.3% in the prediction of the mean peak in-cylinder pressure. The analysis of the calculated sensitivity parameters resulted in the identification of the parameters that significantly impact the solution, thus providing improved insights for selecting the developed method settings. The developed method renders the continuous and non-intrusive in-cylinder pressures monitoring feasible, by using a permanently installed shaft power metre sensor with higher sample rates.

当前大型船用发动机状态评估的实践主要基于使用外部套件测量气缸压力，由于传感器同步和耐久性问题以及无法进行连续监测，这带来了挑战。为了应对这些挑战，本研究旨在开发一种新方法，通过使用大型内燃机的瞬时曲轴扭矩 (ICT) 测量来解决预测所有发动机气缸压力变化的逆问题。该方法是通过考虑初始值问题 (IVP) 技术以及基于 Lyapunov 指数 (LE) 以及基于 Lyapunov 指数 (LE) 的灵敏度参数和稳定性标准计算的直接曲轴动力学模型的集成而开发的。艺术非单调自自适应 Levenberg-Marquardt (NSALMN) 优化算法。该方法使用基于 Weibe 和 sigmoid 函数的不同燃烧模型以及健康、退化和故障发动机条件进行了大量案例研究的测试。推导出的结果表明，在预测平均峰值缸内压力时具有足够的精度，最大误差为 0.3%。对计算出的灵敏度参数进行分析，确定了对解决方案有显着影响的参数，从而为选择开发的方法设置提供更好的见解。通过使用具有更高采样率的永久安装的轴功率计传感器，开发的方法使连续和非侵入式缸内压力监测变得可行。