Aerospace Technic and Technology

The possibility of using the gradientless n-parametric minimization of Powell'64 in the tasks of monitoring the workflow of ship diesel engines is considered. Monitoring the workflow of ship diesel engines includes the problem of cyclical analysis of indicator diagrams in the working cylinders. The problem of data synchronization should be solved - the transfer of pressure charts from the time function to an angle of crankshaft rotation function. It is shown that the hardware detection of the crankshaft rotation phases applying pick-up sensors configured in statics will have errors when the engine is under load. The synchronization task should be solved with the help of an algorithm by analyzing the indicator diagram in real time. Examples of the search for a global minimum of the Rosenbrock test function are given. Applying the Powell'64 method, least square method functionals are minimized in problems of synchronization and modeling of compression-expansion curves in the working cylinder. Cases of data synchronization calculation for low-speed two-stroke and mid-envelope four-stroke marine diesel engines are shown. Taking into account the assumptions made in practice, it was shown that at the point of maximum pressure growth rate on the compression curve, the cylinder volume above the piston can be calculated applying the known geometric dimensions of the cylinder and the P and dP/dφ values obtained from the indicator diagram. The next step is to calculate the first approximation of the position of the top dead center of the piston, and the application of the digital filters is necessary. Finally, the synchronization problem is solved on the basis of the equation dP/dφ = 0, compiled for the section from the start of compression to the start of combustion in the cylinder. The selection of boundary conditions for modeling is shown. The advantage of applying the Powell'64 method is its high efficiency for quadratic functionals. Unlike gradient methods, the Powell'64 method does not require the calculation of derivatives and is universal to minimize complex nonlinear functionals of a general form. The original author's algorithm for data synchronization by analyzing indicator diagrams, which applies the Powell'64 method, is used in the latest versions of the D4.0HT marine diesel engine monitoring systems

non-gradient minimization; the Rosenbrock function; diesel engine operation; compression polytrope; functional

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