The article considers the methodological aspects of the theoretical investigation of marine power plants with thermochemical fuel treatment. The results of the study of the complex influence of temperature, pressure, and the ratio of steam / base fuel on the thermochemical treatment efficiency are presented. The adequacy of the obtained regression dependences was confirmed by the physical modelling of thermochemical fuel treatment processes. For a gas turbine power complex with a thermochemical fuel treatment system, the characteristics of the power equipment were determined separately with further merging of the obtained results and a combination of material and energy flow models. Algorithms, which provide settings for the mathematical models of structural and functional blocks, the optimisation of thermochemical energy transformations, and verification of developed models according to the indicators of existing gas turbine engines, were created. The influence of mechanical energy consumption during the organisation of thermochemical processing of fuel on the efficiency of thermochemical recuperation is analysed.
AbstractNatural frequencies and vibration modes of axial compressor blades are investigated. A refined mathematical model based on the usage of an eight-nodal curvilinear isoparametric finite element was applied. The verification of the model is carried out by finding the frequencies and vibration modes of a smooth cylindrical shell and comparing them with experimental data. A high-precision experimental setup based on an advanced method of time-dependent electronic interferometry was developed for this aim. Thus, the objective of the study is to verify the adequacy of the refined mathematical model by means of the advanced time-dependent electronic interferometry experimental method. The divergence of the results of frequency measurements between numerical calculations and experimental data does not exceed 5 % that indicates the adequacy and high reliability of the developed mathematical model. The developed mathematical model and experimental setup can be used later in the study of blades with more complex geometric and strength characteristics or in cases when the real boundary conditions or mechanical characteristics of material are uncertain.
The required level of reliability of modern gas turbine engines cannot be achieved without ensuring the vibrational strength of the compressor blades. One of the tasks of ensuring vibrational strength is to determine the frequency spectrum of free vibrations, as well as the arising forms of vibrations. Moreover, the most reliable results are achieved by combining experimental and theoretical research methods. Experimental studies of the free vibrations of the blades were carried out by the time-dependent holographic interferometry method. A description of the experimental stand is given, the features of using optical equipment and processing units are indicated. The implemented algorithm for conducting experimental studies is described, the features of the digitization of optical signals implemented in the developed software are indicated, the mathematical equations used in the implementation of this software are presented, and some emerging experimental forms are illustrated. To verify the experimental data based on the finite element method, an updated mathematical model of the free vibrations of compressor blades has been developed. The characteristics of the finite element from which the mathematical model is formed, the basic equations used in the simulation of free vibrations are given. As an object of study, we considered a compressor blade 54 mm high and 37 mm long chord with a peripheral section twist angle of 17°, the considered blade is made of a titanium alloy. For this blade, some waveforms were obtained, the location of the nodal lines was shown, and data obtained experimentally and analytically were compared. An analysis was made of the frequency spectrum of the natural oscillations of the compressor blades, which showed that the difference between the vibration frequencies obtained by experimental and numerical methods for the same modes does not exceed 5 %.
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