Ανάπτυξη μοντέλου πεπερασμένων στοιχείων και δυναμική ανάλυση του στροβίλου της μονάδας IV του ΑΗΣ Αγίου Δημητριόυ της ΔΕΗ

Abstract

The purpose of this dissertation is the modeling and the dynamic analysis of the turbine LMZ K-300-170, which is placed in the unit IV of the thermal power plant in the area of Agios Dimitrios, through computational and experimental methods. The turbine consists of three ro-tors, (Low pressure LP, Intermediate Pressure IP, High Pressure HP), which are connected in line. In the first section, the thesis is focused on the development of a proper and optimal compu-tational model of the turbine. At first, a three dimensional digital model was created through a full process of reverse engineering method and by using the appropriate 3D scanner devices and software (Geomagic, Solidworks). Afterwards, the three parts of the turbine were modeled, including rotors and blades from all stages, with solid finite elements. ANSA software was used for the modeling, while the numerical solution (modal analysis) was accomplished by computational packages Dynamis and Epilysis. The analysis of the results (eigenfrequences and modes), was conducted with software κETA. The Frequency Response Functions were identified through a series of experimental measurements, that intended to the determination of the vibrational behavior of the rotors as free bodies under impact excitation. Comparison be-tween analytical and experimental eigenfrequences denoted 3.75% and 4.13% deviation for the part of high and intermediate pressure, respectively. The next section of the dissertation is centered on the dynamic analysis of the turbine in different rotation velocities. Σhe size of the finite element model, made the dynamic analysis from difficult to impossible. So, a simplified model of the turbine was created at Matlab software, which takes into consideration the gyroscopic effects that appear during turbine‟s rotation. The accuracy of the simplified model was inspected by the comparison with the proper model, through modal analysis in a motionless state. As a result, a mean error of 6.84% occurred, making the simplified model reliable. The dynamic analysis of the simplified model was completed by calculating the eigenvalues and the modes in different rotation velocities.