Investigation of the hydrodynamic processes of a centrifugal pump in a geothermal system

The hydrodynamic and thermodynamic processes of geothermal well extraction are investigated and presented in this paper. The paper presents mathematical models for a multi-level centrifugal pump and pipeline system. The mathematical models were used to evaluate gas (nitrogen) emission in water and its effects on hydrodynamic processes. Experimental studies and mathematical modelling showed that the gas content of the fluid increases the pressure and flow pulsations within a centrifugal pump. The variation in the height of the liquid column in extraction has an influence on characteristics of the multistage centrifugal pump used in wells. First published online 29 March 201

Cluster models, factors and characteristics for the competitive advantage of Lithuanian Maritime sector

Paper analyses several cluster models on the basis of competitiveness: Nine-factor model, Double diamond model, Funnel model of cluster determinants, Destination Competitiveness and sustainability models, which are related to Porter’s Diamond model and concentrate to the classical one - adopt M. Porter’s Diamond model methodology to the evaluation of Lithuanian Maritime sector’s clustering on the basis of competitiveness. Despite the advances in cluster research, this model remains a complex one and something that is hard to adapt to a real economic environment. However, this model with some extends and implications can be applied to explain the emergence and development of Maritime sector clustering. Although clustering analysis on the basis of M. Porter’s Diamond model highlighted its advantages, the interconnection of factors and their influence on the clustering, the economic theory has not yet provided a model that allows both the analysis and the definition of a process for implementing a successful clustering research. The adoption of M. Porter’s Diamond model creates convenient theoretical basis and has practical implication for real Lithuanian Maritime sector’s clustering abilities evaluation. It also helps to systemize basic cluster characteristics, that can be identified in the Maritime industry and measure the reasonable impact factors, which are identified in Lithuanian Maritime sector

Diagnostics procedure for identification of rubs in rotor bearings

It is well known that old design high-power generating machines were on duty for more than 35-40 years and will successfully continue operation after proper renovations and overhauls, this paper considers vibrational characteristics of the old continuously operated 110 mw turbounit with steam turbines and electric generator rotating system running at nominal speed of 3000 rpm. vibration and technological parameters were systematically monitored in the course of 5 years after installation of condition monitoring and diagnostics system, which is based on measurements of rotor relative vibration displacement. it is demonstrated that application of optimized vibration monitoring and diagnostic system and several vibration data formats is effective in evaluation of overhaul quality through vibration severity of rotor system and identification of causes of these vibrations, the research focus in the reported research work is placed on inspection of mechanical effect of horizontal rotor-to-stator rubbing in upper part of journal bearing, the validity of the results is verified during overhauls and renovations, and can reduce the possibility of bearing failures

High power rotor bearing rubs diagnostics procedure

Kauno technologijos universitetasKlaipėdos universitetasTaikomosios informatikos katedraVytauto Didžiojo universiteta

The impact of the internal welding defects on the joint strength

The paper looks at the impact of the internal welding defects on the strength of joints. The tension tests provided the values of the welded joint strength limits depending on the area of sporadic voids, slag intrusions and the field of discontinuities. Considering the results of the conducted experiments, the mathematical relationships between the strength of the welded joint and defected area were concluded. In presence of all three defects, the distance of the defects from the weld surface was measured. It is deduced that the defects nearer to the surface reduce the strength of the welded joint more than those noticed in deeper layers. First published online: 27 Oct 201

Stabilność wirnika z łożyskiem poprzecznym ze smarowaniem gazowym

The paper presents research on dynamics, modeling and the results of exper- imental tests of the rotor system rotating in gas lubricated bearing with a floating bush. The dependence of rotor vibration intensity on the waviness of bearing ele- ments was tested and simulated. It was confirmed experimentally that the amplitude of rotor vibration in gas lubricated bearing with double gas film is basically lower than the one with single gas film. The kinetic orbits of the rotor shaft vibration displacements are presented. Dynamic and mathematical models constructed enable to design bearings that distinct optimal according to the minimal vibration intensity

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Study of dynamics of heavy impeller rotor and failure diagnostics of tilting-pad journal bearings is the object of this paper. Induced rubbing process in the bearings at resonance and increased rubbing phenomenon in both bearings was identified experimentally in situ by measuring radial gaps. Rotational speed was established when gravitational force became dominant over rotor gyroscopic force. Rotating system model was designed, simulated and verified

Stability of rotor with gas-lubricated journal bearing

The paper presents research on dynamics, modeling and the results of exper- imental tests of the rotor system rotating in gas lubricated bearing with a floating bush. The dependence of rotor vibration intensity on the waviness of bearing ele- ments was tested and simulated. It was confirmed experimentally that the amplitude of rotor vibration in gas lubricated bearing with double gas film is basically lower than the one with single gas film. The kinetic orbits of the rotor shaft vibration displacements are presented. Dynamic and mathematical models constructed enable to design bearings that distinct optimal according to the minimal vibration intensityInformatikos fakultetasKauno technologijos universitetasKlaipėdos universitetasVytauto Didžiojo universiteta