Applied Mechanics and Materials Vol. 630

Abstract: Surface texturing is more and more frequently used in modern machines to attain such aims as lubrication enhancement, heat flow intensification and micro-flow stimulation. The development of technologies using concentrated energy flux, e.g. laser technology, has contributed to it. Pumps contain a lot of elements where textured surfaces can be used. The article concentrates on the selection of operating parameters of a picoseconds laser used to produce texturing in elements made of steel, bronze and silicon carbide.

Abstract: High cycle fatigue behavior of the compressor impeller is investigated. On the basis of numerical calculations of the stress-strain state of wheel the prognosis of life time is done. The results show relations between the number of cycles to failure and maximally possible stresses and displacements. Relation of cumulative fatigue damage is researched depending on the number of cycles for the different modes of vibration on resonant frequencies.

Abstract: The article contains the results of studies concerning the effects of selected parameters of the manufacturing process of elastic bellows on their elastic properties and strength. Bellows models were made using additive technology SLS selective laser sintering, in which the material used to construct models was a polyamide PA 2200. Bellows printing process proceeded in a surface parallel to the axis of the bellows and in a surface perpendicular to it. Based on measurements of deformation coefficients of elasticity of bellows were determined, also the measure of the maximum axial force exerted by the bellows while loading the internal pressure was carried out. Comparing the measurement results a significant effect of process parameters on the flexible properties of elastic bellows and their resistance to internal pressure were determined.

Abstract: The stress-strain state of impeller seal made ​​of composite material a centrifugal pump under the thermal effects is investigated based on the classical theory of elasticity of an anisotropic body. Kinematic and static conditions of contact for mating surfaces of adjacent layers are considered ideal. Solution of the problem is obtained in axisymmetric. It is noted that the increase in temperature on the surface of the composite seal has a significant impact on its stress state.

Abstract: An analytical and experimental model was proposed to determine sac volume pressure changes and fuel doses injected into the diesel engine cylinders. The model takes into account friction forces and identifies the mechanical properties of the injector. The engine performance results were analysed statistically. The results of the Lilliefors, Pearson, Shapiro-Wilk and Jarque-Bera tests provided evidence that, under certain engine operating conditions, the null hypothesis about the compatibility of the measurement data with the normal distribution can be rejected. The measurement uncertainty for the injector needle lift was estimated. The engine was powered with diesel or biofuel. The difference between the measured and the predicted fuel doses amounted to approximately 3%.

Abstract: The joint radial-axial oscilations of onemass model of rotor of high-speed pump are considered taking into account hydrodynamic forces, arising up in the radial clearance of annular seals. Connection of axial oscilations with radial is conditioned by dependence of conductivity of annular throttle, consequently, and axial force of balancing device, from the excentricity of shaft in the annular collar. amplitude and phase frequency characteristics of the forced oscilations, excited by harmonically changing pressure and static unbalance.

Abstract: The paper discusses forced combined angular-radial oscillations of rotor centrifugal pump model under the influence of random forcings. System reliability is evaluated using the theory of random functions runs: the probability of finding a random vector of quality system “rotor-annular seals” in the range of admissible values of its parameters is determined. Evaluation of the influence of erosive wear of sealing surfaces in the process of pump operating on reliability system is made.

Abstract: There were considered the technical decisions aimed to modernization of the end floating seals for the centrifugal compressor that increased the limit of the rotor system dynamic stability and reduced the vibration levels.

Abstract: Mathematical modeling of the complex process in the human cardiovascular system is powerful tool to evaluate the dynamic system response for the parameters change. Widely used continuous flow pumps (Left Ventricle Assist Device - LVAD) interacting with the circulatory system and work parameters of the assist device are changing dynamically. Different parameters of the system affect the pump operating conditions and on the contrary. Mathematical modeling of interaction between the cardiovascular system and mechanical assist device allows to identify the dangerous effects in the pump and system operation, and to eliminate such situations in the practical using of such pumps.

Abstract: A pumping station in a fuel storage suffered from pressure pulsations in a petrodiesel pipeline. Check valves protecting the station against back flow made a big noise when disc hit a seat. Due to employees complaints we were asked to solve the problem, which could lead to serious mechanical problems. Pressure measurement in the pipeline showed great pulsations, which were caused by self-excited oscillation of control valves at the downstream end of pipeline. The operating measurement did not catch it because of too low sampling frequency. One dimensional numerical model of the whole hydraulic system was carried out. The model consisted of check valve, pipeline and control valve, which could oscillate, so it was possible to simulate the unsteady flow. When the model was validated, a vessel with nitrogen was added to attenuate pressure pulsations. According to the results of numerical simulation, the vessel was installed on the location. Subsequent measurement proved noticeably lower pulsations and almost no noise.