Vol 4, No 3 (2018)

Cover Page

Full Issue


Various flow channel constructive elements effect on vibroacoustic characteristics of electrohydraulic control devices

Berestovitskij E., Gladilin Y., Solovyev M.


In this article author discuss investigation of control valve flow channel with regulating element equipped with meshed screens set on it. The issue provides engineers and scientist with the results of a series of experiments without using of flow noise muffler at the control system scheme.
The main idea is to obtain technical information on how to exclude the flow noise muffler from the control system's scheme. Such kind of knowledge is considered to be necessary for the following application in the feed water flow control systems meeting modern and next generation requirements of regulatory documents on vibration and flow noise characteristics.
It is discussed the research of the feed water control valve at the test bench mostly. There were designed a several types of scheme for flow channel construction with different meshed screens and they arrangements into it, flow restriction circuits, cartridge constructions etc. It was chosen the two-step pressure reducing scheme of flow channel after the theoretical analysis, which then was produced and fitted with meshed screens at both steps.
It is said in the article that the results of discovery bring out the useless of perforated rubber elements implementation into the flow channel construction. They do not make any effect on the acoustic field of control valve. Besides, application of elastic elements makes difficulties for the manufacturing of flow channel and considered as low reliable.
The issue provides reader with the information on flow noise level and its excess over the established level by the control valve under study. It is shown how to refine the flow channel construction with regulating element up to the modern and next generation requirements. Also, the proposal of how to exclude flow noise muffler from the schemes of control systems are listed.

Journal of Dynamics and Vibroacoustics. 2018;4(3):6-15
pages 6-15 views

Instability and self-oscillations in electro-hydraulic servo drive

Sunarchin R., Mashkov M., Matrosov A.


One of important problems of closed-loop hydraulic systems is ability of self-oscillations. Linear simulation shows unlimited growth of amplitude, but self-oscillations appear in a real hydraulic drive because of wastages, limits of endurance and oscillation energy. Main purpose of the research is to make a numerical simulation to correspond main parameters of self-oscillations of electro-hydraulic servo drive with characteristics of drive. Results of numerical simulation could be improved with transition to nondimensional variables. In this case several nondimensional complexes present whole hydraulic system instead of many variables and parameters in case of dimensional model. Main result is stability and amplitude of self-oscillations of electro-hydraulic servo drive depends of nondimensional variable Sh, if hydraulic time constant is more than mechanical time constant, then less oscillation energy applies to drive. Simulation model in this research is quite far from real electro-hydraulic servo drive, so improvement of simulation is purpose for the future researches.

Journal of Dynamics and Vibroacoustics. 2018;4(3):16-25
pages 16-25 views

Application of holographic interferometry for study rotor stator interaction in turbomachines

Seleznev V.G., Golovchenko I.Y.


In article take up two examples application of holographic interferometry for investigation modes vibrations spinning bladed discs of engines and analysis vibrations taking into account rotor stator interaction.
In the first example blade vibration measurement on operating compressor were carried out to investigate the extent of blade excitation of impeller. Interesting responses of the radial blades to the excitation were obtained with the compressor with the cambered vane diffuser. Unusual and unexpected significant resonance peaks of blade were observable when rotating frequency is near 18000 rpm with maximum stress amplitudes. A vibration test at rest using holographic interferometry was carried out by taking an interferogram of the impeller with one diameter and circle.
In present paper for the first example was shown that strong impeller vibration excited by the diffuser vanes is due to interaction between impeller and diffuser vanes and spinning impeller oscillated with mode one diameter and circle.
In the second example vibrations wheel of turbine was investigated on holographic test stand and during spinning test. At work turbine wheel consisting of stage was find out that dangerous stresses with frequency about 8000 Hz arise from the action of 28 harmonic. At investigation of this wheel on the holographic stand was find mode with 7 diameters on the frequency 7893 Hz.
Strong turbine vibration excited stator vines is due to interaction between turbine wheel and stator vines. As a result spinning turbine wheel oscillated with mode 7 diameters.

Journal of Dynamics and Vibroacoustics. 2018;4(3):26-30
pages 26-30 views

Vibration resistance of the automatic device of axial unloading of the tpu

Gulienko A.


The results of vibration resistance research of automatic device axial unloading of turbopump unit (TPU) are reviewed. The mathematical model of the device of this type is developed. She allows to define at a design stage influence on vibration resistance system key parameters - a range of regulation of axial force, volume of the unloading chamber and compressibility of a working liquid. Frequency characteristics vibration activity and transients on axial moving of a rotor influences in the form of jump and blow are resulted.

Journal of Dynamics and Vibroacoustics. 2018;4(3):31-41
pages 31-41 views

Controlling the vibration process of vibration protection systems with dynamic damping

Chernyshev V., Fominova O.


The article deals with theoretical aspects of controlling the oscillation process in vibration protection systems with a dynamic damping based on the use of modern information technologies. The justification of the principle of minimum and minimax procedure for the formation of optimal control of oscillation processes is given. It is shown that a direct method of integrating the equations of state, when observing the minimax procedure, allows us to find the values of the components of the optimal control vector directly at each integration step. The minimax procedure algorithm of the minimum principle is used to solve the optimization problem of dynamic damping of oscillations. A synthesizing control function is found that allows eliminating resonant phenomena and providing attenuation of transient processes within a single period of kinematic action.

Journal of Dynamics and Vibroacoustics. 2018;4(3):42-49
pages 42-49 views

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