RESONANT OSCILLATIONS WITH A LIMITING AMPLITUDE IN A VIBRATION ELECTROMAGNETIC ACTIVATOR

Abstract

The relevance of the research is caused by the fact that vibration electromagnetic activators are promising for use in various technologies. These technologies are associated with extraction and transportation of georesources, including preparation of drilling fluids and liquefaction of viscous oil products. Vibrating electromagnetic activator is an electric machine of reciprocating motion with an armature-activator, which forms turbulent submerged jets in a treated liquid medium. In the first half-period, the armature-activator is attracted to the wall due to a current pulse in the coils and potential energy is accumulated in the elastic spring. This is a mode of forced oscillations in mechanical system of a vibrating electromagnetic activator. In the second half-period there is no current in the coils and the armature-activator is repelled from the walls due to the spring energy. This is the mode of free oscillations in the mechanical system. Vibration electromagnetic activators should be tuned to the resonant frequency to maximize energy efficiency. The resonant frequency is not constant and depends on the properties of the treated fluid. The shape of the force-induced oscillation must provide oscillations in mechanical system at the resonant frequency with a limiting amplitude. This fact will increase the energy efficiency and performance of a vibration electromagnetic activator. The main aim of the research is to conduct analytical research to provide resonant oscillations with a limiting amplitude in a vibration electromagnetic activator. Methods of the research are based on using ordinary differential equations, Laplace transform, amplitude-frequency characteristics, systems of nonlinear algebraic equations, spectral analysis, comparison of analytical and experimental characteristics. Results. The authors have considered the mode of free oscillations of the armature-activator with the limiting amplitude based on linearized mathematical model of the mechanical vibration electromagnetic activator system. The mode of forced oscillations is proposed to be considered as a natural addition to the mode of free oscillations with a driving force that acts half the period and has a special form. It is shown that the modes of free and forced oscillations substantially depend on the parameters of the mechanical system. Such parameters depend on the properties of the treated liquid medium. The authors carried out the spectral analysis of the driving force, providing resonant oscillations with a limiting amplitude in the vibration electromagnetic activator mechanical system. The paper introduces the technical solution that ensures the control of the vibration electromagnetic activator with automatic tuning to the resonant frequency and the limiting amplitude of oscillations of the armature-activator. This mode maximizes the energy efficiency and productivity of the mixing liquid processed media. Based on a comparison of analytical and experimental frequency characteristics the authors confirmed the hypothesis of admissibility of linearizing the mathematical model of vibration electromagnetic activator mechanical system in an analytical study of the driving force of the optimal form.

Keywords

• drilling fluid
• highly viscous oil product
• vibratory electromagnetic activator
• resonance
• force-induced oscillations
• free oscillations
• forced oscillations
• spectral analysis
• tuning to the resonant frequency
• error estimate