Increase of dynamic stability of a basis at operation of the compressor equipment of the Abazіvka unit of complex gas preparation

The object of research is the basis of the compressor equipment of the complex gas treatment plant at the Abazivka field and the strengthening of the base soils with soil-cement elements, which are proposed to be arranged with the use of drilling technology. The research area is located on the territory of the current Abazivka Integrated Gas Preparation, near the village of Bugaivka, Poltava region, Ukraine. Abazivka Integrated Gas Preparation receives products from wells in Abazivka and Sementsivske deposits. It is proposed to carry out the reconstruction of Integrated Gas Preparation, which includes strengthening the foundation of the compressor model C1004-JGT/2-1 manufactured by «Propak» (Alberta, Canada). The amplitudes of oscillations of the compressor foundation were determined at a speed of 1400 rpm at the appropriate site with geological conditions. The magnitudes of oscillations and subsidence of the compressor foundation of the Abazivka complex of complex gas treatment were investigated experimentally. When determining the amplitudes of oscillations of the compressor foundations, only the amplitudes of oscillations in the direction parallel to the sliding of the pistons were calculated, and the influence of the vertical component of the perturbing forces was not taken into account. It is established that the amplitude of horizontal-rotational oscillations of the upper face of the compressor foundation relative to the horizontal axis exceeds the maximum allowable. It is substantiated that soil cement is a sufficiently strong and waterproof material that can be used to strengthen the base during the construction of equipment foundations. The possibility of application of the technology of application of soil-cement piles, made by brown-mixing technology for strengthening the base under the foundation of the compressor, is described and investigated. It is proposed to reinforce the base with rows of soil-cement elements, which will increase the modulus of deformation of the base, which is represented by loam, light to 14.3 MPa. In the case of strengthening the base, the amplitude of horizontal-rotational oscillations of the upper face of the compressor foundation is much less than the maximum allowable 0.1 mm. The subsidence of the foundation at reinforcement of the base, which does not exceed the maximum allowable value, is determined. Soil-cement elements are proposed to be arranged according to the drilling technology.

Determination of rotational derivatives of a cylinder with a coaxially mounted disk in an air stream

The damped rotational oscillations of a cylinder whose length-to-diameter ratio is nine are considered. In the head part of the cylinder, a disc is mounted coaxially on the leg. The effect of the disk on damping oscillations is described by two parameters: the sum of the rotational derivatives mωz + mθz and the rotational derivative mθz. To determine these parameters in the aerodynamic tunnel of low speeds, an experiment is performed with the flow past a cylinder fixed on an elastic spring suspension. In the experiment, the diameter of the coaxial disk and the distance between the disk and the end of the cylinder varies. Deflected from the equilibrium position, the cylinder performs damping oscillations. The tension of one of the springs of suspension is measured using the strain gauge method. The signal is converted to digital form using the Velleman PCS500A PC oscilloscope and recorded to a file on the computer. Thus, the frequency of oscillations and the dependence of the amplitude of oscillations on time are determined. Disks whose diameter exceeds the diameter of the cylinder do not have a strong effect on the damping of oscillations of an elastically fixed cylinder. Disks of smaller diameter promote rapid damping of the oscillations. The presence of a large-diameter disk leads to a decrease in the coefficient mωz. A small-diameter disk acts in a opposite way.

The effect of externally applied rotational oscillations on FIV characteristics of tandem circular cylinders for different spacing ratios

Purpose This study aims to explore an active control strategy for attenuation of in-line and transverse flow-induced vibration (FIV) of two tandem-arranged circular cylinders. Design/methodology/approach The control system is based on the rotary oscillation of cylinders around their axis, which acts according to the lift coefficient feedback signal. The fluid-solid interaction simulations are performed for two velocity ratios (V_r = 5.5 and 7.5), three spacing ratios (L/D = 3.5, 5.5 and 7.5) and three different control cases. Cases 1 and 2, respectively, deal with the effect of rotary oscillation of front and rear cylinders, while Case 3 considers the effect of applied rotary oscillation to both cylinders. Findings The results show that in Case 3, the FIV of both cylinders is perfectly reduced, while in Case 2, only the vibration of rear cylinder is mitigated and no change is observed in the vortex-induced vibration of front cylinder. In Case 1, by rotary oscillation of the front cylinder, depending on the reduced velocity and the spacing ratio values, the transverse oscillation amplitude of the rear cylinder suppresses, remains unchanged and even increases under certain conditions. Hence, at every spacing ratio and reduced velocity, an independent controller system for each cylinder is necessary to guarantee a perfect vibration reduction of front and rear cylinders. Originality/value The current manuscript seeks to deploy a type of active rotary oscillating (ARO) controller to attenuate the FIV of two tandem-arranged cylinders placed on elastic supports. Three different cases are considered so as to understand the interaction of these cylinders regarding the rotary oscillation.