Vibration effects of the dynamic interaction between a gas-liquid medium and elastic shells

2011

Self Cite

The paper reports experimental data on the nonlinear dynamic deformation of the elastic bottom of a cylindrical shell and the formation of bubbles and their clusters under two-frequency excitationKeywords: gas-liquid mixture, cylindrical shell with elastic bottom, experimental study, formation of bubbles, bubble cluster, two-frequency excitationIntroduction. Many publications [4, 5, 8, 11, 13-16, etc.] study the nonlinear dynamic behavior of a gas-liquid mixture in tanks of various shapes and the nonlinear deformation of elastic elements of partially fluid-filled shells caused by the interaction with the gas-liquid mixture, especially if accompanied by the formation of bubble clusters, under one-frequency excitation.Power plants in real operation conditions and gas-liquid mixtures in tanks of various shapes during various processes sustain complex vibratory loads. In this connection, the dynamic behavior of gas-liquid mixture in cylindrical, spherical, and ellipsoidal rigid shells under two-frequency excitation was studied in [2,4,6]. The nonlinear dynamic deformation of the elastic wall of a cylindrical shell, the formation of gas bubbles and their clusters, the motion of a gas-liquid mixture because of their interaction under two-frequency vibratory excitation were studied in [17].Experimental data on the nonlinear deformation of the elastic bottom of a rigid shell and the free surface of the fluid in it because of the interaction between them and with bubble clusters under one-frequency excitation are reported in [16].The present paper discusses experimental data of the nonlinear dynamic deformation of the elastic bottom and the free surface of the fluid without bubble clusters and the deformation of the bottom, the behavior of the gas-liquid mixture and bubble clusters. We will find and analyze the resonant ratio between the two excitation frequencies and the natural frequencies of the shell-gas-liquid system that causes the most intensive deformation of the elastic bottom of the cylindrical tank and the free liquid surface and intensifies the motion of the gas-liquid mixture, especially when a nonlinear vibrating liquid-bottom-gas system forms.1. Test Specimen, Equipment, and Procedure. The test specimen was a rigid cylindrical shell made of organic glass. Its height Í sh = 500 mm, diameter D sh = 150 mm, and wall thickness d sh = 5 mm. Such a wall thickness prevented the parametric vibrations of the lateral surface. Such vibrations excited by a high-frequency load are known [3,5,8] to be able to cause low-frequency high-amplitude vibrations of the free liquid surface and some kinds of motion of the gas-liquid mixture. The bottom of the shell is a circular elastic steel plate of thickness d bot = 0.5 mm fixed at the edges to the shell end with fit rings and bolts. A VEDS-100 electrodynamic shaker was used to excite vibrations of the shell. To produce two-frequency vibrational excitation, we used a generator built in the frame of the shaker and an external Robotron generator. One of them was used for one-fre...

Section: Deformation Of the Bottom And The Behavior Of The Gas-liquidmentioning

confidence: 91%

Section: Deformation Of the Bottom And The Behavior Of The Gas-liquidmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Dynamics of a cylindrical shell with elastic bottom filled with a gas–liquid mixture and subject to two-frequency excitation

2011

Self Cite

Features of the Motion of a Gas-Liquid Medium in a Compound Shell (Sphere and Truncated Cone) Subject to Vibration

2005

Self Cite

The results from an experimental study into the dynamic behavior of a gas-liquid medium and solid particles in a compound shell (sphere-truncated cone) are reported on. The following processes are studied: formation of gas bubbles and their clusters, strong macroflows, and intensive chaotic motion of the medium in the truncated cone as a nonlinear vibrating liquid-gas system Keywords: gas-liquid medium, compound shell, sphere, truncated cone, local accumulations, vibrationsModern vibration technology has put forward a number of challenges associated with studying the dynamic behavior of gas-liquid systems under periodic actions. Of practical interest is to study the vibrations and dynamic stability of gas bubbles and their clusters in an oscillating liquid contained in tanks of various geometries.The main patterns of motion of gas bubbles in liquids contained in rigid and elastic bodies were studied in [1-4, 10, 12, etc.]. The theoretical and experimental investigations conducted made it possible to gain an insight into the possible modes of motion of gas bubbles in an oscillating liquid and into clustering phenomena resulting in the accumulation of gas somewhere inside the liquid volume. The experiments described in [2][3][4] demonstrated that at certain frequencies and levels of vibration gas bubbles migrate toward the walls and bottom of the vessel, forming there stable gas accumulations. Such bubble clusters change drastically the structure of the gas-liquid medium. In this case, the liquid-gas system as a whole can be regarded as a nonlinear vibrating system in which the gas accumulation plays the role of an elastic element and the liquid column over it, of an inertia element. Note that the geometry of the carrier body (shell) has a significant effect on the behavior of the gas-liquid medium. The studies conducted earlier dealt mainly with simple geometries: cylinder, sphere, ellipsoid, and torus [3-5, 7, 8, 11, 16, 17]. Vibrating bodies of more complex geometry, namely compound cone-shaped shells such as the de Laval nozzle, were addressed in [6,9]. It was revealed that the convergent element between compound cone-shaped shells is responsible for two additional modes of motion: intensive cavitation and chaotic motion.The present paper reports on the results of an experimental study into the possible modes of motion of gas accumulations in a liquid medium contained in a compound shell (sphere and truncated cone). Our main concern will be the chaotic motion of these accumulations, liquid, and solid particles that occurs at certain frequencies and levels of external vibratory actions.1. Model, Equipment, and Technique. The subject of the experiment is a compound shell consisting of a sphere and a truncated cone (Fig. 1) and made of acrylic plastic. The total height of the shell H sh = 270 mm; the height and major and minor diameters of the truncated cone h tc = 140 mm, D tc = 110 mm, and d tc = 50 mm; the inside diameter of the sphere D s = 100 mm; the height and inside diameter of the cylinder connecting the ...

Study of dynamic processes in a rigid cylindrical vessel with elastic bottom partially filled with a liquid

2006

Self Cite

The paper reports on the results from an experimental study of the nonlinear deformation of the elastic bottom of and the free liquid surface in a rigid shell. The shell and liquid interact with each other and with a cluster of gas bubbles produced by vibrational excitation Keywords: gas-liquid medium, cylindrical shell, elastic bottom, cluster of bubbles, vibrations Introduction. The deformation modes of elastic shells with rigid bottom filled with a liquid were experimentally and theoretically investigated in [4, 5, 10-12, etc.]. These are conjugate flexural modes excited by a vibrational load and involved in nonlinear interaction. The same publications studied the dynamic interaction between a liquid-filled elastic cylinder and an oscillating sphere. It is indicated in [2,8] that the nonlinear interaction of vibration modes of the shell and liquid is especially complicated when the amplitude of vibration of the shell wall is of the order (and more) of its thickness. When one of several cylindrical shells filled with a liquid and placed on a common elastic foundation is subjected to a vibrational load, vibrations of the other shells are parametrically excited because of their interaction [15]. The nonlinear deformation of elastic shells and free liquid surface and the chaotic motion of the gas-liquid medium, which are because of the interaction between gas bubble clusters (i.e., a liquid-gas nonlinear vibrating system) and the excited vibration modes and the source of excitation, were experimentally investigated in [5,6,8,13,14]. It is established that these processes occur at resonance.The present paper reports on results from an experimental investigation into specific nonlinear deformation of the elastic bottom of and the free liquid surface in a rigid shell that interact with each other and with clusters of gas bubbles in the vibrating liquid. We will discuss the main mechanisms of formation and the dynamic behavior of gas bubbles and their clusters and the chaotic motion of the gas-liquid medium due to the intensive vibrations of the elastic bottom.1. Model, Experimental Equipment, and Technique. The shell was modeled by an organic-glass cylindrical vessel with height H sh = 500 mm, diameter D sh = 150 mm, and wall thickness d sh = 5 mm. Precisely this thickness was chosen to prevent the parametric vibrations of the lateral surface in the frequency range involved. According to [3,5,8], such high-frequency vibrations may cause various kinds of low-frequency large-amplitude motions of the free liquid surface and motions of the gas-liquid medium. The bottom of the shell is an elastic circular plate of thickness d bt = 0.5 mm made of steel. It is rigidly fastened to the shell along the boundary with fit rings and bolts. A VÉDS-100 electrodynamic shaker was used as a source of mechanical vibrations. The vibration accelerations of the shaker table and the end and elastic bottom of the shell were measured with an IS-318 accelerometer and a D-14 vibration transducer (which are coupled with the measuring unit of th...