Influence Of Fluid Flow Velocity Research Articles

Free vibration and stability analysis of sandwich pipe by considering porosity and graphene platelet effects on conveying fluid flow

In the present study, free vibration and stability analyses of fluid-conveyed sandwich pipe with porous core and graphene platelet reinforced composite in top and bottom layers of face sheets are investigated based on the Timoshenko beam theory. Using Hamilton’s principle, the governing equations of motion are obtained based on the first variations approach. The differential quadrature method (DQM) is used to solve to solve these equations. The effect of volume fraction of porosity in four different relationships, including nonlinear, and exponential, on the natural frequency, stability, and specific weight of the sandwich pipe is studied. Also, three void shape factors of the porous core, including circle geometry, are assumed. Moreover, five famous and popular core materials covering Steel, Aluminum, Al2O3, Cast Iron, and Polyethylene are considered. The influence of fluid flow velocity inside the pipe as an essential parameter on vibration and stability of the structure is illustrated. Three types of composite face sheets, including graphene platelet (GPL), glass fiber (GF), and three-phase (GPL + GF) as well as polymer as matrix, are investigated. Graphene Platelet as reinforcement is added to Glass Fiber for reinforcing composites factsheet layer. This research can be used to manufacture oil and gas transmission and distribution pipelines and chemical processing plants with high stiffness.

Active Vibration Control of a Fluid-Conveying Functionally Graded Cylindrical Shell using Piezoelectric Material

Active vibration control of a smart FG (functionally graded) cylindrical shell conveying fluid in thermal environment is studied theoretically by using a laminated piezoelectric actuator. Velocity feedback control law is implemented to activate the piezoelectric actuator. Considering the electric-thermo-fluid-structure interaction effect, a nonlinear dynamic model of the smart fluid-conveying FG cylindrical shell is developed based on Hamilton’s principle and von-Karman type geometrical nonlinear relationship. The inviscid, incompressible, isentropic and irrotational fluid is coupled into governing equations using the linearized potential theory. The Galerkin’s method is used to obtain the nonlinear governing equations of motion of the coupled system. The multiple time scales approach is applied to solve the resulting governing equations for analysing the nonlinear dynamic characteristics of the coupled system. The influence of fluid flow velocity, feedback control gains of piezoelectric voltage, external excitation and material properties of FGM on the frequency-response curves of system are investigated. The results indicate that the piezoelectric voltage is an effective controlling parameter for vibration control of the system, and the flow velocity can effect significantly the vibration amplitude and nonlinearity of the coupled system.

Three-dimensional dynamics of curved pipes conveying fluid

The paper presents a model describing flow-induced 3D motions of a pipe. The Timoshenko-type model is adopted, accounting for geometric nonlinearities. The state of static equilibrium is governed by twelve nonlinear ordinary differential equations and the boundary problem is solved by numerical methods. Flow-induced pipe vibrations are governed by a system of six partial differential equations with coefficient terms (coefficients) depending on static solutions. The calculation procedure relies on the Galerkin approach with a spline function as a shape function. The pipe shape is defined by parametric equations. Model and the adopted method of analysis are verified through comparing research data provided by other authors. The influence of fluid flow velocity on natural frequencies and vibration modes is analysed for pipes with varied curvature, taking into account extension of the pipe centreline.

Continuous flow production of cationic liposomes at high lipid concentration in microfluidic devices for gene delivery applications

Microfluidics is a powerful technology that allows the production of cationic liposomes by the hydrodynamic focusing method. We first studied a single hydrodynamic focusing (SHF) device, which uses a central stream in which lipids dispersed in ethanol are injected and hydrodynamically compressed by the two aqueous streams. The ethanol diffusion from the inner stream to the aqueous stream encourages the formation of the liposomes. To intensify the mass diffusion and increase the surface area between the two fluids, a second device was designed with double hydrodynamic focusing (DHF). We investigated the influence of fluid flow velocity (Vf), Flow Rate Ratio (FRR) and total lipid concentration (Clip) on the particle size of the CLs produced. The DHF microfluidic device had the ability of using higher Vf values than the SHF device, which resulted in a higher productivity level. Small Angle X-ray Scattering (SAXS) experiments were performed to structurally characterize the cationic liposomes produced by both microfluidic devices. The SAXS results revealed that both devices produce unilamellar cationic liposomes with a very small fraction of multilamellar liposomes; this finding is in agreement with the observations made in the analysis of the liposomes using Transmission Electron Microscopy (TEM). The biological efficacies of the cationic liposomes produced by both microfluidic devices were examined in vitro in HeLa cells, which confirmed their potential for gene delivery and vaccine therapy applications.

Online recognition of the multiphase flow regime and study of slug flow in pipeline

Multiphase flow is the phenomenon existing widely in nature, daily life, as well as petroleum and chemical engineering industrial fields. The interface structure among multiphase and their movement are complicated, which distribute random and heterogeneously in the spatial and temporal scales and have multivalue of the flow structure and state[1]. Flow regime is defined as the macro feature about the multiphase interface structure and its distribution, which is an important feature to describe multiphase flow. The energy and mass transport mechanism differ much for each flow regimes. It is necessary to solve the flow regime recognition to get a clear understanding of the physical phenomena and their mechanism of multiphase flow. And the flow regime is one of the main factors affecting the online measurement accuracy of phase fraction, flow rate and other phase parameters. Therefore, it is of great scientific and technological importance to develop new principles and methods of multiphase flow regime online recognition, and of great industrial background.In this paper, the key reasons that the present method cannot be used to solve the industrial multiphase flow pattern recognition are clarified firstly. Then the prerequisite to realize the online recognition of multiphase flow regime is analyzed, and the recognition rules for partial flow pattern are obtained based on the massive experimental data. The standard templates for every flow regime feature are calculated with self-organization cluster algorithm. The multi-sensor data fusion method is proposed to realize the online recognition of multiphase flow regime with the pressure and differential pressure signals, which overcomes the severe influence of fluid flow velocity and the oil fraction on the recognition. The online recognition method is tested in the practice, which has less than 10 percent measurement error. The method takes advantages of high confidence, good fault tolerance and less requirement of single sensor performance.Among various flow patterns of gas-liquid flow, slug flow occurs frequently in the petroleum, chemical, civil and nuclear industries. In the offshore oil and gas field, the maximum slug length and its statistical distribution are very important for the design of separator and downstream processing facility at steady state operations. However transient conditions may be encountered in the production, such as operational upsets, start-up, shut-down, pigging and blowdown, which are key operational and safety issues related to oil field development. So it is necessary to have an understanding the flow parameters under transient conditions. In this paper, the evolution of slug length along a horizontal pipe in gas-liquid flow is also studied in details and then an experimental study of flowrate transients in slug flow is provided. Also, the special gas-liquid flow phenomena easily encountered in the life span of offshore oil fields, called severe slugging, is studied experimentally and some results are presented.

Online recognition of the multiphase flow regime

The key reasons that the present method cannot be used to solve the industrial multiphase flow pattern recognition are clarified firstly. The prerequisite to realize the online recognition is proposed and recognition rules for partial flow pattern are obtained based on the massive experimental data. The standard templates for every flow regime feature are calculated with self-organization cluster algorithm. The multi-sensor data fusion method is proposed to realize the online recognition of multiphase flow regime with the pressure and differential pressure signals, which overcomes the severe influence of fluid flow velocity and the oil fraction on the recognition. The online recognition method is tested in the practice, which has less than 10 percent measurement error. The method takes advantages of high confidence, good fault tolerance and less requirement of single sensor performance.