Devolatilization of high viscous fluids with high gravity technology

Volatile organic compounds(VOCs)are generally toxic and harmful substances that can cause health and environmental problems.The removal of VOCs from polymers has become a key problem.The effective devolatilization to remove VOCs from high viscous fluids such as polymer is necessary and is of great importance.In this study,the devolatilization effect of a rotating packed bed(RPB)was studied by using polydimethylsiloxane as the viscous fluid and acetone as the VOC.The devolatilization rate and liquid phase volume(KLa)have been evaluated.The results indicated that the optimum conditions were the high-gravity factor of 60,liquid flow rate of 10 L·h^(-1),and vacuum degree of 0.077 MPa.The dimensionless correlation of KLa was established,and the deviations between predicted and experimental values were less than±28%.The high-gravity technology will result in lower mass transfer resistance in the devolatilization process,enhance the mass transfer process of acetone,and improve the removal effect of acetone.This work provides a promising path for the removal of volatiles from polymers in combination with high-gravity technology.It can provide the basis for the application of RPB in viscous fluids.

Highly-Efficient Aerodynamic Optimal Design of Rotor Airfoil Using Viscous Adjoint Method

In order to overcome the efficiency problem of the conventional gradient-based optimal design method,a highly-efficient viscous adjoint-based RANS equations method is applied to the aerodynamic optimal design of hovering rotor airfoil.The C-shaped body-fitted mesh is firstly automatically generated around the airfoil by solving the Poisson equations,and the Navier-Stokes(N-S)equations combined with Spalart-Allmaras(S-A)one-equation turbulence model are used as the governing equations to acquire the reliable flowfield variables.Then,according to multi-constrained characteristics of the optimization of high lift/drag ratio for hovering rotor airfoil,its corresponding adjoint equations,boundary conditions and gradient expressions are newly derived.On these bases,two representative rotor airfoils,NACA0012 airfoil and SC1095 airfoil,are selected as numerical examples to optimize their synthesized aerodynamic characteristics about lift/drag ratio in hover,and better aerodynamic performance of optimal airfoils are obtained compared with the baseline.Furthermore,the new designed rotor with the optimized rotor airfoil has better hover aerodynamic characteristics compared with the baseline rotor.In contrast to the baseline airfoils optimized by the finite difference method,it is demonstrated that the adjoint optimal algorithm itself is practical and highly-efficient for the aerodynamic optimization of hover rotor airfoil.

MASS TRANSFER AND HYDRODYNAMICS IN AN AIRLIFT REACTOR WITH VISCOUS NON-NEWTONIAN FLUID

In an internal loop airlift reactor of 55L working volume,the gas-liquid volumetric oxygenmass transfer coefficient k_Lα,gas holdup ε_G and liquid circulation time t_c were measured with the sol-ution of carboxymethyl cellulose(CMC)to simulate the performance of a reactor with highly viscousbroth.Electric conductivity and oxygen probes were used to measure the local gas holdup,liquidcirculation time and oxygen mass transfer coefficient in the individual sections of the reactor(riser,downcomer and the gas-liquid separating section at the top of the reactor)and the total reactor,respectively.The values of k_Lα for the riser,downcomer and separation sections of the reactor were alsoestimated and compared with that for the total reactor.The results show that,both k_Lα and ε_G in-crease but t_c decreases with increasing gas velocity.Correlations and comparisons with works reportedin the literature are also presented.Data show that the methods developed for k_Lα measurements inthe individual section

Thermal explosion and irreversibility of hydromagnetic reactive couple stress fluid with viscous dissipation and Navier slips

The study examines the thermal explosion branched-chain and entropy generation as a result of irreversibility of hydromagnetic reactive couple stress liquid with viscous heating and Navier slips.The reactive fluid flow is enhanced by heat dependent pre-exponential factor and axial pressure gradient in a porous wall.The flow equations for the non-Newtonian couple stress fluid model and heat transfer are solved by employing a semi-analytical collocation weighted residual method(CWRM).The efficiency and validity of the obtained results was verified with the existing results.The results reveal that at low hysteresis magnetic and viscous dissipation the irreversibility process is minimized and thermodynamic equilibrium is improved.The results from this study can assist in understanding the relationship between thermal and thermal explosions branched-chain.

Review:Recent Development of High⁃Order⁃Spectral Method Combined with Computational Fluid Dynamics Method for Wave⁃Structure Interactions

The present paper reviews the recent developments of a high⁃order⁃spectral method(HOS)and the combination with computational fluid dynamics(CFD)method for wave⁃structure interactions.As the numerical simulations of wave⁃structure interaction require efficiency and accuracy,as well as the ability in calculating in open sea states,the HOS method has its strength in both generating extreme waves in open seas and fast convergence in simulations,while computational fluid dynamics(CFD)method has its advantages in simulating violent wave⁃structure interactions.This paper provides the new thoughts for fast and accurate simulations,as well as the future work on innovations in fine fluid field of numerical simulations.

Transportation of heat through Cattaneo-Christov heat flux model in non-Newtonian fluid subject to internal resistance of particles

Thermal conduction which happens in all phases(liquid,solid,and gas)is the transportation of internal energy through minuscule collisions of particles and movement of electrons within a working body.The colliding particles comprise electrons,molecules,and atoms,and transfer disorganized microscopic potential and kinetic energy,mutually known as the internal energy.In engineering sciences,heat transfer comprises the processes of convection,thermal radiation,and sometimes mass transportation.Typically,more than one of these procedures may happen in a given circumstance.We use the Cattaneo-Christov(CC)heat flux model instead of the Fourier law of heat conduction to discuss the behavior of heat transportation.A mathematical model is presented for the Cattaneo-Christov double diffusion(CCDD)in the flow of a non-Newtonian nanofluid(the Jeffrey fluid)towards a stretched surface.The magnetohydrodynamic(MHD)fluid is considered.The behaviors of heat and mass transportation rates are discussed with the CCDD.These models are based on Fourier’s and Fick’s laws.The convective transportation in nanofluids is discussed,subject to thermophoresis and Brownian diffusions.The nonlinear governing flow expression is first altered into ordinary differential equations via appropriate transformations,and then numerical solutions are obtained through the built-in-shooting method.The impact of sundry flow parameters is discussed on the velocity,the skin friction coefficient,the temperature,and the concentration graphically.It is reported that the velocity of material particles decreases with higher values of the Deborah number and the ratio of the relaxation to retardation time parameter.The temperature distribution enhances when the Brownian motion and thermophoresis parameters increase.The concentration shows contrasting impact versus the Lewis number and the Brownian motion parameter.It is also noticed that the skin friction coefficient decreases when the ratio of the relaxation to retardation time parameter increases.

径向油孔结构对环下润滑高速轴承内部流动特性的影响研究

为了研究径向油孔结构对环下润滑高速轴承内部流动特性的影响规律,根据高速轴承内部流动特征建立了数值计算方法,针对包含输油通道、径向油孔和轴承组件的物理仿真模型开展了油气两相流动计算,对比并讨论了不同径向油孔结构下轴承内部的油气分布和黏性摩擦损失。数值模拟结果表明,径向油孔孔径增大后轴承内部的平均滑油体积分数单调增加且滑油分布更均匀。径向油孔布设在周向油槽的同侧有利于提升轴承内部的平均滑油体积分数,同时滑油沿周向分布的均匀性较好。轴承组件表面扩展参数受径向油孔结构的影响,其变化趋势与平均滑油体积分数的变化相似。全部采用经验公式预测得到的黏性摩擦损失整体偏高,且不能反映径向油孔结构参数的影响,数值模拟和经验公式相结合计算得到的黏性摩擦损失与直接采用数值模拟获得的结果表现出较好的一致性。

新疆高烈度地区A中学教学楼建设消能减震设计研究

高烈度区域更易受到地震影响。研究高烈度区域教学楼消能减震设计有助于后期恢复、减少震后损失,提升生存保障。本文以A中学教学楼为研究对象,分析消能减震目标,采用规范消能减震技术及墙体黏滞流体阻尼器方案。研究结果表明,设防地震作用下教学楼主体弹性,粘滞流体阻尼器在中震下就开始屈服耗能,等效附加阻尼比平均值X向4.56%,Y向6.49%,能够满足3%附加阻尼比的要求,粘滞流体阻尼器效果明显。

Particle characteristics and rheological constitutive relations of high concentration red mud

Red mud has relatively small solid particles （d50= 13.02 μm） and will flow in paste form under high pressure during pipeline transport. Red mud belongs to a two-phase flow of materials with high viscosity and a high concentration of non-sedimentation, homogeneous solid-liquids. It is difficult to test its rheological properties under atmospheric pressure. Measurements such as rotational viscometry can not reflect the real state of the material when it is flowing in a pipe. Tested rheological parameters are somewhat higher than the actual values. In our investigation, grain shape, distinctive modality and grain size distribution of red mud were tested. Based on the principle of tube measurement, rheological experiments on red mud at different concentrations were carried out by using our independently developed tube-type pressure theology test facility, and obtained constitutive equations. We conclude that red mud behaves as non-Newtonian pseudo-plastic fluid in pipe flows. Its consistency and power-law indices vary considerably with different concentrations.

The Strong Solution for the Viscous Polytropic Fluids with Non-Newtonian Potential

The authors study an initial boundary value problem for the three-dimensional Navier-Stokes equations of viscous heat-conductive fluids with non-Newtonian potential in a bounded smooth domain. They prove the existence of unique local strong solutions for all initial data satisfying some compatibility conditions. The difficult of this type model is mainly that the equations are coupled with elliptic, parabolic and hyperbolic, and the vacuum of density causes also much trouble, that is, the initial density need not be positive and may vanish in an open set.

A Phenomenological Gradient Approach to Generalized Constitutive Equations for Isotropic Fluids

An extension of the linear irreversible thermodynamics is proposed through the inclusion of the first gradients of velocity and of the classical local state parameters as additional independent variables in the fundamental energy state equation of a fluid system. We show that consistency of this hypothesis with the energy balance equation leads to generalized nonlinear constitutive equations, which we discuss in terms of an isotropic non-Newtonian viscous fluid.

基于黏滞阻尼器的RC框架抗震性能提升设计

基于性能化设计理念,对既有RC框架结构提出了一种基于黏滞流体阻尼器的抗震性能提升设计方法.以大震作用下的结构弹塑性位移作为性能控制目标,利用等价高阻尼弹性位移反应谱,通过迭代进行原结构和减震结构的弹塑性位移响应计算.利用算例展示了不同黏滞阻尼器速度指数减震方案的设计结果,并与工程实践中常用的基于小震工况设计方法结果进行对比.结果表明,所提方法可以实现性能设计目标且避免直接对结构多次进行弹塑性时程分析,设计过程高效快捷.该方法更适合采用低速度指数的黏滞阻尼器,在阻尼器成本和结构大震位移响应相同的情况下,相比速度指数为0.6的减震方案,采用速度指数为0.2的阻尼器在中、小震作用下的结构位移响应可以分别减小16%和30%.

Analysis of Combined Convective and Viscous Dissipation Effects for Peristaltic Flow of Rabinowitsch Fluid Model

In this article, mathematical modeling for peristaltic flow of Rabinowitsch fluid model is considered in a non-uniform tube with combined effects of viscous dissipation and convective boundary conditions. Wall properties analysis is also taken into account. Non-dimensional differential equations are simplified by using the well-known assumptions of low Reynolds number and long wavelength. The influence of various parameters connected with this flow problem such as rigidity parameter E1, stiffness parameter E2, viscous damping force parameter E3, Brickman number and Biot number are plotted for velocity distribution, temperature profile and for stream function. Results are plotted and discussed in detail for shear thinning, shear thickening and for viscous fluid. It is found that velocity profile is an increasing function of rigidity parameter, stiffness parameter, and viscous damping force parameter for shear thinning and for viscous fluid, due to the less resistance offered by the walls but, quite opposite behavior is depicted for shear thickening fluids. It is seen that Brickman number relates to the viscous dissipation effects, so it contributes in enhancing fluid temperature for all cases.

9度区西昌某体育馆隔震结构设计

本项目位于9度区西昌市,体育馆下部结构为混凝土框架结构、屋顶为管桁架结构体系,依据《建设工程抗震管理条例》采用隔震技术进行结构设计,隔震方案采用橡胶支座、提离装置、黏滞阻尼器组合的方式,隔震支座采用一柱一支座原则布置,黏滞阻尼器在建筑物四周布置。通过YJK计算设防地震作用下的结构整体指标、构件性能、隔震层性能指标,SAUSAGE-PI计算罕遇地震时程分析下的构件性能及隔震层性能指标。结果表明:对于9度高烈度地区多层体育馆,采用上述隔震方案能够有效的降低地震作用,保证大震下“构件中度损伤”的性能目标;提离支座可以有效解决高烈度区隔震支座受拉问题;高烈度区多层建筑隔震支座型号选型控制因素为大震下隔震支座的最大水平位移及拉应力。

高烈度地震区长联大跨连续梁桥减隔震方案分析

为研究高烈度地震区长联大跨连续梁在地震作用下减隔震技术,采用有限元建立跨径(50+8×100+50)m连续梁模型,在罕遇地震作用下,基于传统抗震设计对比双曲面球型减隔震支座、双曲面球型减隔震支座和黏滞流体阻尼共同作用减隔震措施及结构响应分析。结果表明采用双曲球面支座和黏滞流体阻尼器共同作用的减隔震技术为最优方案,各墩地震响应分配均匀、合理。结构纵横位移均在±30cm之内,桥墩及基础处于弹性状态。

压裂液缝内黏滞阻力实验研究

国外研究表明,压裂液的缝内黏滞阻力对气产量影响较大,即使只有0.003 0 kPa的黏滞阻力,也会在一定程度上降低气产量。文中采用支撑剂导流能力测定装置,自创了一套压裂液黏滞阻力的实验测定方法。通过系列实验得知:相同砂比、铺砂浓度条件下,高质量分数瓜胶压裂液的缝内黏滞阻力大于低质量分数瓜胶压裂液;同一套压裂液体系,低砂比段的缝内黏滞阻力大于高砂比段。因此,缝内黏滞阻力造成的支撑缝失效位置主要分布在低砂比段。另外,加入纤维有利于降低压裂液的缝内黏滞阻力。该研究成果为定量研究压裂液在支撑裂缝内的黏滞阻力提供了一套独特、可行的实验方法,在国内少有先例。

黏性流体的二次雾化特性

针对渣油沥青气化工艺,以高温下渣油沥青的雾化为研究背景,选择与其物性相近的甘油水溶液作为模拟介质,进行了黏性液体二次雾化的实验。利用高速摄像仪和图像处理软件,对单个液滴在不同条件下的破裂模式、特征尺度、破裂时间和破裂后的平均液滴直径等进行了观察和分析。结果表明,随着韦伯数(We)的增加,甘油液滴的破裂依次呈现5种不同的模式:袋状破裂、袋状雄蕊破裂、双重袋状破裂、剪切破裂和爆发式破裂。在低We下,液滴直径最大变形率基本相同;在高We下,总破裂时间明显缩短,破裂产生的液滴粒径很小,雾化效果良好。

粘滞流体阻尼器对电视塔的风振响应控制

以合肥电视塔为工程背景,探讨了粘滞流体阻尼器对高耸电视塔在强风作用下风振响应的振动控制.按照随机振动理论,仿真得到了作用在电视塔上的19维互相关的人造脉动风压时程样本曲线,并利用时程样本进行了电视塔的风振响应分析;建立了一种双模型的动力分析方法.对安置了粘滞流体阻尼器的合肥电视塔进行了控制分析;以上塔楼的风振响应为优化目标,对阻尼器的参数进行了优化设计.研究表明,电视塔的风振响应峰值超过了规范的容许值,设置了粘滞流体阻尼器后电视塔的风振响应均有明显的减小,阻尼器消耗了大量的结构能量,采用最优阻尼参数使上塔楼加速度峰值响应下降了43.4%.

聚酯熔融缩聚增黏过程的工程分析

聚酯增黏方法有固相缩聚、溶胀缩聚、熔融缩聚和化学增黏等,熔融缩聚增黏不但高效、清洁,而且产品质量的不均匀性明显改善。具有良好的成膜、更新等传递性能的高黏高效脱挥设备包括缩聚反应器和脱醛设备的结构型式是熔融缩聚增黏过程的关键。

黏滞阻尼器在超高层结构体系中的效率研究

250m以上的超高层结构主要有框架-核心筒、框筒-核心筒和巨型框架-核心筒等三种结构体系.由于超高层结构的高宽比通常较大(5以上),结构的侧向变形往往成为控制因素.随着消能减震技术的不断成熟,黏滞阻尼器越来越多的应用于建筑结构领域.本文分别将黏滞阻尼器均匀布置在上述三种超高层结构体系中,对比其消能减震效果并分析原因,最后建议了黏滞阻尼器在这些结构中的较优布置.