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设计工况下离心泵作液力透平内部流动耗散特性研究
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作者 温小明 林通 +3 位作者 曾晓亮 罗国虎 魏碧胜 朱祖超 《化工设备与管道》 CAS 北大核心 2024年第6期59-68,共10页
离心泵反转作液力透平是一种能量回收装置,但缺点是即使在设计工况下的效率也相对较低。为揭示液力透平的流动耗散特性,文章首先通过流体动能方程构建了涡量与流动耗散之间的关系。随后,基于拟涡能耗散理论对设计工况下的流动耗散进行... 离心泵反转作液力透平是一种能量回收装置,但缺点是即使在设计工况下的效率也相对较低。为揭示液力透平的流动耗散特性,文章首先通过流体动能方程构建了涡量与流动耗散之间的关系。随后,基于拟涡能耗散理论对设计工况下的流动耗散进行了定量计算。最后,对主要损失部件内的拟涡能耗散分布特性与局部主要流动特征进行了关联分析,进而揭示了透平内部流动耗散的发生位置和产生原因。结果表明:拟涡能耗散评估方法能够较为准确地计算透平的流动损失,设计工况下各部件损失占比大到小排列分别为:叶轮、蜗壳、腔体、出口段和进口段。叶轮内局部拟涡能耗散主要发生在吸力面的前缘下游及叶片尾缘附近,叶片前缘冲击、回流、旋涡等不稳定流动是导致叶轮内局部拟涡能耗散的主要原因。蜗壳的拟涡能耗散主要由出口回流、隔舌前缘及壁面处的附着旋涡粘性耗散引起,腔体的拟涡能耗散主要由前腔间隙射流所引起的旋涡耗散及壁面旋涡粘性耗散组成。出口管的流动耗散特性主要受叶轮出流条件的影响,前腔间隙射流会对出口管内的主流产生冲击并引起局部水力耗散。研究结果可为高性能液力透平的设计提供参考。 展开更多
关键词 液力透平 流动耗散 拟涡能 数值模拟 设计工况
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A dynamic analysis of environmental losses from anthropogenic lead flow and their accumulation in China 被引量:1
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作者 梁静 毛建素 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第4期1125-1133,共9页
Substance flow analysis was applied to analyzing the lead emissions in 2010. It turns out that in 2010, for every 1 kg of lead consumed, 0.48 kg lead is lost into the environment. The emissions in 2010 were estimated ... Substance flow analysis was applied to analyzing the lead emissions in 2010. It turns out that in 2010, for every 1 kg of lead consumed, 0.48 kg lead is lost into the environment. The emissions in 2010 were estimated to be 1.89×10^6 t, which were mainly from use (39.20%) and waste management&recycling (33.13%). The accumulative lead in 1960-2010 from the anthropogenic flow was estimated and the results show that the total accumulative lead in this period amounted to 19.54×10^6 t, which was equivalent to 14.26 kg and 2.04 g/m^2 at the present population and territory. 展开更多
关键词 substance flow analysis EMISSION historical accumulation dissipative uses life cycle
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Three-dimensional unsteady squeezing flow with irreversibility 被引量:2
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作者 HAYAT T AHMAD M Waqar +1 位作者 SHEHZAD S A ALSAEDI A 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第11期3368-3380,共13页
This exploration examines unsteady magnetohydrodynamic(MHD) three-dimensional flow of viscous material between rotating plates subject to radiation,Joule heating and chemical reaction.The non-linear partial differenti... This exploration examines unsteady magnetohydrodynamic(MHD) three-dimensional flow of viscous material between rotating plates subject to radiation,Joule heating and chemical reaction.The non-linear partial differential system is re-structured into the ordinary differential expressions by the implication of appropriate transformations.The developed differential equations are computed by homotopy analysis technique.Numerical consequences have been accomplished by various values of emerging parameters.Coefficients of skin friction and heat and mass transfer rates have been scrutinized.Irreversibility analysis is carried out.Influence of various prominent variables on entropy generation is presented.Moreover,the temperature increases for higher Dufour number and concentration distribution reduces against Soret number.Higher squeezing parameter enhances velocity while concentration reduces with an increment in squeezing parameter.Both entropy rate and Bejan number increase against higher diffusion parameter. 展开更多
关键词 Joule heating viscous dissipation magnetohydrodynamic(MHD)flow chemical reaction entropy generation
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Modeling of Fluid Turbulence Modification Using Two-time-scale Dissipation Models and Accounting for the Particle Wake Effect 被引量:6
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作者 于勇 周力行 王保国 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2006年第3期314-320,共7页
Presently developed two-phase turbulence models under-predict the gas turbulent fluctuation, because their turbulence modification models cannot fully reflect the effect of particles. In this paper, a two-time-scale d... Presently developed two-phase turbulence models under-predict the gas turbulent fluctuation, because their turbulence modification models cannot fully reflect the effect of particles. In this paper, a two-time-scale dissipation model of turbulence modification, developed for the two-phase velocity correlation and for the dissipation rate of gas turbulent kinetic energy, is proposed and used to simulate sudden-expansion and swirling gas-particle flows. The proposed two-time scale model gives better results than the single-time scale model. Besides, a gas turbulence augmentation model accounting for the f'mite-size particle wake effect in the gas Reynolds stress equation is proposed. The proposed turbulence modification models are used to simulate two-phase pipe flows. It can properly predict both turbulence reduction and turbulence enhancement for a certain size of particles observed in experiments. 展开更多
关键词 turbulence modification two time scale dissipation model wake effect
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DPM dissipation experiment at MST's experimental mine and comparison with CFD simulation 被引量:9
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作者 ZHENG Yi LAN Hai THIRUVENGADAM Magesh TIEN Jerry C 《Journal of Coal Science & Engineering(China)》 2011年第3期285-289,共5页
Diesel Particulate Matter (DPM) is regulated in the U.S. for both underground coal and metal/nonmetal mines. Today, many underground mines still face difficulty in compliance with DPM regulations. The DPM research c... Diesel Particulate Matter (DPM) is regulated in the U.S. for both underground coal and metal/nonmetal mines. Today, many underground mines still face difficulty in compliance with DPM regulations. The DPM research carried out in Missouri University of Science and Technology (MST) is to use computational fluid dynamics (CFD) to study the DPM distribution in commonly used face areas. The result is expected to be used for selection of DPM reduction strategies and better working practices, which can help the underground mines to meet regulation limits and improve the working environment for the miners. An experiment was conducted at MST's Experimental Mine to validate CFD simulation. DPM was collected at four locations downstream of a stationary diesel engine. The experiment data were then compared with the CFD simulation results. The comparison shows that CFD simulation can forecast the location of DPM concentration with practical accuracy (less than 0.15 m). CFD can be used to further study DPM distribution in commonly used working faces and give guidance to DPM reduction. 展开更多
关键词 DPM DPM dissipation CFD validation study
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Currents and mixing in the northern South China Sea 被引量:3
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作者 刘军亮 蔡树群 王盛安 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2010年第5期974-980,共7页
We investigated the vertical distribution of current velocity data of the entire water column at a site on the continental shelf of the northern South China Sea(SCS) from August 4 to September 6,2007,and found that th... We investigated the vertical distribution of current velocity data of the entire water column at a site on the continental shelf of the northern South China Sea(SCS) from August 4 to September 6,2007,and found that the characteristics of barotropic and baroclinic tides are mainly diurnal.During the observation period,we also estimated the mixing before and after the passage of Typhoon Pabuk.We found that the internal-wave-scale dissipation rate,the turbulent dissipation rate,and the mixing rate in every water layer increased by about an order of magnitude after the typhoon passage.We analyzed a case of abrupt strong current and calculated the mixing rate before,during,and after the typhoon event.The results show that the internal-wave-scale dissipation rate and the mixing rate in every water layer increased by about two orders of magnitude during the event,while the turbulent dissipation rate increased by about an order of magnitude.Passage of the abrupt strong current could also have increased the mixing rate of affected seawater by more than an order of magnitude.However,the passage of the typhoon differed in that there was an increase in mixing only in the lower layer where the abrupt strong current was particularly strong.The variation of the mixing rate may help us to understand the effects of typhoons and abrupt strong currents on the mixing of seawater. 展开更多
关键词 current field TYPHOON abrupt strong current mixing rate South China Sea (SCS)
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Influences of nonassociated flow rules on three-dimensional seismic stability of loaded slopes 被引量:3
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作者 N.GANJIAN F.ASKARI O.FARZANEH 《Journal of Central South University》 SCIE EI CAS 2010年第3期603-611,共9页
The influences of soil dilatancy angle on three-dimensional (3D) seismic stability of locally-loaded slopes in nonassociated flow rule materials were investigated using a new rotational collapse mechanism and quasi-... The influences of soil dilatancy angle on three-dimensional (3D) seismic stability of locally-loaded slopes in nonassociated flow rule materials were investigated using a new rotational collapse mechanism and quasi-static coefficient concept. Extended Bishop method and Boussinesq theorem were employed to establish the stress distribution along the rupture surfaces that are required to obtain the rate of internal energy dissipation for the nonassociated flow rule materials in rotational collapse mechanisms. Good agreement was observed by comparing the current results with those obtained using the translational or rotational mechanisms and numerical finite difference method. The results indicate that the seismic stability of slopes reduces by decreasing the dilatancy angle for nonassociated flow rule materials. The amount of the mentioned decrease is more significant in the case of mild slopes in frictional soils. A nearly infinite slope under local loading, whether its critical failure surface is 2D or 3D, not only depends on the magnitude of the external load, but also depends on the dilataney angle of soil and the coefficient of seismic load. 展开更多
关键词 3D slope stability failure analysis nonassociated flow rule
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Turbulent dissipation and mixing in Prydz Bay 被引量:2
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作者 杨庆轩 田纪伟 +1 位作者 赵玮 谢玲玲 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2013年第2期445-453,共9页
In this paper, we present measurements of velocity, temperature, salinity, and turbulence collected in Prydz Bay, Antarctica, during February, 2005. The dissipation rates of turbulent kinetic energy (e) and diapycna... In this paper, we present measurements of velocity, temperature, salinity, and turbulence collected in Prydz Bay, Antarctica, during February, 2005. The dissipation rates of turbulent kinetic energy (e) and diapycnal diffusivities (Ks) were estimated along a section in front of the Amery Ice Shelf. The dissipation rates and diapycnal diffusivities were spatially non-uniform, with higher values found in the western half of the section where E reached 10.7 W/kg and Kz reached 10.2 mVs, about two and three orders of magnitude higher than those in the open ocean, respectively. In the western half of the section both the dissipation rates and diffusivities showed a high-low-high vertical structure. This vertical structure may have been determined by internal waves in the upper layer, where the ice shelf draft acts as a possible energy source, and by bottom-generated internal waves in the lower layer, where both tides and geostrophic currents are possible energy sources. The intense diapycnal mixing revealed in our observations could contribute to the production of Antarctic Bottom Water in Prydz Bay. 展开更多
关键词 turbulent mixing Prydz Bay Antarctic Bottom Water (AABW) microstructure observation
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Numerical Simulation of the Non-isothermal Viscoelastic Flow Past a Confined Cylinder 被引量:1
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作者 阮春蕾 欧阳洁 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2010年第2期177-184,共8页
A collocated finite volume method on unstructured meshes is introduced to simulate the viscoelastic flow of the polymer melt with viscous dissipation past a confined cylinder.The constitutive equation for the simulati... A collocated finite volume method on unstructured meshes is introduced to simulate the viscoelastic flow of the polymer melt with viscous dissipation past a confined cylinder.The constitutive equation for the simulations is non-isothermal FENE-P model,which is derived from the molecular theories.The temperature effect on the macroscopic fields(e.g.,velocity,stress) and microscopic fields(e.g.,molecular orientation,deformation,stretch) is investigated by comparison of isothermal and non-isothermal situations.This investigation indicates that temperature rise caused by viscous dissipation should not be neglected since it has significant effect on the macroscopic and microscopic properties of the polymer melt. 展开更多
关键词 NON-ISOTHERMAL FENE-P model unstructured meshes finite volume method cylinder flow
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Vortex Dissipation Due to Airfoil-Vortex Interaction
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《Journal of Mechanics Engineering and Automation》 2014年第1期63-71,共9页
The influences due to several AVIs (airfoil-vortex interactions) are studied by using a two-dimensional CFD (computational fluid dynamics) method. The primary goal of this effort is to assess the variation of vort... The influences due to several AVIs (airfoil-vortex interactions) are studied by using a two-dimensional CFD (computational fluid dynamics) method. The primary goal of this effort is to assess the variation of vortex center location and vortex circulation associated with sequential AVI toward an improvement of the hybrid method of CFD and prescribed wake model, which closely relates to predicting the BVI (blade-vortex interaction) noise radiated from a helicopter rotor. The representative of sequential AVI is performed by single vortex and two airfoils. Investigations with respect to vortex center location and vortex circulation after AVIs have been made by varying the miss-distance, which is the vertical distance between the airfoil leading edge and the vortex center. Correlations between miss-distance and vorticity field show that there exists complicated vortex wake flow with several vortices newly induced in 1st AVI. The pressure fluctuation amplitude clarifies that the intensity in 2nd AV1 is significantly low compared to the intensity in 1st AVI due to the influence of vortex dissipation. Simulations turned out to modify the vortex center location represented by the hybrid method using an offset value for a streamwise direction and to dissipate the vortex circulation for improving the accuracy of BVI noise prediction. 展开更多
关键词 Helicopter noise airfoil-vortex interaction vortex dissipation computational fluid dynamics.
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Flux Limiter Lattice Boltzmann Scheme Approach to Compressible Flows with Flexible Specific-Heat Ratio and Prandtl Number
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作者 甘延标 许爱国 +1 位作者 张广财 李英骏 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第9期490-498,共9页
We further develop the lattice Boltzmann (LB) model [Physica A 382 (2007) 502] for compressible flows from two aspects. Firstly, we modify the Bhatnagar Gross Krook (BGK) collision term in the LB equation, which... We further develop the lattice Boltzmann (LB) model [Physica A 382 (2007) 502] for compressible flows from two aspects. Firstly, we modify the Bhatnagar Gross Krook (BGK) collision term in the LB equation, which makes the model suitable for simulating flows with different Prandtl numbers. Secondly, the flux limiter finite difference (FLFD) scheme is employed to calculate the convection term of the LB equation, which makes the unphysical oscillations at discontinuities be effectively suppressed and the numerical dissipations be significantly diminished. The proposed model is validated by recovering results of some well-known benchmarks, including (i) The thermal Couette flow; (ii) One- and two-dlmenslonal FLiemann problems. Good agreements are obtained between LB results and the exact ones or previously reported solutions. The flexibility, together with the high accuracy of the new model, endows the proposed model considerable potential for tracking some long-standing problems and for investigating nonlinear nonequilibrium complex systems. 展开更多
关键词 lattice Boltzmann method flux limiter compressible flows Prandtl number
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Constructal optimization for H-shaped multi-scale heat exchanger based on entransy theory 被引量:16
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作者 FENG HuiJun CHEN LinGen +1 位作者 XIE ZhiHui SUN FengRui 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第2期299-307,共9页
Analogizing with the definition of thermal efficiency of a heat exchanger,the entransy dissipation efficiency of a heat exchanger is defined as the ratio of dimensionless entransy dissipation rate to dimensionless pum... Analogizing with the definition of thermal efficiency of a heat exchanger,the entransy dissipation efficiency of a heat exchanger is defined as the ratio of dimensionless entransy dissipation rate to dimensionless pumping power of the heat exchanger.For the constraints of the total tube volume and total tube surface area of the heat exchanger,the constructal optimization of an H-shaped multi-scale heat exchanger is carried out by taking entransy dissipation efficiency maximization as optimization objective,and the optimal construct of the H-shaped multi-scale heat exchanger with maximum entransy dissipation efficiency is obtained.The results show that for the specified total tube volume of the heat exchanger,the optimal constructs of the first order T-shaped heat exchanger based on the maximizations of the thermal efficiency and entransy dissipation efficiency are obviously different with the lower mass flow rates of the cold and hot fluids.For the H-shaped multi-scale heat exchanger,the entransy dissipation efficiency decreases with the increase in mass flow rate when the heat exchanger order is fixed;for the specified dimensionless mass flow rate M(M<32.9),the entransy dissipation efficiency decreases with the increase in the heat exchanger order.The performance of the multi-scale heat exchanger is obviously improved compared with that of the single-scale heat exchanger.Moreover,the heat exchanger subjected to the total tube surface area constraint is also discussed in the paper.The optimization results obtained in this paper can provide a great compromise between the heat transfer and flow performances of the heat exchanger,provide some guidelines for the optimal designs of heat exchangers,and also enrich the connotation of entransy theory. 展开更多
关键词 constructal theory thermal efficiency entransy dissipation efficiency H-shaped multi-scale heat exchanger generalizedthermodynamic optimization
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The impact of interphase forces on the modulation of turbulence in multiphase flows
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作者 Simon Schneiderbauer Mahdi Saeedipour 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2022年第8期18-28,共11页
The modulation of turbulence by particles has been rigorously investigated in the literature yielding either a reduction or an enhancement of the turbulent kinetic energy at different spatial length scales.However,a g... The modulation of turbulence by particles has been rigorously investigated in the literature yielding either a reduction or an enhancement of the turbulent kinetic energy at different spatial length scales.However,a general description of the turbulence modulation in multiphase flows due to the presence of an interphase force has attracted less attention.In this paper,we investigate the turbulent modulation for interfacial and fluid-particle flows analytically and numerically,where surface tension and drag define the interphase coupling,respectively.It is shown that surface tension and drag appear as additional production/dissipation terms in the transport equations for the turbulent kinetic energies(TKE),which is of particular importance for the turbulence modelling of multiphase flows.Furthermore,we study the modulation of turbulence in decaying homogenous isotropic turbulence(HIT)for both types of multiphase flow.The results clearly unveil that in both cases the energy is reduced at large scales,while the small-scale energy is enhanced compared to single-phase flows.Particularly,at large scales surface tension works against the turbulent eddies and hinders the ejection of droplet from the corrugated interface.In contrast,at the small scales,the surface tension force and the velocity fluctuations are aligned leading to an enhancement of the energy.In the case of fluid-particle flows,particles retain their energy longer than the surrounding fluid increasing the energy at the small scales,while at the large scales the particles do not follow exactly the surrounding fluid reducing its energy.For the latter effect,a considerable dependence on the particle Stokes number is found. 展开更多
关键词 Multiphase turbulence Interfacial flow Fluid-particle flow Volume of fluid method Two-fluid model
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MHD peristaltic flow in an inclined channel with heat and mass transfer
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作者 Maryiam Javed T. Hayat A. Alsaedi 《International Journal of Biomathematics》 2016年第1期191-205,共15页
This paper addresses the peristaltic flow of magnetohydrodynamic viscous fluid in an inclined compliant wall channel. Different wave amplitudes and phases ensure asymme- try in the channel flow configuration. Simultan... This paper addresses the peristaltic flow of magnetohydrodynamic viscous fluid in an inclined compliant wall channel. Different wave amplitudes and phases ensure asymme- try in the channel flow configuration. Simultaneous effects of heat and mass transfer are also considered. Viscous dissipation effect is present. The flow and heat transfer are investigated under long wavelength and low Reynolds number assumption. The expres- sions for stream function, axial velocity, temperature and concentration are obtained. The solution expressions for physical quantities are sketched and discussed. It is found that Brinkman and Hartman numbers have reverse effect on the temperature. 展开更多
关键词 Inclined channel compliant wall viscous dissipation MHD.
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Thermal performance analysis of non-uniform height rectangular fin based on constructal theory and entransy theory 被引量:4
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作者 YANG Ai Bo CHEN Lin Gen +2 位作者 XIE Zhi Hui FENG Hui Jun SUN Feng Rui 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2016年第12期1882-1891,共10页
A model of non-uniform height rectangular fin, in which the variation of base's thickness and width are taken into account, is established in this paper. The dimensionless maximum thermal resistance(DMTR) and the ... A model of non-uniform height rectangular fin, in which the variation of base's thickness and width are taken into account, is established in this paper. The dimensionless maximum thermal resistance(DMTR) and the dimensionless equivalent thermal resistance(DETR) defined based on the entransy dissipation rate(EDR) are taken as performance evaluation indexes. According to constructal theory, the variations of the two indexes with the geometric parameters of the fin are analyzed by using a finite-volume computational fluid dynamics code, the effects of the fin-material fraction on the two indexes are analyzed. It is found that the two indexes decrease monotonically as the ratio between the front height and the back height of the fin increases subjected to the non-uniform height rectangular fin. When the model is reduced to the uniform height fin, the two indexes increase first and then decrease with increase in the ratio between the height of the fin and the fin space. The fin-material fraction has no effect on the change rule of the two indexes with the ratio between the height of the fin and the fin space. The sensitivity of the DETR to the geometric parameters of the fin is higher than that of the DMTR to the geometric parameters. The results obtained herein can provide some theoretical support for the thermal design of rectangular fins. 展开更多
关键词 constructal design entransy theory maximum thermal resistance equivalent thermal resistance rectangular fin generalized thermodynamic optimization
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