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THREE-DIMENSIONAL NUMERICAL SIMULATION OF INTAKE MODEL WITH cross flow

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Journal of Hydrodynamics 2011年第3期23卷 314-324页

作者： HSIAO Shih-Chun Department of Hydraulics and Ocean Engineering National Cheng Kung University

The hydrodynamics of a pump sump consisting of a main channel, pump sump, and intake pipe is examined using Truchas a three-dimensional Navier-Stokes solver, with a Large Eddy Simulation （LES） turbulence model. The numerical results of streamwise velocity profiles and flow patterns are discussed and compared with experimental data of Ansar and Nakato. Fairly good agreement is obtained. Furthermore, unlike Ansar et al.＇s inviscid solution, the proposed numerical model includes the effect of fluid viscosity and considers more realistic simulation conditions. Simulation results show that viscosity affects the prediction of flow patterns and that the streamwise velocity can be better captured by including cross flow. The effects of the submergence Froude number on the free surface and streamwise velocity are also examined. The free surface significantly fluctuates at high submergence Froude number flows and the corresponding distribution of streamwise velocity profiles exhibits a trend different from that obtained for low submergence Froude number flows.

关键词： pump sump cross flow submergence Froude number Large Eddy Simulation （LES）

Nonplanar flow-induced vibrations of a cantilevered PIP structure system concurrently subjected to internal and cross flows

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Acta Mechanica Sinica 2019年第6期35卷 1241-1256页

作者： Z.Y.Liu T.L.Jiang L.Wang H.L.Dai Department of Mechanics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Wuhan 430074China

Pipe-in-pipe(PIP)structures are widely used in offshore oil and gas pipelines to settle thermal insulation issues.A PIP structure system usually consists of two concentric pipes and one softer layer for thermal insulation consideration.The total response of the system is related to the dynamics of both pipes and the interactions between these two concentric pipes.In the current work,a theoretical model for flow-induced vibrations of a PIP structure system is proposed and analyzed in the presence of an internal axial flow and an external cross flow.The interactions between the two pipes are modeled by a linear distributed damper,a linear distributed spring and a nonlinear distributed spring along the pipe length.The unsteady hydrodynamic forces due to cross flow are modeled by two distributed van der Pol wake oscillators.The nonlinear partial differential equations for the two pipes and the wake are further discretized by the aid of Galerkin’s technique,resulting in a set of ordinary differential equations.These ordinary differential equations are further numeri cally solved by using a fourth-order Runge-Kutta integration algorithm.Phase portraits,bifurcation diagrams,an Argand diagram and oscillation shape diagrams are plotted,showing the existence of a lock-in phenomenon and figure-of-eight trajectory.The PIP system subjected to cross flow displays some interesting dynamical behaviors different from that of a single-pipe structure.

关键词： Cantilevered PIP structure Theoretical model flow-induced vibration cross flow Internal flow

Numerical Study and Optimization of a Combined Thermoelectric Assisted Indirect Evaporative Cooling System

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Journal of Thermal Science 2020年第5期29卷 1345-1354页

作者： ZHOU Yuanyuan ZHANG Tao WANG Fang YU Yanshun School of Energy and Power Engineering Nanjing University of Science and TechnologyNanjing 210094China

This paper numerically investigates the performance of a novel combined cross-regenerative cross flow(C-RC)thermoelectric assisted indirect evaporative cooling(TIEC)system.This C-RC TIEC system combines the indirect evaporative cooling and thermoelectric cooling technologies.A heat and mass transfer model is developed to perform the performance analysis and optimization of this novel system.Performance comparison between the novel C-RC TIEC system and a regenerative cross flow TIEC system is conducted under various operating conditions.It is found that the novel system provides better performance with higher coefficient of performance(C O P)and higher dew point effectiveness than the regenerative cross flow TIEC system,especially under smaller working current and smaller number of thermoelectric cooling modules.The performance optimization of the novel system is also made by investigating the influences of primary air parameters,three different mass flow rate ratios,as well as the length ratio of the left wet channel to the whole wet channel.The results show that there exist optimal mass flow rate ratios and wet channel length ratio resulting in the maximum C O P.

关键词： indirect evaporative cooling thermoelectric regenerative cross flow heat and mass transfer optimization

flow Field Investigation in a Trapezoidal Duct with Swirl flow Induced by Impingement Jets

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Chinese Journal of Aeronautics 2011年第1期24卷 8-17页

作者： LIU Haiyong QIANG Hongfu LIU Songling LIU Cunliang 201 Section Xi 'an High- Teeh Institute Xi 'an 710025 China School of Power and Energy Northwestern Polytechnieal University Xi 'an 710072 China

An enlarged model of trapezoidal duct near the leading-edge in the blade is built up. The effects of impingement jets, swirl flow, cross flow and effusion flow are considered. Experiments are performed to measure flow fields in this confined passage and exit holes on one of its side walls. cross flow and effusion flow are induced in the channel by the outflow of side exit hole （SEH） and film cooling hole （FCH）, which are oriented on one end wall and bottom wall of the passage. Detailed flow structures are measured for two impingement angles of 35° and 45° with 6 combinations of outflow ratios. Results show that the small jets impinge the target wall effectively while the large jets contribute to inducing and impelling a strong counter-clockwise vortex in the upper part of the passage. cross flow plays a dominate role for the flow structures in the passage and exit holes. It deflects jets, enhances swirl and deteriorates side exit conditions. Impingement angle is another significant factor for the flow characteristics. Its effect reveals more evidently with cross flow. Within the present test conditions, the mass flow rates and outflow positions of FCHs have no distinct effect on the main flow structures.

关键词： flow fields leading edge impingement jets swirl flow film cooling cross flow

Thermal-Hydraulic Characteristics of Twisted Elliptical Tube Bundle in Staggered Arrangement

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Journal of Thermal Science 2021年第6期30卷 1925-1937页

作者： LI Xiuzhen WANG Lin FENG Rong WANG Zhanwei ZHU Dongsheng Institute of Building Energy and Thermal Science Henan University of Science and TechnologyLuoyang 471023China CAS Key Laboratory of Renewable Energy Guangzhou 510640China School of Mechanical Engineering Shaanxi Key Laboratory of Industrial AutomationShaanxi University of TechnologyHanzhong 723001China

Based on experimental data,numerical simulations by turbulent air flowing across staggered tube bundle composed of twisted elliptical tube(TET)with constant tube wall temperature are conducted in present study.Parametric study on the thermal-hydraulic characteristics of air crossflow in TET bundles is investigated with physical parameters and Reynolds number(Re).The results show that spiral channels created by spiral deformation of TETs have a diversion effect on the air flow,which changes the flow direction of the air near the tube wall.The air in the near wall region is a three-dimensional flow,consisting of a flow perpendicular to the normal direction of the elliptical cross section and a spiral flow along the helicoid on the downstream side and the upstream side.And the interaction of the spiral channels makes the two flows and their mixing more complicated.The excellent heat transfer performance of staggered TET bundles is confirmed by the comparison of the comprehensive heat transfer performance with that of circular tube bundles.The average Nusselt number(Nu)increases with the increase of the aspect ratio(A/B)and with the increase of Re while decreases as the twist pitch(S)increases.The average Euler number(Eu)increases as A/B increases,while it decreases as Re increases and as S increases.Due to the fact that the suitable correlations for staggered TET bundles are not reported,correlations for Nu and Eu obtained from experimental data and numerical results are presented in the multiple forms.

关键词： twisted elliptical tube heat transfer enhancement pressure drop performance cross flow

Numerical investigation on the flow structures in a narrow confined channel with staggered jet array arrangement

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Chinese Journal of Aeronautics 2015年第6期28卷 1616-1628页

作者： Liu Haiyong Liu Cunliang Wu Wenming Section of Engine and Energy Xi'an High-Tech Institute School of Power and Engine Northwestern Polytechnical University

A series of numerical analyses have been performed to investigate the flow structures in a narrow confined channel with 12 staggered circular impingement holes and one bigger exit hole. The flow enters the channel through the impingement holes and exits through the far end outlet. The flow fields corresponding to two jet Reynolds numbers （25000 and 65000） and three channel con- figurations with different ratios of the channel height to the impingement hole diameter （Zr 1, 3, 5） are analyzed by solving the Reynolds averaged Navier-Stokes equations with the realizable k-e turbulence model. Detailed flow field information including the secondary flow, the interaction between the jets and the cross flow, and flow distribution along the channel has been obtained. Comparisons between the numerical and experimental results of the flow fields at the four planes along the channel are performed to validate the numerical method. The calculated impingement pattern, high velocity flow distribution, low velocity separation region and vortices are in good agreement with the experimental data, implying the validity and effectiveness of the employed numerical approach for analyzing relevant flow field.

关键词： Confined channel cross flow flow structure Impingement coolingTurbulence model

PRESSURE-TRANSIENT ANALYSIS OF TWO-LAYERS FRACTAL RESERVOIRS

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Applied Mathematics and Mechanics(English Edition) 1998年第1期19卷 21-26页

作者：李凡华刘慈群 Institute of Porous flow and Fluid Mechanics Academia Sinica Langfang P. R. China

In this article based on the discussion on nonsteady flow of two-layers fractalreservoirs.the solution of generalized C-D equations in Laplace space, and then thesolution under different boundary conditions with considering or not consideringwellbore storage and skin effects are found out. At last. the nature of the solutionunder not considering wellbore storage and skin effects is taken under discussion.

关键词： fractal reservoirs cross flow generalized C-D equation pressuretransient analysis

Experimental Study of High Moisture Content Gas flow Across a Cylinder at Moderate Reynolds Numbers

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Tsinghua Science and Technology 2003年第5期8卷 598-604页

作者： D.M.Christopher 郭亮 Department of Thermal Engineering

The Nusselt number for cross flow of a mixture of air and vapor over a cylinder was measured at moderate Reynolds numbers (30007000) for temperatures from 300℃ to 700℃ and for vapor mass fractions of 0.180.35. Results are also presented for a set of three cylinders aligned perpendicular to the flow for the same range of conditions. The effect of the vapor concentration and temperature on the convection coefficients was investigated to develop a modified Zhukauskas correlation. The results show that the Nusselt number increases as the moisture content increases and that the increase is more than could be accounted for by typical models for the property variations of mixtures. The exponent of the vapor concentration term in the modified correlation is 0.145 for the entire data set indicating the importance of the property variation due to the moisture content.

关键词： high moisture content cross flow convection coefficients heat exchangers