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Impact of Clocking on the Aero-Thermodynamics of a Second Stator tested in a One and a Half Stage HP Turbine

Journal of Thermal Science 2008年第2期17卷 97-110页

作者： N.Billiard G.Paniagua R.Dénos Turbomachinery and Propulsion Department von Karman Institute for fluid dynamics

This paper focuses on the experimental investigation of the time-averaged and time-accurate aero- thermodynamics of a second stator tested in a 1.5 stage high-pressure turbine. The effect of clocking on aerodynamic and heat transfer are investigated. Tests are performed under engine representative conditions in the VKI compression tube CT3. The test program includes four different clocking positions, i.e. relative pitch-wise positions between the fh-st and the second stator. Probes located upstream and downstream of the second stator provide the thermodynamic conditions of the flow field. On the second stator airfoil, measurements are taken around the blade profile at 15, 50 and 85% span with pressure sensors and thin-film gauges. Both time-averaged and time-resolved aspects of the flow field are addressed. Regarding the time-averaged results, clocking effects are mainly observed within the leading edge region of the second stator, the largest effects being observed at 15% span. The surface static pressure distribution is changed locally, hence affecting the overall airfoil performance. For one clocking position, the thermal load of the airfoil is noticeably reduced. Pressure fluctuations are attributed to the passage of the up- stream transonic rotor and its associated pressure gradients. The pattern of these fluctuations changes noticeably as a function of docking. The time-resolved variations of heat flux and static pressure are analyzed together showing that the major effect is due to a potential interaction. The time-resolved pressure distribution integrated along the second stator surface yields the unsteady forces on the vane. The magnitude of the unsteady force is very dependent on the clocking position.

关键词： transonic flow turbines stator clocking forces heat transfer.

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Bell Polynomial Approach and N-Soliton Solutions for a Coupled KdV-mKdV System

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Communications in Theoretical Physics 2012年第7期58卷 73-78页

作者：覃翌高以天于鑫蒙高庆 Ministry-of-Education Key Laboratory of fluid Mechanics and National Laboratory for computational fluid dynamics Beijing University of Aeronautics and Astronautics State Key Laboratory of Software Development Environment Beijing University of Aeronautics and Astronautics

In fluid dynamics, plasma physics and nonlinear optics, Korteweg-de Vries (KdV)-type equations are used to describe certain phenomena. In this paper, a coupled KdV-modified KdV system is investigated. Based on the Bell polynomials and symbolic computation, the bilinear form of such system is derived, and its analytic N-soliton solutions are constructed through the Hirota method. Two types of multi-soliton interactions are found, one with the reverse of solitonic shapes, and the other, without. Both the two types can be considered elastic. For a pair of solutions to such system, u and v, with the number of solitons N even, the soliton shapes of u stay unvaried while those of v reverse after the interaction; with N odd, the soliton shapes of both u and v keep unchanged after the interaction.

关键词： coupled KdV-modified KdV system bilinear form N-soliton solutions binary Bell polynomials symbolic computation soliton interaction

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INFLUENCE OF PHASE RATIO ON PACKING EFFICIENCY IN COLUMNS FOR MASS transfer PROCESSES

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Chinese Journal of Chemical Engineering 1997年第2期5卷 25-34页

作者： Reinhard Billet Michael Schultes Institute of Thermo-and fluid-dynamics Ruhr-University BochumInstitute of Thermo-and Fluid-dynamicsRuhr-University Bochum D-44780 BochumGermanyD-44780 BochumGermany

The phase ratio has been found to affect the packing efficiency in packed *** ac-count for the effect,a model is set up to correlate the height of a mass transfer unit with the phaseratio with reasonable *** also is a correlation that allows to predict the efficiency inquestion at any given liquid-gas ratio using the knowledge of other efficiency values at other liquid-gas ratios.

关键词： phase ratio height of a transfer unit packings

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Conjugate Heat transfer Characterization in Cooling Channels

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Journal of Thermal Science 2012年第3期21卷 286-294页

作者： Beni Cukurel Tony Arts Claudio Selcan von Karman Institute for fluid dynamics Turbomachinery Department Chaussée de Waterloo

Cooling technology of gas turbine blades,primarily ensured via internal forced convection,is aimed towards withdrawing thermal energy from the *** promote heat exchange,the walls of internal cooling passages are lined with repeated geometrical flow disturbance elements and surface *** the heat transfer at the expense of increased pressure loss;the goal is to obtain the highest possible cooling effectiveness at the lowest possible pressure drop *** cooling channel heat transfer problem involves convection in the fluid domain and conduction in the *** coupled behavior is known as conjugate heat *** experimental study models the effects of conduction coupling on convective heat transfer by applying iso-heat-flux boundary condition at the external side of a scaled serpentine *** involve local temperature measurements performed by Infrared Thermography over flat and ribbed slab *** number distributions along the wetted surface are obtained by means of heat flux distributions,computed from an energy balance within the metal *** the flat plate experiments,the effect of conjugate boundary condition on heat transfer is estimated to be in the order of 3%.In the ribbed channel case,the normalized Nusselt number distributions are compared with the basic flow *** the findings with other conjugate and convective iso-heat-flux literature,a high degree of overall correlation is evident.

关键词： conjugate heat transfer turbine cooling channel convection infrared thermography

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Two-Soliton Solutions and Interactions for the Generalized Complex Coupled Kortweg-de Vries Equations

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Communications in Theoretical Physics 2011年第3期55卷 473-480页

作者： GAI Xiao-Ling GAO Yi-Tian YU Xin SUN Zhi-Yuan WANG Lei Ministry-of-Education Key Laboratory of fluid Mechanics and National Laboratory for computational fluid dynamics Beijing University of Aeronautics and Astronautics Beijing 100191 China State Key Laboratory of Software Development Environment Beijing University of Aeronautics and Astronautics Beijing 100191 China

Kortweg-de Vries （KdV）-typed equations have been used to describe certain nonlinear phenomena in fluids and plasmas. Generalized complex coupled KdV （GCCKdV） equations are investigated in this paper. Through the dependent variable transformations and symbolic computation, GCCKdV equations are transformed into their bilinear forms, based on which the one- and two-soliton solutions are obtained. Through the interactions of two solitons, the regular elastic collision are shown. When the wave numbers are complex, three kinds of solitonie collisions are presented：（i） two solitons merge and separate from each other periodically; （ii） two solitons exhibit the attraction and repulsion nearly twice, and finally separate from each other after such type of interaction; （iii） two solitons are ftuctuant in the central region of the collision. Propagation features of solitons are investigated with the effects of the coefficients in the GCCKdV equations considered. Velocity of soliton increase with the a increasing. Amplitude of v increase with the a increasing and decrease with the β increasing.

关键词： generalized complex coupled KdV equations bilinear equations two-soliton solutions interactions symbolic computation

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Enhancing Solar Photovoltaic Efficiency:A computational fluid dynamics Analysis

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Energy Engineering 2025年第1期122卷 153-166页

作者： Rahool Rai Fareed HussainMangi Kashif Ahmed Sudhakar Kumaramsay Faculty of Mechanical and Automotive Engineering Universiti Malaysia Pahang Al-Sultan AbdullahPekan26600PahangMalaysia Faculty of Engineering Science&Technology Hamdard UniversityKarachi74600Pakistan Electrical Engineering Department SUKKUR IBA UniversitySukkur65200Pakistan Berlin School of Business and Innovation BSBI Faculty of Computer Science and InformaticsBerlin12043Germany Automotive Engineering Centre University Malaysia Pahang Al Sultan AbdullahPekan26600PahangMalaysia Centre for Research in Advanced fluid&Processes(fluid Centre) Universiti Malaysia Pahang Al-Sultan Abdullah(UMPSA)Paya BesarKuantan26300PahangMalaysia

The growing need for sustainable energy solutions,driven by rising energy shortages,environmental concerns,and the depletion of conventional energy sources,has led to a significant focus on renewable *** energy,among the various renewable sources,is particularly appealing due to its abundant ***,the efficiency of commercial solar photovoltaic(PV)modules is hindered by several factors,notably their conversion efficiency,which averages around 19%.This efficiency can further decline to 10%–16%due to temperature increases during peak sunlight *** study investigates the cooling of PV modules by applying water to their front surface through computational fluid dynamics(CFD).The study aimed to determine the optimal conditions for cooling the PV module by analyzing the interplay between water film thickness,Reynolds number,and their effects on temperature reduction and heat *** CFD analysis revealed that the most effective cooling condition occurred with a 5 mm thick water film and a Reynolds number of *** specific parameters were found to maximize the heat transfer and temperature reduction *** finding is crucial for the development of practical and efficient cooling systems for PV modules,potentially leading to improved performance and longevity of solar *** cooling fluids or advanced cooling techniques that might offer even better efficiency or practical benefits.

关键词： PV module efficiency water film thickness reynolds number CFD analysis PV/T renewable energy

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Darboux Transformation and Explicit Solutions for Discretized Modified Korteweg-de Vries Lattice Equation

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Communications in Theoretical Physics 2010年第5期53卷 825-830页

作者：闻小永高以天 Ministry-of-Education Key Laboratory of fluid Mechanics and National Laboratory for computational fluid dynamics Beijing University of Aeronautics and Astronautics Department of Mathematics College of SciencesBeijing Information Science and Technology University State Key Laboratory of Software Development Environment Beijing University of Aeronautics and Astronautics

The modified Korteweg-de Vries （mKdV） typed equations can be used to describe certain nonlinear phenomena in fluids, plasmas, and optics. In this paper, the discretized mKdV lattice equation is investigated. With the aid of symbolic computation, the discrete matrix spectral problem for that system is constructed. Darboux transformation for that system is established based on the resulting spectral problem. Explicit solutions are derived via the Darboux transformation. Structures of those solutions are shown graphically, which might be helpful to understand some physical processes in fluids, plasmas, and optics.

关键词： Darboux transformation discretized modified Korteweg-de Vries lattice equation explicit solutions symbolic computation

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A Gas-Kinetic Unified Algorithm for Non-Equilibrium Polyatomic Gas Flows Covering Various Flow Regimes

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Communications in computational Physics 2021年第6期30卷 144-189页

作者： Wen-Qiang Hu Zhi-Hui Li Ao-Ping Peng Xin-Yu Jiang National Laboratory for computational fluid dynamics Beijing University of Aeronautics and AstronauticsBeijing 100191China Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development CenterMianyang 621000China

In this paper,a gas-kinetic unified algorithm(GKUA)is developed to investigate the non-equilibrium polyatomic gas flows covering various *** on the ellipsoidal statistical model with rotational energy excitation,the computable modelling equation is presented by unifying expressions on the molecular collision relaxing parameter and the local equilibrium distribution *** constructing the corresponding conservative discrete velocity ordinate method for this model,the conservative properties during the collision procedure are preserved at the discrete level by the numerical method,decreasing the computational storage and *** and implicit lower-upper symmetric Gauss-Seidel schemes are constructed to solve the discrete hyperbolic conservation equations *** the new GKUA,some numerical examples are simulated,including the Sod Riemann problem,homogeneous flow rotational relaxation,normal shock structure,Fourier and Couette flows,supersonic flows past a circular cylinder,and hypersonic flow around a plate placed *** results obtained by the analytic,experimental,direct simulation Monte Carlo method,and other measurements in references are compared with the GKUA results,which are in good agreement,demonstrating the high accuracy of the present ***,some polyatomic gas non-equilibrium phenomena are observed and analysed by solving the Boltzmann-type velocity distribution function equation covering various flow regimes.

关键词： Gas-kinetic unified algorithm polyatomic gas ellipsoidal statistical model conservative discrete velocity ordinate method implicit scheme

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Optimal selection of annulus radius ratio to enhance heat transfer with minimum entropy generation in developing laminar forced convection of water-Al2O3 nanofluid flow

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Journal of Central South University 2017年第8期24卷 1850-1865页

作者： Siavashi Majid Jamali Mohammad Applied Multi-Phase fluid dynamics Lab. School of Mechanical EngineeringIran University of Science and TechnologyTehranIran

Heat transfer and entropy generation of developing laminar forced convection flow of water-Al_2O_3 nanofluid in a concentric annulus with constant heat flux on the walls is investigated numerically. In order to determine entropy generation of fully developed flow, two approaches are employed and it is shown that only one of these methods can provide appropriate results for flow inside annuli. The effects of concentration of nanoparticles, Reynolds number and thermal boundaries on heat transfer enhancement and entropy generation of developing laminar flow inside annuli with different radius ratios and same cross sectional areas are studied. The results show that radius ratio is a very important decision parameter of an annular heat exchanger such that in each Re, there is an optimum radius ratio to maximize Nu and minimize entropy generation. Moreover, the effect of nanoparticles concentration on heat transfer enhancement and minimizing entropy generation is stronger at higher Reynolds.

关键词： nanofluid heat transfer enhancement forced convection entropy generation annulus radius ratio

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Painlevé Analysis,Soliton Solutions and Bcklund Transformation for Extended (2 + 1)-Dimensional Konopelchenko-Dubrovsky Equations in fluid Mechanics via Symbolic Computation

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Communications in Theoretical Physics 2011年第6期55卷 1017-1023页

作者：许鹏博高以天于鑫王雷林国栋 Ministry-of-Education Key Laboratory of fluid Mechanics and National Laboratory for computational fluid dynamics Beijing University of Aeronautics and Astronautics State Key Laboratory of Software Development Environment Beijing University of Aeronautics and Astronautics

This paper is to investigate the extended(2+1)-dimensional Konopelchenko-Dubrovsky equations,which can be applied to describing certain phenomena in the stratified shear flow,the internal and shallow-water waves, plasmas and other *** analysis is passed through via symbolic ***-form equations are constructed and soliton solutions are *** solutions and interactions are ***-form Backlund transformation and a type of solutions are obtained.

关键词： extended (2 +1)-dimensional Konopelchenko-Dubrovsky equations in fluid mechanics Painleve analysis soliton solutions Backlund transformation symbolic computation

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