检索结果-南通市图书馆

Influence of Vanes and Blades on Ingress in Axial Rim Seal for Turbine Stages

Journal of Thermal Science 2024年第3期33卷 833-846页

作者： REN Ran DU Qiang LIU Guang ZENG Yanlian XIE Lei Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China National Key Laboratory of Science and Technology on Advanced Light-duty Gas-turbine Beijing100190China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing100190China

Hot gas ingestion refers to the phenomenon of mainstream hot gas flowing into the space cavity of a turbine wheel.Previous studies have found that mainstream annulus pressure distribution plays an important role in hot gas ingestion,but due to its complexity,the mechanism of the interaction between mainstream flow and hot gas ingestion remains unclear.This paper adopts the URANS method,and three sealing flow rates are considered,named C_(w)=0,C_(w)=500,and C_(w)=5000.The time-averaged annulus pressure distribution shows that an increase in the sealing flow decreases the pressure value,and the effects of the sealing flow on the pressure distribution of the leading edge of the blade are much more influential than that of the trailing edge of the vane.The unsteady pressure time-space distribution in the annulus indicates that a time-space tilted distribution of pressure at the rim exits when the sealing flow exists.This phenomenon is mainly due to the strong feedback mechanism of the sealing flow to the annulus pressure field.A comparison of the pressure and mean radial velocity distribution of the mainstream shows that the ingestion mainly occurs on the blade side,where the pressure is lower than on the vane side.The flow characteristics at the wheel rim are analyzed with a sealing flow rate C_(w)=5000,and under these conditions,both pressure-induced ingestion and ingestion caused by a passage vortex can be inferred.The three-dimensional and inertial effects of the mainstream at the wheel rim lead to the generation of separation vortices on the blade side,and the presence of separation vortices leads to ingestion along the blade side.At the same time,pressure on the blade side will cause the fluid to have a radial inward flow tendency,which will promote the formation of separation vortices,leading to more serious ingestion in the high-pressure region on the blade side.The blade pressure field can be more significant than the vane trailing pressure field in the rim seal ingestion,and it contributes some explanations

关键词： separation vortex unsteady rim seal the effect of blade on ingestion

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Novel Wavelet-Homotopy Galerkin Method for unsteady Nonlinear Wave Equations

引用

Advances in Applied Mathematics and Mechanics 2023年第4期15卷 964-983页

作者： Yue Zhou Hang Xu State Key Lab of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The Coiflet wavelet-homotopy Galerkin method is extended to solve unsteady nonlinear wave equations for the first time.The Korteweg-de Vries(KdV)equation,the Burgers equation and the Korteweg-de Vries-Burgers(KdVB)equation are examined as illustrative examples.Validity and accuracy of the proposed method are assessed in terms of relative variance and the maximum error norm.Our results are found in good agreement with exact solutions and numerical solutions reported in previous studies.Furthermore,it is found that the solution accuracy is closely related to the resolution level and the convergence-control parameter.It is also found that our proposed method is superior to the traditional homotopy analysis method when dealing with unsteady nonlinear problems.It is expected that this approach can be further used to solve complicated unsteady problems in the fields of science and engineering.

关键词： Coiflet wavelet homotopy analysis method wavelet-homotopy method wave equations unsteady

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Combined effects of Joule heating and nonuniform heat source/sink on unsteady MHD mixed convective flow over a vertical stretching surface embedded in a Darcy-Forchheimer porous medium

引用

Propulsion and Power Research 2022年第2期11卷 276-292页

作者： B.K.Sharma Rishu Gandhi Department of Mathematics Birla Institute of Technology and SciencePilani333031RajasthanIndia

This paper deals with an unsteady magnetohydrodynamics(MHD)heat and masstransfer for a viscous incompressible fluid through a vertical stretching surface embedded ina Darcy-Forchheimer porous medium in the presence of a non-uniform heat source/sink andfirst-order chemical reaction.The porous surface is subjected to a uniform transverse magneticfield.The influence of velocity,thermal,and concentration slip is also investigated.The governing equations are coupled non-linear partial differential equations,which have been converted via similarity transformation into a set of ordinary differential equations.The resultantsystem of non-linear ordinary differential equations has been solved numerically with the helpof the“MATLAB”BVP4C Solver.Results are presented graphically to analyze the effects ofvarious physical parameters discovered in the problem such as Hartmann number(M),Forchheimer number(Fr),Grashof number(Gr),solutal Grashof number(Gc),suction parameter(S),porosity parameter(el),dimensionless velocity slip(Sv),Prandtl number(Pr),dimensionless thermal slip(St),space-dependent heat source/sink parameter(eA1),temperature-dependent heat source/sink(eB)1),Eckert number(Ec),Schmidt number(Sc),chemical reaction parameter(g),unsteadiness parameter(A),and dimensionless concentration slip(Sc)on non-dimensionalvelocity ec0ðhÞ,temperature zðhÞ,and concentration efðhÞprofiles.The influence of these parameters on skin-friction coefficient(C)f),Nusselt number(Nu)x),and Sherwood number(Sh)x)areexpressed in tabular form.It is observed that an enhancement in Fr and el results in the declination of the velocity profile.There is an enhancement in temperature with an increment in theeA)1 and eB)1.The physical representation of flow characteristics that appeared in the problem ispresented using various graphs to depict real-world applications in industrial and engineeringoperations.The results were compared to previous studies,revealing that the two are in goodagreement.The novelty of the present investigation is:To interpre

关键词： Magnetohydrodynamics(MHD) unsteady Heat and mass transfer Non-Darcian porous medium Heat source Joule effect

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

unsteady Pressure Field in a Vaneless Diffuser of a Centrifugal Compressor: An Experimental and Computational Analysis

引用

Journal of Thermal Science 2004年第4期13卷 302-309页

作者： Teemu TURUNEN-SAARESTI Jaakko LARJOLA Lappeenranta University of Technology Laboratory of Fluid Dynamics P.O. Box 20 53851 Lappeenranta FinlandLappeenranta University of Technology Laboratory of Fluid Dynamics P.O. Box 20 53851 Lappeenranta Finland

unsteady static pressure was measured and time-accurate numerical simulations were conducted in order to analyze unsteady behaviour of the centrifugal compressor diffuser. The unsteady static pressure was measured at the diffuser inlet and outlet at three different circumferential positions. Operation points near the surge, the design operation point and operation point near the choke were used in measurements. The time-accurate simulations were conducted at the design operation point and operation point near the choke. The whole compressor was modelled and the low Reynolds number k-εturbulence model was utilized in numerical simulations. The gathered numerical and experimental unsteady pressures were compared with each other.

关键词： centrifugal compressor vaneless diffuser unsteady pressure.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

unsteady magnetohydrodynamic stagnation point flow — closed-form analytical solutions

引用

Applied Mathematics and Mechanics(English Edition) 2019年第4期40卷 449-464页

作者： T.G.FANG F.J.WANG Bo GAO Mechanical and Aerospace Engineering Department North Carolina State University School of Energy & Power Engineering Jiangsu University

This paper investigates the unsteady stagnation point flow and heat transfer of magnetohydrodynamic(MHD) fluids over a moving permeable flat surface. The unsteady Navier-Stokes(NS) equations are transformed into a similarity nonlinear ordinary differential equation, and a closed form solution is obtained for the unsteadiness parameter of 2. The boundary layer energy equation is transformed into a similarity equation,and is solved for a constant wall temperature and a time-dependent uniform wall heat flux case. The solution domain, velocity, and temperature profiles are calculated for different combinations of parameters including the Prandtl number, mass transfer parameter, wall moving parameter, and magnetic parameter. Two solution branches are obtained for certain combinations of the controlling parameters, and a stability analysis demonstrates that the lower solution branch is not stable. The present solutions provide an exact solution to the entire unsteady MHD NS equations, which can be used for validating the numerical code of computational fluid dynamics.

关键词： unsteady stagnation point flow stretching/shrinking sheet magnetohy-drodynamic(MHD) Navier-Stokes(NS)equation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

unsteady Cavitating Flow around a Hydrofoil Simulated Using the Partially-Averaged Navier-Stokes Model

引用

Chinese Physics Letters 2012年第7期29卷 198-202页

作者：季斌罗先武吴玉林许洪元 State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084

Numerical simulations of unsteady cavitating flow around a NACA66-mod hydrofoil were performed using the partially-averaged Navier-Stokes method with different values of the resolution control parameters (f k =1.0-0.2,fε =1).With decreasing fk,the predicted cavitating flow becomes unsteady as the time-averaged turbulent viscosity at the rear part of the attached cavity is gradually reduced.For fk =0.9 and 0.8,the cavity becomes unstable and its length dramatically expands and shrinks,but the calculation fails to predict the vapor cloud shedding behavior observed experimentally.With smaller fk less than 0.7,the cloud shedding behavior is simulated numerically and the predicted cavity shedding frequency increases.With fk =0.2,the whole cavitating flow evolution can be reasonably reproduced including the cavity growth/destabilization observed previously.The reentrant flow along the suction surface of the hydrofoil is the main trigger to cause the vapor cloud shedding.The wall pressure along the hydrofoil surface oscillates greatly due to the dynamic cavity shedding.Comparing the simulations and experiments,it is confirmed that for the PANS method,resolution control parameters of fk =0.2and fε =1 are recommended for numerical simulations of unsteady cavitating flows.Thus,the present study shows that the PANS method is an effective approach for predicting unsteady cavitating flow over hydrofoils.

关键词： unsteady Navier averaged

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Effect of periodic heat transfer on the transient thermal behavior of a convective-radiative fully wet porous moving trapezoidal fin

引用

Applied Mathematics and Mechanics(English Edition) 2023年第4期44卷 653-668页

作者： B.J.GIREESHA M.L.KEERTHI Department of PG Studies and Research in Mathematics Kuvempu UniversityShankaraghatta 577451India

A moving trapezoidal profiled convective-radiative porous longitudinal fin wetted in a single-phase fluid is considered in the current article.The periodic variation in the fin base temperature is taken into account along with the temperature sensitive thermal conductivity and convective heat transfer coefficients.The modeled problem,which is resolved into a non-linear partial differential equation(PDE),is made dimensionless and solved by employing the finite difference method(FDM).The results are displayed through graphs and discussed.The effects of amplitude,frequency of oscillation,wet nature,Peclet number,and other relevant quantities on the distribution of temperature through the fin length and with the dimensionless time are investigated.It is deciphered that the periodic heat transfer gives rise to the wavy nature of the fin thermal profile against time.The analysis is beneficial in the design of fin structures for applications like solar collectors,space/airborne applications,and refrigeration industries.

关键词： convection fully wet porous fin trapezoidal profile moving fin unsteady periodic thermal condition

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

unsteady flow and heat transfer of porous media sandwiched between viscous fluids

引用

Applied Mathematics and Mechanics(English Edition) 2010年第12期31卷 1497-1516页

作者： J. C. UMAVATHI I. C. LIU J. PRATHAP-KUMAR D. SHAIK-MEERA Department of Mathematics Gulbarga University Gulbarga 585106 Karnaktaka India Department of Civil Engineering National Chi Nan University University Road Puli Nantou Hsien 54561 Taiwan China

The problem of unsteady oscillatory flow and heat transfer of porous medin sandwiched between viscous fluids has been considered through a horizontal channel with isothermal wall temperatures. The flow in the porous medium is modeled using the Brinkman equation. The governing partial differential equations are transformed to ordinary differential equations by collecting the non-periodic and periodic terms. Closed-form solutions for each region are found after applying the boundary and interface conditions. The influence of physical parameters, such as the porous parameter, the frequency parameter, the periodic frequency parameter, the viscosity ratios, the conductivity ratios, and the Prandtl number, on the velocity and temperature fields is computed numerically and presented graphically. In addition, the numerical values of the Nusselt number at the top and bottom walls are derived and tabulated.

关键词： unsteady porous medium immiscible fluid horizontal channel analyticalsolution

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

unsteady　PROPELLER　SURFACE　PRESSURE　PREDICTION　WITH　A　POTENTIAL　BASED　PANEL　METHOD

引用

Journal of Hydrodynamics 1995年第4期7卷 35-41页

作者： Chen Jia-dong(China Ship Scientific Research Center, Box 116, Wuxi 214082, P. R. China) China Ship Scientific Research Cent Wuxi China

A potential based panel method for unsteady propeller hydrodynamic analysis is presented,as to predict the unsteady hydrodynamic performance of a propeller subjected to a spatially non-uniform inflow. To satisfy the Kutta condition at the blade tailing rfgr well, a nonlinear pressure pressure condition, besides the linear Knits condition,is implemented at each time step by an iterative scheme, which enhances the precision of the preessure distribution over the blade surface. Some computation results are presented.

关键词： panel method propeller unsteady

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

unsteady three-dimensional boundary layer flow due to a permeable shrinking sheet

引用

Applied Mathematics and Mechanics(English Edition) 2010年第11期31卷 1421-1428页

作者： N.BACHOK A.ISHAK I.POP Department of Mathematics Faculty of ScienceUniversiti Putra Malaysia School of Mathematical Sciences Faculty of Science and TechnologyUniversiti Kebangsaan Malaysia Institute of Mathematical Sciences Faculty of ScienceUniversity of Malaya Faculty of Mathematics University of Cluj

The unsteady viscous flow over a continuously permeable shrinking surface is studied. Similarity equations are obtained through the application of similar transformation techniques. Numerical techniques are used to solve the similarity equations for different values of the unsteadiness parameter, the mass suction parameter, the shrinking parameter and the Prandtl number on the velocity and temperature profiles as well as the skin friction coefficient and the Nusselt number. It is found that, different from an unsteady stretching sheet, dual solutions exist in a certain range of mass suction and unsteadiness parameters.

关键词： unsteady three-dimensional flow boundary layer shrinking sheet dual solution

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：