IMPROVED METHOD OF PARTIAL SIMILARITY OF BOUNDARY LAYER ALONG CURVED SURFACE

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｏｌｕｔｉｏｎｏｆｔｈｅｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓｏｆｂｏｕｎｄ ａｒｙｌａｙｅｒｈａｓｂｅｅｎｉｎｖｏｌｖｅｄｉｎｔｈｅｒｅｓｅａｒｃｈｏｆｈｅａｔｔｒａｎｓ ｆｅｒｅｎｈａｎｃｅｍｅｎｔ ,ｓｃｉｅｎｃｅｏｆｅｎｖｉｒｏｎｍｅｎｔ ,ｃｏｍｂｕｓｔｉｏｎｅｎｇｉｎｅｅｒｉｎｇａｎｄｓｏｏｎ .Ｔｈｅｒｅｈａｖｅｂｅｅｎｖａｒｉｏｕｓｍｅｔｈ ｏｄｓｏｆｓｏｌｖｉｎｇｏｆｔｈｅｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓ .Ｅａｃｈｍｅｔｈｏｄｈａｓｉｔ…     

EFFECTS OF SURFACE CURVATURES ON HYDRAULIC CHARACTERISTICS AND TURBULENT BOUNDARY LAYER

Some hydraulic measurements have been made in buckets of model overflowdams.The effects of surface curvatures of buckets on velocity,pressure and turbulent boundarylayer have been systematically investigated.The results have shown that the effects of surfacecurvatures on velocity distributions are unproportional and the centrifugal pressure coefficientdefined in the report possesses a transitional quality.A definition of turbulent boundary layerthickness of bucket is suggested and the development of turbulent boundary layer is indicated ex-perimentally.It is found the maximum value of relative boundary layer thickness appears about0.25 of relative arc length.     

CONTINUOUS WAVELET TRANSFORM OF TURBULENT BOUNDARY LAYER FLOW

The spatio-temporal characteristics of the velocity fluctuations in a fully-developed turbulent boundary layer flow was investigated using hotwire. A low-speed wind tunnel was established. The experimental data was extensively analyzed in terms of continuous wavelet transform coefficients and their auto-correlation. The results yielded a potential wealth of information on inherent characteristics of coherent structures embedded in turbulent boundary layer flow. Spatial and temporal variations of the low- and high- frequency motions were revealed.     

EXPERIMENTAL STUDY ON TURBULENT BOUNDARY LAYER CHARACTERISTICS OVER STREAMWISE RIBLETS

1 .　INTRODUCTIONIthasbeenformorethanthreedecadessinceNASALangleyshowedthatribletsarereducedinsizetolessthan 30viscouslengthsinheightandspan ,sur facedragreductionsofupto 8%canbeachieved .Peo plehaveengagedintheinvestigationofdragreductionduringtheseyears .Inearlydays ,thedirectdragre ductionmeasurementwaspaidmuchattentionbyusingdragbalance .However ,therecentresearchhasbeenfocusedontheturbulentflowstructureanditscorrela tivelawsoverribletssurface .Turbulentdragreductiontechnologycanber…     

THE NUMERICAL COMPUTATION OF TURBULENT FLOW IN TEE-JUNCTION

A numerical model for calculating the turbulent flow in tee-junction is given in thispaper.The calculations are performed using a finite-difference procedure,and turbulence is ac-counted for by using a two-equation k-ε model of turbulence.Results,consisting of mean veloci-ty profiles and pressure losses due to the junction,have been obtained,and show that the flowsituation in tee-junction is very complex.The computed results agree closely with the experimen-tal data and validate that the present model is reasonable and the numerical calculations are suc-cessful.     

EFFECT OF SOLID PARTICLES ON STABILITY FLOW IN THE BOUNDARY LAYER ON A FLAT PLATE

ＥＦＦＥＣＴＯＦＳＯＬＩＤＰＡＲＴＩＣＬＥＳＯＮＳＴＡＢＩＬＩＴＹＦＬＯＷＩＮＴＨＥＢＯＵＮＤＡＲＹＬＡＹＥＲＯＮＡＦＬＡＴＰＬＡＴＥ￥ＬｉｎＪｉａｎ－ｚｈｏｎｇ；ＺｈｏｕＺｅ－ｘｕａｎＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃｓ，ＳｔａｔｅＫｅｙＬａ...     

TURBULENT BOUNDARY LAYER DEVELOPMENT IN THE ENTRANCE REGION OF A SMOOTH ROUND PIPE

The study of the turbulent boundary layer along a smooth round pipe is of greatsignificance both in practice and in theory.In this paper,the formulae for calculating the tur-bulent boundary layer thickness are obtained by solving the momentum integral equation of theboundary layer in which the assumptions of the logarithmic law and exponential law of velocitydistribution are adopted.The methods for calculating the mean flow velocity in the developingregion of turbulent boundary layer in a round pipe are proposed.The relation between the expo-nent n and the factor μ·δ/ν is studied and a formula for calculating the exponent n is obtained.     

HOT WIRE MEASUREMENT OF TURBULENT BOUNDARY LAYER ON A FILM COOLING PLATE WITH DIFFUSION HOLES

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｆｉｌｍｃｏｏｌｉｎｇｏｆｇａｓｔｕｒｂｉｎｅｓｂｌａｄｅｓａｎｄｃｏｍ ｂｕｓｔｏｒｓｉｓａｔｙｐｉｃａｌｈｅａｔ/ｍａｓｓｔｒａｎｓｆｅｒｐｒｏｂｌｅｍｗｈｉｃｈｈａｓｂｅｅｎｍａｓｓｉｖｅｌｙｓｔｕｄｉｅｄｆｒｏｍ 195 0’ｓ .Ｆｏｒｉｎｃｒｅａｓｉｎｇｔｈｅｅｆｆｉｃｉｅｎｃｙｏｆｇａｓｔｕｒｂｉｎｅｓｔｈｅｉｎｌｅｔｇａｓｔｅｍｐｅｒａｔｕｒｅｈａｓｂｅｅｎｒａｉｓｅｄ .Ｔｈｅｒｅｆｏｒｅ ,ｔｏｐｒｅｖｅｎｔｃｏｒｒｏｓｉｏｎａｎｄｅｒｏｓｉｏｎａｔｔｈ…     

MEASUREMENT OF A WALL-BOUNDED TURBULENT MIXING LAYER FLOW

1.INTRODUCTION Wall boundedturbulentmixinglayerflowsare ofprimarysignificancetovariousindustrialand militaryapplications.Amongothers,thewall boundedturbulentmixinglayerflowoveranopen ingstep,e.g.,gaseductorconfiguration,received agreatdealofattention.Thesecondaryflowen trainedfromtheopeningbythecoherentstruc tures,whicharequasi deterministicallyembedded inthemixinglayer,ismixedwiththemainflow.Suchflowiscloselyrelatedtoplanemixinglayer flowandreattachingflow.However,fewstudies ofitsturbule…     

NUMERICAL CALCULATION OF THREE-DIMENSIONAL TURBULENT FLOW IN A DISTORTING DUCT

A Navier-Stokes procedure based on the Finite Volume Method (FVM) is developed to calculate three-dimensional duct flows with complex geometry. This method is applied to analyze the flow in a distorting duct, and the numercal results are in good a-greement with the experimental ones.     

CALCULATION OF THERMAL AND SALINE TURBULENT FLOW BY k-ε MODEL

1 .　INTRODUCTIONStratifiedflowisakindofflowthatcontainsdensitygradientinthespace .Itisaverycommonphenomenonofflowinginnaturalenvironment,nearthedischargeexitofsewageinthecity ,inthepondusedinindustryandintheriver ,thelakeandthesea ,whereconsistence ,thermalordensitystratificationcanbeformed .Itiswellknownthatdensitystratificationwillexertastronginfluenceonturbulentmixing ;ifthethermalstratificationisexistentatthesametime ,thestateofstratificationwillchange .Ontheotherhand ,changeofthesta…     

INFLUENCE OF COHERENT STRUCTURE ON SCALAR DIFFUSION IN TURBULENT BOUNDARY LAYERS

1.　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｔｕｒｂｕｌｅｎｔｃｏｈｅｒｅｎｔｓｔｒｕｃｔｕｒｅｗａｓｆｏｕｎｄａｎｄｒｅｓｅａｒｃｈｅｄｉｎｔｈｅｒｅｃｅｎｔｔｈｒｅｅｄｅｃａｄｅｓａｎｄｐｒｏｖｉｄｅｄａｓｔｒｏｎｇｉｍｐｅｔｕｓｆｏｒｆｕｒｔｈｅｒｓｔｕ...     

THE STRUCTURE AND SCALE EFFECT OF WALL TURBULENT FLOW

In this paper the structure and scale effect of wall turbulence are investigated.Thecharacteristics of the turbulence structure in the wall region is described.The fact that the turbu-lence in whole flow field is controlled mainly by the structure of wall turbulence is demonstrat-ed.Discussion is concentrated on the scale effects of the streak structure,the vortex structureand the bursting frequency.     

STUDIES ON RETRIEVAL OF THE TURBULIVITY OF ATMOSPHERIC BOUNDARY LAYER

1. INTRODUCTION Human activities mainly occur in the atmospheric boundary layer and turbulent transfer is a key factor for the exchange of substance and energy of the earth-atmosphere system, so atmospheric turbulence must be described accurately for all …     

NUMERICAL SIMULATION OF THE TURBULENT FLOW IN ROTATING DUCT

l.INrnODUCT1oNFlowintherotatingductisakindofphenomenonofturbulentflow,whichisoftenfoundintheengineeringapplications,suchasinthecentrifugalcompressor,centrifugalpumpandturbomachinery.Theinvestigationontheductflowisveryimportantfortheen-gineeringpracticejustasthequalityofflowintheductmakesbiginfluenceontheperfor-manceandefficiencyofthemachine.Thestudyontheflowintherotatingductbeganin6os'.JohnsonL1jmeasuredthevelocityofthemainstreaminthetwodimensionalrotatingduct.Comparedwiththeflowinthestati…     

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF TURBULENT AIR-CUSHION-CASCADE

Experimental and numerical studies of air-cushion-cascade were conducted and described. The SIMPLE algorithm combined with the normal k-ε turbulence model was adopted to simulate the air-phase flow. The experiment was carried out an IFA 300 anemometer. The flow field was measured for different ratios of main-stream velocity to jet velocity, different numbers of gaps and a couple of gap widths. The contur of the air-cushion was obtained, and the numerical calculations gave a closed-form result. The results show that the air-cushion thickness would increase with the increase of the jet volcoity, gap width and gap number mainly determined by the jet in the former half cascade. The possibility to achieve anti-erosion by the turbulent jet was examined and confirmed.     

NUMERICAL STUDY OF THE INFLUENCE OF SURFACE ROUGHNESS OF CYLINDER ON FLOW STRUCTURE

1.　INTRODUCTIONThe quietness is an important mark for the behavior of the submarine,so to decreasethe noise of the submarine becomes more and more important.As engine noise and othernoises have been reduced in these days,the interior noise levels in many submarine applica-tions are significantly affected by the water noise in the case of a submarine athigh cruisingspeed.The main sources of water noise are as follows:( 1 ) pressure fluctuations in the tur-bulent boundary layer;( 2 ) turbul…     

DIRECT RESONANCE OF TURBULENT BOUNDARY LAVER OVER COMPLIANT WALLS

１．　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｍａｉｎｇｏａｌｏｆｔｈｉｓｐａｐｅｒｉｓｔｏｅｘｐｌｏｒｅｔｈｅｐｏｓｓｉｂｉｌｉｔｙｔｏｌｅａｒｎｍｏｒｅａｂｏｕｔｔｈｅｍｅｃｈａｎｉｓｍｏｆｔｕｒｂｕｌｅｎｔｂｏｕｎｄａｒｙｌａｙｅｒｆｌｏｗｉｎｔｅｒａｃｔｉｏｎｓａｎｄｉｔｓｅｆｆｅｃｔｓｏｎｃｏｍｐｌｉａｎｔｗａｌｌｐｅｒｆｏｒｍａｎｃｅ．Ｔｈｅｒｅａｒｅｃｅｒｔａｉｎｐｒｅｒｅｑｕｉｓｉｔｅｃｏｎｄｉｔｉｏｎｓｔｏｆｕｒｔｈｅｒｔｈｅｓｔｕｄｙｏｎｔｈｅｍｅｃｈａｎｉｓｍ，ｉ．ｅ．ｔｈｅｃｏ…     

二维湍流气固两相射流的数值模拟

本文采用两相湍流的Ｋ－ε模型和颗粒湍流扩散的Ｐｅｓｋｉｎ公式，对含有相同尺寸的球状颗粒的圆截面湍流射液进行了数值分析。计算采用对抛物型方程的推进求解技巧。研究了两种不同的阻力系娄公式对两相湍射流的影响。一个阻力系数公式是由谢定国和周红字最近推导出来的，它反映了颗粒体积率和阻力的影响，另一阻力系数公式是Ｃｌｉｆｔ等人根据颗粒球的标准实验阻力曲线推导出来的，计算结果和实验进行了比较。结果表明，谢一周阻