Study on the Effects of Flow in the Volute Casing on the Performance of a Sirocco Fan

The flow at the exit from the runner blade of a centrifugal fan with forward curved blades (a sirocco fan) sometimes separates and becomes unstable. We have conducted many researches on the impeller shape of a sirocco fan, proper inlet and exit blade angles were considered to obtain optimum performance. In this paper, the casing shape were decided by changing the circumferential angle, magnifying angle and the width, 21 sorts of casings were used. Performance tests, inner flow velocity and pressure distributions were measured as well. Computational fluid dynamic calculations were also made and compared with the experimental results. Finally, the most suitable casing shape for best performance is considered.     

Numerical Study on the Suppression of Shock Induced Separation on the Non-Adiabatic Wall

IntroductionThe supersonic flow inevitably encounters the shockwaves that are in contact with the solid walls on which theturbulent boundary layer is developed. This sitUationproduces locally a complex phenomenon known as shockwave/turbulent boundary layer interaction. Basic stlldiesof the complex combinations of heat transfer andcompressibility are required to understand their effects onthe turbulent boundary layer characteristics. If the shockwave is strong enough, then the boundary layer c…     

Numerical Study of the Effects of the Face Velocity on Ceramic Filter

INTRODUCTIONTheproductsofcoalcombustionsuchasNOx,SOx,COb,andparticulatehavebeenstronglyregulatedtoreducepollutionintheearthenvironment.TherecentlydevelopedCleanCoalTechnologies(CCT)knownasPressurizedFluidizedBedCombustion(PFBC)[']andintegratedGasificationCombinedCycle(IGCC)I"']providetheimprovementofthermalefficiencywithsignificalltlyreducedenvironmelltalimpacts.ThusthePFBCandIGCChaveincreasingattentiontoachievestringentenvironmentalprotection.Advancingthetechnologyofthehotg…     

Influence of the cooling rate on the ageing of lead–calcium alloys

Cast lead–calcium alloys were known to be sensitive to experimental parameters, which cause large variations on the ageing and overageing behaviour. From the study of these parameters, the quenching rate was the only significant parameter. A critical cooling rate was defined based on hardness, electrical resistivity and metallographical observations. The inconsistencies in the literature noticed on the evolutions of lead–calcium alloys can now be explained by whether or not this critical cooling rate was respected.     

Study on the Characteristics of Supersonic Coanda Jet

INTRoDUCTI0NTheCoandaeffectthatisanimportamconsequence0fthepressurevariati0nperpendiculart0curvdStreanilines,isthetendencyofafiuldjettoattaChitSelftoaconvexsolidb0dyoranadacentsurface.Inrec6Dtyears,theusefulnessoftheCoandaeffectisencowteredinawiderangeofaPplicationfromfiuldicdevicetoaircraftwingSandfiaPdevices[1~22l.Horiietal.I`-s]shOWdthatafocusedandhiglilystablesPiralfiowwasobtainedusinganozzlewithanannularslitconnectedtoaconicalcylinder.Toimprovthrustvectoring,Bevilaquaetal.[16jin…     

Influences of the Exhaust Flow on the Boundary Layer Flow on the Wafer Surface in Spin Coating System

Recently, development of high technology has been required for the formation of thin uniform film in manufacturing processes of semiconductor as the semiconductor become more sophisticated. Spin coating is usually used for spreading photoresist on a wafer surface. However, since rotating speed of the disk is very high in spin coating, the dropped resist scatters outward and reattaches to the film surface. So, the scattered resist is removed by the exhaust flow generated at the gap between the wafer edge and the catch cup. It is seriously concerned that the stripes called Ekman spiral vortices appears on the disk in the case of high rotating speed and the film thickness increases near the wafer edge in the case of low rotating speed, because it prevent the formation of uniform film. The purpose of this study is to make clear the generation mechanism of Ekman spiral vortices and the influence of exhaust flow on it Moreover the influence of the catch cup geometry on the wafer surface boundary layer flow is investigated.     

A Study of the Influence of Solid Particles on Boiling Hysteresis

Experiments have been performed to determine the effects on boiling hysteresis of locally fluidized particlescontained in a liquid that serves as coolant for electronic equipment.The results show that locally fluidizedparticles can diminish boiling hysteresis.     

Effect of the water–steam phase transition on the electrical conductivity of porous rocks

The effect of the water–steam phase transition on electrical conductivity was experimentally investigated in volcanic and sandstone samples to support the interpretation of resistivity data to determine changes in steam saturation in geothermal reservoirs. The measurements were performed at simulated in situ conditions with controlled pore fluid chemistry, temperature, and confining and pore pressures. At constant temperature (150 °C) and confining pressure, pore fluid was withdrawn from the sample by steadily increasing the volume of the pore fluid system. At the vapor saturation pressure, the pore water progressively boiled to steam, resulting in a continuous conductivity decrease by a factor of approximately 20. The study showed that: (1) for rocks in which conduction is controlled by the pore fluid, the concurrent changes in both electrical conductivity and pore (vapor) pressure are defined by the pore size distribution; the changes in liquid–steam saturation are approximately proportional to those in conductivity and can thus be quantified; and (2) for rocks in which surface conduction is predominant there is no direct relation between conductivity, pore pressure and drained fluid volume; this implies that the conduction mechanism controls the pattern of electrical conductivity variations as steam saturation changes.     

Numerical Simulation of the Flow over a Model of the Cavities on a Butterfly Wing

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Study on the characteristics of evaporation–atomization–combustion of biodiesel

A great deal of research is being carried out on renewable diesel fuels. The number of raw materials (especially waste, animal, and vegetable oils), production technologies, and additives of biodiesel is increasing. In our work, a evaporation–atomization–combustion system consisting of a biomass liquid fuel was designed to produce a laminar premixed flame for studying the combustion–emission characteristics of biodiesel. The combustion characteristics of biodiesel including flame height, flame front area, flame speed, and OH total signal intensity were studied by planar laser-induced fluorescence of OH (OH-PLIF). The emission characteristics of biodiesel (CO, CO₂, and NO) were studied with a flue gas analyzer. The experimental results showed that the flame height, flame front area, flame speed, and the OH total signal intensity changed with the equivalence ratio (Φ). The relationship between the OH radical intensity and the emission of CO/CO₂ was obtained from the OH-PLIF average signal intensity. The [CO]/[CO₂] ratio decreased with the OH-PLIF average signal intensity. Finally, we obtained the relationship between the OH-PLIF average signal intensity and the NO emissions.     

Calculation of Vertical Mixing in Plane Turbulent Buoyant Jets on the Basis of the Algebraic Model of Turbulence

An algebraic model of turbulence,involving buoyancy forces,is used for calculating velocity and temperaturefields in plane turbulent vertical jets in a non-homogeneous stagnant medium.A new approach to the solution ofthe governing system of partial differential equations (continuity,conservation of momentum,heat (buoyancy),turbulent kinetic energy,dissipation rate and mean quadratic temperature fluctuation) is suggested which isbased on the introduction of mathematical variables.Comparison is made between the results of the presentcalculations with experimental and numerical data of other authors.     

Effects of Heterogeneous Condensation on the Transonic Flow Fields on a Bump Model

In the present study, effect of the heterogeneous condensation on the characteristics of shock wave generated on the bump model in the transonic flow field was investigated numerically. As a result, it was found that, for the flow field with steady adiabatic shock wave on the bump model, the condensation with heterogeneous nucleation has a strong effect on the whole flow field, and it reduced the strength of the shock. Furthermore, the total pressure loss was dependent on the concentration of the solid particles per unit volume.     

Effect of sulfites on the performance of LiBOB/γ-butyrolactone electrolytes

γ-Butyrolactone (GBL) increases the irreversible capacity of lithium ion battery when it is employed as the solvent for the lithium bis(oxalate)borate (LiBOB)-based electrolyte. To solve this problem, four sulfites are introduced to the electrolyte. The effects of ethyl sulfite (ES), propylene sulfite (PS), dimethyl sulfite (DMS) and diethyl sulfite (DES) on the LiBOB/GBL-based electrolytes are studied. The ionic conductivity, electrochemical stability, cycle performance and thermal stability of the sulfite containing electrolytes are tested and compared with that of the common electrolyte and the 1 M LiBOB/GBL electrolyte. The results indicate that the cyclic sulfites ES and PS show little benefit to the performance of the electrolyte. However, the linear sulfites DMS and DES could increase the ionic conductivity of the electrolyte and form an effective SEI film on the anode surface. In particular, the 1 M LiBOB/GBL + DMS (3:1 wt.) electrolyte mitigates the irreversible capacity and enhances the first coulomb efficiency and the capacity retention. The thermal stability of the DMS containing electrolyte is also improved and is better than that of the common electrolyte. These beneficial effects make them possibly to be a promising cosolvent for the LiBOB/GBL electrolyte.     

Effect of Exit Geometry of Tail Pipe on the Performance of Pulse Jet Engines

In this paper,the effect of geometries of tube open end on the shock,compression and expansion wavespropagating in the tube was investigated numerically and experimentally.One of them is a conventional straightshock tube with an open end.The other has a divergent tail tube at the exit.Applying a divergent tail tube(flaretube)to an open end shock tube,the period of one-cycle process could be shortened and the pressure behind theexpansion wave produced at the exit of the shock tube could be lowered much more below the atmosphericpressure than that produced in the straight tube.The results suggested that the intake air into the engine wassignificantly increased by applying a flare tube instead of a straight tube.     

Effect of chemisorbed water on the electrical capacity of the lead—acid battery positive plate

A method has been developed for the assessment of the changes in the partial pressures of H₂O and O₂ during the thermal decomposition of PAM sa     

Effects of a Kind of Non-smooth Blade on the Performance of an Axial Fan

This paper presents an experimental investigation of effects of a kind of streamwise-grooved blade on theperformance of an axial-flow fan.The flow field at 25% chord downstream from the trailing edge at hub wasmeasured using a 5-hole pressure probe at different mass-flow conditions.The fan performance of the grooveblades was compared with that of the smooth blades.The measurement results indicate that:(1)the non-smoothblades increase mass flow of the fan at the same throttle conditions except a near stall condition;(2)thenon-smooth blades reduce the relative total pressure loss in the rotor passage and increase the fan's total pressurerise at the test mass-flow conditions except the near stall condition;(3)Negative benefits are obtained at a nearstall condition when the smooth blades are replaced by the non-smooth ones.The fan mass flow decreases 0.9%while the total-pressure rise decreases 2.4% at the near stall condition.     

Experiment on the effect of Pt-catalyst on the characteristics of a small heat-regenerative CH4–air premixed combustor

Heat-regenerative small combustors consisting of a combustion space and a pair of counter-current-channels were fabricated. The methane–air combustion characteristics in the combustion space were examined with and without catalytic platinum wires. The installing locations and scale effects of the platinum wires were varied to distinguish between thermo-fluidic and catalytic effects. Temperature distribution through the channels and the compositions of burned gas were measured. Conclusively, the platinum wires in the upstream channel slightly enhanced flame stabilization by an enhanced heat transfer, not by a catalytic reaction. In contrast, the platinum wire located within the recirculation area of the combustion space promoted the catalytic reaction and extended the self-sustainable reaction conditions when it had sufficient surface area. Two reaction regimes, of an ordinary gas reaction and of a catalytic reaction, were distinguished and a hysteresis in the reaction-mode transition was confirmed through the comparison of CO, O₂, and methane across the transition conditions.