Vane Size Research Articles

The numerical simulation investigates the influence of agitator parameters on particle suspension characteristics

This study investigates the effect of different agitator parameters in a baffleless stirred reactor on solid particle suspension during quaternary ammonium chitosan synthesis. Computational Fluid Dynamics (CFD) simulations investigate different agitator configurations, including blade diameter, rotational speed, and bottom clearance, to optimize chitosan particle distribution. Reducing the bottom clearance reduces particle accumulation, but can create stagnant zones that may disrupt fluid flow. Increasing the rotational speed improves particle distribution until a saturation point is reached. Increasing paddle diameter improves axial fluid circulation. Optimal settings for the vane size of a 180 mm reactor vessel are identified as 0.45 times the diameter, with a speed of 350 rpm, and a bottom clearance of 0.25 times the diameter. These simulations provide critical insight into the suspension of solid particles in baffleless stirred reactors and provide valuable guidance for optimizing stirrer parameters.

Determination of the trajectory of sedition of fluid particles in the forebay of pumping stations

In the article, the determination of the sedimentation territory of turbid particles in the forebay of the irrigation pumping station is aimed at preserving the useful volume of the forebay, in which the forebay of the irrigation pumping station PK-1512+01 GFC (The great Fergana canal) and SEC (Sokh Eastern Canal) located in the large Fergana canal is taken as an object. The review of the literature showed that the deposition of particles is directly related to the following factors, which are affected by the speed of the flow, the diameter of the particle, the difference between the densities of water and the particle, the shape of the particle and the order of movement of the flow, the viscosity of water and other factors. In these studies, we primarily aim to increase the performance of the forebay by defining the particle settling zone to preserve the useful vane size. Calculations of the method of calculating the sedimentation rate of cloudy particles using theoretical and empirical formulas were carried out and conclusions were drawn by comparing the results.

Separation and flow unsteadiness control in a compression corner induced interaction using mechanical vortex generators: Effects of vane size and inter-device spacing

An experimental investigation was conducted to control separation characteristics of a 24° compression corner induced interaction in a Mach 2.0 flow using an array of mechanical vortex generators (VGs) with rectangular vanes (RRV) placed 6.8δ upstream of the interaction. The objective was to study the effect of (i) inter-VG spacing (s/h = 12, 9.5, 8.0, 6.1, 5.7, 5.5, 4.9, and 4.7), (ii) vane chord length (c/h = 7.2, 4.2, and 3.0), and (iii) vane angle (α = 24°, 20°, 18°, and 16°) in controlling the interaction and on the surface flow topology. These modifications reduce the projected area of VGs in the array from the conventional VG design of RRV2 (c/h = 7.2 and s/h = 9.5) to RRV8 (c/h = 3.0 and s/h = 4.7) by 41%. Reducing s/h also reduces the inter-VG region of the separation significantly that helps to achieve maximum reduction in the streamwise extent of separation up to 83% and in the peak rms value up to 80%. The former improves the overall pressure recovery from 3.0 to 3.4, thereby moving closer toward the inviscid value of 3.8. Surface flow topology shows that the VG array splits a single large spanwise separation bubble for no control into multiple smaller scale individual separation cells placed side-by-side all along the span of the interaction. This helps to reduce the magnitude of mass exchange imbalance across each individual separation cell and, hence, stabilizes the overall interaction relative to no control. The best VG configuration of RRV8 shifts the dominant frequency of fluctuations to approximately 2 kHz or St = 0.19, which is nearly an order of magnitude higher than that for no control.

해양복합온도차발전용 복수기 증기 취출 유동 해석

The concept of C-OTEC (Combined-Ocean Thermal Energy Conversion) was proposed to run a heat engine using the temperature difference between the steam exhausted into the condenser of an existing power plant and the deep sea water. To vaporize a working fluid of the heat engine, saturated steam in the condenser needs to be extracted to the evaporator of C-OTEC. Installation of steam guide vanes inside the condenser is considered to effectively extract steam from the condenser to the C-OTEC evaporator. In the present study, three-dimensional computational fluid dynamics analysis of flow inside the condenser with various sizes of steam guide vanes is conducted. Influences of the steam guide vane size upon flow and pressure distributions in the condenser are analyzed using the conventional CFD method while fluid flow and pressure drops inside small complicated channels of plate-type heat exchanger units in the C-OTEC evaporator is equivalently simulated using the porous medium approach. It is found from the analysis results that as the steam guide vane diameter increases, the steam extraction rate as a figure of merit linearly increases while the condenser pressure rise as a penalty exponentially increases. As a result, an optimal size of the steam guide vane for the condenser analyzed in the present study is proposed.

The examination of circular and elliptical vanes under natural convection of nanofluid in a square chamber subject to radiation effects

In this paper, natural convection and radiation heat transfer of alumina-water nano-fluid in a square chamber at 45° has been simulated. The right wall of the chamber is cold, and there is a warm vane in the chamber. The vane can change form into horizontal ellipse, vertical ellipse, and circle. The other parts of the walls are insulated. The simulation was performed by using the algebraic control volume method and the SIMPLE algorithm. The effective parameters include the Rayleigh number, the radiation parameter, the nanoparticle volume percentage, and the vane dimensions. The paper focuses on finding the best vane size for maximum heat transfer. The results show that the intensification of the Rayleigh Number and addition of nanoparticles augments heat transfer. As the Rayleigh number enhances by up to 105, the Nusselt number increases up to 3 times. The intensification of nanoparticles concentration up to 4% also increases the Nusselt by 2.5% compared to water. Adding radiation heat transfer to the chamber can significantly increase heat transfer. Increasing the radiation parameter from 0 to 3 has increased the Nusselt number by more than 7 times. The Nusselt number increases with increases in both vane diameters. Nevertheless, it is strongly dependent on the horizontal diameter, and changes in the vertical diameter have little effect on the average Nusselt Number (Nuave).

Enhancing transverse mixing in streams with submerged vanes

In order to maintain the water quality of moving streams, it is essential to know the process of pollutant mixing. The transverse mixing is very important which is needed to be modeled to understand mixing phenomenon. It was observed that transverse mixing is a strong function of secondary currents, thus, submerged vanes, which are aerofoil skewed at angle of 10°–40° with respect to flow, generate transverse circulations that can be utilized to induce secondary currents in the flow to enhance transverse mixing. Present study is an attempt to utilize submerged vanes as an instrument to enhance the transverse mixing by incorporating various vane configurations. In order to study the effect of vane generated circulations on transverse mixing, experimentations were conducted on three vane sizes and for various row arrangements of vanes attached to bed. An attempt is made to investigate the effect of submerged vane size and rows on transverse velocity, concentration profile and transverse mixing coefficient. It was observed by measurement of concentration profile that transverse mixing was more enhanced for submerged vanes of higher height. It was also observed that as the number of rows is proportional to the transverse mixing. By measuring the transverse velocity profile, it was observed that more and more fluid was advected in transverse direction for higher rows of vanes. By utilizing the observed transverse mixing coefficients, number of vane rows and relative height of vane, a predictor was derived to predict transverse mixing coefficient in the presence of submerged vane rows. It was observed that the derived predictor shows a fair amount of agreement in the result predicted.

Flow properties of fresh concrete by using modified geotechnical Vane shear test

An experimental investigation has been performed to study the efficiency of using modified geotechnical Vane shear test to evaluate the fresh properties of concrete. Different concrete mixes with different coarse aggregates (both type and size) were conducted. Moreover different shapes and sizes of Vane probes were investigated. Also the influence of using enhancing workability admixtures was studied. The results of the shear Vane test were statistically analyzed and compared with those for standard tests. The results reveal that the Vane shear test with modified blades can be simply executed to measure workability of concrete anywhere with a good efficiency. Useful equations with good correlation coefficients are established between the well known standard tests include compacting factor, slump, VeBe and flow tests and the Vane yield method. Size effect phenomenon related to Vane size is recorded for the Vane yield stress results. The results of the Vane yield stress could clearly distinguish between not only mixes made up of different aggregate types but also the aggregate maximum nominal size. The results of the Vane shear test are clearly affected by using enhancing workability admixtures and its dosage. A direct proportion between Vane yield stress results and the companion compacting factors test values is strongly noticed which introduces the Vane test method as a simple instrument that could be simply adapted anywhere to measure the workability of fresh concrete instead of compacting factor that is a laboratory apparatus.

Active magnetic bearing design study

The purpose of this paper is to propose a useful method to implement active magnetic bearings (AMBs) on an existing rotating shaft which rotates on conventional bearings. This is feasible if AMBs can produce the same reaction loads of conventional ones and if the size of vane is large enough to host an AMB. As this substitution could offer some difficulties due to the different size between magnetic bearings and conventional ones, a set of equations are performed to show that a variation of some parameters can solve this problem. The journal ratio is the geometrical parameter introduced to develop the present analysis. The variation of journal ratio does not produce a variation of the pole’s surface so that the reaction load does not change. The results are analyzed by numerical analysis by mathematical relationships involving the design parameters, magneto-static simulations and dynamic simulation on shaft when it is tested by disturbance rejection and reference tracking input in order to analyze the differences on dynamic behavior of the shaft on its suspended sections. Results show that the displacement pattern of the suspended sections remains unchanged, confirming that the reaction load, produced by pole expansion, remains the same varying the journal ratio.

Impact of vane size and separation on radiometric forces for microactuation

A kinetic approach is used to study the feasibility of increasing the efficiency of microactuators that use radiometric force through etching holes in a single radiometer vane. It has been shown that a radiometer that consists of small vanes is capable of producing at least an order of magnitude larger force than a single-vane radiometer that takes up the same area. The optimum gap between the vanes is found to be slightly smaller than the vane size, with the optimum Knudsen number of about 0.05 based on the vane height.

Numerical Unsteady Flow Analysis of a Turbine Stage With Extremely Large Blade Loads

This paper presents the detailed numerical analysis including parametric studies on the aerodynamic excitation mechanisms in a turbine stage due to the unsteady stator-rotor interaction. The work is part of the predesign study of a high-pressure subsonic turbine for a rocket engine turbopump. The pressure level in such turbines can be remarkably high (in this case 54 MPa inlet total pressure). Hence, large unsteady rotor blade loads can be expected, which impose difficult design requirements. The parameter studies are performed at midspan with the numerical flow solver UNSFLO, a 2-D/Q3-D unsteady hybrid Euler/Navier-Stokes solver. Comparisons to 2-D and steady 3-D results obtained with a fully viscous solver, VOLSOL, are made. The investigated design parameters are the axial gap (∼8–29 percent of rotor axial chord length) and the stator vane size and count (stator-rotor pitch ratio ∼1–2.75). For the nominal case the numerical solution is analyzed regarding the contributions of potential and vortical flow disturbances at the rotor inlet using rotor gust computations. It was found that gust calculations were not capable to capture the complexity of the detected excitation mechanisms, but the possibility to reduce excitations by enforcing cancellation of the vortical and potential effects has been elaborated. The potential excitation mechanism in the present turbine stage is found dominant compared to relatively small and local wake excitation effects. The parameter studies indicate design recommendations for the axial gap and the stator size regarding the unsteady rotor load.

Studies with Centrifuge Vane and Penetrometer Apparatus in a Normal Gravity Field

Abstract Small vane and penetrometer devices have been developed to measure soil properties in models during centrifuge operation. To aid the interpretation of vane data from centrifuge models a series of tests was conducted in cakes of kaolin clay in a normal gravity field. In the experimental program the effects of disturbance during insertion, delay between insertion and rotation, rate of rotation and geometry of vane blades were investigated. The results were used to devise a scientific method of operation of the vane apparatus. Subsequent tests were all performed with a vane size of 18 mm diameter by 14 mm high. Penetrometer tests were conducted in cakes of kaolin and Gault clays. Vane shear strengths were used to calibrate the apparatus. The ratio of cone resistance to vane strength was found to increase with increasing over-consolidation ratio. The values also differed considerably between the two clays. Thus, while the penetrometer has the advantage of providing a continuous profile of resistance with depth, some care is required in converting this measurement into undrained shear strength.

Vane testing in peat

An extensive programme of vane testing has been carried out in a peat bog at Escuminac, N.B. to assess the applicability of vane testing to peat. The variables involved in the programme were depth, size of vane, method of insertion, rate of rotation of the vane, and state of peat tested. Vane strength profiles were obtained in a 7 m thick deposit consisting of sphagnum peat (0–4 m), sphagnum carex peat (4–6 m), and carex sphagnum peat (6–7 m). Vane tests were also carried out in the sphagnum peat under anchored Plexiglas sheets to observe the mode of deformation and failure and to measure the movement of markers inserted into the face of the peat. Additional tests were carried out with field vanes in confined sphagnum peat samples in the laboratory.The observed failure surface was essentially cylindrical for all sizes of vane used, but its diameter was consistently 7–10 mm greater than that of the vane for all vane sizes. The sphagnum peat failed at true angles of rotation of between 17 and 40°, leaving a void behind each blade. At maximum torque the peat within each sector started to move monolithically.The moderately decomposed sphagnum moss peat tested is typically neither fibrous nor amorphous, although some fibres and amorphous material are generally present as a result of varying growth and degradation processes. This type of peat could be considered representative of most moss peats with respect to geotechnical behaviour. It is not, however, representative of the less common, truly fibrous sedge peats or of any purely amorphous peat deposits.Analyses of the mode of deformation of the sphagnum peat in vane shear and comparisons with modes of deformation in other types of shear have led the author to conclude that the vane test, in spite of its practical advantages, does not serve any useful purpose in the testing of peat.

Influence of Shear Velocity on Vane Shear Strength

Comparisons of field and laboratory vane shear strength measurements from geotechnical test areas in the San Diego Trough and Gulf of Maine were made to evaluate the influence of vane size, rotation rate, and sample disturbance on vane shear strength. Field vane strengths were observed to be significantly higher than laboratory strengths in both test areas. In-situ strengths obtained with large diameter vanes were consistently higher than strengths obtained with smaller vanes. Comparison of field and laboratory vane strengths with angular shear velocity at the vane blade edges indicated that angular shear velocity can significantly influence vane shear strength measurements. It is recommended that laboratory and field vane shear strengths be determined at a standard angular shear velocity to eliminate many of the uncertainties associated with differences in vane size and rotation rate. An angular shear velocity of 0.5 x 10 - ³ fps (0.15 mm/s) is proposed as the standard for both laboratory and field vane shear strength measurements.

The Vane Test in Organic Soils

In situ vane tests were carried out in a number of different muskeg deposits to examine the mechanism of failure and the effect of variation in vane size and speed of testing. The failure mechanism in peat was found to be similar to that in soft clays. The apparent shear strength varied with vane size but was independent of testing speed. There was an optimum vane size of 10 cm diameter.Block samples were obtained from one site for laboratory vane tests to investigate anisotropy in the strength of the peat. In situ tests for anisotropy using vanes of varying shape confirmed the laboratory results, and showed that strengths on the vertical plane could be 100 % higher than those on the horizontal plane.