Flow Mechanism and Characteristics of Pressure-Equalizing Film Along the Surface of a Moving Underwater Vehicle

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Guihui Ma ◽  
Fu Chen ◽  
Jianyang Yu ◽  
Huaping Liu
Keyword(s):  
Volume Fraction ◽  
Surface Film ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Vortex Pair ◽  
Lateral Force ◽  
Underwater Vehicle ◽  
Vehicle Interior ◽  
Phase Volume Fraction

Pressure-equalizing film is a slice of air layer attached to vehicle exterior with nearly uniform inside pressure, similar to ventilated cavity in composition; it is generated through exhaust process of the inside air chamber as vehicle emerges from deep water, and can reduce the lateral force and pitching moment that vertical launched underwater vehicle suffered. In this work, the emerging process of vehicle from water with pressure-equalizing exhaust was numerically calculated to investigate the evolution and flow characteristics of the generated pressure-equalizing film along its surface. Results indicated that during the whole exhaust process, the film can be obviously classified into different sections according to the distribution of phase volume fraction or pressure. The exhaust velocity ratio and flow rate from vehicle interior chamber were also found to increase as vehicle moves. In the analysis of flow structures, vortex structures such as the horseshoe vortex, “detour-separation” vortex, and counter-rotating vortex pair (CVP) can be figured out in the region of the exhaust hole. Under the effect of re-entrant jet, water around the film tail would be entrained upstream then enter the surface film to mix with the pressure-equalizing air. It leads to the happening of the three-dimensional (3D) wall vortex in the flow field.

Instrumentation For Quantitative Microscopy

1977 ◽  
Vol 35 ◽  
pp. 206-209
Author(s):  
B. Ralph ◽  
A.R. Jones
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Automatic Data ◽  
Phase Volume Fraction ◽  
Statistical Confidence ◽  
Resultant Data ◽  
Automatic Data Collection ◽  
Third Dimension ◽  
Evolution Of Microstructure

In all fields of microscopy there is an increasing interest in the quantification of microstructure. This interest may stem from a desire to establish quality control parameters or may have a more fundamental requirement involving the derivation of parameters which partially or completely define the three dimensional nature of the microstructure. This latter categorey of study may arise from an interest in the evolution of microstructure or from a desire to generate detailed property/microstructure relationships. In the more fundamental studies some convolution of two-dimensional data into the third dimension (stereological analysis) will be necessary.In some cases the two-dimensional data may be acquired relatively easily without recourse to automatic data collection and further, it may prove possible to perform the data reduction and analysis relatively easily. In such cases the only recourse to machines may well be in establishing the statistical confidence of the resultant data. Such relatively straightforward studies tend to result from acquiring data on the whole assemblage of features making up the microstructure. In this field data mode, when parameters such as phase volume fraction, mean size etc. are sought, the main case for resorting to automation is in order to perform repetitive analyses since each analysis is relatively easily performed.

A generalized Archie’s law for n phases

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. E247-E265 ◽  
Author(s):  
Paul W. J. Glover
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Reservoir Rock ◽  
Archie’S Law ◽  
Phase Volume Fraction ◽  
General Law ◽  
Special Cases ◽  
The Matrix ◽  
Definition Of

Archie’s law has been the standard method for relating the conductivity of a clean reservoir rock to its porosity and the conductivity of its pore fluid for more than [Formula: see text]. However, it is applicable only when the matrix is nonconducting. A modified version that allows a conductive matrix was published in 2000. A generalized form of Archie’s law is studied for any number of phases for which the classical Archie’s law and modified Archie’s law for two phases are special cases. The generalized Archie’s law contains a phase conductivity, a phase volume fraction, and phase exponent for each of its [Formula: see text] phases. The connectedness of each of the phases is considered, and the principle of conservation of connectedness in a three-dimensional multiphase mixture is introduced. It is confirmed that the general law is formally the same as the classical Archie’s law and modified Archie’s law for one and two conducting phases, respectively. The classical second Archie’s law is compared with the generalized law, which leads to the definition of a saturation exponent for each phase. This process has enabled the derivation of relationships between the phase exponents and saturation exponents for each phase. The relationship between percolation theory and the generalized model is also considered. The generalized law is examined in detail for two and three phases and semiquantitatively for four phases. Unfortunately, the law in its most general form is very difficult to prove experimentally. Instead, numerical modeling in three dimensions is carried out to demonstrate that it behaves well for a system consisting of four interacting conducting phases.

scholarly journals Flow Characteristics of a 35° Inclined Turbulent Jet in a Crossflow on a Concave Surface

1992 ◽  
Author(s):  
Sang Woo Lee ◽  
Joon Sik Lee ◽  
Taik Sik Lee
Keyword(s):  
Near Field ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Horseshoe Vortex ◽  
Concave Surface ◽  
Velocity Measurements ◽  
Downstream Region ◽  
Type Flow ◽  
Streamwise Pressure Gradient

The effect of the concave curvature on the flow of a streamwise 35° inclined jet issuing into a crossflow boundary layer has been investigated experimentally. Three-dimensional velocity measurements are performed in the near-field and some downstream region of jet exit by using a 5-hole directional probe. Since the main purpose is to investigate solely the effect of the concave curvature, the upper wall of the curved region is adjusted to minimize the effect of the streamwise pressure gradient. The results show that in the vicinity of the jet exit, the bound vortex dominates the flow structure, while in the far downstream region, the concave curvature plays an important role in converting the secondary flow into the Taylor-Görtler type flow. In addition, vortices rotating in the opposite direction with respect to the bound vortex is generated at both sides of the bound vortices, which stimulate the mixing of the jet and crossflow fluid. When the velocity ratio is large, the horseshoe vortex exists in the neighborhood of the jet exit, even though the strength is very weak compared with the bound vortex, however this horseshoe vortex may act as a kind of steady disturbance on the concave surface.

Flow Characteristics of a Low Reynolds Number Jet in Crossflow with an Obstacle Block

2016 ◽  
Vol 9 (1) ◽  
pp. 37-46 ◽  
Author(s):  
Jianlong Chang ◽  
Xudong Shao ◽  
Xiao Hu ◽  
Shuangbiao Zhang
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Velocity Ratio ◽  
Flow Characteristics ◽  
Vortex Pair ◽  
Lower Velocity ◽  
Eddy Simulation ◽  
Jet In Crossflow ◽  
Crossflow Velocity ◽  
Low Reynolds

The jet in crossflow at very low Reynolds number (Re=100) with and without block is performed by means of large eddy simulation for the jet-to-crossflow velocity ratios (r) ranging from 1 to 3, and the corresponding flow characteristics are compared. The results show that the time-averaged particle trajectories of the jet are slightly changed if a block is presented, and the mixed vortices are weakened. The existence of the block also can accelerate the formation of stable counter-rotating vortex pair. At lower velocity ratio (r=1), the block has little effect on the jet in crossflow with a symmetrically positive and negative kidney shaped vortices. As the velocity ratio increases, the effect of block not only can generate an asymmetry of positive and negative kidney shaped vortices, but also it can reinforce the interaction between the positive and negative vortices in the jet in crossflow. The effect of block on the temperature field is also analyzed in detail.

scholarly journals The Effect of Inlet Boundary Layer Thickness on the Flow Within an Annular S-Shaped Duct

1998 ◽  
Author(s):  
Toyotaka Sonoda ◽  
Toshiyuki Arima ◽  
Mineyasu Oana
Keyword(s):  
Boundary Layer ◽  
Flow Pattern ◽  
Pressure Loss ◽  
Total Pressure ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Vortex Pair ◽  
Separated Flow ◽  
Total Pressure Loss ◽  
Centrifugal Impeller

Experimental and numerical investigations were carried out to gain a better understanding of the flow characteristics within an annular S-shaped duct, including the effect of the inlet boundary layer (IBL) on the flow. A duct with six struts and the same geometry as that used to connect compressor spools on our experimental small two-spool turbofan engine was investigated. A curved downstream annular passage with a similar meridional flow path geometry to that of the centrifugal compressor has been fitted at the exit of S-shaped duct. Two types of the IBL (i.e. thin and thick IBL) were used. Results showed that large differences of flow pattern were observed at the S-Shaped duct exit between two types of the IBL, though the value of “net” total pressure loss has not been remarkably changed. According to “overall” total pressure loss, which includes the IBL loss, the total pressure loss was greatly increased near the hub as compared to that for a thin one. For the thick IBL, a vortex pair related to the hub-side horseshoe vortex and the separated flow found at the strut trailing edge has been clearly captured in the form of the total pressure loss contours and secondary flow vectors, experimentally and numerically. The high-pressure loss regions on either side of the strut wake near the hub may act on a downstream compressor as a large inlet distortion, and strongly affect the downstream compressor performance. There is a much-distorted three-dimensional flow pattern at the exit of S-Shaped duct. This means that the aerodynamic sensitivity of S-Shaped duct to the IBL thickness is very high. Therefore, sufficient carefulness is needed to design not only downstream aerodynamic component (for example centrifugal impeller) but also upstream aerodynamic component (LPC OGV).

scholarly journals Numerical Investigation of Vertical Crossflow Jets with Various Orifice Shapes Discharged in Rectangular Open Channel

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1505
Author(s):  
Hao Yuan ◽  
Ruichang Hu ◽  
Xiaoming Xu ◽  
Liang Chen ◽  
Yongqin Peng ◽  
...  
Keyword(s):  
Open Channel ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Turbulent Model ◽  
3D Flow ◽  
Turbulent Characteristics ◽  
Square Jets ◽  
Flow Turbulence ◽  
Vertical Jet

Vertical jet in flowing water is a common phenomenon in daily life. To study the flow and turbulent characteristics of different jet orifice shapes and under different velocity ratios, the realizable k-ε turbulent model was adopted to analyze the three-dimensional (3D) flow, turbulence, and vortex characteristics using circular, square, and rectangular jet orifices and velocity ratios of 2, 5, 10, and 15. The following conclusions were drawn: The flow trajectory of the vertical jet in the channel exhibits remarkable 3D characteristics, and the jet orifice and velocity ratio have a significant influence on the flow characteristics of the channel. The heights at which the spiral deflection and maximum turbulent kinetic energy (TKE) occur for the circular jet are the smallest, while those for square jets are the largest. As the shape of the jet orifice changes from a circle to a square and then to a rectangle, the shape formed by the plane of the kidney vortices and the region above it gradually changes from a circle to a pentagon. With the increase in the velocity ratio, the 3D characteristics, maximum TKE, and kidney vortex coverage of the flow all gradually increase.

scholarly journals Experimental Study on the Flow Characteristics of Streamwise Inclined Jets in Crossflow on Flat Plate

1992 ◽  
Author(s):  
Sang Woo Lee ◽  
Joon Sik Lee ◽  
Sung Tack Ro
Keyword(s):  
Experimental Study ◽  
Flat Plate ◽  
Flow Structure ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Slight Variation ◽  
Injection Angle ◽  
Large Velocity ◽  
Vorticity Dynamics

Experimental study has been conducted to investigate the flow characteristics of streamwise 35° inclined jets, injected into a turbulent crossflow boundary layer on a flat plate. Flow is visualized by schlieren photographs for both normal and inclined jets to determine the overall flow structure with the variation of the velocity ratio. Three-dimensional velocity field is measured for two velocity ratios of 1.0 and 2.0 by using a five-hole directional probe. The visualization study shows that a slight variation of the injection angle produces a significant change in the flow structure. It is recognized that the jet flow is mainly dominated by the turbulence for a small velocity ratio, but it is likely to be influenced by an inviscid vorticity dynamics for a large velocity ratio. Such a trend prevails in the streamwise inclined injection, compared with the normal injection. A pair of bound vortices accompanied with a complex three-dimensional flow is present in the downstream region of the jet exit as in the case of the normal injection, although its magnitude and range are different, and the strength of the bound vortex is strongly dependent on the velocity ratio. The interface between the jet and the crossflow is identified from the vorticity distribution.

scholarly journals Three-Phase 3D Reconstruction of a LiCoO2 Cathode via FIB-SEM Tomography

2016 ◽  
Vol 22 (1) ◽  
pp. 140-148 ◽  
Author(s):  
Zhao Liu ◽  
Yu-chen K. Chen-Wiegart ◽  
Jun Wang ◽  
Scott A. Barnett ◽  
Katherine T. Faber
Keyword(s):  
Focused Ion Beam ◽  
Volume Fraction ◽  
Ion Beam ◽  
Three Dimensional ◽  
Lithium Ion ◽  
Silicone Resin ◽  
Phase Volume Fraction ◽  
Low Viscosity ◽  
Three Phase ◽  
Battery Degradation

AbstractThree-phase three-dimensional (3D) microstructural reconstructions of lithium-ion battery electrodes are critical input for 3D simulations of electrode lithiation/delithiation, which provide a detailed understanding of battery operation. In this report, 3D images of a LiCoO2 electrode are achieved using focused ion beam-scanning electron microscopy (FIB-SEM), with clear contrast among the three phases: LiCoO2 particles, carbonaceous phases (carbon and binder) and the electrolyte space. The good contrast was achieved by utilizing an improved FIB-SEM sample preparation method that combined infiltration of the electrolyte space with a low-viscosity silicone resin and triple ion-beam polishing. Morphological parameters quantified include phase volume fraction, surface area, feature size distribution, connectivity, and tortuosity. Electrolyte tortuosity was determined using two different geometric calculations that were in good agreement. The electrolyte tortuosity distribution versus position within the electrode was found to be highly inhomogeneous; this will lead to inhomogeneous electrode lithiation/delithiation at high C-rates that could potentially cause battery degradation.

scholarly journals Heat Transport Improvement and Three-Dimensional Rotating Cone Flow of Hybrid-Based Nanofluid

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Azad Hussain ◽  
Qusain Haider ◽  
Aysha Rehman ◽  
M. Y. Malik ◽  
Sohail Nadeem ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Volume Fraction ◽  
Liquid Fraction ◽  
Current Model ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Physical Parameters ◽  
Diverse Range

The current research aims to study the mixed convection of a hybrid-based nanofluid consisting of ethylene glycol-water, copper (II) oxide (CuO) and titanium dioxide (TiO2) in a vertical cone. A hybrid base blend model is used to examine the nanofluid’s hydrostatic and thermal behaviors over a diverse range of Reynolds numbers. The application of mixed nanoparticles rather than simple nanoparticles is one of the most imperative things in increasing the heat flow of the fluids. To test such a flow sector, for the very first time, a hybrid-based mixture model was introduced. Also, the mixture framework is a single-phase model formulation, which was used extensively for heat transfer with nanofluids. Comparison of computed values with the experimental values is presented between two models (i.e., the model of a mixture with the model of a single-phase). The natural convection within the liquid phase of phase change material is considered through the liquid fraction dependence of the thermal conductivity. The predicted results of the current model are also compared with the literature; for numerical results, the bvp4c algorithm is used to quantify the effects of nanoparticle volume fraction diffusion on the continuity, momentum, and energy equations using the viscous model for convective heat transfer in nanofluids. Expressions for velocity and temperature fields are presented. Also, the expressions for skin frictions, shear strain, and Nusselt number are obtained. The effects of involved physical parameters (e.g., Prandtl number, angular velocity ratio, buoyancy ratio, and unsteady parameter) are examined through graphs and tables.

Simulation of Gas-Solid Flow Characteristics in Three-Dimensional Rotational Spouted-Fluidized Bed

2014 ◽  
Vol 496-500 ◽  
pp. 913-917
Author(s):  
Xin Feng Long ◽  
Yi Liu ◽  
Bo Lou
Keyword(s):  
Fluidized Bed ◽  
Gas Flow ◽  
Solid Phase ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cylinder Wall ◽  
Flow State ◽  
Solid Flow ◽  
Tangential Wind

In order to study the gas-solid flow characteristics in a rotational spouted-fluidized bed dryer, the eulerian multi-phase model was applied in three-dimensional numerical simulation of a rotational spouted-fluidized bed to analyze the effect of different velocity ratios between bottom and tangential wind on gas and particle velocity distribution characteristics, and the change rule of gas-solid flow state with the time at the velocity ratio of 30 m·s-1/30 m·s-1 was derived. The results show that the increase of tangential wind velocity is propitious to enhance the gas flow rate in the region near the wall and make the gas-solid phase mix sufficiently as well as augment of the contact area of gas and particle phase, and decrease of the gas flow dead zones and the adhesion of viscous materials to cylinder wall. However, the negative pressure formed by the entrainment effect of tangential wind goes against the development of gas flow along the axial direction reducing the penetration effect of axial wind to the granular layer.

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