scholarly journals Investigation Concerning the Fluid Flow in the Mixed-Flow Diffuser

1971 ◽  
Author(s):  
Shinji Honami ◽  
Keizo Tsukagoshi ◽  
Toshimichi Sakai ◽  
Ichiro Watanabe
Keyword(s):  
Boundary Layer ◽  
Fluid Flow ◽  
Velocity Profile ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Pressure Gradients ◽  
Flow Mechanism ◽  
Mixed Flow ◽  
Three Dimensional Flow ◽  
Layer Flow

Velocity profile measurements were performed on the flow in a mixed-flow diffuser with walls having equal cone angles. The aim of the present study is to understand the flow behavior and the relation between the flow patterns and the diffuser losses. The boundary layer flow accompanied by separation on the inner wall and the velocity normal to the diffuser walls were measured in detail to examine the three-dimensional flow behavior in the mixed-flow diffuser. Comparing with the radial diffuser, the mixed-flow diffuser had a more complicated flow mechanism as it had the pressure gradients of transverse and normal directions.

scholarly journals An optimal analysis for Darcy–Forchheimer three-dimensional Williamson nanofluid flow over a stretching surface with convective conditions

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983351 ◽  
Author(s):  
Abdullah Dawar ◽  
Zahir Shah ◽  
Saeed Islam ◽  
Waris Khan ◽  
Muhammad Idrees
Keyword(s):  
Heat Transfer ◽  
Brownian Motion ◽  
Fluid Flow ◽  
Velocity Profile ◽  
Flow Behavior ◽  
Three Dimensional ◽  
And Brownian Motion ◽  
Homotopy Analysis ◽  
Motion Parameters ◽  
The Impact

The augmented thermal conductivity is significant in betterment of heat transfer behavior of fluids. A number of other physical quantities such as density, viscosity, and specific heat play the key role in fluid flow behavior. Investigators have shown that the nanofluids have not only superior heat conductivity but also have better convective heat transfer capability than the base fluids. In this article, the analysis of three-dimensional Williamson fluid has been carried out under investigation. The fluid flow is taken over a linear porous stretching sheet under the influence of thermal radiation. The transformed system of equations has been solved by homotopy analysis method. The impact of embedded parameters on the fluid flow has shown graphically. The velocity profile in x-direction is decreased with the augmented stretching, Williamson, coefficient of inertia, and porosity parameters. The velocity profile in y-direction is increased with the enlarged stretching parameter, while reduced with the augmented Williamson, coefficient of inertia, and porosity parameters. The temperature profile is increased with the enlarged stretching, radiation, thermophoresis, parameter and Brownian motion parameters, and Biot number while decreased with the increased Prandtl number. The concentration profile is increased with the increased thermophoresis parameter and Biot numbers, while decreased with the enlarged stretching and Brownian motion parameters.

Near-Wall Similarity in a Shear-Driven Three-Dimensional Turbulent Boundary Layer

1983 ◽  
Vol 105 (3) ◽  
pp. 263-269 ◽  
Author(s):  
F. J. Pierce ◽  
J. E. McAllister
Keyword(s):  
Boundary Layer ◽  
Velocity Field ◽  
Turbulent Boundary Layer ◽  
Velocity Vector ◽  
Three Dimensional ◽  
Predictive Ability ◽  
Shear Velocity ◽  
Pressure Gradients ◽  
Upper Limit ◽  
Layer Flow

Ten of eleven proposed three-dimensional similarity models identified in the literature are evaluated with direct wall shear, velocity field, and pressure gradient data from a three-dimensional shear-driven boundary layer flow. Results define an upper limit on velocity vector skewing for each model’s predictive ability. When combined with earlier results for pressure-driven flows, each model’s predictive ability with and without pressure gradients is summarized.

Three-Dimensional Flow Within a Turbine Cascade Passage

1977 ◽  
Vol 99 (1) ◽  
pp. 21-28 ◽  
Author(s):  
L. S. Langston ◽  
M. L. Nice ◽  
R. M. Hooper
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Three Dimensional ◽  
Field Tests ◽  
Turbine Cascade ◽  
Three Dimensional Flow ◽  
Aerodynamic Loss ◽  
Wall Flow ◽  
Layer Flow ◽  
End Wall

Detailed measurements of the subsonic flow in a large-scale, plane turbine cascade were made to evaluate the three-dimensional nature of the flow field. Tests were conducted at a passage aspect ratio of 1.0 with a collateral inlet boundary layer. Flow visualization was done on airfoil and endwall surfaces. Velocity and pressure measurements were taken before and behind the cascade and in six axial planes within a cascade passage, using a five-hole probe. Hot wire measurements were taken in the endwall boundary layer within the cascade passage. The characteristics of the endwall boundary layer are presented, showing that three-dimensional separation is an important feature of end-wall flow. A large part of the endwall boundary layer was found to be very thin when compared to the cascade inlet boundary layer. Data showing the growth of aerodynamic loss through the passage are discussed.

EXPERIMENTAL INVESTIGATION OF FLOW RESPONSE TO STATIONARY DISTURBANCE IN ROTATING-DISK FLOW

2019 ◽  
Vol XVI (2) ◽  
pp. 13-22
Author(s):  
Muhammad Ehtisham Siddiqui
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Three Dimensional ◽  
Rotating Disk ◽  
Careful Analysis ◽  
Laboratory Frame ◽  
Transition To Turbulence ◽  
Turbulent Regime ◽  
Mean Velocity ◽  
Layer Flow

Three-dimensional boundary-layer flow is well known for its abrupt and sharp transition from laminar to turbulent regime. The presented study is a first attempt to achieve the target of delaying the natural transition to turbulence. The behaviour of two different shaped and sized stationary disturbances (in the laboratory frame) on the rotating-disk boundary layer flow is investigated. These disturbances are placed at dimensionless radial location (Rf = 340) which lies within the convectively unstable zone over a rotating-disk. Mean velocity profiles were measured using constant-temperature hot-wire anemometry. By careful analysis of experimental data, the instability of these disturbance wakes and its estimated orientation within the boundary-layer were investigated.

Global three-dimensional optimal disturbances in the Blasius boundary-layer flow using time-steppers

2010 ◽  
Vol 650 ◽  
pp. 181-214 ◽  
Author(s):  
ANTONIOS MONOKROUSOS ◽  
ESPEN ÅKERVIK ◽  
LUCA BRANDT ◽  
DAN S. HENNINGSON
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Wave Packets ◽  
Three Dimensional ◽  
Computational Domain ◽  
Initial Condition ◽  
Oblique Wave ◽  
Layer Flow ◽  
Optimal Disturbances ◽  
Matrix Free

The global linear stability of the flat-plate boundary-layer flow to three-dimensional disturbances is studied by means of an optimization technique. We consider both the optimal initial condition leading to the largest growth at finite times and the optimal time-periodic forcing leading to the largest asymptotic response. Both optimization problems are solved using a Lagrange multiplier technique, where the objective function is the kinetic energy of the flow perturbations and the constraints involve the linearized Navier–Stokes equations. The approach proposed here is particularly suited to examine convectively unstable flows, where single global eigenmodes of the system do not capture the downstream growth of the disturbances. In addition, the use of matrix-free methods enables us to extend the present framework to any geometrical configuration. The optimal initial condition for spanwise wavelengths of the order of the boundary-layer thickness are finite-length streamwise vortices exploiting the lift-up mechanism to create streaks. For long spanwise wavelengths, it is the Orr mechanism combined with the amplification of oblique wave packets that is responsible for the disturbance growth. This mechanism is dominant for the long computational domain and thus for the relatively high Reynolds number considered here. Three-dimensional localized optimal initial conditions are also computed and the corresponding wave packets examined. For short optimization times, the optimal disturbances consist of streaky structures propagating and elongating in the downstream direction without significant spreading in the lateral direction. For long optimization times, we find the optimal disturbances with the largest energy amplification. These are wave packets of Tollmien–Schlichting waves with low streamwise propagation speed and faster spreading in the spanwise direction. The pseudo-spectrum of the system for real frequencies is also computed with matrix-free methods. The spatial structure of the optimal forcing is similar to that of the optimal initial condition, and the largest response to forcing is also associated with the Orr/oblique wave mechanism, however less so than in the case of the optimal initial condition. The lift-up mechanism is most efficient at zero frequency and degrades slowly for increasing frequencies. The response to localized upstream forcing is also discussed.

Effects of Nano-Nozzles Cross-Sectional Geometry on Fluid Flow: Molecular Dynamic Simulation

2017 ◽  
Vol 34 (5) ◽  
pp. 667-678 ◽  
Author(s):  
H. Nowruzi ◽  
H. Ghassemi
Keyword(s):  
Fluid Flow ◽  
Velocity Profile ◽  
Cross Sections ◽  
Md Simulation ◽  
Flow Behavior ◽  
Water Model ◽  
Physical Parameters ◽  
Cross Sectional ◽  
Behavior Characteristics ◽  
Fanning Friction Factor

AbstractNano-nozzles are an essential part of the nano electromechanical systems (NEMS). Cross-sectional geometry of nano-nozzles has a significant role on the fluid flow inside them. So, main purpose of the present study is related to the effects of different symmetrical cross-sections on the fluid flow behavior inside of nano-nozzles. To this accomplishment, five different cross-sectional geometries (equilateral triangle, square, regular hexagon, elliptical and circular) are investigated by using molecular dynamics (MD) simulation. In addition, TIP4P is used for atomistic water model. In order to evaluate the fluid flow behavior, non-dimensional physical parameters such as Fanning friction factor, velocity profile and density number are analyzed. Obtained results are shown that the flow behavior characteristics appreciably depend on the geometry of nano-nozzle's cross-section. Velocity profile and density number for five different cross sections of nano-nozzle at three various measurement gauges are presented and discussed.

Rotating Flow Over a Disk Sector

1982 ◽  
Vol 49 (1) ◽  
pp. 13-18
Author(s):  
M. Toren ◽  
A. Solan ◽  
M. Ungarish
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Rotating Flow ◽  
Radial Coordinate ◽  
Large Radius ◽  
Full Circle ◽  
Blasius Boundary Layer ◽  
Layer Flow ◽  
Rotating Boundary ◽  
Limiting Values

The rotating boundary layer flow over a plane sector of angle θs and infinite radius is solved. For sufficiently large radius the radial coordinate is eliminated by a Von Karman transformation, leaving a nonaxisymmetric flow in (θ,z), which cyclically changes over the full circle, from a Blasius boundary layer, to a Bodewadt flow, and to a rotating wake. Leading terms of the three-dimensional perturbation of the Blasius flow, and of the rotating wake are given, and the matching over the full circle is outlined for limiting values of θs.

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