Effect of Drag-Reducing Polymer Injection on the Lift and Drag of a Two- Dimensional Hydrofoil

1974 ◽  
Author(s):  
D. H. Fruman ◽  
T. R. Sundaram ◽  
S. J. Daugard
Keyword(s):  
Two Dimensional ◽  
Polymer Injection ◽  
Lift And Drag ◽  
Drag Reducing Polymer

Lift Effects Associated with Drag-Reducing Polymer Injection on Two-Dimensional Hydrofoils

1976 ◽  
Vol 20 (03) ◽  
pp. 145-151
Author(s):  
Daniel H. Fruman
Keyword(s):  
Injection Velocity ◽  
Pressure Side ◽  
Two Dimensional ◽  
Foil Surface ◽  
Freestream Velocity ◽  
Polymer Injection ◽  
Drag Reducing Additive ◽  
Lift And Drag ◽  
Drag Reducing Polymer ◽  
Drag Ratio

The effect of a boundary-layer injection of drag-reducing additive solutions on the lift and drag of a 10-cm chord, NACA 63A020 symmetrical two-dimensional hydrofoil was investigated for various freestream and injection velocities, foil incidences, and additive concentrations ranging from 50 to 400 ppm of POLYOX WSR 301. The experimental results demonstrate that the lift of the hydrofoil can either increase or decrease depending upon whether the polymer injection is made on the suction or pressure side of the foil surface, respectively. In both cases, however, the drag is reduced. The net result of the injection of the drag-reducing agent is an augmentation of the lift-drag ratio. The magnitude of this augmentation and its dependence on the freestream velocity, the injection velocity, the concentration of polymer, and the incidence of the foil are analyzed.

A Note on Lift and Drag Effects Due to Polymer Injections from Several Locations on a Symmetric Hydrofoil

1978 ◽  
Vol 22 (04) ◽  
pp. 257-258
Author(s):  
A. M. Sinnarwalla ◽  
T. R. Sundaram
Keyword(s):  
Drag Reduction ◽  
Practical Interest ◽  
Injection Rate ◽  
Injection Technique ◽  
Two Dimensional ◽  
Polymer Injection ◽  
Multiple Injections ◽  
Single Location ◽  
Drag And Lift ◽  
Lift And Drag

Introduction - It is well known that the injection of dilute polymer solutions into the boundary layer on two-dimensional hydrofoils produces changes in both the drag and lift of the foils, with the changes being dependent on the polymer [1], 3 its concentration [2], the injection technique [8], the location of the injection slit [1], and the rate of injection [1, 4, 5]. Previous tests [4] have also shown that the observed drag reduction does not necessarily increase linearly with the rate of injection of the polymer. Indeed, beyond a certain injection rate, further increases lead to little or no drag reduction and, in some cases, actually lead to a drag increase. Thus, one question that is of considerable practical interest is the effect of multiple injections of a given amount of polymer from several chordwise locations as compared with that due to the injection from a single location. The present study investigates the effects on lift and drag of a 20.16-cm (8 in) chord NACA 684–010 two-dimensional hydrofoil due to multiple injections of 200-ppm Polyox WSR 301 solution from several chordwise locations. The results indicate that, for a given flux of polymer injection, multiple injections from properly selected locations as compared with the injection from a single location result in a larger drag reduction without adversely affecting the foil lift.

Modeling of unsteady structure of sheet/cloud cavitation around a two-dimensional stationary hydrofoil

2015 ◽  
Vol 231 (3) ◽  
pp. 455-469 ◽  
Author(s):  
Feng Hong ◽  
Jianping Yuan ◽  
Banglun Zhou ◽  
Zhong Li
Keyword(s):  
Volume Fraction ◽  
Cavitating Flow ◽  
Wake Flow ◽  
Two Dimensional ◽  
Cavitating Flows ◽  
Cavitation Model ◽  
Ansys Fluent ◽  
Cloud Cavitation ◽  
Lift And Drag ◽  
Multi Phase

Compared to non-cavitating flow, cavitating flow is much complex owing to the numerical difficulties caused by cavity generation and collapse. In the present work, cavitating flow around a two-dimensional Clark-Y hydrofoil is studied numerically with particular emphasis on understanding the cavitation structures and the shedding dynamics. A cavitation model, coupled with the mixture multi-phase approach, and the modified shear stress transport k-ω turbulence model has been developed and implemented in this study to calculate the pressure, velocity, and vapor volume fraction of the hydrofoil. The cavitation model has been implemented in ANSYS FLUENT platform. The hydrofoil has a fixed angle of attack of α = 8° with a Reynolds number of Re = 7.5 × 105. Simulations have been carried out for various cavitation numbers ranging from non-cavitating flows to the cloud cavitation regime. In particular, we compared the lift and drag coefficients, the cavitation dynamics, and the time-averaged velocity with available experimental data. The comparisons between the numerical and experimental results show that the present numerical method is capable to predict the formation, breakup, shedding, and collapse of the sheet/cloud cavity. The periodical formation, shedding, and collapse of sheet/cloud cavity lead to substantial increase in turbulent velocity fluctuations in the cavitation regimes around the hydrofoil and in the wake flow.

scholarly journals Planar flows past thin multi-blade configurations

1996 ◽  
Vol 324 ◽  
pp. 355-377 ◽  
Author(s):  
F. T. Smith ◽  
S. N. Timoshin
Keyword(s):  
Boundary Layer ◽  
Numerical Solutions ◽  
Reynolds Numbers ◽  
Laminar Flows ◽  
Two Dimensional ◽  
Boundary Layer Equations ◽  
Require Solution ◽  
Lift And Drag ◽  
Planar Flows ◽  
Steady Laminar

Two-dimensional steady laminar flows past multiple thin blades positioned in near or exact sequence are examined for large Reynolds numbers. Symmetric configurations require solution of the boundary-layer equations alone, in parabolic fashion, over the successive blades. Non-symmetric configurations in contrast yield a new global inner–outer interaction in which the boundary layers, the wakes and the potential flow outside have to be determined together, to satisfy pressure-continuity conditions along each successive gap or wake. A robust computational scheme is used to obtain numerical solutions in direct or design mode, followed by analysis. Among other extremes, many-blade analysis shows a double viscous structure downstream with two streamwise length scales operating there. Lift and drag are also considered. Another new global interaction is found further downstream. All the interactions involved seem peculiar to multi-blade flows.

Numerical and experimental analysis of two-dimensional separated flows over a flexible sail

2002 ◽  
Vol 466 ◽  
pp. 319-341 ◽  
Author(s):  
O. LORILLU ◽  
R. WEBER ◽  
J. HUREAU
Keyword(s):  
Velocity Field ◽  
Numerical Data ◽  
Separated Flows ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Two Dimensional Model ◽  
Wake Model ◽  
Lift And Drag ◽  
Particle Imaging ◽  
Good Agreement

This paper is a numerical analysis of the flow over a exible sail with the usual two-dimensional model of ideal weightless incompressible fluid. The sail is assumed to be impervious, inelastic and weightless, and may or may not be mounted on a mast. Separated or attached flows are considered at any angle of attack. Our method is validated by numerical and experimental results, i.e. the sail shape and velocity field are determined by particle imaging velocimetry, and lift and drag by aerodynamic balance. Despite the simplicity of the wake model we use (the Helmholtz model), the computed free streamline geometry and especially the sail shape are in good agreement with the experimental and numerical data.

A free-streamline model of the two-dimensional sail

1970 ◽  
Vol 42 (3) ◽  
pp. 433-446 ◽  
Author(s):  
J. P. Dugan
Keyword(s):  
Two Dimensional ◽  
Drag Coefficients ◽  
The Moment ◽  
Lift And Drag

The two-dimensional sail is considered in a free-streamline model to complement the oft-considered airfoil model which is limited to small angles of attack. The shape of the sail, the lift and drag coefficients, and the moment are obtained for various angles of attack and states of tension.

Lift and drag in two-dimensional steady viscous and compressible flow

2015 ◽  
Vol 784 ◽  
pp. 304-341 ◽  
Author(s):  
L. Q. Liu ◽  
J. Y. Zhu ◽  
J. Z. Wu
Keyword(s):  
Mach Number ◽  
Viscous Flow ◽  
Compressible Flow ◽  
Velocity Component ◽  
Transverse Velocity ◽  
The Body ◽  
Far Field ◽  
Two Dimensional ◽  
Wide Range ◽  
Lift And Drag

This paper studies the lift and drag experienced by a body in a two-dimensional, viscous, compressible and steady flow. By a rigorous linear far-field theory and the Helmholtz decomposition of the velocity field, we prove that the classic lift formula $L=-{\it\rho}_{0}U{\it\Gamma}_{{\it\phi}}$, originally derived by Joukowski in 1906 for inviscid potential flow, and the drag formula $D={\it\rho}_{0}UQ_{{\it\psi}}$, derived for incompressible viscous flow by Filon in 1926, are universally true for the whole field of viscous compressible flow in a wide range of Mach number, from subsonic to supersonic flows. Here, ${\it\Gamma}_{{\it\phi}}$ and $Q_{{\it\psi}}$ denote the circulation of the longitudinal velocity component and the inflow of the transverse velocity component, respectively. We call this result the Joukowski–Filon theorem (J–F theorem for short). Thus, the steady lift and drag are always exactly determined by the values of ${\it\Gamma}_{{\it\phi}}$ and $Q_{{\it\psi}}$, no matter how complicated the near-field viscous flow surrounding the body might be. However, velocity potentials are not directly observable either experimentally or computationally, and hence neither are the J–F formulae. Thus, a testable version of the J–F formulae is also derived, which holds only in the linear far field. Due to their linear dependence on the vorticity, these formulae are also valid for statistically stationary flow, including time-averaged turbulent flow. Thus, a careful RANS (Reynolds-averaged Navier–Stokes) simulation is performed to examine the testable version of the J–F formulae for a typical airfoil flow with Reynolds number $Re=6.5\times 10^{6}$ and free Mach number $M\in [0.1,2.0]$. The results strongly support and enrich the J–F theorem. The computed Mach-number dependence of $L$ and $D$ and its underlying physics, as well as the physical implications of the theorem, are also addressed.

Vortex-Induced Rotations of a Pair of Laterally Arranged Square Cylinder in a Two-Dimensional Microchannel

2020 ◽  
Author(s):  
Lichun Li ◽  
Shanshan Li ◽  
Zhe Yan ◽  
Zhenhai Pan
Keyword(s):  
Reynolds Number ◽  
Fluid Structure Interaction ◽  
Interaction Mechanism ◽  
Time History ◽  
Two Dimensional ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Velocity Magnitude ◽  
Square Cylinders ◽  
Lift And Drag

Abstract This paper investigates the dynamic response of two freely rotatable rigid square cylinders to two-dimensional laminar flow in a microchannel. The square cylinders are laterally pinned side-by-side in the microchannel with a single freedom of rotation. Finite volume method coupled with a dynamic mesh technique is developed and validated to reveal the detailed motion characteristics of the cylinders and nearby flow structures. Under small Reynolds number (Re = 50), both cylinders oscillate periodically. The oscillate curves (rotating angle v.s. time) are symmetrical with each other but with a certain phase difference. At Re = 150, both cylinders oscillate randomly. Under high Reynolds number (Re = 300), the two cylinders both keep rotating in the opposite direction with the velocity magnitude fluctuating drastically around 1.75. Important motion details are presented to understand the Fluid-Structure interaction mechanism under different Reynolds number, including the time history of rotating angles and rotating velocities, lift and drag coefficients on the cylinders, distribution of pressure around the cylinder sides. Both pressure-induced torque and the shear induced one are obtained and their contributions to both cylinders’ rotation characteristics are quantitatively evaluated. Vortex structures and streamlines around the cylinders at specific moments are also revealed in this paper to help understanding the fluid-structure interaction phenomenon.

LIFT AND DRAG OF A TWO-DIMENSIONAL PAD SLIDING UPON A POROUS SURFACE

1996 ◽  
Vol 20 (4) ◽  
pp. 349-363
Author(s):  
André Desseaux ◽  
Jean-Luc Menet
Keyword(s):  
Approximate Solution ◽  
Vertical Velocity ◽  
Similarity Solution ◽  
Numerical Results ◽  
Porous Surface ◽  
Quasilinearization Method ◽  
Two Dimensional ◽  
Governing Equations ◽  
Lift And Drag ◽  
Asymptotic Formulation

We consider the influence of withdrawal or injection of a fluid through a porous surface on the flow limited by a long parallel slider. Due to the no-slip conditions, the flow lacks of symmetry. But, a choice for a vertical velocity independent on the gap between the two surfaces is equivalent to a classical similarity solution. Then, the governing equations are reduced to a set of three ordinary differential equations. The quasilinearization method is a powerful tool to resolve these equations as soon as a first approximate solution is known. In both cases of small and large values for Re, we present an asymptotic formulation and use these first solutions for the scheme. A comparison with our numerical results shows that, respectively, these two approximations can be used until Re<5 for the first one and if Re>25 for the second. The different numerical results (velocity profiles, pressure, lift and drag) as functions of Re are analysed and compared with other published values.

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