Wall Effects in Cavitating Hydrofoil Flow

1957 ◽  
Vol 1 (04) ◽  
pp. 31-50
Author(s):  
Hirsh Cohen ◽  
C. D. Sutherland ◽  
Tu Yih-O
Keyword(s):  
Flat Plate ◽  
Linear Theory ◽  
Cavity Length ◽  
Two Dimensional ◽  
Cavity Model ◽  
Transition Flow ◽  
Wall Effects ◽  
Special Cases ◽  
Two Dimensional Flow ◽  
Cavitating Hydrofoil

A linearized version of the transition-flow cavity model is used to obtain the effects of solid channel walls on cavitating hydrofoils. The formulation is in terms of two dimensional flow but includes any shape hydrofoil within the scope of the linear theory and any location of the foil between the walls. The case of the flat plate foil is considered in numerical detail. Three special cases of position, the foil midway between walls, near to only one wall, and the foil in an infinite stream (walls infinitely far apart), are taken up. The effect of the walls on lift and cavity length are discussed for each case.

A non-linear theory for a full cavitating hydrofoil in a transverse gravity field

1967 ◽  
Vol 29 (2) ◽  
pp. 317-336 ◽  
Author(s):  
Bruce E. Larock ◽  
Robert L. Street
Keyword(s):  
Gravity Field ◽  
Linear Theory ◽  
Mixed Boundary ◽  
Linear Method ◽  
Two Dimensional ◽  
Mixed Boundary Value Problem ◽  
Cavity Model ◽  
Cavity Size ◽  
Non Linear ◽  
Cavitating Hydrofoil

An analysis is made of the effect of a transverse gravity field on a two-dimensional fully cavitating flow past a flat-plate hydrofoil. Under the assumption that the flow is both irrotational and incompressible, a non-linear method is developed by using conformal mapping and the solution to a mixed-boundary-value problem in an auxiliary half plane. A new cavity model, proposed by Tulin (1964a), is employed. The solution to the gravity-affected case was found by iteration; the non-gravity solution was used as the initial trial of a rapidly convergent process. The theory indicates that the lift and cavity size are reduced by the gravity field. Typical results are presented and compared to Parkin's (1957) linear theory.

A Numerical Optimization Technique Applied to the Design of Two-Dimensional Cavitating Hydrofoil Sections

1996 ◽  
Vol 40 (01) ◽  
pp. 28-38
Author(s):  
Shigenori Mishima ◽  
Spyros A. Kinnas
Keyword(s):  
Numerical Optimization ◽  
Cavity Length ◽  
Optimization Technique ◽  
Cavitation Number ◽  
Quadratic Functions ◽  
Two Dimensional ◽  
Systematic Design ◽  
Hydrodynamic Analysis ◽  
Total Drag ◽  
Cavitating Hydrofoil

A numerical nonlinear optimization technique is applied to the systematic design of two-dimensional partially or supercavitating hydrofoil sections. The design objective is to minimize the hydrofoil drag for given lift and cavitation number. The hydrodynamic analysis of the cavitating hydrofoil is performed in nonlinear theory, via a low-order potential-based panel method. The effects of viscosity are taken into account via a uniform friction coefficient applied on the wetted foil surface. The total drag, lift, cavitation number, and other quantities involved in the imposed constraints, are expressed in terms of quadratic functions of the main parameters of the hydrofoil geometry, angle of attack, and the cavity length. The optimization is based on the method of multipliers by coupling the Lagrange multiplier terms and the penalty function terms. The robustness and convergence of the method are extensively investigated, and the results are compared with those from applying other design methods.

The slow transverse motion of a flat plate through a non-diffusive stratified fluid

1971 ◽  
Vol 47 (1) ◽  
pp. 171-181 ◽  
Author(s):  
G. S. Janowitz
Keyword(s):  
Viscous Fluid ◽  
Shear Layer ◽  
Flat Plate ◽  
Kinematic Viscosity ◽  
Vertical Plate ◽  
The Body ◽  
Vertical Shear ◽  
Transverse Motion ◽  
Two Dimensional ◽  
Two Dimensional Flow

We consider the two-dimensional flow produced by the slow horizontal motion of a vertical plate of height 2b through a vertically stratified (ρ = ρ0(1 - βz)) non-diffusive viscous fluid. Our results are valid when U2 [Lt ] Ub/ν [Lt ] 1, where U is the speed of the plate and ν the kinematic viscosity of the fluid. Upstream of the body we find a blocking column of length 10−2b4/(Uν/βg. This column is composed of cells of closed streamlines. The convergence of these cells near the tips of the plate leads to alternate jets. The plate itself is embedded in a vertical shear layer of thickness (Uν/βg)1/3. In the upstream portion of this layer the vertical velocities are of order U and in the downstream portion of order Ub/(Uν/βg)1/3 ([Gt ] U). The flow is uniform and undisturbed downstream of this layer.

Resistance of Two Inclined Parallel Flat Plates Placed in Tandem on a Stream-Wise Flat Plate in Two-Dimensional Flow

1993 ◽  
Vol 207 (6) ◽  
pp. 393-397
Author(s):  
R C Mehta ◽  
C R Rao ◽  
Y N Dubey
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Flat Plate ◽  
Flow Direction ◽  
Considerable Extent ◽  
Appreciable Effect ◽  
Two Dimensional ◽  
Flat Plates ◽  
Dimensional Flow ◽  
Two Dimensional Flow

The paper presents the results of an experimental study on the drag coefficient of two inclined parallel flat plates, placed on a stream-wise flat plate, in tandem, in two-dimensional flow. The effects on the drag coefficient of Reynolds number, the inclination of the plates to the flow direction and the relative spacing between plates were studied. It is observed that, while the Reynolds number has no appreciable effect, the other parameters influence the drag coefficient to a considerable extent. The results are corrected for blockage effect and comparisons are made with the data collected by other investigators.

On the drag of two-dimensional flow about a normal flat plate

1998 ◽  
Author(s):  
Chih-Yung Wen ◽  
Chih-Hsien Chuang ◽  
Tzu-Yao Lin
Keyword(s):  
Flat Plate ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Two Dimensional Flow

An Inviscid Analysis in Polar Coordinates of Flow Between Two Flat Plates

1993 ◽  
Vol 60 (1) ◽  
pp. 65-69
Author(s):  
D. N. Contractor
Keyword(s):  
Numerical Solution ◽  
Flat Plate ◽  
Equation Of Motion ◽  
Polar Coordinates ◽  
Two Dimensional ◽  
Bernoulli Equation ◽  
Simultaneous Solution ◽  
Flat Plates ◽  
External Point ◽  
Two Dimensional Flow

An inviscid analysis is conducted of two-dimensional flow between a flat plate pivoting about an external point and falling onto another plate at rest. The motion of the fluid between the two plates is analyzed by the simultaneous solution of the unsteady Bernoulli equation, the equation of continuity, and the equation of motion for the plate. Numerical solution of the equations resulted in velocities and pressures along the plate as a function of time. The pressures were integrated to yield forces and moments on the falling plate. The results are compared with the motion of a horizontal flat plate falling vertically onto a rigid stationary flat plate. The two results are similar to one another.

Effect of Separation on Partial Cavitation

1988 ◽  
Vol 110 (2) ◽  
pp. 182-189 ◽  
Author(s):  
C. Pellone ◽  
A. Rowe
Keyword(s):  
Boundary Layer ◽  
Calculation Method ◽  
Cavitating Flow ◽  
Experimental Results ◽  
Separation Point ◽  
Two Dimensional ◽  
Flow Conditions ◽  
Partial Cavitation ◽  
Two Dimensional Flow ◽  
Cavitating Hydrofoil

Partially cavitating flow around a hydrofoil in a confined two-dimensional flow is presented. The calculation method, based on the singularities technique combined with a minimisation method, is adapted to open configurations. With this extension, cavity wakes not necessarily merging with the upper-side of the foil can be treated. In the case of subcavitating flow, a boundary layer calculated is made, indicating a separation point downstream of which the flow becomes separated. In this area, an imaginary streamline (wake) is introduced to simulate the effect of separation. The choice of different forms of wake clearly shows the influence of wake form on the value of results. The process is extended to the case of cavitating flow for wakes developing behind the cavity. The method is applied to a test cavitating hydrofoil placed in a tunnel. Several cavity wakes progressively diverging from the foil were tested. The results obtained, compared with experimental results, show the great importance of achieving more accurate modelling of flow conditions behind cavities.

Steady two-dimensional flow past a normal flat plate

1991 ◽  
Vol 42 (4) ◽  
pp. 584-604 ◽  
Author(s):  
D. B. Ingham ◽  
T. Tang ◽  
B. R. Morton
Keyword(s):  
Flat Plate ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Flow Past ◽  
Two Dimensional Flow
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