Exact Supercavitating Cascade Theory

1975 ◽  
Vol 97 (4) ◽  
pp. 419-428 ◽  
Author(s):  
O. Furuya
Keyword(s):  
Experimental Data ◽  
Flat Plate ◽  
Present Method ◽  
Functional Equations ◽  
Two Dimensional ◽  
Circular Arc ◽  
Nonlinear Functional ◽  
Cascade Theory ◽  
Supercavitating Flow ◽  
Method Show

A nonlinear exact theory to investigate a steady two-dimensional supercavitating flow past a cascade of arbitrarily shaped blades is presented. The solutions obtained by numerically solving a system of nonlinear, functional equations are compared with the available experimental data for flat-plate cascades and with linearized theories for both flat-plate and circular arc cascades. The force coefficients calculated with the present method show considerably smaller values than those of the linearized theories, as is expected.

Evaluation of Pressure Distribution on a Cavitating Hydrofoil With Flap

1967 ◽  
Vol 11 (02) ◽  
pp. 93-108
Author(s):  
Z. L. Harrison ◽  
Duen-pao Wang
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Pressure Distribution ◽  
Flat Plate ◽  
Flow Model ◽  
Wake Flow ◽  
Two Dimensional ◽  
The Moment ◽  
Cavitating Hydrofoil ◽  
General Method

A general method is established to calculate the pressure distribution and the moment of force for a two-dimensional, supercavitating hydrofoil with a flap. The wake flow model is adopted to describe the configuration of the flow field. Some numerical results for a supercavitating flat plate with a flap are compared with the corresponding experimental data.

Experiments on Circular-Arc and Flat-Plate Hydrofoils

1958 ◽  
Vol 2 (01) ◽  
pp. 34-67
Author(s):  
Blaine R. Parkin
Keyword(s):  
Flat Plate ◽  
High Speed ◽  
Cavity Flow ◽  
Hydrodynamic Characteristics ◽  
Water Tunnel ◽  
Pitching Moment ◽  
Two Dimensional ◽  
Circular Arc ◽  
Wide Range ◽  
Good Agreement

An investigation in the High-Speed Water Tunnel of the two-dimensional hydrodynamic characteristics of sharp-edged hydrofoils is described. The lift, drag, and pitching moment were measured in cavitating and noncavitating flows for flat-plate and circular-arc profiles. The theory of Wu for the forces on sharp-edged profiles in full-cavity flow and the experimental results showed good agreement over a wide range of attack angles.

Hypersonic viscous interaction on curved surfaces

1970 ◽  
Vol 43 (3) ◽  
pp. 497-511 ◽  
Author(s):  
J. L. Stollery
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Flow Field ◽  
Flat Plate ◽  
Hypersonic Flow ◽  
Curved Surfaces ◽  
Two Dimensional ◽  
Alternative Analysis ◽  
Viscous Interaction ◽  
Wedge Pressure

Cheng's analysis of strong viscous interaction between a laminar boundary layer growing over a flat plate and the external hypersonic flow field is extended to cover curved surfaces. It is demonstrated that the solutions for some concave surfaces are oscillatory and quantitatively unrealistic. The reason for this behaviour is that the Busemann term in the Newton–Busemann pressure law used in Cheng's analysis over-corrects for centrifugal effects. The removal of the Busemann term or the substitution of the tangent-wedge pressure law results in an alternative analysis which can cover both strong and weak viscous interaction over a wide variety of two-dimensional shapes. A number of examples are included together with comparative experimental data.

An Experimental and Theoretical Study on Cavitating Cascades and Their Application to Cavitating Propellers

1985 ◽  
Vol 29 (01) ◽  
pp. 23-38
Author(s):  
Okitsugu Furuya ◽  
Shin Maekawa
Keyword(s):  
Experimental Data ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Simple Method ◽  
Cascade Theory ◽  
Wide Range ◽  
Line Theory ◽  
Lifting Line ◽  
Lifting Line Theory

In order to develop an analytical tool for predicting the off-design performance of supercavitating propellers over a wide range of operating conditions, a lifting-line theory was combined with a two-dimensional supercavitating cascade theory. The results of this simple method provided fairly accurate predictions for the performance at fully developed cavitating conditions. It was indicative that the fully developed supercavitating (s/c) propellers had strong cascade effects on their performance, and also that the three-dimensional propeller geometry corrections could properly be made by the lifting-line theory. However, the predicted performance with this propeller theory showed a significant deviation from experimental data in the range of J's larger than Jdesign, where partially cavitating conditions are expected to occur. Effort was then made on improving the prediction capability of the above propeller theory at partially cavitating (p/c) conditions. A new nonlinear partially cavitating cascade theory was then developed to provide a proper 2-D loading basis under such conditions. Two-dimensional cascade experiments were then conducted to prove the accuracy of the p/c and s/c cascade theories. The measured forces and flow observations obtained in these experiments shed a new light on the relationship between the forces and cavitation numbers at small angles of incidence. Corrected lift and drag forces were then used in the propeller program. The calculated results for KT and KQ with the new force data successfully correlated with the experimental data, now covering a large J-range where the partially cavitating conditions exist.

Modelling of Moisture Movement in Wood during Outdoor Storage

2001 ◽  
Vol 6 (2) ◽  
pp. 3-14 ◽  
Author(s):  
R. Baronas ◽  
F. Ivanauskas ◽  
I. Juodeikienė ◽  
A. Kajalavičius
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
Climatic Conditions ◽  
Two Dimensional ◽  
Moisture Movement ◽  
Finite Difference Technique ◽  
Long Term Storage ◽  
Space Formulation ◽  
Term Storage

A model of moisture movement in wood is presented in this paper in a two-dimensional-in-space formulation. The finite-difference technique has been used in order to obtain the solution of the problem. The model was applied to predict the moisture content in sawn boards from pine during long term storage under outdoor climatic conditions. The satisfactory agreement between the numerical solution and experimental data was obtained.

scholarly journals Modelling Weirs in Two-Dimensional Shallow Water Models

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2152
Author(s):  
Gonzalo García-Alén ◽  
Olalla García-Fonte ◽  
Luis Cea ◽  
Luís Pena ◽  
Jerónimo Puertas
Keyword(s):  
Experimental Data ◽  
Shallow Water ◽  
Shallow Water Equations ◽  
Water Model ◽  
Two Dimensional ◽  
Shallow Water Model ◽  
Experimental Dataset ◽  
River Hydraulics ◽  
Shallow Water Models ◽  
Water Models

2D models based on the shallow water equations are widely used in river hydraulics. However, these models can present deficiencies in those cases in which their intrinsic hypotheses are not fulfilled. One of these cases is in the presence of weirs. In this work we present an experimental dataset including 194 experiments in nine different weirs. The experimental data are compared to the numerical results obtained with a 2D shallow water model in order to quantify the discrepancies that exist due to the non-fulfillment of the hydrostatic pressure hypotheses. The experimental dataset presented can be used for the validation of other modelling approaches.

Steady detonation propagation in a circular arc: a Detonation Shock Dynamics model

2016 ◽  
Vol 807 ◽  
pp. 87-134 ◽  
Author(s):  
Mark Short ◽  
James J. Quirk ◽  
Chad D. Meyer ◽  
Carlos Chiquete
Keyword(s):  
Surface Wave ◽  
Angular Speed ◽  
Order Correction ◽  
Two Dimensional ◽  
Normal Surface ◽  
Circular Arc ◽  
First Order ◽  
Shock Dynamics ◽  
First Order Correction ◽  
Steady Detonation

We study the physics of steady detonation wave propagation in a two-dimensional circular arc via a Detonation Shock Dynamics (DSD) surface evolution model. The dependence of the surface angular speed and surface spatial structure on the inner arc radius ($R_{i}$), the arc thickness ($R_{e}-R_{i}$, where $R_{e}$ is the outer arc radius) and the degree of confinement on the inner and outer arc is examined. We first analyse the results for a linear $D_{n}$–$\unicode[STIX]{x1D705}$ model, in which the normal surface velocity $D_{n}=D_{CJ}(1-B\unicode[STIX]{x1D705})$, where $D_{CJ}$ is the planar Chapman–Jouguet velocity, $\unicode[STIX]{x1D705}$ is the total surface curvature and $B$ is a length scale representative of a reaction zone thickness. An asymptotic analysis assuming the ratio $B/R_{i}\ll 1$ is conducted for this model and reveals a complex surface structure as a function of the radial variation from the inner to the outer arc. For sufficiently thin arcs, where $(R_{e}-R_{i})/R_{i}=O(B/R_{i})$, the angular speed of the surface depends on the inner arc radius, the arc thickness and the inner and outer arc confinement. For thicker arcs, where $(R_{e}-R_{i})/R_{i}=O(1)$, the angular speed does not depend on the outer arc radius or the outer arc confinement to the order calculated. It is found that the leading-order angular speed depends only on $D_{CJ}$ and $R_{i}$, and corresponds to a Huygens limit (zero curvature) propagation model where $D_{n}=D_{CJ}$, assuming a constant angular speed and perfect confinement on the inner arc surface. Having the normal surface speed depend on curvature requires the insertion of a boundary layer structure near the inner arc surface. This is driven by an increase in the magnitude of the surface wave curvature as the inner arc surface is approached that is needed to meet the confinement condition on the inner arc surface. For weak inner arc confinement, the surface wave spatial variation with the radial coordinate is described by a triple-deck structure. The first-order correction to the angular speed brings in a dependence on the surface curvature through the parameter $B$, while the influence of the inner arc confinement on the angular velocity only appears in the second-order correction. For stronger inner arc confinement, the surface wave structure is described by a two-layer solution, where the effect of the confinement on the angular speed is promoted to the first-order correction. We also compare the steady-state arc solution for a PBX 9502 DSD model to an experimental two-dimensional arc geometry validation test.

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