A Note on Gravity Effects in Supercavitating Flow

1965 ◽  
Vol 9 (01) ◽  
pp. 39-45
Author(s):  
R. L. Street
Keyword(s):  
Gravity Field ◽  
Quantitative Agreement ◽  
Cavitation Number ◽  
Number Range ◽  
First Order ◽  
Average Value ◽  
Flow Past ◽  
Supercavitating Flow ◽  
Gravity Effects ◽  
Linearized Theory

Two approximations to the linearized theory for supercavitating flow about slender bodiesare applied to the case of flow past a slender wedge in a transverse gravity field. The additional lift and moment forces arising as a result of the gravity field are calculated by theories that are expected to hold when the gravity effects are of first-order smallnessconsistent with the linearization appi'oximations. The lift and moment coefficients obtained from the two approximations are in general quantitative agreement over the most important cavitation-number range. The results obtained confirm the validity of the average-value approximation introduced by Parkin.

Supercavitating Flow About a Slender Wedge in a Transverse Gravity Field

1963 ◽  
Vol 7 (03) ◽  
pp. 14-23
Author(s):  
R. L. Street
Keyword(s):  
Gravity Field ◽  
First Order ◽  
Flow Past ◽  
Supercavitating Flow ◽  
Linearized Theory

In this paper a linearized theory is developed for supercavitating flow past a slender strut or wedge in a transverse gravity field. The theory is expected to be valid when the effects of the gravity field are of first-order smallness consistent with the linearization approximations. The additional lift and moment forces acting on the strut as a result of the gravity field are calculated. The transverse gravity field is found to produce additional forces which should be considered in hydrodynamic design.

scholarly journals The Effect of a Longitudinal Gravitational Field on the Supercavitating Flow Over a Wedge

1961 ◽  
Vol 28 (2) ◽  
pp. 188-192 ◽  
Author(s):  
A. J. Acosta
Keyword(s):  
Gravitational Field ◽  
Drag Coefficient ◽  
Froude Number ◽  
Cavitation Number ◽  
Streamline Flow ◽  
Flow Past ◽  
Supercavitating Flow ◽  
Linearized Theory

The free-streamline flow past a symmetrical wedge in the presence of a longitudinal gravitational field is determined with a linearized theory. The proportions of the cavity depend upon the cavitation number and Froude number. The drag coefficient is likewise affected by gravity, though to a smaller extent.

Experiments on Gravity Effects in Supercavitating Flow

1966 ◽  
Vol 10 (02) ◽  
pp. 119-121
Author(s):  
T. Kiceniuk ◽  
A. J. Acosta
Keyword(s):  
Gravitational Field ◽  
Froude Number ◽  
Flow Past ◽  
Supercavitating Flow ◽  
Gravity Effects

Experiments on the effect of a transverse gravitational field on the supercavitating flow past a wedge tend to confirm predictions based on linearized free-streamline theory. A small though systematic dependence upon Froude number not accounted for by the existing theory is revealed, however.

A linearized theory for rotational supercavitating flow

1963 ◽  
Vol 17 (4) ◽  
pp. 513-545 ◽  
Author(s):  
Robert L. Street
Keyword(s):  
Shear Flow ◽  
Flow Past ◽  
Supercavitating Flow ◽  
Harmonic Perturbation ◽  
Two Dimensional Flow ◽  
Slender Bodies ◽  
Linearized Theory ◽  
Particular Solution ◽  
Effects Of Rotation ◽  
Rotational Problem

In this paper methods are given for establishing qualitative and quantitative measures of the effects of rotation in supercavitating flows past slender bodies. A linearized theory is developed for steady, two-dimensional flow under the assumption that the flow has a constant rotation throughout. The stream function of the rotational flow satisfies Poisson's equation. By using a particular solution of this equation, the rotational problem is reduced to a problem involving Laplace's equation and harmonic perturbation velocities. The resulting boundary-value problem is solved by use of conformal mapping and singularities from thinairfoil theory. The theory is then applied to asymmetric shear flow past wedges and hydrofoils and to symmetric shear flow past wedges. The presence of rotation is shown to create significant changes in the forces acting on the slender bodies and in the shape and size of the trailing cavities.

Supercavitating Flow Past Slender Delta Wings

1959 ◽  
Vol 3 (04) ◽  
pp. 17-22
Author(s):  
Marshall P. Tulin
Keyword(s):  
Jet Flow ◽  
Cavitation Number ◽  
Conical Flow ◽  
Delta Wings ◽  
Flow Past ◽  
Supercavitating Flow ◽  
Leading Edges ◽  
Surface Increase

The supercavitating flow past slender delta wings is studied. Theory is developed for a conical flow involving cavities which spring from the leading edges of the delta and cover a part of the top of the wing; the center part of the wing top is assumed to be wetted by a kind of re-entrant jet flow. Results are obtained for the two separate asymptotic cases in which the cavitation number is either very small or very large. The widths of the cavities on the wing upper surface increase with decreasing σ and the lift decreases. It is shown that the upper surface never becomes completely enveloped in a cavity even for σ = 0. Finally, the lift of a fully cavitated wing (σ = 0) is estimated to be approximately 4/10 of its fully wetted lift.

Leading-Edge Correction for the Supercavitating Flat-Plate Hydrofoil

1978 ◽  
Vol 100 (3) ◽  
pp. 276-280
Author(s):  
Allen Plotkin
Keyword(s):  
Exact Solution ◽  
Flat Plate ◽  
Asymptotic Expansions ◽  
Potential Flow ◽  
Leading Edge ◽  
Cavitation Number ◽  
Matched Asymptotic Expansions ◽  
First Order ◽  
Flow Past

A leading-edge correction is obtained via the method of matched asymptotic expansions to the first-order linearized solution for the potential flow past a supercavitating flat-plate hydrofoil at zero cavitation number. The composite expansions for the pressure on the plate and the shape of the upper cavity are seen to compare well with the exact solution due to Rayleigh.

On Flow Past a Supercavitating Cascade of Cambered Blades

1972 ◽  
Vol 94 (1) ◽  
pp. 163-168 ◽  
Author(s):  
C. C. Hsu
Keyword(s):  
Numerical Results ◽  
Points Of Interest ◽  
Flow Past ◽  
Supercavitating Flow ◽  
Linearized Theory ◽  
Flow Through

A linearized theory for supercavitating flow through a cascade of cambered blades is developed. Numerical results illustrating various points of interest are presented.

Linearized Theory of Supercavitating Hydrofoils in Subsonic Liquid Flow

1977 ◽  
Vol 99 (2) ◽  
pp. 311-318
Author(s):  
Tetsuo Nishiyama
Keyword(s):  
Incompressible Flow ◽  
Liquid Flow ◽  
Sound Speed ◽  
Gas Flow ◽  
Three Dimensional ◽  
Cavitation Number ◽  
Compressibility Effect ◽  
Linearized Theory ◽  
Velocity Pressure ◽  
Subsonic Region

In order to clarify the compressibility effect, the perturbed flow field of the supercavitating hydrofoil in subsonic region is examined by a linearized technique and, as a result, the general corresponding rule of the compressible flow to the incompressible one is proposed to obtain the characteristics of the supercavitating hydrofoil. The main contents are summarized as follows: (i) Basic relations between velocity, pressure, and sound speed are shown in subsonic liquid flow within the framework of linearization. (ii) The correspondence of the steady, characteristics of the two and three dimensional supercavitating hydrofoils in subsonic liquid flow to ones in incompressible flow is clarified. Hence we can readily calculate the characteristics by simple correction to ones in incompressible flow. (iii) Numerical calculations are made to show the essential differences of the compressibility effect between liquid and gas flow, and also the interrelated effect between cavitation number and Mach number on the characteristics of the supercavitating hydrofoils.

scholarly journals Density-thermal dependence of sedimentary associations calls to reinterpreting detailed gravity surveys

2015 ◽  
Vol 58 ◽  
Author(s):  
Vagif G. Gadirov ◽  
Lev V. Eppelbaum
Keyword(s):  
Gravity Field ◽  
Underground Water ◽  
Temperature Data ◽  
Field Analysis ◽  
Thermal Dependence ◽  
Temperature Changes ◽  
Buried Objects ◽  
Gravity Effects ◽  
Hydrocarbon Deposits ◽  
Hydrocarbon Deposit

<p>The modern gravimetric equipment allows to register very small effects of gravity field changes and can be applied solving different geological, geophysical and environmental problems. However, sometimes insufficient calculation of various kinds of geological noise complicates effective application of detailed gravity field analysis. One of such factors is the temperature regime over and outside different buried objects of investigation. In this paper temperature changes in a subvertical zone over a hydrocarbon deposit and outside its contour are analyzed. The integrated density change and corresponding gravity effects are calculated for the Muradkhanly oil deposit situated within the south-east part of the Middle Kura Depression (central Azerbaijan). Calculation of these effects on the basis of density- temperature data correlation analysis could significantly improve the microgravity field examination over the hydrocarbon deposits. The similar correction procedure may be applied also over underground water horizons and some environmental targets.</p>

scholarly journals Cavitating flow-induced unsteady pressure pulsations in a low specific speed centrifugal pump

2018 ◽  
Vol 5 (7) ◽  
pp. 180408 ◽  
Author(s):  
Ning Zhang ◽  
Bo Gao ◽  
Zhong Li ◽  
Qifeng Jiang
Keyword(s):  
Critical Point ◽  
Cavitation Bubble ◽  
Pressure Wave ◽  
High Energy ◽  
Cavitation Number ◽  
Centrifugal Pumps ◽  
Pressure Pulsations ◽  
Measuring Point ◽  
Number Range ◽  
Cavitation Region

With the development of cavitation, the high-energy pressure wave from a cavitation bubble collapsing is detrimental to the stable operation of centrifugal pumps. The present paper concentrates on pressure pulsations under cavitation conditions, and pressure amplitudes at the blade-passing frequency ( f BPF ) and RMS values in the 0–500 Hz frequency band are combined to investigate cavitation-induced pressure pulsations. The results show that components at f BPF always dominate the pressure spectrum even at the full cavitation stage. For points P1–P7 on the volute side wall, with a decreasing cavitation number, the pressure energy first remains unchanged and then it rises rapidly after the critical point. For point In1 in a volute suction pipe located close to the cavitation region, the pressure energy changes slightly at high cavitation numbers; then for a particular cavitation number range, the pressure energy decreases, and finally increases again. For different flow rates, the pressure energy at the critical point is much lower than the initial amplitude at the non-cavitation condition for In1. This demonstrates that the cavitation cloud in the typical stage is partially compressible, and the emitted pressure wave from a collapsing cavitation bubble is absorbed and attenuated significantly. Finally, this leads to the pressure energy decreasing rapidly for the measuring point In1 near the cavitation region.

Sign in / Sign up

Export Citation Format

Share Document