Experimental Studies of High-Speed Cavitated Flows

Savchenko, Yu. N.; Vlasenko, Yu. D.; Semenenko, V. N.

doi:10.1615/interjfluidmechres.v26.i3.80

Cited by 34 publications

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“…General Problem Formulation. As already mentioned in the introduction, it is experimentally established fact [11] that a bubble forms around a supercavitating body. This supercavity has the form of a strongly elongated ellipsoid (aspect ratio of 70 to 200) that wholly encloses the moving body and contacts it only at the nose.…”

Section: Introductionmentioning

confidence: 89%

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Impact of a long thin body on a cylindrical cavity in liquid: A plane problem

Kubenko

2006

Int Appl Mech

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An approach is developed to the investigation of the shock interaction between a long thin cylindrical body and a cylindrical cavity in an infinite compressible perfect liquid. This process accompanies the suðercavitation of the body. Three typical cases of cross-sectional dimensions of the body and the cavity are examined. For each case, a mixed nonstationary boundary-value problem with an unknown moving boundary is formulated. The unknown quantities are expanded into Fourier series. An auxiliary problem is solved using the Laðlace transform to establish the relationship between the pressure and the velocity on the cavity surface. As a result, the problem is reduced to an infinite system of Volterra equations of the second kind solved simultaneously with the equation of transverse motion and the equation of the contact boundary. An asymptotic solution valid at the initial stage of interaction is obtained for all the three cases, and a numerical solution is found for the most typical case Keywords: shock interaction, suðercavitation, mixed problem 1. Introduction. A promising line of development of water (or, more specifically, underwater) transport is the creation of so-called supercavitating vehicles. Supercavitation is observed when a large vapor or gas bubble occurs behind a body passed by a rapidly streaming water. If such a bubble completely envelopes the moving body, the drag on it reduces significantly. In this case, the body, in effect, flies in a vapor/gas cavity and contacts with the liquid only at its nose equipped with a cavitator. The principles of high-speed hydrodynamics were developed and outlined in, e.g., [9]. Over the last decades, studies of supercavitation have been conducted in Russia, the USA, and Ukraine. Velocities close to the speed of sound in water were reached under laboratory conditions [11]. The prospects of implementing the supercaviation technology seem appealing. This explains the interest to supercavitation as a problem of high-speed hydromechanics.A specific feature of the process in question is the almost inevitable transverse motion of the body within the supercavity because of the instability of the primary (longitudinal) motion. The motion manifests itself over a wide range of velocities and consists in alternating impacts of the body on the lower and upper walls of the supercavity. This undesirable phenomenon causes the primary motion to loss energy or even to cease. Studying the laws governing the existence and development of transverse shock motion would help to create means for the stabilization of longitudinal motion. Previous studies (see, e.g., [12,18]) were mainly based on the assumption that the liquid is incompressible and the transverse velocity is given. The incompressible liquid model does not make reliable predictions at the early stage of shock interaction (this model predicts infinite hydrodynamic pressure at the initial moment of interaction, which defies common sense). Moreover, it appears expedient to study this process for an arbitrary relationship betw...

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Section: Introductionmentioning

confidence: 89%

“…Over the last decades, studies of supercavitation have been conducted in Russia, the USA, and Ukraine. Velocities close to the speed of sound in water were reached under laboratory conditions [11]. The prospects of implementing the supercaviation technology seem appealing.…”

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confidence: 99%

Impact of a long thin body on a cylindrical cavity in liquid: A plane problem

Kubenko

2006

Int Appl Mech

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“…The hydrodynamic and kinematic characteristics of the process are obtained Introduction. Recently, it has been experimentally proved that it is possible to create underwater vehicles based on supercavitation as a new physical principle of motion of bodies in water [14][15][16]24]. A supercavitating body is fully enveloped by a gas bubble, supercavity, and moves inside it at speeds commensurable with the speed of sound in water.…”

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confidence: 99%

“…Supercavitation arouses considerable interest of researchers. Recent results on supercavitation can be found in, e.g., [18,19].One of the challenges regarding supercavitation is to ensure stable motion of a body in a cavity [12,[14][15][16]24]. Only the nose of a supercavitating body is in contact with the surface of the cavity.…”

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Impact of a spherical rigid body on the surface of a cavity in a compressible liquid: An axisymmetric problem

Kubenko

Gavrilenko

2008

Int Appl Mech

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The shock interaction of a spherical rigid body with a spherical cavity is studied. This nonstationary mixed boundary-value problem with an unknown boundary is reduced to an infinite system of linear Volterra equations of the second kind and the differential equation of motion of the body. The hydrodynamic and kinematic characteristics of the process are obtained Introduction. Recently, it has been experimentally proved that it is possible to create underwater vehicles based on supercavitation as a new physical principle of motion of bodies in water [14][15][16]24]. A supercavitating body is fully enveloped by a gas bubble, supercavity, and moves inside it at speeds commensurable with the speed of sound in water. Supercavitation arouses considerable interest of researchers. Recent results on supercavitation can be found in, e.g., [18,19].One of the challenges regarding supercavitation is to ensure stable motion of a body in a cavity [12,[14][15][16]24]. Only the nose of a supercavitating body is in contact with the surface of the cavity. The drag exerted by water on the body within the contact region generates an overturning moment about the body's center of mass, making supercavitation unstable. This instability causes lateral impacts of the body against the surface of the cavity, which strongly affects the behavior of the body. This is why study into the impact of the body on the cavity surface is of importance.The supercavitation of a cylindrical body in a cylindrical cavity was studied in [5,22] and [8,19] considering the liquid to be incompressible and compressible, respectively. The hydrodynamic and kinematic loads (plane problem) were determined there.The motion of a spherical body in a spherical cavity (axisymmetric problem) was studied in a similar way. However, many scientists who studied axisymmetric cavities were mainly interested in their geometry, including the relationships between the cavity length and width, between the cavitation number and the body dimensions, and between the body length and the cavitation number [4,11].A spherical body's penetration of the surface of a spherical cavity in a compressible liquid was studied in [9, 20] and the hydrodynamic and kinematic characteristics of the process were determined there. In [9], an axisymmetric problem was formulated and its asymptotic solution was found for the initial stage of the process in the case of an infinitesimal air gap (the body and the cavity have the same transverse dimensions).In [20], a general problem formulation for an arbitrary air gap (a mixed nonstationary initial-boundary-value problem with an unknown boundary varying with time) was given, infinite governing systems of Volterra equations of the second kind were derived, and asymptotic solutions were obtained for the cases of small and infinitesimal air gaps. The present paper, which is based on the results from [20], gives a general problem formulation for an arbitrary air gap, derives infinite governing systems of Volterra equations of the second kind, and solves them nume...

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Some Singularities in Fluid Dynamics and Their Bifurcation Analysis

Zhang

Yan

2016

Nonlinear Systems and Complexity

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Experimental Studies of High-Speed Cavitated Flows

Cited by 34 publications

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Impact of a long thin body on a cylindrical cavity in liquid: A plane problem

Impact of a long thin body on a cylindrical cavity in liquid: A plane problem

Impact of a spherical rigid body on the surface of a cavity in a compressible liquid: An axisymmetric problem

Some Singularities in Fluid Dynamics and Their Bifurcation Analysis

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