SU958891A1 - Method of creating sea-way in experiment pool - Google Patents

Description

(54) METHOD FOR CREATING AN EXCITATION IN THE EXPERIENCE BASIN

one

The invention relates to experimental hydromechanics, in particular, to installations for the creation of artificial waves in experimental basins, which is necessary for the study of the hydrodynamic characteristics of ship models.

There is a known method of creating waves in the EXPERIMENT pool to study the dynamics of floating objects, in which the plate immersed in the pool water is pivotally attached to the bottom of the pool in a vertical position and oscillates at the free end 1.

The disadvantage of this method is that in this case two systems of waves arise, one of which is parasitic and requires the presence of wave-suppressing devices for its destruction. In addition, this method is characterized by an uneven wave generated by the plate.

There is also known a method of creating waves, in which a horizontal plate is moved in the horizontal direction with simultaneous vibrations in the vertical plane of its center of gravity and its angular oscillations relative to the latter 2.

However, this method of creating waves does not allow one to obtain an ideal system of harmonic waves, since this generates two systems of the latter, directed in the same direction — against the movement of the plate. By changing the design parameters of the oscillation mechanism, one of the wave systems can be significantly weakened, but it cannot be completely destroyed in a large frequency range without significantly attenuating the useful wave system, which leads to a decrease in the reliability of the amplitude and phase-frequency characteristics of the objects.

The purpose of the invention is to improve the reliability of the phase and amplitude-frequency characteristics of the test objects and to ensure the creation of a single system of harmonic waves.

Claims (2)

The goal is achieved by moving the plate with a shift of its angular oscillations relative to the oscillations of the center of the tin plate in the vertical plane in phase by -5- (2n-1) while observing the following ratio of the amplitudes of these oscillations. H) (), where Ats is the amplitude of the vertical oscillations of the center of the body of the plate; Augl is the amplitude of the plate angular oscillations about its center of gravity; Vo is the plate moving speed; 6 - circular oscillation frequency; 3 | Rh — Bessel functions of the first and second order of the 1st kind; g is the acceleration of the earth's t goteni; n is the number of the natural row (1, 2, b is the width of the plate. The application of the proposed method is carried out as follows. In a test basin equipped with a towing cart, a plate is installed on the latter in the horizontal plane, behind which is the object under study, for example, a ship model. the movement of the towing carriage simultaneously moves the plate along the MOHHtigq oMy law in a vertical plane and the plate oscillates about an axis passing perpendicular to the direction of movement through the center of the tube. plate with phase displacement of angular oscillations relative to oscillations of its center of gravity (2p 1). During the tests, the previously mentioned ratio of the amplitudes of these oscillations should be observed. The proposed method of creating waves in the test basin increases the accuracy of the amplitude and phase-frequency characteristics of the objects under study, as it allows creating a single system of harmonic waves whose parameters relative to the object under study are stable and do not depend on the length of the basin. The invention of the method of creating a wave in a test basin using a horizontal plate and moving plate with simultaneous harmonic oscillations about the center of gravity in the vertical plane and angular oscillations about the vertical axis passing through the center of the plate gravity, characterized in that In order to improve the reliability of the phase and amplitude-frequency characteristics of the test objects and ensure the creation of a single system of harmonic waves, the movement of the plate with the displacement of its angular oscillations oTHOCHTejjbHo oscillations of the center of gravity in the vertical plane out of phase by | - (2p-1) while observing the following ratio of the amplitudes of these oscillations Lit VL I l 1 Augl-6 + t TR where tin plate; Aug is the amplitude of the plate's angular oscillations relative to its center of gravity; PP - the rate of movement of the plastiy; 6 - circular oscillation frequency; Oh, Bessel functions of the first and second order of the 1st kind; g is the acceleration of the earth's t goteni; n - the number of natural p yes (1,2, 3, ...); B is the plate width. Sources of information taken into account in the examination 1. Modern foreign shipbuilding hydrodynamic laboratories. Review of the Research Institute of them. Acad. A. N. Krylov. L., “Shipbuilding, 1969, p. 75 2. USSR author's certificate number 601588, cl. O 01 M 10/00, 1978 (about. Totype).