SU439437A1 - A device for determining the hydrodynamic characteristics of a ship model when rolling on calm water - Google Patents

Description

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Devices are known for determining the hydrodynamic characteristics of a ship model when rolling on calm water, which contain a rocking chair with medium and extreme legs mounted on a support, and an electric drive with a rocker mechanism.

However, such devices are structurally complex and unreliable in action.

The purpose of the invention is to simplify the design of the device and increase its reliability in operation. For this, the rocking chair is made with double-sided consoles that interact with a removable stand of the model, the free end of which is equipped with a two-armed spring-loaded lever pivotally attached to the support, and the end of the middle rocking stand is attached to the wings, equipped with a conductive roller electrically connected through an interrupter, an electric pulse former , reversible transducer and rheostat with an electric motor drive. In this extreme rack rocking chair is equipped with a spring-loaded joint.

FIG. 1 schematically shows the device described in perspective; in fig. 2 shows electrical circuit diagram of the device.

A removable stand 2, connected by a hinge 3 to a lever 4 mounted on a hinged support 5, and connected by a hinge 6 to an adjustable force spring 8 attached to the support 7, is rigidly attached to the ship’s model 1.

With the stand 2, through the hinges 9 is connected a rocking chair, made in the form of a body 10, one example, of tubular form, mounted on stationary hinge supports 11 with the possibility of swinging and carrying double-sided consoles 12, to one end of each of which the hinges 9 are rigidly attached.

The housing 10 also carries posts 13 and 14. A vertical rod 15 is pivotally attached to the top of the rack 14, the upper end of which has a hinge 16 with the possibility of only vertical movement and is connected to an adjustable force spring 17 attached to the support 18. The rack 13 is pivotally connected with interchangeable spring 20, for example a plate. To the top of the rack 13 is rigidly attached to the rocker 21, kinematically

connected by an electrically conductive roller 22 to a crank 23, driven, for example, via a gear train 24 to rotate from a motor 25, the rotation speed of which is regulated by a rheostat 26. The drive unit is in the form of

motor 25 and gears 24 are articulated on bearings 27 so as to rotate around the axis of rotation of crank 23.

The measuring device is made in the form of a contactor 28, kinematically connected with

transmission output shaft 24 and electrically

associated with the stopwatch 29, as well as in the form of a spring-loaded arrow 30, rigidly attached to the casing of the electric motor 25 and -directed to the scale 31, tared, for example, in Gsm of torque. A plate 32 is attached to the arrow 30, lowered into the oil bath 33, serving as a damper for the angular oscillations of the drive unit.

The device also includes an automatic engine speed control system 25, made in the form of a mercury chopper 34 mechanically connected to the rocking chair, and two contacts 35, which are installed positively to one another in places corresponding to the dead points of the wings 21 flush with its guide surfaces. Moreover, the contacts are electrically isolated from the backstage, but connected to the chopper 34 by an electrically conductive roller 22 and two electric impulse generators 36, for example, multivibrators in standby mode, electrically connected to a reversible electric impulse converter 37 to move the rheostat 26, which is connected to the power circuit motor 25, preferably in its field winding. The fixed supports 5, 7, And, 18 and 27 are adjustable in height.

When tested on a vertical roll, the model I is lowered into an experienced pool, a rack 2 is attached to it, which is connected by a hinge 3 to the lever 4, and through the support 5 and the hinge 6 with the spring 8. The force of the latter is adjusted by moving the support 7 so that the model receives the specified draft. At the same time, the hinge 3 and the hinge of the support 5 are installed in the same horizontal plane. By adjusting the height of the supports 11, they are brought into a common horizontal plane with hinges 9, which are attached to the rack 2. Then the parts 15-20 adjust the frequency of the natural oscillations of the rocker with the model attached to it. By lowering the drive unit, the roller 22 is inserted inside the link 21.

When starting the engine 25, the roller 22 causes the rocker 21 in an oscillating motion, as a result of which the rocker oscillates, and with it the model 1. In this case, the roller, pressing one of the contacts 35, triggers one of the formers 36, the reversing converter 37 and the rheostat engine 26. As a result, the rotational speed of the engine 25 changes until the number of revolutions per minute of Krivoschin -23 becomes equal to the number of natural oscillations of the rocking chair with the model for the same period. After that, using the switch and contactor 28, the operator actuates. Seconds 29, observes and records his readings. By virtue of reactive motion, the drive unit, and with it the arrow 30, adjusted to the natural frequency of the oscillation is much less than the lower natural frequency of the oscillation with

model reject. On a scale of 31, the position of the arrows is observed visually and is recorded by the operator. The recorded readings of the hand 30 and the stopwatch 29 are used to calculate the drag coefficient.

and the coefficient of added mass with vertical helix.

In the course of rolling test, model 1 is installed in the experimental pool so that its diametrical plane coincides

with an oscillation axis of the rocking chair, and rigidly attached to the brackets 12 or to the rocking body 10. Rack 2 dismantled. All others are tuned and operated as in the roll test.

When testing for keel rolling, the model is installed in an experimental pool so that its diametrical plane is perpendicular to the oscillation axis of the rocking chair, and rigidly attached to the rocking chair. The rest of the test

It is the same as the rolling test.

Subject invention

A device for determining the hydrodynamic characteristics of a ship model when rolling on calm water, containing a rocking chair with medium and extreme legs, mounted on a support, and an electric drive with a rocker mechanism, characterized in that, in order to simplify its design and increase reliability, the rocking chair is balanced with two-sided brackets that interact with a removable stand model, the free end of which

equipped with a double-shouldered spring-loaded lever, pivotally attached to the support, and the end of the pillar rack is attached to the wings, equipped with a conductive roller, electrically connected through an interrupter,

electric pulse shaper, reversing transducer and a rheostat with a drive electric motor, with the extreme rocking post equipped with a spring-loaded hinge.

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