SU1362969A1 - Method of measuring axial force of ship propeller and device for effecting same - Google Patents

Abstract

The invention relates to experimental hydrodynamics associated with the study of the interaction characteristics of a rowing viit and a ship hull. The purpose of the invention is to improve the accuracy of measuring the axial force of the ship's propeller. When rotated in the forward direction, the propeller develops an axial force, which presses the shaft 1 to the bearings 4 of the bearing 5. Under the action of / / / / / t 28 61 Fi9.1 force, the shaft 1 receives the longitudinal deformation, converted by the strain gages 6 into an electrical signal, which is recorded on the tape of the recorder 15, simultaneously on the latter, the longitudinal stirring of the shaft 1 is recorded. An electrical signal proportional to the longitudinal movement of the shaft 1 comes from strain gauges mounted on an elastic beam. An electrical signal, proportional to the second derivative of the longitudinal movement of the shaft 1, is also recorded on the tape recorder 15 and is also fed to the strain resistor, but after double differentiation by the block 16. At the time of reversing the rotation of shaft 1, an axial force occurs on the propeller if it is equal to the frictional force shaft 1, it moves in the direction of drawing out of the vessel and moves away from the bearing 4, bearing 5. The resulting longitudinal deformation is measured by resistors 6 cp f-ly, 3 ill. with e (L with O5 GhE with 05 with / yes R l

Description

one

The invention relates to experimental hydrodynamics associated with the study of the characteristics of the interaction of the propeller and the hull of the vessel, and can be used to measure the axial force of the propeller of a full-scale vessel in various navigation modes, including active navigation in ice.

The aim of the invention is to improve the accuracy of measuring the axial force of the ship's propeller.

Figure 1 shows the layout of the sensors for longitudinal deformation and movements of the propeller shaft and their connections with the recording equipment; figure 2 - sensor longitudinal movements; on fig.Z - oscillographic recording of longitudinal deformations and shaft movements.

On the propeller shaft 1, installed between the stern seal 2 and the liners 3 and 4 of the thrust bearing 5, are mounted the strain gauges of the sensor 6 of the longitudinal deformations of the propeller shaft, collector rings 7, the deadwood on the facing of the shaft 8.

The elastic beam 9 of the longitudinal displacement sensor (figure 2) is equipped with electric converters 10. The fixed end of the elastic beam is rigidly fixed to the bracket 11, which is fixed to the body of the stern tube.

The opposite end of the beam through the ball 12, reinforced in the beam, abuts against the end 13 of the bronze facing of the propeller shaft. The screw 14 allows for the necessary initial deflection of the beam, sufficient to measure the longitudinal movements of the propeller shaft during its compression and pulling. The electrical output of the displacement transducer is connected directly to the recorder 15 and at the same time the electrical output of the longitudinal shaft deformation sensor is connected through the differentiating device 16, e the registrar,

The device with which the method is carried out works in the following way.

 When rotated in the forward direction, the propeller develops an axial force T (t), which presses the shaft 1 to the inserts 4 of the support sub-holder 5. Under the action of the force T (t), the shaft 1 obtains longitudinal deformation.

ten

25

x and i i s 20

( but

. 35

converted by the strain gauges 6 into an electrical signal that is recorded on the tape of the recorder 15. Simultaneously, the tape recorder 15 records the longitudinal movement x (t) of the shaft 1, an electrical signal proportional to the longitudinal movement of the shaft 1, comes from the strain gauges 10 mounted on an elastic beam 9.

An electrical signal, proportional to the second derivative x (t) of the longitudinal movement of the propeller shaft 1, is also recorded on the tape of the recorder 15; this electrical signal also comes from the strain gauges 10, but after double differentiation by the differentiating device 16,

 one ;

Thus, at any time; time tj on the tape recorder, we have a graphical record of the axial force T of the longitudinal movement of the propeller shaft x. and speed up.

 „N longitudinal displacement x ,.

At the time of reversing the direction of rotation of the propeller shaft 1 and on the propeller, an axial force develops.

T. Lee, which is directed towards the extension of the propeller shaft from the vessel. At time t, when the value of the axial. turns out to be equal to the friction strength of the propeller shaft in the stern shaft, the shaft will begin to move in the direction of drawing out of the vessel and move away from the liners 4 of the thrust bearing 5. Time point t. the propeller shaft is thrust into the insert 3 of the thrust bearing 5, and from this point in time the shaft will receive some longitudinal strain, which will be measured by the strain gages 6, in the time interval from t to t the propeller shaft will not be deformed, therefore the electrical signal of the longitudinal strain sensor 6 in this The time span is the initial reading of the axial force of the ship's propeller.

It is practically impossible to determine the time interval from t to t only from a graphic record of the longitudinal deformation K. Here comes the graphic recording of the longitudinal movements of the propeller shaft x (t). The displacements due to the longitudinal deformation of the propeller shaft are relatively small and amount to

EL 10.10

ten

0.2 mm

10 is the relative longitudinal deformation of the propeller shaft; mm - the length of the propeller shaft.

The movement of the propeller shaft X., associated with its free movement between the plates 3 and 4 of the thrust bearing 5, amounts to about 3-5 mm, to be overcome in a relatively short period of time. This process is characteristic of the graphical recording of the longitudinal movements x (t) of the propeller shaft (Fig. 3). By recording x (t), the time interval of the highest rate of change in the magnitude of the longitudinal movements x (t) during reversal is determined.

Through the middle of this gap (point a), the vertical straight line is brought to the intersection with the curve of the graphical recording of the longitudinal strain; CII T (t).

The intersection point b corresponds to the undeformed state of the propeller shaft, t, e, is the desired initial reading of the value of t (t).

The magnitude of the axial force in some.

In other cases, the formula

for example, by

T (t) - U (t) - Uo - ah (t A, where T (t) is the axial force in the function

time; U (t) is an electrical signal,

proportional shaft deformation; Uo - electrical signal

corresponding to the initial countdown;

ten

15

x (t) is the second derivative of the signal of the propeller shaft displacement sensor;

a - coefficient proportional to the mass of the propeller shaft;

A - coefficient.

Claims (1)

Invention Formula 1, A method for measuring the axial force of a ship's propeller, consisting in measuring the longitudinal deformation of the propeller shaft, determining the initial reference of the axial force of the propeller, and determining the value of the axial force by calculation, about t0 five At the same time as measuring the longitudinal deformation of the propeller shaft, its longitudinal movement is measured, the direction of rotation of the propeller shaft is reversed and. at the moment of the highest rate of change in the magnitude of the longitudinal movement during reversal, an initial count of the axial force is determined, 2, A device for measuring the axial force of the propeller of the vessel, containing Q holding sensor for the longitudinal deformation of the propeller shaft, located between the stern seal and the thrust bearing, and connected through a pulling device with a recorder, characterized in that A longitudinal displacement sensor for the propeller shaft is inserted between the thrust bearing and the stern seal, the fixed part of which is rigidly connected to the hull of the vessel, and the movable part is mounted slidably along the guide the propeller shaft, wherein the sensor output is connected with the registrar. five 0 -to one (V J 8v . X Compiled by V.Godzikovsky Editor Yu.Sereda Tehredjj.Serdyukova Corrector V.But ha Order 6390/28 Circulation .776Subscription VNII1Sh State Committee of the USSR for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4