Unit for researching coupled and partial oscillations of ship's shaft line

Abstract

FIELD: shipbuilding.SUBSTANCE: device for studying vibrations of a ship's propeller shaft comprises a frame on which supports are rigidly secured, an asynchronous motor is rigidly secured in the left part of the frame, the shaft rests on an extended support with a housing and a liner, a disk is rigidly secured to the right end of the shaft, a load generator with a power unit is mounted and rigidly secured to the frame, the shaft of which is connected to the shaft of the asynchronous motor by a V-belt drive, an additional extended support with a housing and a liner is made in the device, both extended supports are rigidly secured to supports made adjustable in height, a housing with strain gauge measuring equipment is rigidly fixed to the surface of the shaft, a receiver of signals from the measuring equipment is rigidly mounted to the lower part of the frame, an alternating current electromagnet with a built-in control device is rigidly secured to the right on the frame.EFFECT: increase in the accuracy of experimental studies of shaft line vibrations by improving the design of the device.1 cl, 1 dwg

Description

[0001] The invention relates to the field of shipbuilding and can be used to implement experimental methods for studying coupled vibrations: transverse-torsional, transverse-longitudinal, torsional-longitudinal and partial vibrations of ship propellers.

[0002] A known technical device is a test rig for testing models of a ship's propeller line (patent RU 2 972, 1995), comprising a base and an engine mounted thereon with the possibility of mutual movement, bearing supports, a simulator of the loads of a connecting rod and piston group, made in the form of two guides with replaceable masses placed on the axis of roller bearings mounted on the same axis with the possibility of reciprocating movement, characterized in that the rig is additionally equipped with a thrust, intermediate and propeller shafts placed on movable supports with the possibility of mutual movement along the axis of the propeller line, a thrust bearing, a propeller with removable, self-centering blades and a device for simulating its operation, for example, in the form of a bath placed under the hub of the propeller.

[0003] The disadvantages of the device are its design complexity and high cost.

[0004] The closest prototype in technical essence and purpose is a device for studying coupled and partial oscillations of a ship's propeller shaft (Patent RU 241 345, 2026), containing a frame on which supports are rigidly fixed, an asynchronous motor is fixedly fixed in the left part of the frame, the shaft rests on an extended support with a housing and a liner, a disk is fixedly fixed at the right end of the shaft, a load generator with a power unit is installed and rigidly fixed on the frame, the shaft of which is connected to the shaft of the asynchronous motor by a V-belt drive.

[0005] This device has a number of disadvantages that do not allow for a full study of the vibrations of the ship's propeller shaft: the impossibility of adjusting the position of the shaft, the inability to install measuring equipment on the shaft surface, the lack of a support simulating the shaft's bow bearing, and the inability to study longitudinal vibrations.

[0006] The technical result is an increase in the accuracy of experimental studies of shaft line vibrations by improving the design of the device.

[0007] It is achieved by the fact that in the known device, containing a frame on which supports are rigidly fixed, an asynchronous motor is rigidly fixed in the left part of the frame, the shaft rests on an extended support with a housing and an insert, a disk is rigidly fixed on the right end of the shaft, a load generator with a power unit is installed and rigidly fixed on the frame, the shaft of which is connected to the shaft of the asynchronous motor by a V-belt drive, an additional extended support with a housing and an insert is made in the device, both extended supports are rigidly fixed on supports made adjustable in height, a housing with strain gauge measuring equipment is rigidly fixed on the surface of the shaft, a receiver of signals from the measuring equipment is rigidly mounted on the lower part of the frame, an alternating current electromagnet with a built-in control device is rigidly fixed on the right side of the frame.

[0008] The creation of an additional extended support with a housing and a liner allows us to study the operating processes of the shaft line, which is additionally supported by the bow stern tube bearing, for which the proposed support is used.

[0009] Making the supports adjustable in height allows changing the position of the shaft and conducting studies on the influence of alignment on the vibration parameters during shaft rotation.

[0010] Installation of a housing with strain gauge measuring equipment on the shaft surface provides the possibility of placing primary converters, sensors and a signal transmitter in close proximity to the object of study and increases the accuracy of the obtained experimental data (see Kushner, G. A. Registration of vibration parameters of ship shafting by the method of dynamic strain gauge / G. A. Kushner / / Marine technologies: problems and solutions - 2025: Collection of articles based on the materials of the scientific and practical conference of teachers, graduate students and employees of the FSBEI HE "KSMU", Kerch, April 22-25, 2025. - Kerch: Kerch State Marine Technological University, 2025. - pp. 68-71. - EDN XWMZWC).

[0011] Installing the measuring equipment signal receiver in the lower part of the frame ensures the safety of experimental research and the possibility of connecting a computer to transmit signals via wires.

[0012] The installation of an AC electromagnet with a built-in control device makes it possible to study longitudinal vibrations by simulating an axial load on a shaft with a given amplitude, frequency and duty cycle (patent SU 943905, 1982).

[0013] The drawing shows an installation for studying the associated and partial vibrations of a ship's propeller shaft (Fig. 1 - general view).

[0014] The design of the installation consists of a frame 1, on which an asynchronous motor 2 is rigidly fixed. The shaft of the motor 2 is connected to the shaft of a load generator installed on the frame 1 with a power unit 3 via a V-belt transmission 4. The asynchronous motor 2 is connected via a flange connection (not shown in the drawing) to the shaft 5, which rests on extended supports with liners 6, rigidly fixed to height-adjustable supports 7 connected to the frame 1. A housing with strain gauge measuring equipment 8, connected via radio communication with a signal receiver of the measuring equipment 9, is fixedly fixed on the surface of the shaft 5, a metal disk 10 is rigidly fixed on the right end of the shaft 5. An alternating current electromagnet with a built-in control device 11 is rigidly fixed on the right side of the frame 1.

[0015] The device operates as follows. Asynchronous motor 2 transmits torque to shaft 5 via V-belt drive 4. The device's design elements allow for the study of vibrations and their combinations.

[0016] To study the parameters of torsional vibrations of the shaft line at different rotation speeds of shaft 5 of the installation, it is necessary to create a pulsed torque with adjustable parameters: amplitude, frequency, duty cycle, as well as an adjustable braking torque (patent RU 41171, 2004).

[0017] Torsional vibrations during rotation of shaft 5 with flywheel mass in the form of disk 10 are excited by a load generator with power unit 3, which is an electric machine operating in generator mode and creating a variable braking load. The load generator's braking torque is determined by varying the generator's armature winding current, which is provided by a power unit with an electronic generator with variable frequency, amplitude, and pulse duty cycle.

[0018] The study of transverse vibration parameters is enabled by the ability to regulate the excitation load frequency by varying the shaft speed of asynchronous motor 2 using a built-in frequency converter. The study of transverse vibration resonance is possible by varying the following parameters of the vibration system: the liner material, the bearing clearance, the material and diameter of shaft 5, the location of supports 7, and the alignment of shaft 5.

[0019] To study longitudinal vibrations during operation of the installation, the possibility of magnetic interaction between disk 10 (ferromagnetic material) and an alternating current electromagnet with a built-in control device 11 with a given amplitude, frequency and duty cycle is provided.

[0020] Experiments to study transverse-torsional vibrations of a shaft line are possible by simultaneously operating a load generator with a power unit, varying the frequency, amplitude, and duty cycle, and by changing the flywheel mass (disk size) and selecting system parameters that cause changes in the transverse vibration parameters (liner material, plain bearing clearance, shaft material and diameter, support location, shaft alignment), as well as shaft rotational speed. When the frequency of external forces matches or is a multiple of the system's natural vibration frequency, the strain gauge instrumentation obtains experimental data on the emerging resonance phenomenon. Similarly, the setup allows for the study of combinations of transverse-longitudinal and torsional-longitudinal vibrations.

[0021] The experiment showed that the proposed device, due to its design, allows us to study not only partial vibrations (transverse, torsional, longitudinal) but also their combinations (associated transverse-torsional, transverse-longitudinal, torsional-longitudinal) with the simultaneous action of the corresponding elements of the device (described above), as well as resonance phenomena (test report attached).

[0022] The proposed setup offers several advantages over the prototype. A load generator with power unit 3 allows for the simulation of torsional vibrations of varying amplitude, frequency, and duty cycle. Extended supports with bushings 6 allow the setup's operation to approximate conditions typical of a ship's propeller shaft. Height-adjustable supports 7 expand the scope of studies examining the influence of shaft 5 alignment on transverse vibration parameters. Attaching a housing with strain gauge equipment 8 and a signal receiver for the measuring equipment 9 to the bottom of frame 1 on shaft 5 reduces transmission time and improves the accuracy of the experimental data. An AC electromagnet with a built-in control device 11 enables the study of longitudinal vibrations.The proposed design of the installation allows for increasing the accuracy of studies of coupled and partial oscillations of a ship's propeller shaft by increasing the accuracy of simulating the propeller shaft operation under real operating conditions and confirms the stated technical result.

[0023] Example of a specific implementation. Asynchronous motor 2 (AHP100S4) with a power of 3 kW and a shaft speed of up to 1500 rpm is connected to shaft 1 made of 35 steel with a diameter of 25 mm and a length of 1 meter. A metal disk 10 with a mass of 2 kg and a diameter of 200 mm is attached to the right end of the shaft. The rotation frequency of the motor shaft is regulated by a frequency converter (see Vasiliev, D. A. Optimization of the operating mode of an asynchronous motor with a squirrel-cage rotor / D. A. Vasiliev, L. A. Panteleeva, E. I. Gracheva / / News of higher educational institutions. Problems of power engineering. - 2022. - Vol. 24, No. 6. - Pp. 92-101. - DOI 10.30724 / 1998-9903-2022-24-6-92-101. - EDN KKLFZS).

[0024] An additional extended support with a casing and a bushing simulates the operation of a propeller shaft, additionally resting on the bow sterntube bearing. The inner diameter of both bushings is 25 mm, the bushings can be replaced with bushings of a larger inner diameter with a step of 0.5 mm up to 28 mm. The material of the bushings is caprolon, fluoroplastic, rubber, and babbitt can also be used (see Rodygin, V. V. Methods of monitoring the technical condition and requirements of classification societies for the inspection of sterntube devices of modern ships / V. V. Rodygin / / Operation of marine transport. - 2017. - No. 1 (82). - P. 70-76. - EDNZFEAZZ).

[0025] The supports, made adjustable in height, allow changing the position of the shaft axis relative to the axis of the asynchronous motor by up to 5°, depending on the selected diameter of the liners in the extended supports (see Kushner, G. A. Study of the influence of the slope of the ship's shaft line on the parameters of transverse vibrations / G. A. Kushner, V. A. Mamontov, V. V. Shakhov / / Marine Bulletin. - 2021. - No. 3 (79). - Pp. 69-71. - EDN RRYKHC).

[0026] A housing with strain gauge measuring equipment is rigidly fixed on the shaft surface, which includes: 2FKP-5-400 strain gauges, a strain gauge with a CAN interface, and a CAN-radio channel interface converter. A receiver of measuring equipment signals is rigidly installed on the lower part of the frame: a Radio Channel-CAN interface converter, an Ethernet / Wi-Fi-CAN interface converter (see Zemtsovsky N.V. From the experience of using domestic equipment for torsiography of rudder propellers / N.V. Zemtsovsky, A.I. Lychakov / / Issues of sustainable development of society. - 2022. - No. 1. - pp. 176-183. - DOI 10.34755 / IROK.2021.33.42.027. - EDN EMHOZH).

[0027] Positive effect - the proposed device allows to increase the accuracy and expand the range of experimental studies of associated and partial transverse, torsional and longitudinal vibrations of shaft lines.

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