In connection with the construction of the nuclear submarine fleet in the USSR, Mechanical Engineering Research Institute named after Academician A.A. Blagonravov of the USSR Academy of Sciences (the IMASH) along with other organizations was involved in the designing and developing  the novel mechanisms and machines applied in naval engineering that have the required advanced vibro-acoustic characteristics.

 

At all stages of the development of nuclear submarines (APL) from the first to the fourth generations, the IMASH carried out scientific support and directly participated in theoretical developments and in the design of mechanisms. At the same time, the IMASH participated at the plant delivery tests of the head and serial main turbo-gear units (GTZA) and block steam turbine units (BPTU) at the test installations of the Leningrad Kirov Plant (LKZ) and the Kaluga Turbine Plant (KTZ), and the IMASH also participated in full-scale tests of nuclear submarines (APL) and surface ships (NК).

 

The special complexity, novelty and comprehensiveness of the research problems  assigned tobe solved by the IMASH's staff should be emphasized. While solving problems of vibroacoustics of nuclear submarine engines and vehicles, IMASH's employees carried out more than 40 research and development works, 12 experimental and design works, took part in acoustic development and testing of 35 nuclear submarines and surface ships, produced more than 11 collections of scientific papers [1-11] and made a significant contribution to the treasury of fundamental research in the field of modern machine science.

The complexity of the tasks assigned predetermined a comprehensive approach to the conducting the theoretical and experimental studies of vibro-acoustic processes arising in machines and mechanisms. This approach included: the study of the physical nature of the appearance of oscillations in real (ie relatively inaccurate and deformable) mechanisms; revealing the possibilities of influencing their vibro-acoustic characteristics; development of constructive and technological methods of reducing vibrations in the source and on the ways of their spreading from the mechanisms into the environment.

 

For studying the problems of noise and vibrations of power plants, the Department of Vibroacoustics of Machines was established at the IMASH, which was headed by the noted specialist in the field of gears,  Sc. D. (Engineering), Prof. M.D. Genkin. Possessing outstanding organizational skills, Prof. M.D. Genkin drew to the study of the problem of noise and vibration mechanisms several groups of young specialists from the Bauman MVTU, MAI, MFTI: mechanical engineers, acoustic physicists and radio electronics. Realizing the importance of experimental methods for studying vibro-acoustic processes in machines, Prof. M.D. Genkin paid great attention to the development of experimental research methods. As a result of the successful joint activity of Prof. M.D. Genkin and the management of the LKZ (Leningrad Kirov Plant), a unique experimental testing equipment has been purchased for the IMASH, various test installations have been obtained. Later, active participation in the acquisition of novel test installations and the setting-up a computer center  at that Department was made by Academician K.V. Frolov.

In the early 60-ies the IMASH, the Acoustic Institute (AKIN) and the A.N. Krylov Central Research Institute (TsNII named after Academician A.N.Krylov) conducted together the first full-scale experimental studies of the spatial oscillations of the GTZA combi-reducer manufactured by the LKZ (with analysis of noise, vibrations and dynamic forces) on a surface warship. To carry out these tests, a unique multi-point system was created and mounted on the ship for tracking and processing information on spatial vibrations and multipoint effect of GTPA on foundation and hull structures. It has been performed for the first time in the USSR, at least in the field of vibroacoustics. The switching system collected synchronous information from 150 sensors in various modes of ship movement.

 

As a result, the influence of the structural features of the gearbox and the main turbine elements on vibration and noise was revealed, the dynamic characteristics of foundations were determined, a set of measures to improve the GTZA was developed.

 

On the basis of the compiled and purchused measuring installations and equipment, the techniques of multichannel synchronous measurements were developed, which made it possible to apply correlation methods of analysis and thereby significantly increase the information content of the measurements. At the same time, the first expanded viewpoint was obtained in the USSR about real vibrational processes taking place in large-capacity ship's gearboxes. In the future, the tried-and-tested methods for measuring vibrations formed the basis for the work of Acoustic Services established at the LKZ, KTZ, at the Northern Machine Building Enterprise (SPM) and at the South Turbine Plant (UTZ, Nikolaev town, the Ukraine).

The Academic Council on the comprehensive problem "Hydrophysics" established in 1967 by the Academy of Sciences of the USSR helped the academic institutions, including the IMASH, in organizing and conducting scientific research in the field of reducing the noise of submarines. For many years that Academic Council was successfully headed by the President of the USSR Academy of Sciences, Academician A.P. Alexandrov, and then by the Academician A.V. Gaponov-Grekhov.

 

The vast volume of research was carried out by the IMASH's research staff on the vibration studies of GTZA gearboxes and on the development of methods for vibroacoustic measurements in full-scale conditions (in the period of development of the 2^nd generation of nuclear submarines). The IMASH's staff was awarded the 1973 State Prize of the USSR for the accomplished research, among the laureates of the award were the following sientists of the IMASH: M.D. Genkin, V.K. Grinkevich, V.I. Panchenko, Yu.E. Glazov, L.V. Sukhorukov, A.P.Loleyte and D.V. Makurin.

The structure of the Department of Vibro-Acoustics, consisting firstly of four, and then of 14 laboratories, allowed by joined efforts to solve the problems of noise and vibration of machines and structures. Studies were conducted in several areas, simultaneously and interrelatedly. As a result of careful studies of a complex mechanical system, it became clear that one of the main sources for the generation of vibrations and noise in ship power plants is the planetary reducer of the GTZA or of the BPTU, which predetermined a further program for R & D work.

 

 A scheme for a two-stage planetary gearbox was developed in collaboration between the the LKZ and the IMASH, which formed the basis for all the BPTUs manufactured by the LKZ. Having relatively small weight dimensions and having geometric symmetry, the proposed planetary reducer made it possible to implement simply the vibration isolation of transverse oscillations, which determined the vibroactivity of the existing rear-mounted reducers of surface ships.

 

Due to the large number of studies performed on various problems, we confine ourselves to the following main examples of the accomplished research:

 

Development of a unified physics & mathematical model of the "Mechanisms - the Hull of the Submarine - Environment"System

The development of the so-called through calculation method, i.e. method of calculating the oscillations of the "BPTU-Shaft-Screw-Hull-Environment" Model, was carried out at the laboratory headed by G.V. Tarkhanov. Later this approach was called "acoustic design".

 

The interconnectedness of the oscillations of the complex mechanical structure and the radiation of the hull into the environment required an integrated approach to the creation of its physico-mathematical model (FMM), which allows analyzing design variants and evaluating their vibroactivity over the pressure field in the environment at the design stage. In solving problems in this area, dynamic models, calculation methods and computer programs were developed in the corresponding reports.

 

Further development was given to experimental methods for detecting the vibration patterns of complex structures and dynamic loads acting in sources of oscillation excitation. The method of rationing the vibroactivity of ship mechanisms based on dynamic reactions transmitted through support and non-fixed connections to foundation structures is substantiated.

 

Methods for experimental studies of mechanisms and equipment in bench and field conditions have been developed. Among these methods are: measurement of dynamic compliance under the impact of a system of phased vibro-exciters; measurement of the levels of vibrations and reactions in the connections with a smooth change in the speed of rotation and subsequent tracking analysis with the frequency of the source of excitation; measurement of dynamic forces transmitted through vibration isolators using special dynamometers.

 

Development of active methods to reduce the vibration of ship equipment and methods for estimating the detection range of  a  submarine. Development of methods and means of vibration measurements.

 

Development of methods and means of vibroacoustic diagnostics.

 

Investigations of the accuracy of manufacturing and stiffness of elements, kinematics and statics of planetary reducers.

 

Investigations of the processes of excitation of oscillations in gears.

Development of active vibration protection systems for marine engineering.