Large resources of thermal and industrial waters at a temperature of 100–150°С can be employed to generate electricity in both a single-circuit thermal cycle with direct usage of natural steam in condensing turbines and a double-circuit cycle with a low-boiling working fluid. Both options require high capital expenditures for their implementation. A new power-generation method on the basis of low-grade heat is to install a full-flow hydro-steam turbine (HST), which utilizes the heat of separated liquid from a geothermal station or the heat of industrial waters, in a single-circuit thermal cycle. Capital expenditures for these units are much lower since special equipment for preparation of the working fluid is not required. The efficiency of a hydro-steam turbine is directly related to the efficiency of its main element, which is the Laval nozzle. Designing this turbine requires reliable data on the performance of a Laval nozzle with a high expansion ratio when it operates on highly subcooled water. Such information can only be obtained experimentally since this region of operation of Laval nozzles has been poorly studied as of yet. To determine the required characteristics of the nozzles, an experimental setup was designed and manufactured with a set of Laval nozzles, including nozzles with different opening angles of the diverging section and nozzles with an oblique cut. The working fluid was water under conditions close to the operating conditions in an HST. The results are presented of the experimental study of Laval nozzles in a wide range of expansion ratios for operation on boiling water. The experiments were performed at different pressures downstream of the nozzle, and their results were compared with previously obtained experimental data. The experimental setup and design features of the nozzle are described. The experimental data on the flow coefficient, velocity coefficient, expansion ratio, initial conditions, nozzle shapes, and size effect, on which the conclusions made are based, have been analyzed. Characteristics have been found that enable us to predict the efficiency of a reaction hydro-steam turbine and properly calculate its output.

В цикле водогрейной котельной имеется низкопотенциальный источник энергии в виде конденсата в рабочей контуре. Реактивная гидропаровая турбина (ГПТ) – простой и дешевый способ использования этой энергии. Приведена принципиальная схема включения ГПТ в цикл котельной, предполагающая отвод отработавшего пара ГПТ в конденсатор с последующей закачкой в схему котловой воды. Описаны конструкции основных узлов ГПТ мощностью 20 кВт. Опытная установка ГПТ обеспечивает простой срок окупаемости до 4 лет.

A description is given of the causes by which the transmission of vibration and airborne noise from equipment to the environment should be controlled. The paths of this transmission and applicable ways for its reduction by passive and active methods are examined. It has been demonstrated that pipelines, even vibration-isolated from the equipment by means of expansion joints, can transmit and even amplify vibration from the installation in a wide frequency range. It is noted that reducing the vibration of pipelines is important for effective vibration isolation of equipment in power and transport machine building, shipbuilding, and of oil and gas pipelines at pump stations. Effective control of the vibration and noise transmission to the environment has been shown to require a preliminary comprehensive analysis of the importance of all paths of their transmission. A description is given of a dedicated universal research test facility for a comprehensive study of the possibility and methods for reducing the transmission of vibration and airborne noise from operating equipment with a flow of working fluid through piping using passive and active methods.

The results of experimental and computational studies to identify the reasons for the increase in the vibration transmission through compensators of pipelines with liquid by several orders of magnitude with increasing frequency are considered. The descriptions of the found physical and computational models of this phenomenon are given. The results of experimental studies carried out on a special stand to study the possibility of reducing this transmission in a wide range of oscillation frequencies from 10 to 300 Hz by an order of magnitude or more by means of passive and active vibration damping methods are given. It has been shown experimentally that in the case of active spatial damping of dynamic forces behind the compensator, the mutual influence of the damping channels can significantly change the efficiency of the system.

An analysis from the results of investigation into spatial active damping of pressure fluctuations, vibrations, and vibration forces transferred from power facilities via expansion joints in their piping is presented. Vibration transfer from power facilities via piping can be several orders of magnitude greater than along the support structures. This fact should be kept in mind in designing vibration isolation of power equipment from the foundation and the environment through pipelines in the power and transport engineering, shipbuilding, and in oil and gas pipelines in pumping stations. To reduce the transfer of vibrations via a pipeline by means of vibration-isolating expansion joints, it is necessary to decrease their structural stiffness and the forces induced by fluctuations of the working fluid pressure in an expansion joint in a wide frequency band using structural or active methods. A review of the available publications has not revealed, except for the studies performed within the scope of this investigation, any analysis of the interaction between the fluid fluctuations and vibration in the expansion joints or information on reducing the transfer of vibrations and pressure fluctuations via expansion joints in liquid-carrying pipelines. The effectiveness of various multichannel spatial active vibration protection systems whose feedback circuit includes regulators in the form of standard band-pass filters has been studied experimentally. The effect that the interaction of active vibration force damping channels has on the damping efficiency, which may be caused by the cross sensitivity of three-component vibration force sensors during damping of the vibration forces, has been revealed. The active spatial vibration damping of a pipeline downstream of the expansion joint has also demonstrated the interaction of active vibration damping channels resulting in a noticeable change in the damping effectiveness. The effectiveness of the investigated options varied from 10 to 32 dB (reducing fluctuations, transfer of vibration, and forces transmission by 3–30 times) both at individual frequencies and in frequency bands in the range between 10 and 500 Hz.

— The article presents the results from studying methods and means for reducing the transfer of vibration and pressure pulsations from power installations through elastic vibration isolators of pipelines carrying liquids (cooling water, condensate, or petroleum products) by suppressing the vibration forces and pulsations of the medium by active suppression systems. The results of studies into this subject carried out within the framework of the agreement between the Russian Scientific Foundation and the Tsiolkovskii Kaluga State University are reported. The article discusses the results from calculation and experimental studies aimed at determining the influence of liquid on the vibration-isolating performance of different kinds of pipeline compensators, including those based on bellows, sleeve-type ones made of rubber cord materials, those based on rubber cord shells, and compensators of a new type containing elastic inserts made using thin-layered rubber-metal elements with the minimal interaction between the structure and working medium. The investigations were carried out with the aim to minimize the transfer of vibration through the compensator by improving its design. The results from experimental studies into the effectiveness of joint suppression of the vibration and pressure pulsations by active methods for reducing the transfer of vibration from power installations to the foundation by means of pipeline compensators are presented. It is shown both analytically and experimentally that there is a frequency band in which the vibration forces transferred through the compensator structure are suppressed by the forces from pressure pulsations. The transfer of vibration becomes a factor of ten or more less than it is in the compensator tested without liquid. A physical explanation for this phenomenon is given, and ways of using it in practice are suggested. A two-channel active vibration protection system with a digital control device containing controllers in the form of standard Butterworth, Chebyshev, and band-pass filters, as well as resonance sections in its feedback circuit, is experimentally studied. With the active joint wide-band suppression of vibration forces and pressure pulsations determining the transfer of vibration through the compensators of pipelines with liquid, the effectiveness was found to be up to 32 dB in the frequency band from 10 to 350 Hz.

The authors have developed and investigated experimentally physical and mathematical models to calculate pressure pulsations and dynamic loads produced by them, which determine vibration transfer through compensators of pipelines with a liquid. The loads caused by pressure pulsations may substantially increase with frequency. Consideration has been given to vibration transfer over the structure of the compensator′s elastic elements. The authors have shown analytically and have confirmed experimentally the presence of a broad frequency range, in which the compensation of the forces transferred over the structure by the forces from pressure pulsations occurs. Vibration transfer may be reduced ten or more times compared to the transfer over the structure of the compensator with a liquid. The revealed phenomenon has been explained physically, and the ways of using it in practice have been proposed. At frequencies exceeding this range, the presence of the liquid enhances vibration transfer through the compensator.

The absence of literature data on active reduction of the transmission of vibrations and pulsations of pressure through pipeline compensators with liquid is noted. A prototype of active broadband vibration damping system has been studied. The system is intended to determine the transmission of pressure pulsations through pipeline compensators with liquid. We present the results of active system testing with electromagnetic vibrator as a source of compensating force, a piezoceramic emitter as a source of compensating pressure pulsations, and a digital control device. Reducing the forces and pressure pulsations to 18 dB in the frequency band from 10 to 246 Hz has been obtained.

AbstractThe absence of literature data on active reduction of the transmission of vibrations and pulsations of pressure through pipeline compensators with liquid is noted. A prototype of active broadband vibration damping system has been studied. The system is intended to determine the transmission of pressure pulsations through pipeline compensators with liquid. We present the results of active system testing with electromagnetic vibrator as a source of compensating force, a piezoceramic emitter as a source of compensating pressure pulsations, and a digital control device. Reducing the forces and pressure pulsations to 18 dB in the frequency band from 10 to 246 Hz has been obtained.

Results are presented of experimental investigation into the stability of the motion of a liquid in a horizontal heat exchanger provided with a ventilation shaft and inclined toward the ventilation shaft. The process of natural circulation reversal is described, and equations for assessing reversal angle are presented.