Maximum Allowable Rotational Speed for Internal Combustion Engine Flywheels

1995 ◽  
Author(s):  
Author(s):  
Dmitry Sergeevich Kobyakov ◽  
Oleg Stanislavovich Khvatov

The variants of transformerless power topologies of ship diesel generator sets of variable rotational speed are considered. A power circuit of a diesel generator set of variable rotational speed on the basis of an active voltage rectifier and a buffer energy store, which has the highest efficiency in terms of weight and size and performance, is proposed. A block diagram of a control system for semiconductor converters as part of a diesel generator set of variable rotational speed is presented. The control system of the active voltage rectifier is implemented upon the principle of regulation according to the position of the generalized voltage vector of the network. In order to increase the energy efficiency of the inverter diesel generator set there has been developed the algorithm for smooth control of the rotational speed of the internal combustion engine using setting mechanism of suspend mode. The proposed algorithm (gradient descent method) is borrowed from the neural network technologies and allows calculating the rotation frequency of the internal combustion engine shaft corresponding to the minimum specific fuel consumption when operating at the current fractional load. In MatLab Simulink computer environment a simulation model of a variable-frequency diesel generator set based on active voltage rectifier was developed and transients were studied. The results of simulation modeling of the dynamic modes of the load switching have been presented, taking into account its size and nature; the indicators of the specific fuel consumption of the internal combustion engine as part of a diesel generator set of variable rotational speed are presented, as well. Using a variable-speed diesel generator set based on an active voltage rectifier has been proved to allow ensuring the required quality indicators of the generated electricity when the internal combustion engine is operating at lower energy-efficient rotation frequencies in the fractional load mode.


2019 ◽  
Vol 302 ◽  
pp. 01012
Author(s):  
Marietta Markiewicz ◽  
Natalia Dluhunovych

The internal combustion engine is the powerhouse of motor vehicles. The basic fuel used for self-ignition engine powering is diesel oil. The efficiency of an internal combustion engine depends on many factors and is defined by such parameters as power output, torque, and the engine rotational speed. The engine performance parameters can be improved by modification of the manufacturer’s computer software that controls the engine operation. The study presents results of tests of a drive unit involving adjusting the fuel injection controller settings. The modifications involved increasing the fuel dose and the air charge pressure. Tests were carried out on a load bearing chassis dynamometer. The research object was a self-ignition engine with 109 KM power and Common Rail injection system. Power and torque measurements were carried out for the engine rotational speed range up to 4000 rev/min. It was found that modifications of the manufacturer’s engine computer software contribute to power and torque increase for all the rotational speeds.


Author(s):  
В. В. Руденко ◽  
И. В. Калужинов ◽  
Н. А. Андрущенко

The presence in operation of many prototypes of UAVs with propeller propellers, the use of such devices at relatively low altitudes and flight speeds makes the problem of noise reduction from UAVs urgent both from the point of view of acoustic imperceptibility and ecology.The aim of the work is to determine a set of methods that help to reduce the visibility of UAVs in the acoustic range. It is shown that the main source of noise from the UAV on the ground is the power plant, which includes the engine and the propeller. The parameters of the power plants influencing the processes that determine the acoustic signature of the UAV were investigated. A comprehensive analysis of the factors affecting visibility was carried out. The power plants include two-stroke and four-stroke engines, internal combustion and two-blade propellers. The use of silencers on the exhaust of the internal combustion engine was considered. The spectral characteristics of the acoustic fields of the propeller-driven power plants for the operating sample of the UAV "Eco" were obtained. The measurements were carried out in one-third octave and 1/48 octave frequency bands under static conditions. The venue is the KhAI airfield. Note that the propellers that were part of the power plants operated at Reynolds numbers (Re0,75<2*105), which can significantly affect its aerodynamic and acoustic characteristics. It is shown that when choosing a UAV control system, one should take into account the fact that two-stroke piston engines are the dominant source in the noise of propeller-driven control systems in the absence of a hood and mufflers in the intake and exhaust tracts. The use of a four-stroke internal combustion engine significantly reduces the noise of the control system. In the general case, the position of the boundaries of the zone of acoustic visibility of a UAV at the location of the observer is determined by the ratio between the intensity of acoustic radiation perceived by the observer from the UAV and the intensity of sound corresponding to the natural acoustic background and depends on the degree of manifestation of acoustic effects accompanying the propagation of sound in a turbulent atmosphere - the refraction of sound waves. Absorption and dissipation of acoustic energy. The calculation and comparison of the UAV detection range was carried out taking into account the existing natural maskers.The results of experimental studies are presented that allow assessing the degree of acoustic signature of the UAV. A set of measures aimed at reducing the intensity of the acoustic signature of the UAV in various regions of the radiation spectrum has been determined.


Author(s):  
Oleksandr Gryshchuk ◽  
Volodymyr Hladchenko ◽  
Uriy Overchenko

This article looks at some comparative statistics on the development and use of electric vehicles (hereinafter referred to as EM) as an example of sales and future sales forecasts for EM in countries that focus on environmental conservation. Examples of financial investments already underway and to be made in the near future by the largest automakers in the development and distribution of EM in the world are given. Steps are taken to improve the environmental situation in countries (for example, the prohibition of entry into the city center), the scientific and applied problem of improving the energy efficiency and environmental safety of the operation of wheeled vehicles (hereinafter referred to as the CTE). The basic and more widespread schemes of conversion of the internal combustion engine car (hereinafter -ICE) to the electric motor car (by replacing the gasoline or diesel electric motor), as well as the main requirements that must be observed for the safe use and operation of the electric vehicle. The problem is solved by justifying the feasibility of re-equipment of the KTZ by replacing the internal combustion engine with an electric motor. On the basis of the statistics collected by the State Automobile Transit Research Institute on the number of issued conclusions of scientific and technical expertise regarding the approval of the possibility of conversion of a car with an internal combustion engine (gasoline or diesel) to a car with an electric motor (electric vehicle), the conclusions on the feasibility of such conclusion were made. Keywords: electricvehicles, ecological safety, electricmotor, statistics provided, car, vehicle by replacing.


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