Closure to “Discussion of ‘Gas Lubrication of a Ringless Piston in an Internal Combustion Engine Under Dynamic Loading’” (1989, ASME J. Tribol., 111, p. 394)

1989 ◽  
Vol 111 (2) ◽  
pp. 395-396
Author(s):  
Z. Mouralatos
1988 ◽  
Vol 110 (4) ◽  
pp. 718-726 ◽  
Author(s):  
Z. P. Mourelatos

A theoretical model is presented to solve the transient, two-dimensional, compressible Reynolds equation for a gas bearing. The Newton-Raphson method is used on the governing nonlinear Reynolds equaion while the Galerkin’s method is employed to solve the resulting linear equations for the correction term. The numerical solution of the pressure distribution of an infinitely long, plane-wedge, slider bearing compares very well with the analytical (exact) solution. This theoretical model is then used to calculate the trajectory of a ringless piston within the cylinder of an I. C. engine under a given dynamic loading. The flexible polyhedron unconstrained minimization method is used to find the equilibrium position of the piston within the cylinder for each crankangle. It was found that a 40 mm long ringless piston can support a uniform side load of about 50 Newtons at 2000 r/min running on a gas film. However, the same piston can sustain a nonuniform side load with a much higher peak value (three to five times the uniform load) which lasts approximately 20 to 30 degrees of crankangle only. The sustainable side load by gas lubrication is much lower than the peak piston side load of conventional internal combustion engines.


Author(s):  
М.Р. Василевский ◽  
В.А. Александров

Данное исследование имеет прикладной характер и направлено на решение проблемы, возникшей на АО «Петербургский тракторный завод» (далее – АО «ПТЗ»). Была поставлена задача – теоретически определить динамическую нагруженность трансмиссии трактора Кировец К-4, чтобы исключить возможность неправильной конструкторской компоновки трансмиссии трактора, вследствие чего могло бы возникать разрушение карданного вала между двигателем внутреннего сгорания и коробкой передач. Исследование проведено на трехмассовой математической модели. Математической описание составлено в форме уравнений Лагранжа II рода. This research is of a direct applied nature and is aimed at solving the problem that arose at JSC «Peterburgsky Traktotny Zavod» (hereinafter referred to as JSC "PTZ"). The task was set to theoretically determine the dynamic load of the Kirovets K-4 tractor transmission, in order to exclude the possibility of incorrect design layout of the tractor transmission, in consequence of which, there could be a destruction of the driveshaft between the internal combustion engine and the transmission. The study was conducted on a three-mass mathematical model. The mathematical description is in the form of Lagrange equations of the second kind.


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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