Building construction machinery and equipment - Portable, hand-held, internal combustion engine-driven abrasive cutting machines

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.

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257. Airport “Checked Baggage” Screener Exposure to Internal Combustion Engine Exhaust Products

10.3320/1.2758718 ◽

2005 ◽

Author(s):

M. Methner ◽

L. Delaney

Keyword(s):

Internal Combustion Engine ◽

Combustion Engine ◽

Internal Combustion ◽

Engine Exhaust

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CONVERTING THE VEHICLE BY REPLACING THE INTERNAL COMBUSTION ENGINE

Avtoshliakhovyk Ukrayiny ◽

10.33868/0365-8392-2019-4-260-29-35 ◽

2019 ◽

pp. 29-35

Author(s):

Oleksandr Gryshchuk ◽

Volodymyr Hladchenko ◽

Uriy Overchenko

Keyword(s):

Internal Combustion Engine ◽

Electric Vehicle ◽

Electric Motor ◽

Combustion Engine ◽

Internal Combustion ◽

Environmental Safety ◽

Environmental Conservation ◽

Sales Forecasts ◽

Financial Investments ◽

Near Future

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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