Wyniki wyszukiwania - Biblioteka Nauki

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Dry friction damper for supercritical drive shaft

100%

Perkowski W.

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tom Vol. 23, No. 4

389--396

EN

In this article the construction and mathematical model of a dry friction damper with radial gap, designed for dumping flexural vibrations of a supercritical propulsion shaft (developed previously during design works made in Institute of Aviation on propulsion system for an ultralight IS-2 helicopter), while passing through the resonance is presented. Some results of mathematical and numerical analyses of such a system (supercritical shaft + damper) behaviour are also presented – among other things, very distinctive behaviour of the shaft, while passing through resonance, is shown. From a theoretical point of view, it is interesting that certain range of damper parameters, obtained in the course of numerical analysis, lead to chaotic vibrations of the system (they were also observed in practice). From a practical point of view, it will be interesting that the article shows a way how to create a dimensionless (and therefore general) parameters of the system: supercritical shaft and friction damper and also simple engineering methodology for selection of suitable (for the correct operation of the shaft) damper parameters depending on the parameters of the shaft, developed during series of analyses. The practical aspect of the problem seems to be particularly important, as the supercritical propulsion shaft equipped with a friction damper can be very structurally simple, light and inexpensive, and still it is not widely used, probably because of certain doubts aroused in the constructors by the term: “resonant vibrations”.

2

Analiza drgań wału doprowadzajacego napęd do przekładni ogonowej śmigłowca ultralekkiego

100%

Perkowski W.

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tom Nr 4 (213)

148-160

PL

W artykule przedstawiono model obliczeniowy do wyznaczania krytycznych prędkości obrotowych oraz analizy amplitudy drgań wału doprowadzającego napęd do przekładni ogonowej ultralekkiego śmigłowca o masie startowej ok. 800 kg. Zaprezentowano niektóre, otrzymane wyniki obliczeń, przy czym zasadniczo skupiono się na nadkrytycznym wale dwupodporowym (podpory na końcach) z tarciowym, szczelinowym tłumikiem drgań giętnych, ale pokazano też pewne wyniki analizy dla wału z trzema podporami, z podporą środkową o liniowej lub nieliniowej sprężystości.

3

Pneumatyczna wyrzutnia startowa bezpilotowych samolotów

63%

Moldenhawer A. , Perkowski W.

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tom Nr 7 (216)

74-81

PL

W artykule przedstawiono skrótowo przebieg przeprowadzonych w ILot prac nad zaprojektowaniem, zbudowaniem i przetestowaniem pneumatycznej wyrzutni startowej WP1. Została ona opracowana na potrzeby rodziny samolotów bezpilotowych zaprojektowanych, zbudowanych i użytkowanych w ITWL.

EN

The article presents briefly the course of work carried out in Institute of Aviation on the design, constructing and testing a pneumatic launcher WP1. It has been developed for unmanned aicraft family designed, built and operated at Air Force Institute of Technology.

4

Measurements of pressure in front of shock wave : assessment of methodology influence on the measurement results on the basis of experiments with the shock tube

45%

Perkowski W. , Irzycki A. , Kawalec M. , Łukasik B. , Snopkiewicz K.

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tom Vol. 20, No. 4

333--340

EN

The experiments, described in the article, are related to research of a rotating detonation that has been conducted in the Institute of Aviation in Warsaw since 2009, under the OPIE project: “Turbine engine with detonation combustion chamber”. Measurements of the shock wave parameters, are among the most difficult in the art. This is due to high speed of the wave transition, and above all, a very small thickness of the shock wave. For the purposes of the mentioned project, a methodology for measuring pressure on the rotating detonation wave was developed. It included the type of sensors, their location and their protection from heat and flames. In order to determine the capabilities, limitations and accuracy of the method that was used, a series of experiments were planned and carried out. They enabled the assessment of the impact, on the measurement of pressure in the shock wave, of the following factors: the location of the sensor (frontal and lateral) relative to the shock wave front, protrusion or retraction of the sensor in its housing, the covering of the sensor with a protective layer (such as a high temperature silicon). This paper presents the results of the experiments that were carried out with use of a small shock tube of a simple design. The high-pressure part of the tube (so-called “driver”) was charged with the compressed nitrogen gas. The membrane was designed to be torn by pressure and pressure magnitude of the shock wave were measured by a “twin pair” of the Kistler 603B type piezoelectric sensors, one of which was always the reference sensor.

5

Study on kerosene atomization process under a high speed air stream

45%

Perkowski W. , Irzycki A. , Snopkiewicz K. , Grudzień Ł. , Kawalec M.

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tom Vol. 18, No. 4

341-347

EN

For the needs of fuel-injection system development for the experimental detonation combustion chamber with a rotating detonation (PoiG - Project: "Turbine engine with detonation combustion chamber") a series of experiments with injection of kerosene under a high speed air stream was performed at the Institute of Aviation. The proper preparation of combustible mixture is very important for the initiation and sustenance of a rotating detonation. The task in case of kerosene-air mixture is far more difficult than for mixtures of hydrogen-air or kerosene-oxygen. A simple stream injector has been tested as a base system, and the kerosene was injected perpendicular to the air stream vector directly from the plane wall of the constant cross-section channel. The process of injection and atomization of kerosene was observed in the special transparent visualization chamber, enabling the spray observation of two mutually perpendicular directions. In subsequent experiments air pressure, air temperature and air flow velocity as well as and injection pressure of kerosene were varied. The tested process was photographed and, in case of chosen experiments, filmed using a high-speed digital camera. The surveys were aimed at identifying and assessing of following parameters of fuel atomization process: the range of the fuel stream and filling grade of research channel with aerosol, aerosol homogeneity and the size of forming it droplets, the possible presence of fuel streams flowing down the walls of channel. The resulting photos allowed for more comprehensive, but only a qualitative assess of the spraying process, while the filmed small regions of visualization chamber allowed the counting down and dimensioning of droplets. This paper presents a test facility and measuring techniques applied during the research activity and selected results of carried out tests.