Method for digital processing shadow images of supersonic gas flowing over aircraft structural parts

Аuthors

Tarasenko O. S.^*, Bodryshev V. V.^**, Abashev V. M.^***

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

*e-mail: os-tarasenko@yandex.ru
**e-mail: soplom@mail.ru
***e-mail: abashevVM@mai.ru

Abstract

The study of gas stream flowing over solid bodies is highly relevant for development of aviation and rocket-and-space equipment. Such research is carried out using unique stand units with flowing visualization. Gas-dynamic flow visualization itself is performed using various equipment and processed using various methods. Shadow and schlieren images are widely known. They are based on the phenomenon of light deflection when it passes through transparent medium density inhomogenuities. When gas flowing field is visualized using the schlieren method, illumination variation is in proportion to gas density gradient in the area under consideration, and when the shadow method applied, variation in the illumination is determined by the degree of density gradient variation.

Both the shadow and the schlieren method provide for production of 2D images, which can be successfully used for following up the pattern of gas stream flowing over an object, but are almost useless for quantitative estimation.

The purpose of the study is developing a method for digital processing shadow images and determination of the parameter characterizing the image and correlating with the basic gas stream parameters (velocity, pressure and density). Application of this method will allow determining gas flow operational properties (for example, pressure) at any point of the stream, thus making possible the analysis of the respective design solution and choosing its best variant. In this paper image intensity (brightness) is suggested as the basic image analysis parameter.

The obtained results contribute not only to better understanding of the physical constituent of supersonic gas flow, but also to determination of the real gas flow intensity values with their further processing by pressure estimation.

Keywords:

ultrasonic gas-dynamic flow, experimental studies, image intensity, image intensity histogram, pressure, gas flow velocity, compression wave, Mach number, Mach wave

References

1. Znamenskaja I.A., Gvozdeva L.G., Znamenskij N.V. Metody vizualizacii v mehanike gaza (Visualization Methods in Gas Flow Mechanics), Moscow, MAI, 2001, 57 p.

2. Abashev V.M., Bodryshev V.V., Tarasenko O.S. Tezisy dokladov II Mezhdunarodnogo nauchnogo seminara «Dinamicheskoe deformirovanie i kontaktnoe vzaimodejstvie tonkostennyh konstrukcij pri vozdejstvii polej razlichnoj fizicheskoj prirody», Kremenki, 2015, pp. 9-10.

3. Zhuravel’ I.M. Kratkij kurs teorii obrabotki izobrazhenij" URL: http://matlab.exponenta.ru/imageprocess/book2/index.php

4. Abashev V.M., Prudnikov A.G., Son E.E. Tezisy dokladov 29th Congress of the International Council of the Aeronautical Sciences Modern research areas of solid hypersonic ramjet engines. St. Petersburg, 2014, p. 2.

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