Aerospace Technic and Technology

The subjects of the study are methods and devices of generating gas mixtures with a specified accuracy and a high repeatability of the component dosing. The purpose of the article is to develop an algorithm for controlling the fuel mixture generation system for precision thermal pulse treatment. In that behalf, the research tasks are the improvement of the critical hole method with reference to the thermal pulse treatment and the methodology development of parameters assigning for mixture generation system ensuring high accuracy and repeatability of the dosing of its components and heat flows in thermal pulse treatment. The following results are obtained. The method of dynamic mixture formation based on the method of critical holes is proposed. Its special advantage is that during the filling of the chamber, the components of the fuel mixture expire from the pre-filled intermediate pressure vessels with the controlled volume without the application of any regulating devices. The technique for choosing the diameters of critical apertures, the volumes of intermediate tanks and the initial pressure in them, providing accuracy of components dosing at the level 0,01 % is developed. The technical solutions that allow to stabilize the value of heat flow during thermal pulse treatment, considering the operation dynamics of the valves in the mixture generation system and the variable temperature of the chamber walls are proposed. The following conclusions are formulated. The method of generating fuel mixtures for precision thermal pulse treatment based on the method of critical holes is proposed. It is characterized by the fact that during the mixture formation, the free exhaust of gases from pre-filled intermediate tanks is applied. The developed procedure for calculating the parameters of the mixture generator on the basis of the proposed method makes it possible to determine the ratio of the areas of the critical holes, the volumes of the tanks, the initial pressure in them and the time of filling the chamber according to the given composition and pressure of the mixture at normal temperature. The algorithm for controlling the generation of a mixture for precision thermal pulse processing is developed. The necessity of controlling the opening and closing speed of the gas supply valves is shown taking into account the required ratio of the areas of critical holes. To ensure a stable value of heat fluxes during cyclic thermal pulse treatment, it is shown that it is necessary to simultaneously monitor the charge mass and the pressure in the chamber when the fuel mixture is supplied, followed by correcting the treatment time according to the calculated initial temperature of the fuel mixture

precision thermal pulse treatment; gas mixture generation; dosing accuracy

Plankovskii, S. I., Shipul’, O. V., Zaklinskii, S. A. Perspektivy primeneniya sovremennykh metodov generatsii gazovykh smesei dlya pretsizionnoi termoimpul'snoi obrabotki [Application perspectives of modern methods for gas mixtures generating to precision thermal pulse treatment]. Aviatsionno-kosmicheskaya tekhnika i tekhnologiya – Aerospace technic and technology, 2017, no. 3 (138), pp. 85–93.

ISO 6145-6:2016. Gas analysis – Preparation of calibration gas mixtures using dynamic methods – Part 6: Critical flow orifices. ISO/TC 158, 2017. 27 p.

Brewer, P. J., Goody, B. A., Gillam, T., Brown, R. J. C., Milton, M. J. T. High-accuracy stable gas flow dilution using an internally calibrated network of critical flow orifices. Measurement science and technology, 2010, vol. 21, no. 1, pp. 115902-1–8. DOI: 10.1088/0957-0233/21/11/115902.

Brewer, P. J., Miñarro, M. D., Amico di Meane, E., Brown, R. J. C. A high accuracy dilution system for generating low concentration reference standards of reactive gases. Measurement, 2014, vol. 47, pp. 607–612. DOI: 10.1016/j.measurement.2013.09.045.

Słomińska, M., Konieczka, P., Namieśnik, J. New developments in preparation and use of standard gas mixtures. Trends in Analytical Chemistry, 2014, vol. 62, pp. 135–143. DOI: 10.1016/j.trac.2014.07.013.

Plankovskyy, S., Shypul, O., Tryfonov, O., Zaklinskyy, S. Dynamic method of gas mixtures creation for plasma technologies. Problems of atomic science and technology. Series: Plasma Physics, 2018, no. 5 (117). pp. 10–14.

Zvegintsev, V. I. Gazodinamicheskie ustanovki kratkovremennogo deistviya. Ch. 1: Ustanovki dlya nauchnykh issledovanii [Gas-dynamic installations of short-term action. Part 1: Installations for scientific research]. Novosibirsk, Parallel' Publ., 2014. 550 p.

Mamontov, M. A. Voprosy termodinamiki tela peremennoi massy [The problems of thermodynamics of a body with variable mass]. Moscow, Oborongiz Publ., 1961. 56 p.

Adonin, S. M., Manzhalei, V. I. O teplootdache produktov detonatsii gazovoi smesi v kamere [About heat transfer of detonation products of a gas mixture in a chamber]. Nestatsionarnye problemy mekhaniki – Non-stationary problems of mechanics, 1986, vol. 74, pp. 3–10.

Ryabokon', M. P. O koeffitsiente szhatiya strui pri istechenii gaza cherez otverstie s ostroi vkhodnoi kromkoi [About the coefficient of compression of the jet when the gas flows through a hole with a sharp entrance edge]. Uchenye zapiski TsAGI – Scientific notes TsAGI, 1977, vol. VIII, no. 1, pp. 43–51.

Luhtura, F. I. K voprosu ob ustanovivshemsya rezhime istecheniya gaza iz osesimmetrichnykh otverstii i sopel [To the question of the steady-state regime for the outflow of gas from axisymmetric apertures and nozzles]. Visnyk Pryazovs'koho derzhavnoho tekhnichnoho universytetu. Seriya: Tekhnichni nauky – Reporter of the priazovskyi state technical university. Section: Technical Sciences, 2015, vol. 30, no. 1, pp. 213–225.