COMBUSTION RESEARCH OF IMPINGING GAS JETS AT STABILIZATION OF THE FLAME FRONT ON A VERTICAL SURFACE

The conditions of stabilization of combustion of detached gas jets on the vertical surface of the range of nozzle diameters d0 = 1.6–3.0 mm are investigated. The mechanism of flame stabilization of a detached gas jet on a vertical surface is shown, which allows to increase the gas flow rate through one nozzle by 3 or more times with stable combustion, compared to diffusion combustion of a free gas jet, which is not stabilized. The optimal distance to the vertical refractory surface in the nozzle calibers for the creation of slot bottom burner devices has been established. The necessity of using the minimum angles of attack till failure of combustion, which were experimentally founded, for the construction of slot bottom burner devices, is substantiated. It is experimentally established that starting from the gas pressure in the collector-pipe near 500 mmwg and, accordingly, the speed of its flow through the nozzle is more than near 100 m/s at a distance to the vertical surface on which the flame is stabilized 15 < L/d0 <= 30, for the range of nozzle diameters d0 = 1.6–3.0 mm, dimensionless area base sg/s0 of the elliptical cylinder Eb, less than 2–2.5 times of the maximum observed at a distance L/d0 near 40. Bibl. 15, Fig. 6.

Stabilization of combustion front in supersonic flow using streamer’s discharge

Thermodynamic analysis shows that for flights with velocities exceeding six sound velocities, it is required to burn fuel not in a subsonic but in a supersonic flow. The aim of this work is to investigate the possibility of creating a stationary combustion front in a supersonic flow by igniting the mixture with an attached microwave discharge. Discharges are created on the resonator by means of a pulsed source of quasi-optical microwave radiation. This method of initiation is one or two orders of magnitude more economical than other known methods of plasma ignition and combustion stabilization. A numerical evaluation and comparison with experiment of the propagation velocity of a subcritical streamer discharge in a stationary medium and in a supersonic drifting flow are performed. Experiments have been conducted to ignite a flat flow of propane-air mixture, as well as ignition of the propane stream fed into the airflow, which simulates the operation of the fuel injector. In all cases, the experiments confirmed a steady fuel combustion, which was controlled by the temperature measurements with a thermocouple.

Diffusion Combustion Of The Round Microjet Mixture Of Hydrogen With Metane, Helium And Nitrogen

The purpose of the given work will consist in an experimental studies of the diffusion combustion features of the hydrogen round microjet mixtures with the metane, helium and nitrogen. It is found, that the mechanism and characteristics of a microjet and a flame evolution at diffusion combustion of the hydrogen mixture with the metane, helium or nitrogen are connected with the «bottleneck» flame area formation, as well as in a situation of a pure hydrogen microjet diffusion combustion. It is revealed, that process of diffusion combustion of a hydrogen / metane mixture in a round microjet is accompanied by stage-by-stage stages of a turbulent flame detachment at preservation of combustion in the «bottleneck» flame area, and, at last extinction of microjet combustion that correlates with combustion process of a similar microjet of pure hydrogen. It is found, that all above-listed stages of a hydrogen / metane mixture combustion are realized in a range considerably smaller speeds of a microjet (200÷500 m/sec), than in a similar situation of a pure hydrogen microjet combustion (600÷800 m/sec). It is shown, that at diffusion combustion of a mixture of hydrogen with metane or helium or nitrogen in a round microjet for stabilization of combustion with growth of a microjet speed it is necessary to increase a portion of hydrogen (or to reduce a portion of an impurity) in a mixture of gases.