S. I. Gritsinin

Application of MW Plasma Generator for Ignition of Kerosene/Air Mixture

The goal of this paper is to determine the range of dependable ignition and combustion stabilization of lean mixtures and to extend the working range with the aim to improve efficiency and environmentally acceptable characteristics of jet engines. Microwave (MW) plasma generators were employed to initiate combustion in kerosene/air streams. Experiments were carried out in a model frontal device (MFD) of turbojet combustor under different ignition and stabilization conditions. The MW plasma igniter was mounted behind an MFD of the turbojet combustor. The MFD was flowed around by air stream parameters: Mach number <i>M</i>_air = 0.1-0.35, temperature <i>T</i>_air = 280&nbsp;K - 565&nbsp;K, and the kerosene/air mixture equivalence ratios were phi = 0.3-1.5 . Results were compared with the ignition data by a standard aviation spark plug. It was shown that, in the case of the use of the MW igniter, the stable ignition range is expended to lean fuel/air mixtures or larger air flow velocities.

Pulsed microwave discharge in a capillary filled with atmospheric-pressure gas

A pulsed microwave coaxial capillary plasma source generating a thin plasma filament along the capillary axis in an atmospheric-pressure argon flow is described. The dynamics of filament formation is studied, and the parameters of the gas and plasma in the contraction region are determined. A physical model of discharge formation and propagation is proposed. The model is based on the assumption that, under the conditions in which the electric fields is substantially below the threshold value, the discharge operates in a specific form known as a self-sustained-non-self-sustained (SNS) microwave discharge.

EFFECT OF INPUT ENERGY LEVEL ON IGNITION PERFORMANCE OF MW SURFACE DISCHARGE SPARK PLUG

The problem of fuel/air mixture ignition in a speedy airflow with help of microwave (MW) plasma generators (PG) applied to jet engines. Results of experimental researches of two MW PG types based on use of flame and surface MW discharges with flowing by airflow and without one. MW PGs were fed from standard magnetron of 0.8 − 1.0 kW power and MW wave length λ = 12.4 cm. For comparison of ignition performance of traditional spark plug and MW PGs the tests of model frontal device of GTE main combustor involving ring niche cavity flameholder were conducted at airflow parameters М = 0.1 − 0.3 and Тair = 400 − 520 К under the variable fuel/air equivalence ratios φΣ = 0.35 − 1.3. The region of air flow and fuel parameters which ensured stable ignition and combustion was found and comparison was done under the same test conditions with the region for traditional spark plug. Decrease of average power required by MW PG of surface discharge from 100 W down to 3 W by means of reduction of discharge duration from 10 ms down to 1ms and its energy from 20 J down to 2 J and frequency repetition from 50 Hz to 1.5 Hz correspondingly did not cause worsening of MW PG ignition performance. It was shown that the range of flow parameters and fuel/air access values was much wider for MW PG as compared with the spark plug.

A biresonant plasma source based on a gapped linear microwave vibrator

The operating principle of a novel microwave plasma source—a linear microwave vibrator with a gap—is discussed. The source is placed on a microwave-transparent window of a chamber filled with a plasma-forming gas (argon or methane). The device operation is based on the combination of two resonances—geometric and plasma ones. The results of experimental tests of the source are presented. For a microwave frequency of 2.45 GHz, microwave power of ≤1 kW, and plasma-forming gas pressure in the range 5 × 10−2–10−1 Torr, the source is capable of filling the reactor volume with a plasma having an electron density of about 1012 cm−3 and electron temperature of a few electronvolts.

Coaxial microwave plasma source

Physical principles underlying the operation of a pulsed coaxial microwave plasma source (micro-wave plasmatron) are considered. The design and parameters of the device are described, and results of experimental studies of the characteristics of the generated plasma are presented. The possibility of application of this type of plasmatron in gas-discharge physics is discussed.

Microexplosions initiated by a microwave capillary torch on a metal surface at atmospheric pressure

The interaction of the plasma of a microwave capillary argon torch with a metal surface was studied experimentally. It is shown that the interaction of the plasma jet generated by the capillary plasma torch with the metal in atmospheric-pressure air leads to the initiation of microexplosions (sparks) on the metal surface. As a result, the initially smooth surface acquires a relief in the form of microtips and microcraters. The possibility of practical application of the observed phenomenon is discussed.

Numerical analysis of a microwave torch with axial gas injection

The characteristics of a microwave discharge in an argon jet injected axially into a coaxial channel with a shortened inner electrode are numerically analyzed using a self-consistent equilibrium gas-dynamic model. The specific features of the excitation and maintenance of the microwave discharge are determined, and the dependences of the discharge characteristics on the supplied electromagnetic power and gas flow rate are obtained. The calculated results are compared with experimental data.