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The article presents the results of investigating the relation between flame chemiionization and the flame temperature and pressure in a variable- volume combustion chamber. Functional dependences of flame temperature and maximum pressure on the electron current caused by flame chemiionization, fundamental characteristics of flame propagation and combustion efficiency are presented. Comparison of the temperature calculated by the proposed method with experimental data shows that with the excess air factor of 0.8 to 1.15, the precision is more than 85%. Comparison of the maximum pressure obtained experimentally and calculated by the refined Vibe model, using the proposed formulas, showed good agreement. The results of the work can be used to predict and monitor maximum flame temperature and pressure in the combustion chamber of an internal combustion engine and other power plants using an ionization probe.

The feasibility of using ionization sensor for the investigation and diagnosis of the fuel combustion process in piston power plants with spark ignition is substantiated. It is shown that in order to expand the functions and increase the reliability of operation and signal processing accuracy of the ionization sensor it is necessary to know the impact of the flame fluctuating velocity on the latter. Based on the analysis of published data and in-house research a mechanism of the effect of fluctuation velocity on the electrical conductivity of hydrocarbon flame is proposed, estimated by the value of ion current. A formula for calculating the ion current is proposed, which includes the fluctuation velocity, the flame temperature and the concentration of carbon particles in the fuel. For methane-air flame, it was revealed that for U' 8 m/s an increase of ion current is observed, which is due to increased flame temperature and concentration of carbonaceous fuel particles in the zone of chemical reactions of the flame. When U' 8 m/s the ion current decreases due to the growth of heat consumption for heating the incoming fuel in the flame front, directly proportional to the fluctuation velocity. The results can be used to predict and monitor characteristics of turbulence in the combustion chambers of power plants with the aid of the ionization sensor.

The use of ionization sensors for the study and diagnosis of the combustion process in gas-turbine power plants is substantiated in the paper. The review of literature data and in-house research show that thermionic emission of electrons from incandescent carbon particles plays a decisive role in the mechanism of ionization of flame sprayed in a stream of liquid hydrocarbon fuels. It is shown that as liquid fuel is injected into the circulation area of a bluff body the area of maximum concentration of electrons that determine the conduction current is located in the circulation area. When liquid fuel is injected in the flame holder the zone of maximum electron density is located in the zone between the recirculation mixing zone and the slipstream. It was found experimentally that the distance between the region of maximum electron density and the stabilizer base is determined by the quantity of the fuel sprayed, the initial temperature, the flow turbulence and the gas flow rate. The results can be used to predict and monitor the characteristics of turbulent flame in combustion chambers of power plants with the help of ionization sensors. They also make it possible to create a system of continuous monitoring and control of ignition and combustion processes ensuring minimum concentration of toxic emissions in the exhaust combustion products.