CFD Design of Waste Heat Boiler Burner in the Education System of Masters Heat Engineering Specialties

Modern CFD methods for calculating combustion processes make it possible to take into account changes in temperatures, heat loads, rates of coolants, as well as further changes in fuel quality. To develop the skills of CFD design and understanding of combustion processes among future specialists in thermophysical specialties, work was carried out to simulate the burner device of a waste heat boiler. For the study, the design of the gas burner of the waste heat boiler RB-70-4.0-440, which operates as a part of the power unit at the LLC “Rubezhansky Cardboard and Container Plant” in the city of Rubezhnoe, was selected. When constructing a geometric model, the hydraulic resistance to the flow of the supply and distribution manifolds was taken into account. To simplify the calculations, the problem was carried out in a two-dimensional, axisymmetric formulation. Analyzing the computational combustion models, the Non-Premixe Combustion model was chosen, which made it possible to take into account the entry of fuel and oxidizer into the reaction zone by two different flows, as well as turbulent diffusion flame propagation. Six variants of models were investigated: the first three variants with a flame tube with a solid disc with diameters of 32, 48, 56 mm, the next three variants, had a burner with a discontinuous disk 32 mm in diameter at a distance of 6, 16, 32 mm from the flame tube. As a result of the research, the optimal shape of the burner was chosen, which corresponds to model 4, and provides a high-quality combustion process, as evidenced by the high temperature of the torch and the lowest temperature at the disk. The conducted research gives future masters the skills of modeling combustion processes in power equipment.

Design and development of combustion chambers for gas turbine engines based on calculations of various levels of complexity

The article proposes a method for designing combustion chambers for gas turbine engines based on a combination of the use of calculations in a one-dimensional and three-dimensional formulation of the problem. This technique allows you to quickly design at the initial stage of creating and development of the existing combustion chambers using simplified calculation algorithms. At the final stage, detailed calculations are carried out using three-dimensional numerical calculations. The method includes hydraulic calculations, on the basis of which the distribution of the air flow passing through the main elements of the combustion chamber is determined. Then, the mixing of the gas flow downstream of the flame tube head and the air passing through the holes in the flame tube is determined. The mixing quality determines the distribution of local mixture compositions along the length of the flame tube. The calculation of the combustion process is carried out with the determination of the combustion efficiency, temperature, concentrations of harmful substances and other parameters. The proposed method is tested drawing on the example of a combustion chamber of the cannular type. The results of numerical calculations, experimental data and values obtained using the proposed method for various operating modes of the engine are compared.

Thermal Analysis and Structural Optimization of High-Efficiency Fuel Submersible Hot Water Machine

Based on the oil quality of diesel oil, the thermal efficiency and fuel consumption of the fuel-burning submersible hot water machine were calculated. The structure of the fuel-burning submersible hot water machine was designed. The heat transfer calculation of the flame tube and convection surface of the high-efficiency fuel submersible hot water machine was carried out, and the overall heat balance of the system was checked. ANSYS was used to analyze and study the mechanical and thermodynamic properties of the fuel-based submersible hot water machine, and the simulation results were compared with the theoretical calculation results. The thermal field of the flame tube and the threaded tube was simulated, and the influence of the temperature field on the flame tube was analyzed. The changes in the total deformation and strength of the flame tube under the thermal structure coupling were studied. The thermal efficiency of oil-fired submersible hot water machine was studied, and the relevant factors affecting the thermal efficiency of oil-fired submersible hot water machine were put forward. The main factors affecting thermal efficiency were analyzed and mathematically modeled. The air supply model and the convective heat transfer model of the threaded tube were established. The main parameters that affected the thermal efficiency of the threaded tube were optimized. In the end, the design scheme of a high-efficiency fuel-type submersible hot water machine was obtained.

Study of Adiabatic Flame Temperature of a Jet Combustor using a Non-Circular Inlet

An experimental investigation on heat transfer at various zones of the combustion chamber has been carried out using a non-circular inlet at the flame tube. With an aim to improve the turbulent level in flow, the non-circular section used here is an elliptical one. In addition to this, two rectangular tabs are placed at major axis of the ellipse to achieve an efficient mixing of fuel and air. Fuel used for combustion is kerosene while LPG gas is used for pre ignition. Fuel is fed to the chamber by gravity system and it has been atomized by two fish tank pumps. Ignition of the fuel is done by spark plug with a separate setup. The setup comprises of growler and CDI coil which are powered electrically. During the experiment, combustion has been initiated by allowing the air from blower to the chamber. The fuel is sprayed into the flame tube through fuel injector placed at a specified distance. After the proper mixing of fuel and air, the mixture is ignited by spark plug setup. Initially LPG gas was used for preheating followed by kerosene for combustion. Fuel tank has been calibrated for mass flow rate. The experiment has been carried out for different intervals of time and the heat transferred from the flame tube wall and chamber wall is been measured using an infrared gun (ray gun) by pointing laser on the wall. The temperatures at different zones have been measured. It is seen that the overall heat transfer at secondary zone is minimum when compared with other zones for the same period of time. This indicates that if the fuel injector is placed before the secondary zone, then a maximum flame temperature can be obtained. This leads to an improvement in efficiency of the combustion chamber.

Influence of plasma-chemical products on process stability in a low-emission gas turbine combustion chamber

The article describes the stability of gaseous fuel combustion in gas turbine low-emission combustion chambers with the plasma-chemical assistance. The mathematical model of unsteady processes in a low-emission combustion chamber with a plasma-chemical stabilizer that takes into consideration the impact of low-temperature plasma on aerodynamics flow in a combustion chamber and the characteristics of heat release is developed. A methodology of a numerical experiment concerning the stability of gaseous fuel combustion in a combustion chamber with plasma assistance using computational fluid dynamics, which enhances the efficiency of designing and adjustment, is proposed. Practical recommendations for improvement of stability of a gas turbine combustion chamber with partially premixed lean fuel–air mixtures, working on gaseous fuels, are developed. They allow to reduce pressure fluctuations inside the flame tube by 10–35%, to decrease spectral power of static pressure in the flame tube in 1.5–2.0 times, to reduce nitrogen oxide emission up to 33.6 ppm in the exit section while retaining a carbon monoxide emission level, that corresponds modern international ecological standards.

Influence of plasma-chemical products on process stability in a low-emission gas turbine combustion chamber

The article describes the stability of gaseous fuel combustion in gas turbine low-emission combustion chambers with the plasma-chemical assistance. The mathematical model of unsteady processes in a low-emission combustion chamber with a plasma-chemical stabilizer that takes into consideration the impact of low-temperature plasma on aerodynamics flow in a combustion chamber and the characteristics of heat release is developed. A methodology of a numerical experiment concerning the stability of gaseous fuel combustion in a combustion chamber with plasma assistance using computational fluid dynamics, which enhances the efficiency of designing and adjustment, is proposed. Practical recommendations for improvement of stability of a gas turbine combustion chamber with partially premixed lean fuel–air mixtures, working on gaseous fuels, are developed. They allow to reduce pressure fluctuations inside the flame tube by 10–35%, to decrease spectral power of static pressure in the flame tube in 1.5–2.0 times, to reduce nitrogen oxide emission up to 33.6 ppm in the exit section while retaining a carbon monoxide emission level, that corresponds modern international ecological standards.