Vol 12, No 3-2 (2013): Vestnik SSAU

The article describes the defects of airfoil shroud platforms of the high pressure turbine of an NK-36ST engine for ground application and shows corrective actions for defect elimination. The structure of a light airfoil shroud platform that can increase the blade lifetime is introduced. 

This article presents an analysis of the work processes in a thermomechanical compressor. Design data on changes in gas pressure and mass in the compressor are given and its efficiency is calculated.

The article presents an approach to analyzing the stress-strain state of the YMZ-238 crankshaft after surface roller hardening. The approach is based on dynamic modeling of the stress-strain state of the crankshaft stress concentrators. The real-time modeling of roller hardening makes it possible to get a diagram of residual stresses occurring in the strengthened surface layer of the fillets. The next step is the analysis of the part’s stress-strain state applying the boundary conditions corresponding to the operating conditions of the engine. The dynamic research of the stress-strain state of the crankshaft makes it possible to analyze the manufacturing technology and identify the origin of cracks in stress concentrators taking into account the improvement of fatigue resistance resulting from hardening treatment.

To provide stable operation and confident firing up in the main combustion chamber of a gas turbine engine under high-altitude flight conditions a new scheme of a pneumatic- type starting nozzle is developed. The firing tests carried out in a full-scale low-emission combustion chamber showed their principal fitness for work. The results of the experimental study of two versions of starting nozzles for the purpose of determining  comparative starting and stalling characteristics at different heights are presented in the paper.

The paper presents a  numerical solution of full Navier-Stokes equations for an intensively swirling flow in  an axisymmetric channel disc-loaded in the input cross-section and supplied with a throttle of the peripheral slot type at the opposite end of the channel with a central hole for feeding additional masses of gas. The flow patterns, thermodynamic parameter distribution fields are obtained. The results of numerical computation are compared to the experimental data for vortex tubes with an additional stream. Formation of large-scale vortex structures is noted. The results of numerical calculation and computer visualization can be used to further refine the physical model and methodology for calculating characteristics of vortex tubes.

Materials for providing the thermal state of the elements of a two-staged gas turbine combustion chamber for terrestrial applications are presented. The factors that affect the temperature of combustor can rings are analyzed. A significant influence of flow characteristics and range of burners in the main loop on the combustor can wall temperature is shown and it is also shown that the task of ensuring acceptable combustor can wall temperature in accordance with the TOR is reduced, first of all, to the task of providing an optimum structure of the flow of fluid in the inner cavity of the combustor can.

The methodology of one- dimensional calculation of the combustion chamber existing  at SSAU has been significantly complemented: a) the uneven distribution of fuel in the combustion zone and its combustion in the range of excess air ratio 0.55 ... 1.65 has been taken into account; b) the amount of vaporized fuel at each site is determined by considering the size of evaporating droplets; c) for each fraction of the fuel burnt  the equilibrium composition and the adiabatic equilibrium flame temperature is determined; d) a scheme of mixing the combustion products with the secondary combustion air and mixing air is proposed in order to evaluate the non-uniformity of the temperature of exhaust gas at the output of the combustor; e) a mixing quality factor is introduced. The impact of the completeness of mixing, composition and temperature of the gas on the quantity of nitrogen oxides along the length of the flame tube, the NO emission index  and the non-uniformity of the temperature field in the output section is assessed. The updated method of calculation is illustrated by the low- emission aviation turbine engine combustor.

The problems of heat transfer in thermoacoustic converters are discussed in the framework of analysis of studies of heat exchangers of thermoacoustic converters with a view of summarizing the concepts of physical processes of heat transfer in parameters of the theory of heat transfer, fluid dynamics and wave theory.

The paper presents design research of mixing real gas in swirl flows of swirl burners of gas turbine engine combustion chambers in the ANSYS CFX program. The peculiarities of heat exchange of a swirl flow with the environment and the zone of reverse currents are investigated. The results of the numerical research and the previous physical experiment are shown to be in good qualitative and quantitative agreement.

The paper presents software for the calculation of temperature conditions of spacecraft, its advantages and disadvantages are discussed. The main idea is using combined software for the generation of structural members of a spacecraft thermal model taking into account the labor input of constructing such a model.

The article presents the analysis of published data and results of experimental studies performed by the authors regarding the effect of combustion promoters – peroxides and hydro-peroxides on the turbulent burning rate of fuel TS-1. It was determined that the specific pulse thrust of the model pulse-detonating engine may be increased by 2.5 - 3.0 times. The same goes for the degree and burning rate of the fuel-air mixture. The authors explain the mechanism of action of promoters for increasing the activity of the fuel-air mixture in the process of combustion.

Emission characteristics and temperature non-uniformity at the outlet of a gas turbine engine combustion chamber were simulated in bench test conditions. Simulation results were compared with the experimental data. The adequacy of the applicability of the turbulence and combustion models was investigated. The influence of the deformation intensity of the flame source in the combustion model and the constant swirl in the RNG k-e turbulence model on the distribution of parameters inside the combustion chamber and the emission characteristics is shown. Good agreement of the simulation results and the experimental data is obtained.

The article presents gas flow parameters in four cross- sections of the engine at the flight speed of 8M at the altitude of 20 km for various hydrocarbon fuels. The data were obtained with the use of a multi-purpose program complex. The analysis of the obtained results allowed determining the level of requirements for the basic properties of fuels for hyper-sonic ramjet engines and arguments in favour of developing a new fuel for hypersonic ram-flow jet engines as well as new methods for its evaluation.

A numerical solution of differential equations describing the motion and heat exchange in the boundary layer is used to simulate heat transfer in a tube of thermal stratification. The numerical solution proves that the use of heat pipes will make it possible to increase the efficiency of a tube of thermal stratification.