scholarly journals Числове дослідження змішування в системі генерації газової суміші

2021 ◽  
pp. 39-48
Author(s):  
Віталій Євгенович Гайдачук ◽  
Ольга Володимирівна Шипуль ◽  
Сергій Олександрович Заклінський ◽  
Вадим Олегович Гарін ◽  
Олег Валерійович Трифонов ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Gas Flow ◽  
Numerical Study ◽  
Stoichiometric Composition ◽  
Initial Pressure ◽  
Temperature Fields ◽  
Gas Mixture ◽  
Technical Solution ◽  
Generation System ◽  
Gas Dynamic

The subject of research is a gas-dynamic process of mixture formation with a given component mass fraction during overflow through the mixer nozzles in the mixture generation system. The aim of the study is the scientific and experimental evaluation of the mixer technical solutions to ensure the accuracy and homogeneity of the gas mixture. The current work conducts numerical study on the flow of a gas flow through the mixer nozzles of the mixture generation system, ensuring its stoichiometric component composition and homogeneity. The problem is solved by developing adequate mathematical models of gas-dynamic flow and analyzing the results of numerical simulations. The following results were obtained. A mixer with the nozzles in the mixture generation system has been created and a technical solution for its design has been scientifically substantiated. The areas of flow sections of mixer nozzles are experimentally established. A mathematical model of generating a mixture with a given component mass fraction was developed and a series of numerical experiments was conducted to study its overflow through the mixer. A 3D simulation was conducted using ANSYS CFX software. The stationary formulation of the problem is applied. In the nozzles of closed overflow of the mixer, the heat exchange of the gas flow with the walls is taken into account by solving a separate problem and determining the corresponding heat transfer coefficients. At the inputs to the mixer, the ratio of the initial pressure of the components of the mixture is determined, which ensures its stoichiometric composition. The fields of the gas flow velocities, the mass flow rate of the components of the gas mixture through the mixer, and pressure and temperature fields are obtained. Based on the simulation results, it was found that the design of the developed mixer ensures the creation of a gas mixture with a homogeneity of at least 3%. With a constant pressure ratio of the mixture components to the mixer inlet, the gas mixturedosing accuracy can be achieved at least 1%.

scholarly journals Numerical Simulation of Secondary Flow in Gas Turbine Disc Cavities, Including Conjugate Heat Transfer

1996 ◽  
Author(s):  
Y.-H. Ho ◽  
M. M. Athavale ◽  
J. M. Forry ◽  
R. C. Hendricks ◽  
B. M. Steinetz
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Conjugate Heat Transfer ◽  
Gas Flow ◽  
Numerical Study ◽  
Labyrinth Seal ◽  
Temperature Fields ◽  
Heat Transfer Analysis ◽  
Flow Rates ◽  
Turbine Disc

A numerical study of the flow and heat transfer in secondary flow elements of the entire inner portion of the turbine section of the Allison T-56/501D engine is presented. The flow simulation included the interstage cavities, rim seals and associated main path flows, while the energy equation also included the solid parts of the turbine disc, rotor supports, and stator supports. Solutions of the energy equations in these problems usually face the difficulty in specifications of wall thermal boundary conditions. By solving the entire turbine section this difficulty is thus removed, and realistic thermal conditions are realized on all internal walls. The simulation was performed using SCISEAL, an advanced 2D/3D CFD code for predictions of fluid flows and forces in turbomachinery seals and secondary flow elements. The mass flow rates and gas temperatures at various seal locations were compared with the design data from Allison. Computed gas flow rates and temperatures in the rim and labyrinth seal show a fair 10 good comparison with the design calculations. The conjugate heat transfer analysis indicates temperature gradients in the stationary intercavity walls, as well as the rotating turbine discs. The thermal strains in the stationary wall may lead to altered interstage labyrinth seal clearances and affect the disc cavity flows. The temperature, fields in the turbine discs also may lead to distortions that can alter the rim seal clearances. Such details of the flow and temperature fields are important in designs of the turbine sections to account for possible thermal distortions and their effects on the performance. The simulation shows that the present day CFD codes can provide the means to understand the complex flow field and thereby aid the design process.

scholarly journals NUMERICAL STUDY OF THE EXHAUST GAS FLOW OF TV3-117 TYPE ENGINES IN COMPOSITION WITH A SCREEN - EXHAUST DEVICE

ScienceRise ◽  
2020 ◽  
Vol 4 ◽  
pp. 17-23
Author(s):  
Mykhailo Kinaschuk
Keyword(s):  
Total Pressure ◽  
Gas Flow ◽  
Numerical Study ◽  
Experimental Studies ◽  
Flow Path ◽  
Constructive Method ◽  
Pressure Losses ◽  
Gas Dynamic ◽  
Scientific Results ◽  
Separation Zones

The object of research is a screen-exhaust device in the TV3-117 engine of the Mi-8 helicopter. Investigated problem: The problem of equalizing the flow in the exhaust nozzle is solved. As a result of the numerical study, the total pressure losses are calculated and the flow structures in the structural elements of the exhaust nozzle and the screen-exhaust device (SED) are analyzed. Main scientific results: Obtained Gas-dynamic parameters of the flow in the SED flow path are obtained and the verification of injection processes between the working circuits along the path in the SED design is done. Numerical modeling of gas flows in the SED flow path makes it possible to study in detail the characteristics of the flow at any of its points, as well as to determine the values of hydrodynamic losses associated with the formation of a boundary layer and the emergence of separation zones. A constructive method for leveling the gas-dynamic flow is proposed by installing a blade in the form of an aerodynamic profile in a standard engine exhaust nozzle. Two variants of engine nozzles are investigated under the same boundary conditions using a standard exhaust nozzle with and without a blade. The influence of uneven flow in the exhaust nozzle on the nature of the flow in the SED is shown. An insignificant equalization of the flow in the exhaust nozzle using the installed blade led to a decrease in the total pressure loss in the SED by more than 1 %. The area of practical use of the research results: The results of calculations and modeling can be used for computational and experimental studies aimed at improving the flow path of the exhaust nozzle and the screen-exhaust device by the developers of new military aviation equipment or when modernizing the existing helicopter fleet. Scope of application of the innovative technological product: a new screen-exhaust device has been proposed for left and right TV3-117 engines of all types, which can be installed on the Mi-8MSB-V, Mi-8MT, Mi-14, Mi-24 helicopters. It is competitive and has significantly higher technical and economic indicators compared to known analogues.

scholarly journals Design of high efficiency centrifugal compressors stages

2018 ◽  
Vol 54 (5) ◽  
pp. 4-9
Author(s):  
M. Kalinkevych ◽  
V. Ihnatenko ◽  
O. Bolotnikova ◽  
O. Obukhov
Keyword(s):  
Velocity Distribution ◽  
Dynamic Characteristics ◽  
Gas Flow ◽  
High Efficiency ◽  
Initial Pressure ◽  
Modern Trend ◽  
Centrifugal Compressors ◽  
Gas Dynamic ◽  
High Efficient ◽  
Loss Coefficients

The modern trend in compressor industry is an extension of the use of multi-shaft centrifugal compressors. Multi-shaft compressors have a number of advantages over single-shaft. The design of such compressors gives opportunity to use an axial inlet for all stages and select the optimum rotational speed for each pair of impellers, which, along with the cooling of the gas after each stage, makes possible to achieve high levels of efficiency. The design of high-efficiency centrifugal compressor stages can be performed on the basis of highly effective stage elements. Such elements are: impellers with spatial blades, vaned and channel diffusers with given velocity distribution. In this paper, impellers with axial-radial blades are considered. The blade profile is determined by the specified pressure distribution along the blade. Such design improves the structure of the gas flow in the interblade channels of the impeller, which leads to an increase in its efficiency. Characteristics of loss coefficients from attack angles for impellers were obtained experimentally. Vaned and channel diffusers, the characteristics of which are given in this article, are designed with the given velocity distribution along the vane. Compared to the classic type of diffuser, such diffusers have lower losses and a wider range of economical operation. For diffusers as well as for impellers, characteristics of loss coefficients from attack angles were obtained. High efficient impellers and diffusers and obtained gas-dynamic characteristics were used in the design of a multi-shaft compressor unit for the production of liquefied natural gas. The initial pressure of the unit is 3bar. The obtained characteristics of loss coefficients from attack angles for the considered impellers and diffusers make it possible to calculate the gas-dynamic characteristics of high-efficient centrifugal compressors stages. The high-efficient centrifugal compressors stages can be designed using high-efficient elements, such as: impeller with spatial blades and vaned diffuser with given velocity distribution.

scholarly journals Mathematical and Numerical Study of a Dusty Knudsen Gas Mixture

2019 ◽  
Vol 168 (1) ◽  
pp. 17-31
Author(s):  
Frédérique Charles ◽  
Francesco Salvarani
Keyword(s):  
Numerical Study ◽  
Gas Mixture ◽  
Knudsen Gas

Numerical Study on the Removal of Hydrogen and Nitrogen from the Melt of Medium Carbon Steel in Vacuum Tank Degasser

2013 ◽  
Vol 762 ◽  
pp. 253-260 ◽  
Author(s):  
Shan Yu ◽  
Jyrki Miettinen ◽  
Seppo Louhenkilpi
Keyword(s):  
Carbon Steel ◽  
Liquid Steel ◽  
Gas Flow ◽  
Numerical Study ◽  
Vacuum Treatment ◽  
Medium Carbon Steel ◽  
Transfer Coefficients ◽  
Ansys Fluent ◽  
Medium Carbon ◽  
Cell Expression

The steelmaking field has been seeing an increased demand of reducing hydrogen and nitrogen in liquid steel before casting. This is often accomplished by vacuum treatment. This paper focuses on developing a numerical model to investigate the removal of hydrogen and nitrogen from the melt of medium carbon steel in a commercial vacuum tank degasser. An activity coefficient model and the eddy-cell expression are implemented in the ANSYS FLUENT code to compute the activities of related elements and mass transfer coefficients of hydrogen and nitrogen in liquid steel. Several cases are simulated to assess the effect of gas flow rate and initial nitrogen content in liquid steel on degassing process and the calculated results are compared with industrial measured data.

Numerical Analysis of Flow Fields and Temperature Fields in a Regenerative Heating Furnace for Steel Pipes

2018 ◽  
Vol 10 (3) ◽  
Author(s):  
Yi Han ◽  
Feng Liu ◽  
Xin Ran
Keyword(s):  
Temperature Field ◽  
Flow Field ◽  
Flow Velocity ◽  
Gas Flow ◽  
Flow Fields ◽  
Heating Furnace ◽  
Temperature Fields ◽  
Turbulent Layer ◽  
Steel Pipes ◽  
Pipe Blanks

In the production process of large-diameter seamless steel pipes, the blank heating quality before roll piercing has an important effect on whether subsequently conforming piping is produced. Obtaining accurate pipe blank heating temperature fields is the basis for establishing and optimizing a seamless pipe heating schedule. In this paper, the thermal process in a regenerative heating furnace was studied using fluent software, and the distribution laws of the flow field in the furnace and of the temperature field around the pipe blanks were obtained and verified experimentally. The heating furnace for pipe blanks was analyzed from multiple perspectives, including overall flow field, flow fields at different cross sections, and overall temperature field. It was found that the changeover process of the regenerative heating furnace caused the temperature in the upper part of the furnace to fluctuate. Under the pipe blanks, the gas flow was relatively thin, and the flow velocity was relatively low, facilitating the formation of a viscous turbulent layer and thereby inhibiting heat exchange around the pipe blanks. The mutual interference between the gas flow from burners and the return gas from the furnace tail flue led to different flow velocity directions at different positions, and such interference was relatively evident in the middle part of the furnace. A temperature “layering” phenomenon occurred between the upper and lower parts of the pipe blanks. The study in this paper has some significant usefulness for in-depth exploration of the characteristics of regenerative heating furnaces for steel pipes.

Numerical Study of Methane and Air Combustion Inside Heat-Recirculating Combustors

2013 ◽  
Author(s):  
Yanxia Li ◽  
Zhongliang Liu ◽  
Yan Wang ◽  
Jiaming Liu
Keyword(s):  
Gas Flow ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Central Area ◽  
Small Scale ◽  
Inlet Velocity ◽  
Strong Convection ◽  
Simulation Results ◽  
Lean Fuel ◽  
Set Up

A numerical model on methane/air combustion inside a small Swiss-roll combustor was set up to investigate the flame position of small-scale combustion. The simulation results show that the combustion flame could be maintained in the central area of the combustor only when the speed and equivalence ratio are all within a narrow and specific range. For high inlet velocity, the combustion could be sustained stably even with a very lean fuel and the flame always stayed at the first corner of reactant channel because of the strong convection heat transfer and preheating. For low inlet velocity, small amounts of fuel could combust stably in the central area of the combustor, because heat was appropriately transferred from the gas to the inlet mixture. Whereas, for the low premixed gas flow, only in certain conditions (Φ = 0.8 ～ 1.2 when ν0 = 1.0m/s, Φ = 1.0 when ν0 = 0.5m/s) the small-scale combustion could be maintained.

Numerical Study of Flow and Cooling Characteristics of Impinging Liquid Jets on a Moving Plate

2010 ◽  
Author(s):  
Sangil Son ◽  
Gihun Son ◽  
Ilseouk Park ◽  
Piljong Lee
Keyword(s):  
Level Set ◽  
Numerical Study ◽  
Jet Impingement ◽  
Temperature Fields ◽  
Liquid Jets ◽  
Moving Plate ◽  
Gas Phases ◽  
Steel Making ◽  
Single Jet ◽  
Interfacial Motion

Liquid jet impingement on a moving plate, which is applicable to cooling of hot plates in a steel-making process, is investigated numerically by solving the conservation equations of mass, momentum and energy in the liquid and gas phases. The free-surface or liquid-gas interface is tracked by an improved level-set method incorporating a sharp-interface technique for accurate imposition of stress and heat flux conditions on the liquid-gas interface. The level-set approach is combined with a non-equilibrium k-ε turbulence model. The computations are made for multiple jets as well as a single jet to investigate their flow and cooling characteristics. Also, the effects of moving velocity of plate, jet velocity and nozzle pitch on the interfacial motion and the associated flow and temperature fields are quantified.

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